Patent Publication Number: US-2023148226-A1

Title: Compositions of stable formulations of varenicline salt or base form with control on nitroso impurities

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application claims priority from, and incorporates by reference the entire disclosure of, U.S. Provisional Application 63/273,134 filed on Oct. 28, 2021. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to formulations of varenicline salt or base form that are known to form nitroso impurities and more particularly, but not by way of limitation, to compositions of stable formulations of varenicline salt or base form with control on nitroso impurities. 
     BACKGROUND 
     This section provides background information to facilitate a better understanding of the various aspects of the disclosure. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art. 
     Currently, various pharmaceuticals such as varenicline (7,8,9,10-tetrahydro-6,10-methano-6H-pyrazino(2,3-h)(3)benzazepinex) form nitroso group impurities, including N-nitroso-varenicline (NVC). NVC is classified as probable human carcinogen. NVC is detected in FDA approved drug product that led to recall of various drug products. Currently, the Food and Drug Administration (FDA) indicates an acceptable daily intake limit of 37 ng/day. 
     Previous studies have been conducted on various formulations of varenicline containing compositions. These studies showed zero nitroso group impurities levels at initial time, but eventually failed in stability testing. Tablet formulations of varenicline using various excipients did not prevent formation of nitroso group impurities when exposed to 40° C./75% relative humidity (RH) for 1 week. 
     SUMMARY OF THE INVENTION 
     This summary is provided to introduce a selection of concepts that are further described below in the Detailed Description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it to be used as an aid in limiting the scope of the claimed subject matter. 
     In an embodiment, the present disclosure pertains to a stable formulation of a varenicline salt or base form containing composition that prevents or reduces formation of a nitroso impurity until the end of stated expiration or longer. In some embodiments, the composition includes varenicline and at least one pharmaceutical excipient. In some embodiments, the at least one pharmaceutical excipient includes a magnesium salt and at least one of dicalcium phosphate, polyethylene glycol, or polyethylene oxide. In some embodiments, the magnesium salt can include, without limitation, magnesium aluminum silicate, magnesium aluminometasilicate, magnesium carbonate, magnesium oxide, magnesium silicate, magnesium stearate, magnesium sulfate, magnesium trisilicate, and combinations thereof. In some embodiments, a weight ratio of the varenicline to the at least one pharmaceutical excipient ranges from 1 to 99 to 99 to 1% w/w. In some embodiments, the at least one pharmaceutical excipient is a protective pharmaceutical ingredient. 
     In some embodiments, the composition further includes at least one other drug. In some embodiments, the at least one other drug includes a tertiary or quaternary amine or non-amine groups in its structure. In some embodiments, the at least one other drug can include, without limitation, dapagliflozin, empagliflozin, ertugliflozin, and canagliflozin. 
     In some embodiments, the nitroso impurity can include, without limitation, N-nitroso-varenicline, N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitroso-N-methyl-4-aminobutanoic acid, N-nitrosoisopropylethyl amine, N-nitrosodiisopropylamine, N-nitrosodibutylamine, N-nitroso-irbesartan, 1-methyl-4-nitrosopiperazine as nitroso impurities, other nitroso group containing molecules, and combinations thereof. 
     In some embodiments, the composition is stable against formation of the nitroso impurity when the composition packed in a high-density polyethylene (HDPE) bottle, blister pack, or container is exposed to 25° C./60% relative humidity (RH) for 18 months or longer, or 40° C./75% RH for six months or longer. In some embodiments, the composition reduces formation of the nitroso impurity to an acceptable level. In some embodiments, the acceptable level is at or below 37 ng throughout the shelf-life. In some embodiments, the composition is stable against formation of the nitroso impurity, or reduces formation of the nitroso impurity, when the composition is exposed to 25° C./60% relative humidity (RH) or 40° C./75% RH, or during in-use condition (30° C./75% RH). 
     In some embodiments, the composition has a form including, without limitation, immediate release, extended release, delayed release or enteric release, delayed extended release or enteric extended release, controlled release, a tablet, a capsule, a pill, a granule, a pellet, a solution, a suspension, an emulsion, a semi-solid, and combinations thereof. 
     In some embodiments, the at least one pharmaceutical excipient includes a cyclodextrin compound present in the composition in a range from 1 to 95% w/w. In some embodiments, the cyclodextrin compound can include, without limitation, alpha-cyclodextrin, beta-cyclodextrin, gamma-cyclodextrin, randomly methylated beta-cyclodextrin, hydroxypropyl beta-cyclodextrin, hydroxypropyl gamma-cyclodextrin, sulfobutyl ether beta-cyclodextrin, and combinations thereof. 
     In some embodiments, the at least one pharmaceutical excipient includes a polydimethylsiloxane compound present in the composition in a range from 1 to 95% w/w. In some embodiments, the polydimethylsiloxane compound can include, without limitation, dimethicone, cyclomethicone, silica dimethyl silylate, simethicone, and combinations thereof. 
     In some embodiments, the at least one pharmaceutical excipient includes a polyhydric alcohol including, without limitation, glycerin, propylene glycol, butylene glycol, propylene carbonate, monothioglycerol, polyethylene glycol (molecular weight of less than 1,000), and combinations thereof. In some embodiments, the polyhydric alcohol is present in the composition in a range from 1 to 95% w/w. 
     In some embodiments, the at least one pharmaceutical excipient includes a calcium salt present in the composition in a range from 1 to 95% w/w. In some embodiments, the calcium salt can include, without limitation, calcium carbonate, dicalcium phosphate, tricalcium phosphate, calcium sulfate, calcium citrate, calcium pyrophosphate, calcium silicate, calcium trisilicate, calcium stearate, sodium calcium aluminosilicate, and combinations thereof. In some embodiments, the magnesium salt is present in the composition in a range from 1 to 95% w/w. 
     In some embodiments, the at least one pharmaceutical excipient includes at least one of a sodium, potassium, or aluminum salt present in the composition in a range from 1 to 95% w/w. In some embodiments, the at least one of a of sodium, potassium, and aluminum salt can include, without limitation, sodium silicate, potassium silicate, sodium aluminosilicate, and combinations thereof. 
     In some embodiments, the at least one pharmaceutical excipient can include, without limitation, kaolin, bentonite, and silicon dioxide present in the composition in a range from 1 to 95% w/w. In some embodiments, the at least one pharmaceutical excipient is a long carbon chain acid is saturated or unsaturated with carbon length varied from 4 to 26. In some embodiments, the long carbon chain acid can include, without limitation, lauric acid, myristic acids, palmitic acids, stearic acid, adipic acid, lipoic acid, omega-3 fatty acids, and combinations thereof. 
     In some embodiments, the at least one pharmaceutical excipient includes a long chain carbon alcohol present in the composition in a range from 1 to 95% w/w. In some embodiments, the long chain carbon alcohol can include, without limitation, cetyl alcohol, cetostearyl alcohol, stearyl alcohol, tocopherol, isobutyl alcohol, myristyl alcohol, octyldodecanol, oleyl alcohol, lanolin alcohols, cholesterol, and combinations thereof. 
     In some embodiments, the at least one of dicalcium phosphate, polyethylene glycol, or polyethylene oxide includes at least one of polyethylene glycol or polyethylene oxide with a molecular weight that varies from 1,000 to 10,000,000. In some embodiments, the at least one pharmaceutical excipient includes at least one of cellulose acetate, cellulate butyrate, ethyl cellulose, or cellulose acetate present in the composition in a range from 1 to 95% w/w. 
     In some embodiments, the at least one pharmaceutical excipient includes at least one of polydecene or hydrogenated polydecene present in the composition in a range from 1 to 95% w/w. In some embodiments, the pharmaceutical excipient includes a polymer including, without limitation, acrylic acid (CARBOPOL®), amino methacrylate copolymer, ammonio methacrylate copolymer, ethyl acrylate and methyl methacrylate copolymer, methacrylic acid and ethyl acrylate copolymer, methacrylic acid and methyl methacrylate copolymer, and combinations thereof. In some embodiments, the polymer is present in the composition in a range from 1 to 95% w/w. 
     In some embodiments, the composition includes an antioxidant. In some embodiments, the antioxidant includes, without limitation, butylated hydroxy anisole, butylated hydroxy toluene, sodium/potassium metabisulfites, sodium/potassium sulfite, cysteine, methionine, sodium or calcium ascorbate, fatty acid esters of ascorbic acid, tocopherols, alpha, gamma or delta tocopherol and its esters, 4-hydroxyresorcinol, erythorbic acid, sodium erythorbate, propyl gallate, octyl gallate, tertiary butyl hydroquinone, and combinations thereof. In some embodiments, the antioxidant is present in the composition in a range from 0.001 to 5% w/w. In some embodiments, the composition includes a chelating agent. In some embodiments, the chelating agent includes, without limitation, ethylenediaminetetraacetic acid, edetate sodium, edetate disodium, edetate calcium disodium, edetate tripotassium, edetate dipotassium, and combination thereof. In some embodiments, the chelating agent is present in the composition in a range from 0.001 to 5% w/w. In some embodiments, the magnesium salt includes magnesium stearate. In some embodiments, the at least one of dicalcium phosphate, polyethylene glycol or polyethylene oxide includes polyethylene oxide. 
     In an additional embodiment, the present disclosure pertains to a stable formulation of a varenicline salt or base form containing composition that prevents or reduces formation of a nitroso impurity until the end of stated expiration or longer. In some embodiments, the composition includes varenicline and at least one pharmaceutical excipient. In some embodiments, the at least one pharmaceutical excipient includes magnesium stearate and at least one of dicalcium phosphate, polyethylene glycol, or polyethylene oxide. In some embodiments, a weight ratio of the varenicline to the at least one pharmaceutical excipient ranges from 1 to 99 to 99 to 1% w/w. In some embodiments, the at least one pharmaceutical excipient is a protective pharmaceutical ingredient. 
     In another embodiment, the present disclosure pertains to a method of making a stabilized formulation of a varenicline salt or base form composition that prevents or reduces formation of a nitroso impurity. In general, the method includes adding a pharmaceutical excipient to a varenicline salt or base form. In some embodiments, the pharmaceutical excipient includes a magnesium salt and at least one of dicalcium phosphate, polyethylene glycol, or polyethylene oxide. In some embodiments, the magnesium salt includes, without limitation, magnesium aluminum silicate, magnesium aluminometasilicate, magnesium carbonate, magnesium oxide, magnesium silicate, magnesium stearate, magnesium sulfate, magnesium trisilicate, and combinations thereof. In some embodiments, a weight ratio of the varenicline salt or base form to the pharmaceutical excipient ranges from 1 to 99 to 99 to 1% w/w. In some embodiments, the pharmaceutical excipient is a protective pharmaceutical agent. 
     In some embodiments, the magnesium salt includes magnesium stearate. In some embodiments, the at least one of dicalcium phosphate, polyethylene glycol, or polyethylene oxide includes polyethylene oxide. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the subject matter of the present disclosure may be obtained by reference to the following Detailed Description when taken in conjunction with the accompanying Drawings wherein: 
         FIG.  1    illustrates N-Nitroso-varenicline (NVC). 
     
