Patent Publication Number: US-2003235617-A1

Title: Pharmaceutical dosage form for mucosal delivery

Description:
[0001] This application claims priority of U.S. provisional application Serial No. 60/355,703 filed on Feb. 7, 2002. 
    
    
     
       FIELD OF THE INVENTION  
       [0002] The present invention relates to pharmaceutical compositions suitable for intraoral administration to provide delivery of a drug via the oral mucosa.  
       BACKGROUND OF THE INVENTION  
       [0003] Pharmaceutical dosage forms suitable for placement in the mouth of a subject, for example in the sublingual or buccal spaces of the mouth, to permit absorption of a drug into the subject&#39;s bloodstream via the oral mucosa, are well known. See for example Rathbone, ed. (1996)  Oral Mucosal Drug Delivery,  Marcel Dekker; in particular the articles therein by Kellaway &amp; Warren, “Mucoadhesive hydrogels for buccal delivery,” pp. 221-239, and by Rathbone et al., “Systemic oral mucosal drug delivery and delivery systems,” pp. 241-284.  
       [0004] It is often desired that such intraoral dosage forms, particularly those intended for sublingual administration, release the drug rapidly to provide onset of therapeutic benefit as soon as possible after administration. For this reason dosage forms for intraoral administration are conveniently formulated as “soft” tablets, i.e., tablets subjected to only a low degree of compaction during manufacture and/or having a relatively low amount of binding agent, to enable rapid disintegration in the oral cavity and thereby rapid drug release. Typically such tablets are not coated, as commonly used film coatings can delay disintegration of a tablet and result in slower drug release than may be desirable.  
       [0005] The low compaction of typical intraoral, particularly sublingual, tablets and the lack of a protective coating thereon tends to result in such tablets being friable and therefore subject to breakage and attrition during packaging, shipping and dispensing.  
       [0006] U.S. Pat. No. 6,326,028 to Nivaggioli et al., incorporated herein by reference, discloses a tablet coating comprising gellan gum. Such a coating is said to be useful for tablets to be taken orally, and to confer benefits in appearance, identification, mouth feel, reduced dust, stability, color and/or swallowability.  
       [0007] International Patent Publication No. WO 00/40226 discloses compounds useful in treating sexual dysfunction in men and women, these compounds being of formula (I)  
                 
 
       [0008] or pharmaceutically acceptable salts thereof, wherein  
       [0009] R 1 , R 2  and R 3  are the same or different and are H, C 1-6  alkyl (optionally phenyl substituted), C 3-5  alkenyl or alkynyl or C 3-10  cycloalkyl, or where R 3  is as above and R 1  and R 2  are cyclized with the attached N atom to form pyrrolidinyl, piperidinyl, morpholinyl, 4-methylpiperazinyl or imidazolyl groups;  
       [0010] X is H, F, Cl, Br, I, OH, C 1-6  alkyl or alkoxy, CN, carboxamide, carboxyl or (C 1-6  alkyl)carbonyl;  
       [0011] A is CH, CH 2 , CHF, CHCl, CHBr, CHI, CHCH 3 , C═O, C═S, CSCH 3 , C═NH, CNH 2 , CNHCH 3 , CNHCOOCH 3 , CNHCN, SO 2  or N;  
       [0012] B is CH, CH 2 , CHF, CHCl, CHBr, CHI, C═O, N, NH or NCH 3 , and n is 0 or 1; and  
       [0013] D is CH, CH 2 , CHF, CHCl, CHBr, CHI, C═O, O, N, NH or NCH 3 ;  
       [0014] with various provisos indicated therein. WO 00/40226 further contemplates prescription of the drug (R)-5,6-dihydro-5-(methylamino)-4H-imidazo[4,5-ij]-quinolin-2(1H)-one (Z)-2-butenedioate (1:1) to male and female subjects at a dose of 1-3 mg, to be taken 0.5-1 h before engaging in sexual activity, and indicates that at such a dose and timing of administration the drug is therapeutically effective. No information is provided as to the route of administration or nature of dosage form.  
       [0015] The class of compounds proposed for treatment of sexual dysfunction in WO 00/40226 was earlier disclosed in U.S. Pat. No. 5,273,975 to Moon et al. to have therapeutically useful central nervous system activity. Above-cited International Patent Publication No. WO 00/40226 and U.S. Pat. No. 5,273,975 are incorporated herein by reference. Certain compounds of the above class are the subject of a paper by Heier et al. (1997), “Synthesis and biological activities of (R)-5,6-dihydro-N,N-dimethyl-4H-imidazo[4,5,1-ij]quinolin-5-amine and its metabolites”,  J. Med. Chem.  40, 639-646.  
