Abstract:
A pharmaceutical composition comprising at least one active ingredient, a carrier substance and a preservative dissolved in the carrier substance, the preservative comprising sodium silver chloride compound, is disclosed.

Description:
This application is a continuation of application Ser. No. 07/763,341, filed Sep. 20, 1991, now abandoned entitled: PRESERVATION FOR PHARMACEUTICAL PRODUCTS. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention refers to a preservative for pharmaceutical products, especially for ophthalmic pharmaceuticals, nasal spray, ear drops and corresponding veterinary products. 
     Pharmaceutical products in the form of solutions, suspensions or ointments which are applied directly from a container may get in contact with the body fluids of the user or microorganisms of the environment. Therefore, there is a danger of contamination of the product in the container by bacteria contained in the body fluid. On the other hand the use of preservatives in pharmaceuticals is limited in that any interference with the pharmaceutically active ingredients and any noxious effect to the user is to be avoided. 
     2. Description of the Prior Art 
     Especially for preserving ophthalmic pharmaceuticals it has been well documented in the literature that benzalkonium chloride, chlorobutanol, thimerosal, methyl and propyl parabens have many drawbacks and disadvantages. The most common complaints included burning, stinging, and irritation upon instillation. Also, there is a 5% to 15% incidence of allergic reactions to these preservatives. Thimerosal has been shown to exhibit an allergic response as high as 20% in some studies. Thimerosal is a mercurial derivative, therefore, has raised concerns for long-term usage as well. As a result of allergic reactions to thimerosal, almost all ophthalmic products that contained thimerosal have had formulation changes to one of the other available preservatives. 
     Another characteristic of these preservatives is that they have been shown to cause a disruption of the cornea epithelium upon instillation. Documentation via SEM (scanning electron microscopy) has demonstrated these epithelial changes in the literature. 
     Obviously, a lot of other preservative substances are known for several purposes and applications. Among them a sodium silver chloride compound has been used for sterilizing water, especially drinking water, and other aqueous solutions as e.g. homeopathic solutions. 
     SUMMARY OF THE INVENTION 
     Hence, it is an object of the invention to provide a preservative for use in a wide range of pharmaceutical substances and compositions, i.e. substances containing pharmaceutically active ingredients as e.g. antibiotics, anti-inflammatories or anti-infectives etc. and which in use may be contaminated by body fluids of the user or microorganisms of the environment. 
     It is a further object of the invention to provide a preservative for use in pharmaceuticals which preservative is chemically inert towards the major pharmaceutically active ingredients and has a high bacteriocidal and bacteriostatic effect against possible contaminations in pharmaceuticals. 
     Still another object of the invention is to provide a preservative for use in pharmaceuticals which is harmless for the user of the pharmaceuticals and does not interfere with the medical treatment. 
     These objects are achieved by using a sodium silver chloride compound as a preservative in pharmaceutical products. Though, as already mentioned the sterilizing effect of this substance in water was known as such, it surprisingly has been found that this substance is especially advantageous as a preservative in pharmaceuticals, especially ophthalmic drugs, nasal sprays, ear drops and corresponding veterinary products and therefore is suited to replace the prior used substances thereby avoiding the above mentioned problems, especially allergic reactions to the known preservatives in pharmaceuticals. 
     It is sufficient to add an amount of 0.0005 to 0.1 weight % of sodium silver chloride compound to the pharmaceutical composition to be preserved in order to keep it sterile for the time of use. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. 
     The following examples of pharmaceuticals in which a sodium silver chloride compound salt is used as a preservative mainly refer to ophthalmic pharmaceuticals in the form of solutions, suspensions and ointments. The drugs and drug categories as such are known to the man skilled in the art and the invention is not limited to these drug categories. Sodium silver chloride compounds used in the invention are known as such. 
     Preferably this sodium silver chloride compound contains Ag +  -ions replacing part (in the range of 1%) of the Na +  -ions in the NaCl basis, so that there is an excess of NaCl which allows on one hand more accurate dosing and on the other hand provides the necessary amount of effective reagent. 
     It has been found in sterility tests that the sodium silver chloride compound in concentrations of 1 to 2 mg/100 ml is effective against the following micro-organismus: 
     Escherichia coli ATCC 8739 
     Pseudomas aeruginosa ATCC 9027 
     Staphylococcus aureus ATCC 6538 
     Candida albicans ATCC 10231 
     Aspergillus niger ATCC 16404 
     The test arrangements were in accordance with USP XXI. 
    
    
     EXAMPLE 1 
     Antibiotics 
     An ophthalmic antibiotic in the form of a solution or a suspension contains 0.001 weight % of sodium silver chloride complex as preservative. The active agent may be a single ingredient (gentamicin, tobramycin, ofloxacin), a combination of ingredients (neomycin/polymyxin, gramicidin), a single ingredient with steroids (gentamicin, prednisolone acetate) or combinations with steroids (neomycin, polymyxin/dexamethasone). In the case of eye drops containing tobramycin as a single active ingredient the composition comprises: 0.3 weight % tobramycin (active ingredient ); 0.001 weight % sodium silver chloride compound (preservative); excip. ad collyrium tamponat. The indications are bacterial infections of the eye. 