    
    
     DETAILED DESCRIPTION 
     It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the disclosure. These are, of course, merely examples and are not intended to be limiting. The section headings used herein are for organizational purposes and are not to be construed as limiting the subject matter described. 
     The U.S. Food and Drug Administration (FDA) has identified N-Nitroso-varenicline (NVC), N-nitrosoquinapril, N-nitroso sitagliptin, N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitroso-N-methyl-4-aminobutanoic acid (NMBA), N-nitrosoisopropylethyl amine (NIPEA), N-nitrosodiisopropylamine (NDIPA), Nnitrosodibutylamine (NDBA), N-nitroso-varenicline, N-nitroso-irbesartan, 1-methyl-4-nitrosopiperazine (MNP), 1-cyclopentyl-4-nitrosopiperazine (CPNP) and N-nitrosomethylphenylamine (NMPA) as nitroso impurities. Nitrosamine compounds are potent genotoxic agents in several animal species, and some are classified as probable or possible human carcinogens by the International Agency for Research on Cancer (IARC). A nitrosamine compound is illustrated in  FIG.  1   . These compounds have been referred to as “cohort of concern” compounds in the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidance for industry M7(R1) Assessment and Control of DNA Reactive (Mutagenic) Impurities in Pharmaceuticals to Limit Potential Carcinogenic Risk. The guidance recommends control of any known mutagenic carcinogen, such as, for example, nitroso-compounds, at or below a level such that there would be a negligible human cancer risk associated with the exposure to potentially mutagenic impurities. 
     The FDA has been recalling angiotensin receptor blockers class of drug (losartan, valsartan, etc.), ranitidine, nizatidine, metformin, and varenicline commercial formulations due to presence of nitroso impurities. The FDA has recommended acceptable limits of nitroso impurities. Acceptable daily intake limit is 96 ng/day for NDMA and NMBA, 26.5 ng/day for NDEA, NMPA, NIPEA, and NDIPA, and 37 ng/day for NVC. The scale of recalls for a number of commonly used drug products with NDMA impurities are massive and surprising. 
     A variety of reasons have been assigned to the formation, or possibility of formation, of NDMA. The FDA guidance on nitroso impurities lists a number of sources of secondary, tertiary, or quaternary amines that can form nitrosamines. These can include, for example, vendor-sourced raw materials, recovered solvents, catalysts, and reagents as sources of contamination, quenching processes in certain reaction mixtures, and a lack of process optimization and/or control. 
     Laboratory efforts, as discussed in further detail herein, have shown that varenicline stable dosage forms can be formulated with protective pharmaceutical excipients. The stable formulation prevents or reduces the formation of nitrosamine impurities on exposure to room temperature (25° C./60% relative humidity; RH), in-use (30° C./75% RH), and at accelerated temperature and/or humidity conditions (40° C./75% RH) for the shelf life or estimated shelf life of the product of two years or more. 
     Accordingly, the present disclosure pertains to various pharmaceutical compositions of varenicline salt or base form, which are either stable against the formation of nitroso impurities, or reduce the formation and keep the nitroso impurities level below the FDA recommended level when stored at room temperature (25° C./60% RH), in-use condition (30° C./75% RH), and high temperature and/or humidity conditions (40° C./75% RH). 
     Definitions 
     To facilitate understanding of the present disclosure, several terms are defined herein below. Those left undefined have meanings as commonly understood by a person of ordinary skill in the art relevant to this disclosure. Although various examples are provided with respect to the definitions given below, it will be understood that these examples impose no limitations to the definitions as set forth herein. 
     In some embodiments, the composition is stable against the formation of a nitroso impurity. In some embodiments, the composition reduces formation of the nitroso impurity to an acceptable level. In some embodiments, the acceptable level nitroso impurities are at or below 26.5 to 96 ng/day. In some embodiments, the composition is stable against the formation of the nitroso impurity or reduces formation of the nitroso impurity to acceptable limits when the composition is exposed to 25° C./60% RH or 40° C./75% RH. In some embodiments, the composition has a form that includes, without limitation, immediate release, extended release, delayed release, controlled release, a tablet, a capsule, a pill, a granule, a pellet, a solution, a suspension, an emulsion, a semi-solid, and combinations thereof. In some embodiments, dosage form is called stable, where nitroso impurity is within the acceptable limit throughout its shelf life or during in-use condition (30° C./75% RH). 
     The term “varenicline salt” means a salt of varenicline with an organic acid such as tartaric acid, succinic acid, fumaric acid, lactic acid, malic acid, malonic acid, oxalic acid, citric acid to form tartrate, succinate, fumarate, lactate, malate, malonate, oxalate, citrate salt of the varenicline. 
     The term “varenicline base” means varenicline itself without any chemical association with other chemical species. 
     The terms “immediate release” (IR) mean a release of majority the drug to an aqueous environment over a period of seconds to no more than about 120 minutes. 
     The terms “extended release” or “extended-release” (ER) assume the definition as widely recognized to those of ordinary skill in the art of pharmaceutical sciences. For example, an extended-release dosage form will release the drug slowly over an extended period (e.g., 4, 6, 8, 10, 12, 16, 20, or 24 hours). 
     The terms “delayed release” or “enteric release” are used interchangeably. They refer to pharmaceutical compositions that prevents drug release in acidic pH of stomach but released the drug in lower part of duodenum or small intestine. 
     The terms “delayed extended release” or “enteric extended release” are used interchangeably. They refer to pharmaceutical compositions that prevents drug release in acidic pH of stomach but released the drug in lower part of duodenum or small intestine in extended release manner. 
     The term “pills” are drug-containing tablets or capsules of all sizes and shapes intended for oral administration in humans. 
     The term “pellets” are dosage forms composed of small, solid particles of uniform shape sometimes called “beads”. Typically, pellets are nearly spherical, but this is not required. Pellets may be administered orally (gastrointestinal) or by injection. 