       [0016] International Patent Publication No. WO 99/16442, incorporated herein by reference, discloses a sustained-release tablet formulation of (R)-5,6-dihydro-5-(methylamino)-4H-imidazo [4,5-ij]-quinolin-2(1H)-one (Z)-2-butenedioate (1:1) for treatment of Parkinson&#39;s disease.  
       [0017] European Patent Application No. 0 992 240, incorporated herein by reference, discloses cGMP-PDE inhibitory compounds said to be useful in treatment of male erectile dysfunction and proposes transmucomembranous administration, for example in the form of sublingual preparations, of such compounds.  
       [0018] Heaton (1996), “Buccal apomorphine”,  Journal of Urology  155, 49, reports efficacy of a sublingual formulation of apomorphine in treatment of male non-organic erectile dysfunction.  
       [0019] U.S. Pat. No. 5,985,889 to El-Rashidy et al., incorporated herein by reference, proposes sublingual administration of apomorphine for treatment of male psychogenic erectile dysfunction. Various sublingual tablet formulations of apomorphine hydrochloride are disclosed therein.  
       [0020] International Patent Publication No. WO 00/35457, incorporated herein by reference, proposes use of apomorphine for treatment of male organic, e.g., vasculogenic, erectile dysfunction, and exemplifies use of a sublingual tablet formulation of apomorphine hydrochloride. WO 00/35457 further suggests that nausea, a common side effect of apomorphine, can be controlled by inclusion of an anti-emetic agent such as nicotine in the formulation.  
       [0021] U.S. Pat. No. 6,121,276 to El-Rashidy &amp; Ronsen, incorporated herein by reference, discloses flavored sublingual tablets containing apomorphine hydrochloride and nicotine.  
       [0022] U.S. Pat. No. 5,994,363 to El-Rashidy &amp; Ronsen, incorporated herein by reference, discloses a treatment regime with apomorphine that is said to reduce side effects such as nausea, vomiting, yawning and cardiovascular effects.  
       [0023] U.S. Pat. Nos. 5,624,677 and 5,888,534, both to El-Rashidy et al. and incorporated herein by reference, discloses a prolonged release sublingual formulation of apomorphine.  
       [0024] International Patent Publication No. WO 01/49292, incorporated herein by reference, discloses sublingual tablets of apomorphine providing prolonged release of the drug, said to be useful in treatment of Parkinson&#39;s disease.  
       [0025] International Patent Publication No. WO 00/42992, incorporated herein by reference, discloses a dosage unit comprising a water-soluble hydrocolloid and sildenafil citrate in a mucoadhesive film said to be suitable for application to the oral mucosa. Pharmacokinetic data presented in WO 00/42992 indicate no faster absorption into the bloodstream with sublingual application of such a film than with a commercial tablet formulation of sildenafil citrate (Viagra®) at the same dosage.  
       [0026] International Patent Publication No. WO 01/10406, incorporated herein by reference, discloses compositions said to be suitable for a wide range of routes of administration of sildenafil citrate, including buccal and sublingual routes. Preferred compositions disclosed are said to comprise a solution, gel, semisolid, suspension, metered dose device, transdermal patch or film. It is indicated that such compositions can include a gelling system, for example gellan gum 0.5% to 10%.  
       [0027] International Patent Publication No. WO 02/05820, incorporated herein by reference, discloses film dosage forms comprising sildenafil citrate. These dosage forms are prepared by nixing a solid dispersion of sildenafil citrate and a water soluble sugar with a hydrocolloid and optionally other ingredients, and are said, upon placement on a mucosal surface, to form a coating that subsequently disintegrates and dissolves to release sildenafil. Gellan sodium salt is listed among hydrocolloids said to be useful in such film dosage forms.  
       [0028] U.S. Pat. No. 6,291,506 to Levin, incorporated herein by reference, discloses that the ophthalmic drug carvedilol can be formulated for ocular administration by suspending it in an agent such as gellan gum that will increase corneal contact time with the drug. Other possible delivery modes for the drug are contemplated therein. A claim is included to a method wherein the drug is delivered by a selection of routes including sublingually.  
       [0029] U.S. Pat. No. 6,297,240 to Embleton, incorporated herein by reference, discloses an intraorally deliverable composition comprising an ophthalmic drug, for example a drug useful in lowering intraocular pressure.  