     EXAMPLE 2 
     Anti-Allergy 
     An ophthalmic anti-allergic-composition in the form of a solution or suspension comprises as active agents 0.5 weight % of antazolin. sulfuric. and 0.025 weight % of naphazoline. nitric. As preservative 0.001 weight % of sodium silver chloride compound is provided. Indications are allergic affections of the conjunctiva. 
     EXAMPLE 3 
     Anti-glaucoma 
     An anti-glaucoma preparation in liquid form comprises: pilocarpine hydrochloride (5 mg ) as active agent: hydroxypropylmethylcellulose; sodium silver chlorid compound (0.01 mg) as preservative; excip. ad collyr. ad 1 ml. Other anti-glaucoma ophthalmic products include epinephrine, dipivefrin, carbachol. Other major categories include: Prostaglandins, topical carbonic Anhydrase Inhibitors, BetaBlockers, ACE and Renin Inhibitors, Calcium Channel Blockers, Forskolln and Analogues. These products are used topically for lowering intraocular pressure and will benefit from use of sodium silver chloride compound as a preservative. 
     EXAMPLE 4 
     Anti-Herpetic/Anti-Viral Agents 
     Idoxurin is an active agent for use in eye drops (0.1%) or ointments (0.25%) and is effective as an antiherpetic composition. The composition further comprises 0.001 weight % of sodium silver chloride compound as a preservative. 
     EXAMPLE 5 
     Anti-Infectives 
     As ophthalmic anti-infective sodium sulfacetamide is known as single ingredient in eye drops (10%). The solution is preserved by sodium silver chloride compound (0.001%). Other anti-infective eye drops may comprise combinations of ingredients or a single ingredient with steroids. An example for the last mentioned type is sodium sulfacetamide (10%)/prednisolone (0.25%) which also can be preserved by 0.001 weight % of sodium silver chloride compound. 
     EXAMPLE 6 
     Anti-inflammatories 
     Dexa-methasone is a known anti-inflammatory agent. A pharmaceutical composition in the form of eye drops contains dexamethasone (0.1% ), hydroxypropylmethylcellulose (0.5%), sodium silver chloride compound as preservative (0.001%) and excip. ad collyrium tamponat. 
     EXAMPLE 7 
     Artificial Tears/Ocular Lubricants 
     As can be seen from the above examples, several pharmaceutical compositions comprise hydroxypropyl-methylcellulose. This is a substance with abirritant effect to the eyes. The preservative of the invention can be used with this substance in artificial tear compositions comprising e.g. hydroxypropyl-methylcellulose (1%); sodium silver chloride compound (0.001%); excip. ad collyrium tamponat. 
     EXAMPLE 8 
     Contact Lens Solutions 
     Contact lens solutions are isotonic solutions used for cleaning and desinfecting contact lenses and for soaking and wetting the same. In these isotonic solutions the preservative of the invention can be contained as a bacteriostatic agent in a concentration of 0.001 to 0.002 weight %. 
     EXAMPLE 9 
     Decongestants 
     Phenylephrine HCl (0.1%-10%) is an example for a known decongestant ophthalmic agent. A decongestant composition in the form of eye drops contains tetrahydrazoline or phenylephrine HCl (0.12%), hydroxypropyl-methylcellulose (0.5% ), sodium silver chloride complex (0.001% ) as preservative and excip. ad collyrium tamponat. 
     EXAMPLE 10 
     Diagnostic Agents 
     Diagnostic ophthalmic agents are used for a diagnostic dilatation of the pupil of the eye, which e.g. can be effected by tropicamide (0.5%) in the form of eye drops. As a preservative sodium silver chloride compound (0.001%) is added. 
     EXAMPLE 11 
     Hypertonic Solutions 
     Hypertonic saline ointments and solutions with NaCl concentrations of 2 to 5% are used e.g. for the treatment of edema of the cornea. Since sodium silver chloride compound is NaCl based it is especially suited as a preservative for such compositions at a concentration of 0.001% to 0.002%. 
     EXAMPLE 12 
     Irrigation Solutions 
     Ophthalmic irrigation solutions are sterile balanced salt solutions for the external irrigation of the eye. The sterility is maintained by sodium silver chloride complex. A irrigation solution e.g. contains: sodium chloride (0.64% ), potassium chloride (0.075% ), calcium chloride (0.048% ), magnesium chloride (0.03% ), sodium acetate (0.39%), sodium citrate (0.17%), sodium silver chloride compound (0.001% ) and purified water. 
     EXAMPLE 13 
     Topical Anesthetics 
     Topical anesthetics are used for surface anesthesia in ophthalmology. As the active ingredient proparacaine (proxymetacaine-hydrochloride) is used in a concentration of 0.5% in combination with sodium silver chloride compound (0.001%) as preservative in excip. ad collyrium tamponat. 
     As already mentioned above sodium silver chloride compound can be used also as preservative in nasal spray or ear drops, which during their application may be contaminated in the container by body fluids of the user. 
     The preceding examples illustrate the wide range of application of sodium silver chloride compound for the preservation of pharmaceutical products which makes it suited to generally replace a lot of known preservatives for drugs especially for ophthalmic drugs. 
     While there are described present preferred embodiments of the invention, it is to be understood that the invention is not limited thereto, but may be otherwise variously embodied and practiced within the scope of the following claims.