     The term “solution” refers to a homogenous molecular mixture of a pharmaceutical composition where all the composition components are present in molecular form. 
     The term “suspension” refers to non-homogenous particulate dispersion of pharmaceutical composition in a liquid vehicle. At least one of the components is present in particulate form in the composition. 
     The term “emulsion” refers to non-homogenous droplet dispersion of a pharmaceutical composition in liquid components. The liquid components are not miscible when mixed together. 
     The term “semi-solid” refers to a pharmaceutical composition where consistency of the formulation falls in between solid and liquid. Examples of semi-solid dosage forms can include, without limitations, creams, pastes, gels, ointments, lotions, liniments, and the like. 
     The terms “pharmaceutically acceptable excipient”, “excipient”, and “pharmaceutically acceptable carrier” are used interchangeably. They refer to a substance, other than the drugs, with which the drug is formulated. 
     The terms “protective pharmaceutically excipient”, “protective acceptable pharmaceutical excipient”, “protective excipient”, and “protective pharmaceutically acceptable carrier” are used interchangeably. They refer to a substance, other than the drugs, with which the drug is formulated to protect and/or reduce the formation of nitrosamine impurities. Protective pharmaceutical excipients belong to the following categories that can include, without limitation, cyclodextrin, dimethylsulfoxide, polyhydric alcohols, calcium salts, magnesium salts, sodium silicate, potassium silicate, aluminum silicate, long chain carbon acids, sodium, calcium, magnesium and zinc salts of long chain carbon acids, long chain carbon alcohols, esters of long chain carbon acids, long chain hydrocarbons, polymer of ethylene glycol, ester of cellulose, non-ionic surfactants, volatile oils, esters of sucrose derivatives, acrylate polymers, esters of citrate derivatives, polydecene, and polydecene hydrogenated. 
     Protective excipients of cyclodextrin are a family of cyclic oligosaccharide and are composed of five or more α-D-glucopyranoside units linked 1→4. Examples of cyclodextrin include, without limitation, alpha-cyclodextrin, beta-cyclodextrin, gamma-cyclodextrin sulfobutyl ether beta-cyclodextrin, hydroxypropyl beta-cyclodextrin, methylated beta-cyclodextrin, and randomly methylated beta-cyclodextrin. 
     Examples of protective excipients of a dimethylsilane category includes, without limitation, dimethicone, silica dimethyl silylate, simethicone, and cyclomethicone. 
     Protective excipients of polyhydric alcohols contain at least two alcohol group. Examples of polyhydric alcohol include, without limitation, glycerin, propylene glycol, hexylene glycol, xylitol, sorbitol, propylene carbonate, butylene glycol, polyethylene glycol, and monothioglycerol. 
     Protective excipients of calcium salts contain calcium and non-calcium parts. Non-calcium parts can be carbon or non-carbon. Examples of calcium salts include, without limitation, dicalcium phosphate, tricalcium phosphate, calcium carbonate, calcium sulfate, calcium stearate, calcium citrate, calcium pyrophosphate, calcium silicate, sodium calcium aluminosilicate, and tricalcium silicate. 
     Protective excipients of magnesium salts contain magnesium and non-magnesium parts. Non-magnesium parts can be carbon or non-carbon. Examples of magnesium salts include, without limitation, magnesium carbonate, magnesium oxide, magnesium sulfate, magnesium stearate, magnesium silicate, magnesium trisilicate, magnesium aluminum silicate, talc, magnesium aluminometasilicate, and attapulgite. 
     Protective excipients of sodium, potassium, and/or aluminum are silicate minerals. Examples of sodium, potassium, and/or aluminum silicate include, without limitation, sodium silicate, potassium silicate, and sodium aluminosilicate. 
     Protective excipients of long carbon chain acids category contain saturated and unsaturated 4-26 carbons. Examples include, without limitation, stearic acid, lauric acid, myristic acid, palmitic acid, oleic acid, lauric acid, caprylic acid, adipic acid, tocopherol, lipoic acid, omega-3-fatty acids, and sorbic acid. 
     Protective excipients of sodium, potassium, magnesium, zinc, and aluminum salt of long chain carbon acids contain 4-26 carbons, saturated and/or unsaturated. Examples of sodium, potassium, magnesium, zinc, and aluminum salt of long chain carbon acids include, without limitation, sodium stearate, sodium lauryl sulfate, calcium stearate, magnesium stearate, aluminum monostearate, sodium stearyl fumarate, zinc stearate, and sodium cetostearyl sulfate. 
     Protective excipients of long carbon chain alcohols contain 4-26 carbons, saturated and/or unsaturated. Examples of long carbon chain alcohols include, without limitation, cetyl alcohol, cetostearyl alcohol, cholesterol, stearyl alcohol, isobutyl alcohol, myristyl alcohol, octyldodecanol, oleyl alcohol, lanolin alcohols, and inositol. 
     Protective excipients of esters of long carbon chain category contains saturated and/or unsaturated acids. Examples of ester of long carbon chain esters include, without limitation, almond oil, peanut oil, sesame oil, soybean oil, corn oil, cottonseed oil, coconut oil, coconut oil, hydrogenated, palm kernel oil, palm oil, palm oil, hydrogenated, rapeseed oil, fully hydrogenated, rapeseed oil, superglycerinated fully hydrogenated, sunflower oil, cetyl palmitate, canola oil, castor oil, safflower oil, soybean oil, hydrogenated, castor oil, hydrogenated, vegetable oil, hydrogenated, type I, olive oil, diacetylated monoglycerides, ethyl oleate, hard fat, cocoa butter, glyceryl behenate, glyceryl dibehenate, ethylene glycol stearates, glyceryl monooleate, glyceryl monostearate, isopropyl isostearate, isopropyl myristate, isopropyl palmitate, isostearyl isostearate, oleyl oleate, glyceryl distearate, glyceryl mono and dicaprylate, glyceryl mono and dicaprylocaprate, glyceryl monocaprylate, glyceryl monocaprylocaprate, glyceryl monolinoleate, glyceryl tricaprylate, glyceryl tristearate, medium-chain triglycerides, triacetin, and mono- and di-glycerides. 
     Protective excipients of esters of long carbon chain category contain greater than 10-30 carbons saturated and/or unsaturated acids. Examples include, without limitation, paraffin, mineral oil, petrolatum, hydrogenated lanolin, wax, microcrystalline, wax, carnauba, bee wax, and candelilla wax. 
     Protective excipients of polyethylene glycol contain polymers of ethylene glycol having 100-10,000,000 molecular weight. Examples of polymer of ethylene glycol are polyethylene glycol and polyethylene oxide. 