       SUMMARY OF THE INVENTION  
       [0030] There is now provided a pharmaceutical tablet comprising an intraorally disintegratable core and an excipient coating adherent thereto, wherein the coating comprises gellan gum.  
       [0031] The tablet is suitable for intraoral administration, for example for delivery of a drug contained in the core of the tablet to a subject, for example a human subject, at least in part by absorption of the drug via oral mucosa of the subject. The term “intraoral” herein refers to administration by placement of the tablet in the mouth of the subject, where the tablet disintegrates and/or dissolves. Intraoral administration herein is therefore distinct from conventional oral administration of a tablet, wherein the tablet is swallowed prior to substantial disintegration or dissolution. For intraoral administration, the tablet can be placed in or on any part of the mouth, but placement of the tablet in the sublingual or buccal spaces is preferred.  
       [0032] An “intraorally disintegratable” core herein is a core that, in the absence of a coating, disintegrates readily in the mouth. Where the core comprises a drug, the drug is released and becomes available for mucosal absorption as the core disintegrates. Typically, an intraorally disintegratable core is of low hardness (e.g., less than about 4 SCU).  
       [0033] An “excipient coating” herein is a coating consisting, at least at the time of application of the coating to the core, only of excipient materials, i.e., having substantially no drug present therein. It will be understood that during manufacture and storage some migration of a drug substance can potentially occur from the core to the coating of a tablet of the invention, but this is generally minimal and does not remove such a tablet from the scope of the present invention. It is important to note that according to the invention a drug substance, if present in the tablet, is largely confined to the core where it is not commingled with gellan gum.  
       [0034] Therefore a further embodiment of the invention is a pharmaceutical tablet comprising a drug in a therapeutically and/or prophylactically effective amount, the tablet having an intraorally disintegratable core and a coating adherent thereto, wherein the coating comprises gellan gum, and substantially all, for example at least about 90%, of the drug is located in the core and is not commingled with gellan gum.  
       [0035] The present invention provides a solution to a long-standing problem in the art in that a soft tablet suitable for intraoral administration, which normally is very friable, and therefore vulnerable to breakage and attrition during manufacture, packaging, shipping and dispensing, can be made more robust without significant reduction in rate of disintegration in the mouth. A coating comprising gellan gum as contemplated herein confers such robustness, as measurable by reduced breakage and/or attrition of the tablet prior to administration, yet does not result in appreciable retardation of disintegration upon placement of the tablet in the mouth. Tablet coatings widely used for swallowable tablets, for example film coatings comprising a cellulosic polymer such as hydroxypropylmethylcellulose or ethylcellulose, are generally unsuitable for tablets intended for intraoral administration because these coatings tend to inhibit intraoral disintegration of such tablets and/or mucosal absorption of a drug contained in such tablets. Another problem with film coatings comprising a cellulosic polymer is that such coatings tend to become detached from the underlying tablet core as film flakes in the mouth. This can lead to an unpleasant oral sensation and can induce the subject to swallow the tablet rather than retain it in the mouth.  
       [0036] Furthermore, the highly friable tablets that are generally used for intraoral drug delivery are difficult to coat with cellulosic polymers by processes known in the art. By contrast, a coating comprising gellan gum as contemplated herein can be applied to a highly friable core according to a coating process disclosed herein, without unacceptable breakage or attrition of cores during the coating process.  
       [0037] Tablets of the invention can possess one or more additional advantages over intraorally administrable tablets of prior art. For example, a tablet of the invention can have one or more of a glossy and/or color-enhancing appearance, improved organoleptic quality such as flavor and/or mouth feel, and improved mucoadhesion resulting in better retention or “seating” of the tablet at the site of placement and/or enhanced mucosal absorption of a drug contained in the tablet.  
       [0038] Coated tablets as provided herein are generally less expensive and/or more convenient to prepare, package and dispense than other hydrocolloid-containing dosage forms such as films and gels.  
       [0039] Other features, advantages and benefits of the invention will be apparent from the description that follows.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0040] A tablet of the invention can be a placebo tablet, i.e., containing no drug or other active agent in the core thereof. Preferably a tablet of the invention contains in the core a therapeutically and/or prophylactically useful amount of a drug, more preferably a drug that is advantageously delivered by intraoral administration. In principle any drug is deliverable intraorally, but in practice intraoral administration is particularly advantageous for certain classes of drugs and drug products, for example:  
       [0041] (a) drugs more readily or more rapidly absorbed via the oral mucosa than in the gastrointestinal tract;  
       [0042] (b) drugs subject to first-pass metabolism in the liver;  
       [0043] (c) smoking cessation products, for example those containing nicotine;  
       [0044] (d) antibacterial drugs;  
       [0045] (e) drugs to treat ophthalmic disorders;  
       [0046] (f) analgesics, antipyretics and anti-inflammatories, for example NSAIDs (nonsteroidal anti-inflammatory drugs) including selective cyclooxygenase-2 (COX-2) inhibitory drugs;  
       [0047] (g) drugs to treat sexual dysfunction, for example dopaminergic agonists; etc.  