     Protective excipients of cellulose ester category are acetate, ethyl, and butyl esters of cellulose. Examples include, without limitation, cellulose acetate, cellulose acetate butyrate, and ethyl cellulose. 
     Protective excipients of non-ionic surfactants contain polar head groups that are not electrically charged. Examples of non-ionic surfactants include, without limitation, diethylene glycol monoethyl ether, egg phospholipids, propylene glycol monolaurate, propylene glycol dilaurate, polypropylene glycol 11 stearyl ether, lauroyl polyoxylglycerides, linoleoyl polyoxylglycerides, polyglyceryl 3 diisostearate, polyglyceryl dioleate, polyoxyl 10 oleyl ether, polyoxyl 15 hydroxystearate, polyoxyl 20 cetostearyl ether, polyoxyl 35 castor oil, polyoxyl 40 castor oil, hydrogenated, polyoxyl 40 stearate, polyoxyl lauryl ether, polyoxyl stearate, tyloxapol, polyoxyl stearyl ether, polysorbate 20, polysorbate 40, polysorbate 60, polysorbate 80, sorbitan monolaurate, sorbitan monooleate, sorbitan monopalmitate, sorbitan monostearate, sorbitan sesquioleate, sorbitan trioleate, stearoyl polyoxylglycerides, caprylocaproyl polyoxylglycerides, oleoyl polyoxylglycerides, nonoxynol 9, octoxynol 9, vitamin E polyethylene glycol succinate, polyethylene glycol monomethyl ether, and polaxamers. 
     Protective excipients of volatile oils contain either volatile components and/or components that volatize at room temperature. Example of volatile oils include, without limitation, menthol, peppermint, peppermint oil, peppermint spirit, rose oil, thymol, anise oil, and eucalyptus oil. 
     Protective excipients of sucrose derivatives contain esters between sucrose and fatty acids of 4-26 carbons. Examples of sucrose derivatives include, without limitation, sucrose diacetate hexaisobutyrate, sucrose palmitate, and sucrose stearate. 
     Protective excipients of acrylate polymers are copolymer of amino methacrylate, ammonio methacrylate, acrylic acid (CARBOPOL®), ethyl acrylate, methyl methacrylate, methacrylic acid ethylene glycol, and/or vinyl alcohol. Examples of acrylate polymers include, without limitation, amino methacrylate copolymer, ammonio methacrylate copolymer, ethyl acrylate and methyl methacrylate copolymer, ethylene glycol and vinyl alcohol graft copolymer, methacrylic acid and ethyl acrylate copolymer, and methacrylic acid and methyl methacrylate copolymer. 
     Protective excipients of derivatives of citrate are esters of citric acids. Examples of derivatives of citrates include, without limitation, acetyltributyl citrate, acetyltriethyl citrate, tributyl citrate, and triethyl citrate. 
     Antioxidants are substances that act as a reductant and reacts with an oxidant, and therefore, prevent oxidation/autooxidation reaction of degradation. Examples of antioxidants are, without limitation, butylated hydroxy anisole (BHA), butylated hydroxy toluene (BHT), sodium/potassium metabisulfites, sodium/potassium sulfite, cysteine, methionine, sodium or calcium ascorbate, fatty acid esters of ascorbic acid, tocopherols, alpha, gamma or delta tocopherol and its esters, 4-hydroxyresorcinol, erythorbic acid, sodium erythorbate, propylgallate, octyl gallate, ascorbic acid, tertiary butyl hydroquinone, and combinations thereof. 
     Chelating agent are chemical compounds that react with metal ions from participating in oxidation reaction. It forms a stable, water-soluble complex. They are also known as chelants, chelators, or sequestering agents. Examples of chelating agent are, without limitation, ethylenediaminetetraacetic acid, edetate sodium, edetate disodium, edetate calcium disodium, edetate tripotassium, edetate dipotassium, and combination thereof. 
     Categories of non-protective excipients include, for example, diluents, disintegrants, super-disintegrants, lubricants, glidants, binders, hydrophilic polymers, surfactants, coatings, and the like. Examples of non-protective excipients include, without limitation, carrageenan, hydroxypropyl methylcellulose, hydroxypropyl cellulose, sucralose, xylose, chondroitin sulfate sodium, psyllium, acarbose, acetylated distarch adipate, acetylated distarch oxypropanol, acetylated distarch phosphate, acetylated distarch glycerol, pectinic acid, sorbose, carob bean gum, carrageenan, carboxymethyl cellulose, sodium carboxymethyl cellulose, dextran, methyl acrylate, ethyl acrylate, succinyl distarch glycerol, starch sodium succinate, starch sodium octenyl succinate, starch aluminum octenyl succinate, starch acetate, sodium hydroxide gelatinized starch, hydroxypropyl starch, hydroxypropyl distarch phosphate, hydroxypropyl distarch glycerol, distarch phosphate, chitosan, pectin, pectinic acid, distarch oxypropanol, distarch glycerol, gellan gum, tragacanth, povidone, carrageenan, sodium alginate, sodium starch glycolate, xylitol, alginic acid, croscarmellose sodium, guar gum, sorbitol, starch, pregelatinized starch, hydroxypropyl starch, hydrogenated starch hydrolysate, maltose, lactitol, microcrystalline cellulose, cellulose, dextrates, dextrin, dextrose, erythritol, fructose, invert sugar, sucrose diacetate hexaisobutyrat, caramel, hydroxyethyl cellulose, hypromellose acetate succinate, hypromellose phthalate, isomalt, maltitol, ethylcellulose, ethyl acrylate and methyl methacrylate copolymer, cellaburate, cellacefate, cellulose acetate, carboxymethylcellulose calcium, carboxymethylcellulose sodium, galactose, inositol, gelatin, lactose, mannitol, trehalose, pullulan, polydextrose, and tagatose. 
     WORKING EXAMPLES 
     Reference will now be made to more specific embodiments of the present disclosure and data that provides support for such embodiments. However, it should be noted that the disclosure below is for illustrative purposes only and is not intended to limit the scope of the claimed subject matter in any way. 
     NVC impurities can be analyzed by a variety of methods. Any method that is used needs to be validated and one such method is developed and validated as described herein. 
     Liquid chromatography—mass spectrometry (LCMS) method development for NVC. Ultra-pressure liquid chromatography (UPLC) was used to detect NVC in samples. An ACQUITY™ UPLC™ H-Class PLUS System was utilized with the following configuration. The needle was washed with 80:20 methanol:water and the sample temperature was 10° C. The injection volume was 25 μL and a WATERS™ Acquity UPLC BEH Phenyl 1.7 μm 2.1×100 mm column was used having a column temperature of 30° C. Mobile phase A was 0.1% formic acid in water, and mobile phase B was acetonitrile. A 0.5 mL/min flow rate was utilized. Table 1 and Table 2, shown below, illustrate gradient method parameters and LCMS method validation for NVC, respectively. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Gradient elution method. 
               
            
           
           
               
               
               
            
               
                 Time (min) 
                 % A 
                 % B 
               
               
                   
               
            
           
           
               
               
               
            
               
                 0 
                 95 
                 5 
               
               
                 3.5 
                 95 
                 5 
               
               
                 3.51 
                 5 
                 95 
               
               
                 6 
                 5 
                 95 
               
               
                 6.01 
                 95 
                 5 
               
               
                 10 
                 95 
                 5 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 LCMS method validation data for NVC. 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                   
                 Mean/Mean ± 
               
               
                   
                   
                   
                   
                 Standard Deviation 
               
               
                 Parameters 
                 Day 1 
                 Day 2 
                 Day 3 
                 (SD) 
               
               
                   
               
            
           
           
               
            
               
                 Linearity 
               
            
           
           
               
               
               
               
               
            
               
                 Correlation Coefficient 
                 0.995 
                 0.997 
                 0.995 
                 0.996 ± 0.001 
               
               
                 Slope 
                 320287 
                 354696 
                 342954 
                 339312.33 ± 17491.17  
               
               
                 y-Intercept 
                 592308 
                 528407 
                 554295 
                 558336.67 ± 32141.65  
               
               
                 Analytical range 
                   
                   
                 10-100 
               
               
                 (ng/mL) 
               
               
                 Calibrators 
                 8 
                 8 
                 8 
                 8    
               
               
                 Limit of Detection 
                 1.303 
                 1.303 
                 1.303 
                 1.303 
               
               
                 (LOD; ng/mL) 
               
               
                 Limit of Quantitation 
                 3.122 
                 3.122 
                 3.122 
                 3.122 
               
               
                 (LOQ; ng/mL) 
               
            
           
           
               
            
               
                 Accuracy (% Relative Standard Deviation (RSD), n = 5) 
               
            
           
           
               
               
               
               
               
            
               
                  10 ng/mL 
                 105.62 
                 104.30 
                 99.84 
                 103.25 ± 3.03  
               
               
                  30 ng/mL 
                 103.66 
                 104.28 
                 99.82 
                 102.59 ± 4.42  
               
               
                  50 ng/mL 
                 98.98 
                 104.29 
                 101.88 
                 101.72 ± 2.66  
               
               
                 100 ng/mL 
                 101.22 
                 106.54 
                 104.44 
                 104.07 ± 2.68  
               
            
           
           
               
            
               
                 Precision (% RSD, n = 5) 
               
            
           
           
               
               
               
               
               
            
               
                  10 ng/mL 
                 3.28 
                 2.39 
                 3.57 
                 3.08 ± 0.61 
               
               
                  30 ng/mL 
                 2.82 
                 2.46 
                 2.68 
                 2.65 ± 0.18 
               
               
                  50 ng/mL 
                 3.66 
                 3.54 
                 2.38 
                 3.19 ± 0.71 
               
               
                 100 ng/mL 
                 2.66 
                 3.60 
                 4.62 
                 3.63 ± 0.98 
               
               
                   
               
            
           
         
       
     
     Screening excipients for varenicline. Excipients were screened to determine which excipients were promoting nitroso impurities. Varenicline and excipients were physically mixed in 1:1 weight ratio and exposed to 40° C./75% RH for 4 weeks (Table 3 and Table 4). 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 N-Nitroso-varenicline content in individual component. 
               
            
           
           
               
               
               
            
               
                   
                 Component 
                 N-Nitroso-varenicline (ng) 
               
               
                   
                   
               
               
                   
                 Varenicline Tartrate 
                 0 
               
               
                   
                 Croscarmellose Sodium 
                 0 
               
               
                   
                 Lactose Monohydrate 
                 0 
               
               
                   
                 Microcrystalline Cellulose 
                 0 
               
               
                   
                 Magnesium Stearate 
                 0 
               
               
                   
                 Magnesium Aluminum Silicate 
                 0 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Excipients screening for N-Nitroso-varenicline formation. 
               
            
           
           
               
               
            
               
                   
                 N-Nitroso-varenicline (ng/1 mg Varenicline) 
               
            
           
           
               
               
               
               
            
               
                   
                   
                   
                 4-Week 
               
               
                 Drug 
                 Excipient 
                 Initial 
                 (40° C./75% RH) 
               
               
                   
               
               
                 Varenicline 
                 Croscarmellose Sodium 
                 25.9 ± 1.9 
                 40.2 ± 7.9 
               
               
                 Tartrate 
                 Lactose Monohydrate 
                 38.4 ± 4.8 
                 52.6 ± 6.4 
               
               
                   
                 Microcrystalline 
                 38.4 ± 5.1 
                 54.6 ± 9.2 
               
               
                   
                 Cellulose 
                 32.6 ± 3.9 
                 33.9 ± 2.8 
               
               
                   
                 Magnesium Stearate 
                 32.6 ± 2.8 
                 32.8 ± 2.6 
               
               
                   
                 Magnesium Aluminum 
               
               
                   
                 Silicate 
               
               
                   
               
            
           
         
       
     
     Example 1—Control formulation (VF1). A blend of microcrystalline cellulose, croscarmellose sodium, magnesium stearate and varenicline was prepared by mixing (Table 5) followed by compression into 8 mm tablets. NVC content of &gt;150 ng/tablets was found in the compressed tablets (control) before exposure to stability condition. The tablets were exposed to 40° C./75% RH and monitored for NVC impurity. NVC content in the tablet was 185.6 ng/tablet after three months exposure to stability condition, which is five folds of allowed limit (37 ng) (Table 8). 
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Composition of control (unstable) Formulation 
               
               
                 (VF1) of varenicline tartrate tablets. 
               
            
           
           
               
               
               
               
            
               
                   
                 Ingredient 
                 Amount (mg) 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Varenicline Tartrate (mg) 
                 0.85 
                 1.71 
               
               
                   
                 Microcrystalline Cellulose (mg) 
                 149.15 
                 148.29 
               
               
                   
                 Croscarmellose Sodium (mg) 
                 43 
                 43 
               
               
                   
                 Magnesium Stearate (mg) 
                 7 
                 7 
               
               
                   
                 Total (mg) 
                 200 
                 200 
               
               
                   
                   
               
            
           
         
       
     
     Example 2-3. Stable immediate release varenicline tartrate formulations were prepared by direct compression. Briefly, varenicline tartrate was mixed with polyethylene oxide 100,000 molecular weight and magnesium aluminum silicate (VSF1) or dicalcium phosphate (VSF2) followed by lubrication with magnesium stearate and compression (Table 6 and Table 7). Magnesium aluminum silicate and polyethylene oxide were used as a disintegrant, and a dry binder, respectively. The tablets were exposed to 40° C./75% RH in high-density polyethylene (HDPE) bottles, which is consider a very exaggerated condition and monitored for NVC impurity. NVC content in the stable formulation was 16.4±2.6 and 18.2±3.8 after three months exposure to 40° C./75% RH in HDPE bottle which significantly &gt;10 folds less than control formulations. Furthermore, NVC content in both the formulation is significantly less than FDA limit of 37 ng (Table 8). 
     