       [0048] “First-pass metabolism” as mentioned above is a problem with gastrointestinal delivery of some drugs, it being noted that absorption of a drug into the bloodstream from the gastrointestinal tract exposes the drug to metabolism in the liver during its first pass through the circulatory system. By contrast, blood from capillary beds in the oral mucosa drains directly into systemic circulation and avoids first-pass metabolism. See Rathbone et al., op. cit.  
       [0049] More generally, the drug present in the core of a tablet of the invention can be selected from the following illustrative classes: ACE inhibitors; α-adrenergic agonists; β-adrenergic agonists; α-adrenergic blockers; β-adrenergic blockers (beta blockers); alcohol deterrents; aldose reductase inhibitors; aldosterone antagonists; amino acids; anabolics; analgesics (both narcotic and non-narcotic); anesthetics; anorexics; antacids; anthelmintics; antiacne agents; antiallergics; antiandrogens; antianginal agents; antianxiety agents; antiarrythmics; antiasthmatics; antibacterial agents and antibiotics; antialopecia and antibaldness agents; antiamebics; antibodies; anticholinergic drugs; anticoagulants and blood thinners; anticolitis drugs; anticonvulsants; anticystitis drugs; antidepressants; antidiabetic agents; antidiarrheals; antidiuretics; antidotes; antiemetics; antiestrogens; antiflatulents; antifungal agents; antigens; antiglaucoma agents; antihistaminics; antihyperactives; antihyperlipoproteinemics; antihypertensives; antihyperthyroid agents; antihypotensives; antihypothyroid agents; anti-infectives; anti-inflammatories (both steroidal and nonsteroidal); antimalarial agents; antimigraine agents; antineoplastics; antiobesity agents; antiparkinsonian agents and antidyskinetics; antipneumonia agents; antiprotozoal agents; antipruritics; antipsoriatics; antipsychotics; antipyretics; antirheumatics; antisecretory agents; anti-shock medications; antispasmodics; antithrombotics; antitumor agents; antitussives; antiulceratives; antiviral agents; anxiolytics; bactericidins; bone densifiers; bronchodilators; calcium channel blockers; carbonic anhydrase inhibitors; cardiotonics and heart stimulants; chemotherapeutics; choleretics; cholinergics; chronic fatigue syndrome medications; CNS stimulants; coagulants; contraceptives; cystic fibrosis medications; decongestants; diuretics; dopamine receptor agonists; dopamine receptor antagonists; enzymes; estrogens; expectorants; gastric hyperactivity medications; glucocorticoids; hemostatics; HMG CoA reductase inhibitors; hormones; hypnotics; immunomodulators; immunosuppressants; laxatives; medicaments for oral and periodontal diseases; miotics; monoamine oxidase inhibitors; mucolytics; multiple sclerosis medications; muscle relaxants; mydriatics; narcotic antagonists; NMDA receptor antagonists; oligonucleotides; ophthalmic drugs; oxytocics; peptides, polypeptides and proteins; polysaccharides; progestogens; prostaglandins; protease inhibitors; respiratory stimulants; sedatives; serotonin uptake inhibitors; sex hormones including androgens; smoking cessation drugs; smooth muscle relaxants; smooth muscle stimulants; thrombolytics; tranquilizers; urinary acidifiers; urinary incontinence medications; vasodilators; vasoprotectants; and combinations thereof.  
       [0050] It will be understood that any reference herein to a particular drug compound includes tautomers, stereoisomers, enantiomers, salts and prodrugs of that compound and is not specific to any one solid-state form of the drug.  
       [0051] In one embodiment a drug contained in the core of the tablet is a smoking cessation drug, for example nicotine, a nicotine metabolite or a non-nicotine aid to smoking cessation such as bupropion or ibogaine.  