       
         
           
               
             
               
                 TABLE 6 
               
             
            
               
                   
               
               
                 Composition of stable Formulation-1 (VSF1) 
               
               
                 of varenicline tartrate tablets. 
               
            
           
           
               
               
               
               
            
               
                   
                 Ingredient 
                 Amount (mg) 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Varenicline tartrate (mg) 
                 0.85 
                 1.71 
               
               
                   
                 Polyox (Molecular Weight 100,000) 
                 149.15 
                 148.29 
               
               
                   
                 (Containing 0.005-0.025% Butylated 
               
               
                   
                 Hydroxytoluene) (mg) 
               
               
                   
                 Magnesium Aluminum Silicate (mg) 
                 43 
                 43 
               
               
                   
                 Magnesium Stearate (mg) 
                 7 
                 7 
               
               
                   
                 Total (mg) 
                 200 
                 200 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 7 
               
             
            
               
                   
               
               
                 Composition of stable Formu1ation-2 (VSF2) 
               
               
                 of varenicline tartrate tablets. 
               
            
           
           
               
               
               
               
            
               
                   
                 Ingredient 
                 Amount (mg) 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Varenicline Tartrate (mg) 
                 0.85 
                 1.71 
               
               
                   
                 Dicalcium Phosphate (mg) 
                 149.15 
                 148.29 
               
               
                   
                 Magnesium Aluminum Silicate (mg) 
                 43 
                 43 
               
               
                   
                 Magnesium Stearate (mg) 
                 7 
                 7 
               
               
                   
                 Total (mg) 
                 200 
                 200 
               
               
                   
                   
               
            
           
         
       
     
     Summary of results for selected varenicline tablets formulations. Table 8 and Table 9, shown below, illustrates NVC in ng in various formulations. 
     
       
         
           
               
             
               
                 TABLE 8 
               
             
            
               
                   
               
               
                 Results of N-Nitroso-varenicline in the 
               
               
                 formulations exposed to 40° C./75% RH 
               
            
           
           
               
               
               
            
               
                   
                 N-Nitroso-varenicline (ng/1 mg Varenicline) 
                   
               
            
           
           
               
               
               
               
            
               
                 Formulation 
                 Initial 
                 1 Month 
                 3 Months 
               
               
                   
               
               
                 VF1 (Control) 
                 150 ± 11.5 
                 162.4 ± 13.8 
                 185.6 ± 16.3 
               
               
                 VSF1 (Stable) 
                 0 
                 0 
                 16.4 ± 2.6 
               
               
                 VSF2 (Stable) 
                 0 
                 0 
                 18.2 ± 3.8 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 9 
               
             
            
               
                   
               
               
                 Results of N-Nitroso-varenicline in the 
               
               
                 formulations exposed to 25° C./60% RH 
               
            
           
           
               
               
               
            
               
                   
                 N-Nitroso-varenicline (ng/1 mg Varenicline) 
                   
               
            
           
           
               
               
               
               
            
               
                 Formulation 
                 Initial 
                 1 Month 
                 3 Months 
               
               
                   
               
               
                 VF1 (Control) 
                 150 ± 11.5 
                 158.4 ± 14.6 
                 166.8 ± 12.9 
               
               
                 VSF1 (Stable) 
                 0 
                 0 
                 13.2 ± 1.8 
               
               
                 VSF2 (Stable) 
                 0 
                 0 
                 16.1 ± 2.4 
               
               
                   
               
            
           
         
       
     
     These new formulations have shown to prevent NVC formation. This is advantageous as NVC is a known carcinogen, causing varenicline formulations to be recalled. With the concern that varenicline can form NVC if stored for a long period of time in heat and humidity, it is advantageous to manufacture varenicline such that it is able to prevent NVC formation. The compositions above do not form NVC or level is below FDA limit, even if the drug is stored at 40° C. and 75% RH. Currently, the FDA allows up to 37 ng/day of NVC in varenicline formulation. If the amount is greater than that, the products are recalled from markets as they are considered harmful. The above formulations meet, or fall below, the 37 ng/day requirement imposed by the FDA. 
     These new formulations have shown to prevent NVC formation. This is advantageous as NVC is a known carcinogen, causing varenicline formulations to be recalled. With the concern that VRN can form NVC if stored for a long period of time in heat and humidity, it is advantageous to manufacture varenicline such that it is able to prevent NVC formation. The compositions above do not form NVC or level is below FDA limit, even if the drug is stored at 40° C. and 75% RH. Currently, the FDA allows up to 37 ng/day of NVC in varenicline formulation. If the amount is greater than that, the products are recalled from markets as they are considered harmful. The above formulations meet, or fall below, the 37 ng/day requirement imposed by the FDA. 
     In view of the aforementioned, the present disclosure generally relates to pharmaceutical compositions and manufacturing, and in particular, but not by way of limitation on new pharmaceutical compositions of varenicline salt or base form with improved stability. The present disclosure utilizes the new pharmaceutical compositions for the formulation, preparation, or manufacturing of immediate release, extended release or controlled release tablets, delayed release or enteric release, delayed extended release or enteric extended release, capsules, pills, granules, pellets, solutions, suspensions, emulsions, and semi-solid formulations. These pharmaceutical compositions are stable and reduce the formation of nitroso impurities in the pharmaceutical compositions. In some embodiments, the excipients of the present disclosure can be added to existing commercial compositions to form drugs with improved stability. 
     In a particular aspect, the present disclosure pertains to a stable pharmaceutical composition of varenicline salt or base form. In general, the compositions include, without limitation: (a) varenicline salt or base form (s); (b) a protective pharmaceutical excipient(s); and optionally (c) a pharmaceutically acceptable processing aid(s), such as, for example, a flow promotor, a solvent, a bulking agent, and the like. In some embodiments, the compositions of the present disclosure: (i) contain at varenicline salt or base form and at least one protective pharmaceutical excipient; and (ii) has a mass ratio of drug to protective pharmaceutical excipient(s) ranging from 0.1 to 99 to 99 to 1% w/w. 
     In a particular aspect, the present disclosure pertains to a stable pharmaceutical composition of varenicline salt or base form. In general, the compositions include, without limitation: (a) varenicline salt or base form (s); (b) a protective/non-protective pharmaceutical excipient(s); (c) an antioxidant(s) and optionally (c) a pharmaceutically acceptable processing aid(s), such as, for example, a flow promotor, a solvent, a bulking agent, and the like. In some embodiments, the compositions of the present disclosure: (i) contain varenicline salt or base form and at least an antioxidant; and (ii) has a mass ratio of an antioxidant(s) ranging from 0.001 to 5% w/w. 
     In a particular aspect, the present disclosure pertains to a stable pharmaceutical composition of varenicline salt or base form. In general, the compositions include, without limitation: (a) varenicline salt or base form (s); (b) a protective/non-protective pharmaceutical excipient(s); (c) a chelating agent(s) and optionally (c) a pharmaceutically acceptable processing aid(s), such as, for example, a flow promotor, a solvent, a bulking agent, and the like. In some embodiments, the compositions of the present disclosure: (i) contain varenicline salt or base form and a chelating agent; and (ii) has a mass ratio of a chelating agent(s) ranging from 0.001 to 5% w/w. 
     In a particular aspect, the present disclosure pertains to a stable pharmaceutical composition of varenicline salt or base form. In general, the compositions include, without limitation: (a) varenicline salt or base form (s); (b) a protective/non-protective pharmaceutical excipient(s); (c) an antioxidant(s); (c) a chelating agent(s) and optionally (d) a pharmaceutically acceptable processing aid(s), such as, for example, a flow promotor, a solvent, a bulking agent, and the like. In some embodiments, the compositions of the present disclosure: (i) contain varenicline salt or base form and at least an antioxidant and a chelating agent; and (ii) has a mass ratio of an antioxidant(s) and a chelating agent(s) ranging from 0.001 to 5% w/w. 
     In another aspect, the present disclosure provides a stable formulation of an immediate release, extended release or controlled release tablet, delayed release or enteric release, delayed extended release or enteric extended release, capsule, pills, granules, pellets, solution, suspension, emulsion, and/or semi-solid dosage forms. Additionally, the present disclosure provides a stable formulation to protect or reduce the formation of nitroso impurities when exposed to room temperature, in-use and accelerated temperatures and humidity conditions. 
     In another embodiment, the present disclosure pertains to a stable formulation of varenicline salt or base form composition that prevents or reduces formation of a nitroso impurity. In some embodiments, the composition includes varenicline salt or base form and a protective pharmaceutical excipient(s). In some embodiments, a weight ratio of the drug to the protective pharmaceutical excipient(s) ranges from 1 to 99 to 99 to 1% w/w. 
     In some embodiments, the composition is stable against the formation of a nitroso impurity. In some embodiments, the composition reduces formation of the nitroso impurity to an acceptable level. In some embodiments, the acceptable level nitroso impurities is at or below 26.5 to 37 ng/day. In some embodiments, the composition is stable against the formation of the nitroso impurity or reduces formation of the nitroso impurity when the composition is exposed to 25° C./75% RH or 40° C./75% RH. In some embodiments, the composition has a form that includes, without limitation, immediate release, delayed release or enteric release, delayed extended release or enteric extended release, controlled release, a tablet, a capsule, a pill, a granule, a pellet, a solution, a suspension, an emulsion, a semi-solid, and combinations thereof. 
     In some embodiments, the protective pharmaceutical excipient includes a cyclodextrin compound. In some embodiments, the cyclodextrin compound is present in the composition in a range from 1 to 95% w/w. In some embodiments, the cyclodextrin compound includes, without limitation, alpha-cyclodextrin, beta-cyclodextrin, gamma-cyclodextrin, randomly methylated beta-cyclodextrin, hydropropyl beta-cyclodextrin, hydropropyl gamma-cyclodextrin, sulfobutyl ether beta-cyclodextrin, and combinations thereof. 
     In some embodiments, the protective pharmaceutical excipient includes a polydimethylsiloxane compound. In some embodiments, the polydimethylsiloxane compound is present in the composition in a ranged from 1 to 95% w/w. In some embodiments, the polydimethylsiloxane compound includes, without limitation, dimethicone, cyclomethicone, silica dimethyl silylate, simethicone, and combinations thereof. 
     In some embodiments, the protective pharmaceutical excipient includes a polyhydric alcohol. In some embodiments, the polyhydric alcohol is present in the composition in a range from 1 to 95% w/w. In some embodiments, the polyhydric alcohol includes, without limitation, glycerin, propylene glycol, butylene glycol, propylene carbonate, monothioglycerol, polyethylene glycol (molecular weight of less than 1,000), and combinations thereof. 
     In some embodiments, the protective pharmaceutical excipient includes a calcium salt. In some embodiments, the calcium salt is present in the composition in a range from 1 to 95% w/w. In some embodiments, the calcium salt includes, without limitation, calcium carbonate, dicalcium phosphate, tricalcium phosphate, calcium sulfate, calcium citrate, calcium pyrophosphate, calcium silicate, calcium trisilicate, calcium stearate, sodium calcium aluminosilicate, and combinations thereof. 
     In some embodiments, the protective pharmaceutical excipient includes a magnesium salt. In some embodiments, the magnesium salt is present in the composition in a range from 1 to 95% w/w. In some embodiments, the magnesium salt includes, without limitation, magnesium aluminum silicate, magnesium aluminometasilicate, magnesium carbonate, magnesium oxide, magnesium silicate, magnesium stearate, magnesium sulfate, magnesium trisilicate, and combinations thereof. 
     In some embodiments, the protective pharmaceutical excipient includes at least one of a sodium, potassium, or aluminum salt. In some embodiments, the at least one of a sodium, potassium, or aluminum salt is present in the composition in a range from 1 to 95% w/w. In some embodiments, the at least one of a of sodium, potassium, and aluminum salt includes, without limitation, sodium silicate, potassium silicate, sodium aluminosilicate, and combinations thereof. 
     In some embodiments, the protective pharmaceutical excipient includes, without limitation, kaolin, bentonite, and silicon dioxide. In some embodiments, the protective pharmaceutical excipient includes, without limitation, kaolin, bentonite, and silicon dioxide and is present in the composition in a range from 1 to 95% w/w. 
     In some embodiments, the protective pharmaceutical excipient is a long carbon chain acid. In some embodiments, the long carbon chain acid is saturated or unsaturated with carbon length varied from 4 to 26. In some embodiments, the long carbon chain acid is present in the composition in a range from 1 to 95% w/w. In some embodiments, the long carbon chain acid includes, without limitation, lauric acid, myristic acids, palmitic acids, stearic acid, adipic acid, lipoic acid, omega-3 fatty acids, and combinations thereof. 