       [0052] Illustratively, a smoking cessation drug can be selected from nicotine and metabolites thereof (e.g., cotinine, norcotinine, nornicotine, nicotine N-oxide, cotinine N-oxide, 3-hydroxycotinine and 5-hydroxycotinine), ibogaine, bupropion and metabolites thereof (e.g., the erythro- and threo-amino alcohols of bupropion, the erythro-amino diol of bupropion and hydroxybupropion), lobeline, selegiline, risperidone and its 9-hydroxy metabolite, desmethylselegiline, substituted pyridine derivatives (e.g., 1-[(6-chloro-3-pyridinyl)methyl]-2-imidazolidine, 1-[(6-chloro-3-pyridinyl)methyl]-2-imidazothiazole and analogs thereof), methcamylamine, desipramine, fluoxetine, ropinirole, trimethaphan, trimethaphan camsylate, doxepin, 2-(3-chlorophenyl)-3,5,5-trimethyl-2-morpholinol, anxiolytics (e.g., isovaleramide), γ-vinyl GABA (GVG), epibatidine and derivatives thereof, 7-azabicyclo-[2.2.1]-heptane and -heptene compounds, naltrexone, nalmefene, ketamine, hexamethonium, pentolinium, dihydro-β-erythroidine, erysodine, d-tubocurarine, pempidine, chlorisondamine, amantadine, hetero-oxy alkanamines, benzylidene- and cinnamylidene-anabasines, azaindole-ethylamine derivatives, N-(pyridinylmethyl)-heterocyclylideneamines and NK-1 receptor antagonists (e.g., 9-bromo-1,2,3,4,5,6-hexahydro-1,5-methano-pyrido[1,2-a][1,5]diazocin-8-one).  
       [0053] In another embodiment a drug contained in the core of the tablet is an antibacterial drug. Illustratively such a drug can be an antibiotic, for example an aminoglycoside, amphenicol, ansamycin, carbapenem, cephalosporin, cephamycin, monobactam, oxacephem, penicillin, lincosamide, macrolide, polypeptide or tetracycline; or a synthetic antibacterial, for example a 2,4-diaminopyrimidine, nitrofuran, oxazolidinone, quinolone or analog thereof, sulfonamide or sulfone. Presently preferred antibacterials include the following illustrative examples: amikacin, azithromycin, cefixime, cefoperazone, cefotaxime, ceftazidime, ceftizoxime, ceftriaxone, chloramphenicol, ciprofloxacin, clindamycin, colistin, domeclocycline, doxycycline, erythromycin, gentamicin, lincomycin, linezolid, mafenide, methacycline, minocycline, neomycin, norfloxacin, ofloxacin, oxytetracycline, pirlimycin, polymyxin B, pyrimethamine, silver sulfadiazine, sulfacetamide, sulfisoxazole, tetracycline, tobramycin, trimethoprim and combinations thereof. In one embodiment an antibacterial drug present in the core of the tablet is an oxazolidinone, for example selected from (S)-N-[[3-[3-fluoro-4-[4-(hydroxyacetyl)-1-piperazinyl]phenyl]-2-oxo-5-oxazolidinyl]methyl]acetamide (eperezolid), (S)-N-[[3-[3-fluoro-4-[4-(morpholinyl)phenyl]-2-oxo-5-oxazolidinyl]methyl]acetamide (linezolid), N-[(5S)-3-[3-fluoro-4-[4-(2-fluoroethyl)-3-oxo-1-piperazinyl]phenyl-2-oxo-5-oxazolidinyl]methyl]acetamide, (S)-N-[[3-[5-(3-pyridyl)thiophen-2-yl]-2-oxo-5-oxazolidinyl]methyl]acetamide, and (S)-N-[[3-[5-(4-pyridyl)pyrid-2-yl]-2-oxo-5-oxazolidinyl]methyl]acetamide hydrochloride.  
       [0054] In another embodiment a drug contained in the core of the tablet is an antimigraine agent. Illustratively such an agent can be an alkylxanthine, for example caffeine; a dopamine D 2  receptor agonist, for example alpiropride or lisuride; a GABA A  receptor modulator, for example ganaxolone; a 5-hydroxytriptamine (5-HT) receptor agonist, for example almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan or zolmitriptan; ergot or a derivative thereof, for example ergotamine or dihydroergotamine; or a vasomodulator, for example dotarizine, fonazine or lomerizine.  
       [0055] In another embodiment a drug contained in the core of the tablet is useful in treating or preventing an ophthalmic disorder.  
       [0056] Illustratively such an ophthalmic drug can be an antibacterial, for example selected from the classes listed above.  