     In some embodiments, the protective pharmaceutical excipient includes at least one of a sodium, magnesium, zinc, or aluminum salt of a long carbon chain acid. In some embodiments, at least one of a sodium, magnesium, zinc, or aluminum salt of the long carbon chain acid is saturated or unsaturated, and wherein carbon length varies from 4 to 26. In some embodiments, the at least one of a sodium, magnesium, zinc, or aluminum salt of the long carbon chain acid is present in the composition in a range from 1 to 95% w/w. In some embodiments, the at least one of a sodium, magnesium, zinc, or aluminum salt of the long carbon chain acid includes, without limitation, magnesium stearate, zinc stearate, aluminum stearate, sodium lauryl sulfate, and combinations thereof. 
     In some embodiments, protective pharmaceutical excipient includes a long chain carbon alcohol. In some embodiments, the long chain carbon alcohol is present in the composition in a range from 1 to 95% w/w. In some embodiments, the long chain carbon alcohol is saturated or unsaturated, and wherein carbon length varies from 4 to 26. In some embodiments, the long chain carbon alcohol includes, without limitation, cetyl alcohol, cetostearyl alcohol, stearyl alcohol, tocopherol, isobutyl alcohol, myristyl alcohol, octyldodecanol, oleyl alcohol, lanolin alcohols, cholesterol, and combinations thereof. 
     In some embodiments, the protective pharmaceutical excipient includes a mono, di, and/or trigylceryl ester of a long chain carbon acid. In some embodiments, the mono, di, and/or trigylceryl ester of long chain of the carbon acid is present in the composition in a range from 1 to 95% w/w. In some embodiments, the mono, di, and/or trigylceryl ester is saturated or unsaturated. In some embodiments, the mono, di, and/or trigylceryl ester of the long chain carbon acid includes, without limitation, glyceryl behenate, glyceryl dibehenate, palm kernel oil, palm oil, hydrogenated palm oil, rapeseed oil, rapeseed oil hydrogenated, sunflower, coconut oil, castor oil, canola oil, and combinations thereof. 
     In some embodiments, the protective pharmaceutical excipient includes a long chain hydrocarbon. In some embodiments, the long chain hydrocarbon is present in the composition in a range from 1 to 95% w/w. In some embodiments, the long chain hydrocarbon is saturated or unsaturated. In some embodiments, the long chain hydrocarbon is obtained from an animal or plant source. In some embodiments, the long chain hydrocarbon includes, without limitation, paraffin, carnauba wax, microcrystalline wax, candelilla wax, mineral oil, and combinations thereof. 
     In some embodiments, the protective pharmaceutical excipient includes at least one of polyethylene glycol or polyethylene oxide. In some embodiments, the at least one of polyethylene glycol or polyethylene oxide is present in the composition in a range from 1 to 95% w/w. In some embodiments, the at least one of polyethylene glycol or polyethylene oxide has a molecular weight that varies from 100 to 10,000,000. 
     In some embodiments, the protective pharmaceutical excipient includes at least one of cellulose acetate, cellulate butyrate, ethyl cellulose, or cellulose acetate. In some embodiments, the at least one of cellulose acetate, cellulate butyrate, ethyl cellulose, or cellulose acetate is present in the composition in a range from 1 to 95% w/w. 
     In some embodiments, the protective pharmaceutical excipient includes a non-ionic surfactant. In some embodiments, the non-ionic surfactant is present in the composition in a range from 1 to 95% w/w. In some embodiments, the non-ionic surfactant includes, without limitation, polysorbate, sorbitan, polyglyceryl dioleate, polyoxyl 10 oleyl ether, poloxamer, and combinations thereof. 
     In some embodiments, the protective pharmaceutical excipient includes at least one of polydecene or hydrogenated polydecene. In some embodiments, the at least one of polydecene or hydrogenated polydecene is present in the composition in a ranged from 1 to 95% w/w. 
     In some embodiments, the protective pharmaceutical excipient includes dimethyl sulfoxide. In some embodiments, the dimethyl sulfoxide is present in the composition in a range from 1 to 95% w/w. 
     In some embodiments, the protective pharmaceutical excipient includes a volatile oil. In some embodiments, the volatile oil is present in the composition in a range from 1 to 95% w/w. In some embodiments, the volatile oil includes, without limitation, menthol, peppermint, peppermint oil, peppermint spirit, rose oil, thymol, anise oil, eucalyptus oil, and combinations thereof. 
     In some embodiments, the protective pharmaceutical excipient includes a polymer that includes, without limitation, acrylic acid (CARBOPOL®), amino methacrylate copolymer, ammonio methacrylate copolymer, ethyl acrylate and methyl methacrylate copolymer, methacrylic acid and ethyl acrylate copolymer, methacrylic acid and methyl methacrylate copolymer, and combinations thereof. In some embodiments, the polymer is present in the composition in a range from 1 to 95% w/w. 
     In some embodiments, the protective pharmaceutical excipient includes at least one of sucrose diacetate hexaisobutyrate, sucrose palmitate, or sucrose stearate. In some embodiments, the at least one of sucrose diacetate hexaisobutyrate, sucrose palmitate, or sucrose stearate is present in the composition in a range from 1 to 95% w/w. 
     In some embodiments, the protective pharmaceutical excipient includes at least one of acetyltributyl citrate, acetyltriethyl citrate, tributyl citrate, or triethyl citrate. In some embodiments, the at least one of acetyltributyl citrate, acetyltriethyl citrate, tributyl citrate, or triethyl citrate is present in the composition in a range from 1 to 95% w/w. 
     In some embodiments, the protectant includes an antioxidant including, without limitation, butylated hydroxy anisole (BHA), butylated hydroxy toluene (BHT), sodium/potassium metabisulfites, sodium/potassium sulfite, cysteine, methionine, sodium or calcium ascorbate, ascorbic acid, fatty acid esters of ascorbic acid, tocopherols, alpha, gamma or delta tocopherol and its esters, 4-hydroxyresorcinol, erythorbic acid, sodium erythorbate, propylgallate, octyl gallate, tertiary butyl hydroquinone, and combinations thereof. In some embodiments, the antioxidant is present in the composition in a range from 0.001 to 5%. 
     In some embodiments, the protectant includes a chelating agent including, without limitation, ethylenediaminetetraacetic acid, edetate sodium, edetate disodium, edetate calcium disodium, edetate tripotassium, edetate dipotassium, and combination thereof. In some embodiments, the antioxidant is present in the composition in a range from 0.001 to 5%. 
     In an additional embodiment, the present disclosure pertains to a method of making a stabilized formulation of varenicline salt or base form composition that prevents or reduces formation of a nitroso impurity. In some embodiments, the method includes adding a pharmaceutical excipient(s) to varenicline salt or base form. In some embodiments, a weight ratio of the drug(s) to the protective pharmaceutical excipient(s) ranges from 1 to 99 to 99 to 1% w/w. In some embodiments, the pharmaceutical excipient(s) is a protective pharmaceutical excipient. 
     In a further embodiment, the present disclosure pertains to a method of making a stable formulation of varenicline salt or base form composition that prevents or reduces formation of a nitroso impurity. In some embodiments, the method includes adding a pharmaceutical excipient(s) to varenicline salt or base form and adding an antioxidant(s) to the drug(s). In some embodiments, a weight ratio of the pharmaceutical excipient ranges from 0.01 to 99 to 99 to 1% w/w. In some embodiments, a weight ratio of the antioxidant(s) ranges from 0.001 to 5% w/w. In some embodiments, the pharmaceutical excipient(s) is at least one of a protective or non-protective pharmaceutical excipient. 
     In a further embodiment, the present disclosure pertains to a method of making a stable formulation of varenicline salt or base form composition that prevents or reduces formation of a nitroso impurity. In some embodiments, the method includes adding a pharmaceutical excipient(s) to varenicline salt or base form and adding a chelating agent(s) to the drug(s). In some embodiments, a weight ratio of the pharmaceutical excipient(s) ranges from 0.01 to 99 to 99 to 1% w/w. In some embodiments, a weight ratio of the chelating agent(s) ranges from 0.001 to 5% w/w. In some embodiments, the pharmaceutical excipient(s) is at least one of a protective or non-protective pharmaceutical excipient. 
     In a further embodiment, the present disclosure pertains to a method of making a stable formulation of varenicline salt or base form composition that prevents or reduces formation of a nitroso impurity. In some embodiments, the method includes adding a pharmaceutical excipient(s) to varenicline salt or base form and adding an antioxidant(s) and chelating agent(s) to the drug(s). In some embodiments, a weight ratio of the pharmaceutical excipient(s) ranges from 0.01 to 99 to 99 to 1% w/w. In some embodiments, a weight ratio of the antioxidant(s) and chelating agent(s) ranges from 0.001 to 5% w/w. In some embodiments, the pharmaceutical excipient(s) is at least one of a protective or non-protective pharmaceutical excipient. 
     Although various embodiments of the present disclosure have been illustrated in the accompanying Drawings and described in the foregoing Detailed Description, it will be understood that the present disclosure is not limited to the embodiments disclosed herein, but is capable of numerous rearrangements, modifications, and substitutions without departing from the spirit of the disclosure as set forth herein. 
     The term “substantially” is defined as largely but not necessarily wholly what is specified, as understood by a person of ordinary skill in the art. In any disclosed embodiment, the terms “substantially”, “approximately”, “generally”, and “about” may be substituted with “within [a percentage] of” what is specified, where the percentage includes 0.1, 1, 5, and 10 percent. 
     The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the disclosure. Those skilled in the art should appreciate that they may readily use the disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the disclosure. The scope of the invention should be determined only by the language of the claims that follow. The term “comprising” within the claims is intended to mean “including at least” such that the recited listing of elements in a claim are an open group. The terms “a”, “an”, and other singular terms are intended to include the plural forms thereof unless specifically excluded.