       [0057] Alternatively or in addition, such an ophthalmic drug can illustratively be an antiglaucoma or intraocular pressure lowering agent, such as (a) an α-adrenergic agonist or sympathomimetic, e.g., adrenolone, apraclonidine, brimonidine or dipivefrin; (b) a β-adrenergic blocker, e.g., acebutolol, adaprolol, alprenolol, atenolol, betaxolol, bufetolol, bufuralol, bunitrolol, bunolol, bupranolol, carteolol, carvedilol, cetamolol, dexpropanolol, labetalol, levobunolol, metipranolol, metoprolol, nadolol, nifenalol, oxyprenolol, penbutolol, pindolol, practolol, pronethalol, propranolol, sotalol, timolol, tolamolol, toliprolol or vaninolol; (c) a carbonic anhydrase inhibitor, e.g., acetazolamide or dorzolamide; or (d) a prostaglandin or analog thereof, e.g., PGF 2α  analogs such as bimatoprost, latanoprost, travoprost and unoprostone isopropyl.  
       [0058] Alternatively or in addition, such an ophthalmic drug can illustratively be a miotic, e.g., carbachol, physostigmine or pilocarpine.  
       [0059] Alternatively or in addition, such an ophthalmic drug can illustratively be an anti-inflammatory agent, for example an NSAID, more preferably a selective COX-2 inhibitory drug, for example selected from those listed below.  
       [0060] In another embodiment a drug contained in the core of the tablet is an analgesic, antipyretic or anti-inflammatory agent, e.g., aceclofenac, acemetacin, e-acetamidocaproic acid, acetaminophen, acetaminosalol, acetanilide, acetylsalicylic acid (aspirin), S-adenosylmethionine, alclofenac, alclometasone, alfentanil, algestone, allylprodine, alminoprofen, aloxiprin, alphaprodine, aluminum bis(acetylsalicylate), amcinonide, amfenac, aminochlorthenoxazin, 3-amino-4-hydroxybutyric acid, 2-amino-4-picoline, aminopropylon, aminopyrine, amixetrine, ammonium salicylate, ampiroxicam, amtolmetin guacil, anileridine, antipyrine, antrafenine, apazone, beclomethasone, bendazac, benorylate, benoxaprofen, benzpiperylon, benzydamine, benzylmorphine, bermoprofen, betamethasone, bezitramide, α-bisabolol, bromfenac, p-bromoacetanilide, 5-bromosalicylic acid acetate, bromosaligenin, bucetin, bucloxic acid, bucolome, budesonide, bufexamac, bumadizon, buprenorphine, butacetin, butibufen, butophanol, carbamazepine, carbiphene, carprofen, carsalam, celecoxib, chlorobutanol, chloroprednisone, chlorthenoxazin, choline salicylate, cinchophen, cinmetacin, ciramadol, clidanac, clobetasol, clocortolone, clometacin, clonitazene, clonixin, clopirac, cloprednol, clove, codeine, codeine methyl bromide, codeine phosphate, codeine sulfate, cortisone, cortivazol, cropropamide, crotethamide, deflazacort, desomorphine, desonide, desoximetasone, dexamethasone, dexoxadrol, dextromoramide, dezocine, diampromide, diclofenac, difenamizole, difenpiramide, diflorasone, diflucortolone, diflunisal, difluprednate, dihydrocodeine, dihydrocodeinone enol acetate, dihydromorphine, dihydroxyaluminum acetylsalicylate, dimenoxadol, dimepheptanol, dimethylthiambutene, dioxaphetyl butyrate, dipipanone, diprocetyl, dipyrone, ditazol, droxicam, emorfazone, enfenamic acid, enoxolone, epirizole, eptazocine, etersalate, ethenzamide, ethoheptazine, ethoxazene, ethylmethylthiambutene, ethylmorphine, etodolac, etofenamate, etonitazene, etoricoxib, eugenol, felbinac, fenbufen, fenclozic acid, fendosal, fenoprofen, fentanyl, fentiazac, fepradinol, feprazone, floctafenine, fluazacort, flucloronide, flufenamic acid, flumethasone, flunisolide, flunixin, flunoxaprofen, fluocinolone acetonide, fluocinonide, fluocortin butyl, fluocortolone, fluoresone, fluorometholone, fluperolone, flupirtine, fluprednidene, fluprednisolone, fluproquazone, flurandrenolide, flurbiprofen, formocortal, fosfosal, gentisic acid, glafenine, glucametacin, glycol salicylate, guaiazulene, halcinonide, halometasone, haloprednone, hydrocodone, hydrocortamate, hydrocortisone, hydromorphone, hydroxypethidine, ibufenac, ibuprofen, ibuproxam, imidazole salicylate, indomethacin, indoprofen, isofezolac, isoladol, isomethadone, isonixin, isoxepac, isoxicam, ketobemidone, ketoprofen, ketorolac, p-lactophenetide, lefetamine, levorphanol, lofentanil, lonazolac, lornoxicam, loxoprofen, lysine acetylsalicylate, mazipredone, meclofenamic acid, medrysone, mefenamic acid, meperidine, meprednisone, meptazinol, mesalanine, metazocine, methadone, methotrimeprazine, methylprednisolone, metiazinic acid, metofoline, metopon, mofebutazone, mofezolac, morazone, morphine, morphine hydrochloride, morphine sulfate, morpholine salicylate, myrophine, nabumetone, nalbuphine, 1-naphthyl salicylate, naproxen, narceine, nefopam, nicomorphine, nifenazone, niflumic acid, nimesulide, 5′-nitro-2′-propoxyacetanilide, norlevorphanol, normethadone, normorphine, norpipanone, olsalazine, opium, oxaceprol, oxametacine, oxaprozin, oxycodone, oxymorphone, oxyphenbutazone, papaveretum, paramethasone, paranyline, parecoxib, parsalmide, pentazocine, perisoxal, phenacetin, phenadoxone, phenazocine, phenazopyridine hydrochloride, phenocoll, phenoperidine, phenopyrazone, phenyl acetylsalicylate, phenylbutazone, phenyl salicylate, phenyramidol, piketoprofen, piminodine, pipebuzone, piperylone, piprofen, pirazolac, piritramide, piroxicam, pranoprofen, prednicarbate, prednisolone, prednisone, prednival, prednylidene, proglumetacin, proheptazine, promedol, propacetamol, propiram, propoxyphene, propyphenazone, proquazone, protizinic acid, proxazole, ramifenazone, remifentanil, rimazolium metilsulfate, rofecoxib, salacetamide, salicin, salicylamide, salicylamide o-acetic acid, salicylic acid, salicylsulfuric acid, salsalate, salverine, simetride, sufentanil, sulfasalazine, sulindac, superoxide dismutase, suprofen, suxibuzone, talniflumate, tenidap, tenoxicam, terofenamate, tetrandrine, thiazolinobutazone, tiaprofenic acid, tiaramide, tilidine, tinoridine, tixocortol, tolfenamic acid, tolmetin, tramadol, triamcinolone, tropesin, valdecoxib, viminol, xenbucin, ximoprofen, zaltoprofen or zomepirac.  
       [0061] In a particular embodiment such a drug is a selective COX-2 inhibitory drug, for example a compound of formula (II):  
                 
 
       [0062] or a prodrug thereof or a pharmaceutically acceptable salt thereof, wherein:  
       [0063] A is a substituent selected from partially unsaturated or unsaturated heterocyclyl and partially unsaturated or unsaturated carbocyclic rings, preferably a heterocyclyl group selected from pyrazolyl, furanonyl, isoxazolyl, pyridinyl, cyclopentenonyl and pyridazinonyl groups;  
       [0064] X is O, S or CH 2 ;  
       [0065] n is 0 or 1;  
       [0066] R 11  is at least one substituent selected from heterocyclyl, cycloalkyl, cycloalkenyl and aryl, and is optionally substituted at a substitutable position with one or more radicals selected from alkyl, haloalkyl, cyano, carboxyl, alkoxycarbonyl, hydroxyl, hydroxyalkyl, haloalkoxy, amino, alkylamino, arylamino, nitro, alkoxyalkyl, alkylsulfinyl, halo, alkoxy and alkylthio;  
       [0067] R 12  is methyl, amino or aminocarbonylalkyl;  
       [0068] R 13  is one or more radicals selected from hydrido, halo, alkyl, alkenyl, alkynyl, oxo, cyano, carboxyl, cyanoalkyl, heterocyclyloxy, alkyloxy, alkylthio, alkylcarbonyl, cycloalkyl, aryl, haloalkyl, heterocyclyl, cycloalkenyl, aralkyl, heterocyclylalkyl, acyl, alkylthioalkyl, hydroxyalkyl, alkoxycarbonyl, arylcarbonyl, aralkylcarbonyl, aralkenyl, alkoxyalkyl, arylthioalkyl, aryloxyalkyl, aralkylthioalkyl, aralkoxyalkyl, alkoxyaralkoxyalkyl, alkoxycarbonylalkyl, aminocarbonyl, aminocarbonylalkyl, alkylaminocarbonyl, N-arylaminocarbonyl, N-alkyl-N-arylaminocarbonyl, alkylaminocarbonylalkyl, carboxyalkyl, alkylamino, N-arylamino, N-aralkylamino, N-alkyl-N-aralkylamino, N-alkyl-N-arylamino, aminoalkyl, alkylaminoalkyl, N-arylaminoalkyl, N-aralkylaminoalkyl, N-alkyl-N-aralkylaminoalkyl, N-alkyl-N-arylaminoalkyl, aryloxy, aralkoxy, arylthio, aralkylthio, alkylsulfinyl, alkylsulfonyl, aminosulfonyl, alkylaminosulfonyl, N-arylaminosulfonyl, arylsulfonyl and N-alkyl-N-arylaminosulfonyl, R 13  being optionally substituted at a substitutable position with one or more radicals selected from alkyl, haloalkyl, cyano, carboxyl, alkoxycarbonyl, hydroxyl, hydroxyalkyl, haloalkoxy, amino, alkylamino, arylamino, nitro, alkoxyalkyl, alkylsulfinyl, halo, alkoxy and alkylthio; and  
       [0069] R 14  is selected from hydrido and halo.  
       [0070] In a preferred composition according to the present embodiment the selective COX-2 inhibitory drug is a compound having the formula (III):  
                 
 
       [0071] where R 15  is a methyl, amino or imide group, R 16  is hydrogen or a C 1-4  alkyl or alkoxy group, X is N or CR 17  where R 17  is hydrogen or halogen, and Y and Z are independently carbon or nitrogen atoms defining adjacent atoms of a five- to six-membered ring that is unsubstituted or substituted at one or more positions with oxo, halo, methyl or halomethyl groups. Preferred such five- to six-membered rings are cyclopentenone, furanone, methylpyrazole, isoxazole and pyridine rings substituted at no more than one position.  
       [0072] In another preferred composition according to the present embodiment the selective COX-2 inhibitory drug is a compound having the formula (IV):  
                 
 
       [0073] or a prodrug thereof or a pharmaceutically acceptable salt thereof, where X″ is O, S or N-lower alkyl; R 18  is lower haloalkyl; R 19  is hydrogen or halogen; R 20  is hydrogen, halogen, lower alkyl, lower alkoxy or haloalkoxy, lower aralkylcarbonyl, lower dialkylaminosulfonyl, lower alkylaminosulfonyl, lower aralkylaminosulfonyl, lower heteroaralkylaminosulfonyl, or 5- or 6- membered nitrogen-containing heterocyclosulfonyl; and R 21  and R 22  are independently hydrogen, halogen, lower alkyl, lower alkoxy, or aryl.  
       [0074] A particularly useful compound of formula (IV) is (S)-6,8-dichloro-2-(trifluoromethyl)-2H-1-benzopyran-3-carboxylic acid.  
       [0075] In yet another preferred composition according to the present embodiment the selective COX-2 inhibitory drug is a 5-alkyl-2-arylaminophenylacetic acid or derivative thereof. Particularly useful compounds of this class are 5-methyl-2-(2′-chloro-6′-fluoroanilino)phenylacetic acid and pharmaceutically acceptable salts thereof.  
       [0076] Illustratively, celecoxib, deracoxib, valdecoxib, parecoxib, rofecoxib, etoricoxib, 2-(3,5-difluorophenyl)-3-[4-(methylsulfonyl)phenyl]-2-cyclopenten-1-one, (S)-6,8-dichloro-2-(trifluoromethyl)-2H-1-benzopyran-3-carboxylic acid, 2-(3,4-difluorophenyl)-4-(3-hydroxy-3-methyl-1-butyoxy)-5-[4-(methylsulfonyl)phenyl]-3-(2H)-pyridazinone and salts thereof are useful in compositions of the present embodiment.  
       [0077] For example, the selective COX-2 inhibitory drug or prodrug thereof can be selected from celecoxib, valdecoxib, parecoxib, rofecoxib, etoricoxib, (S)-6,8-dichloro-2-(trifluoromethyl)-2H-1-benzopyran-3-carboxylic acid and salts thereof In another embodiment, a drug contained in the core of the tablet is useful in treatment and/or prevention of sexual dysfunction in male and/or female subjects. Such a drug can illustratively be (a) a phosphodiesterase type 5 (PDE5) inhibitor, e.g., sildenafil, tadalafil or vardenafil, (b) a cyclic GMP phosphodiesterase inhibitor, (c) a cyclic AMP activator, (d) an α-adrenergic antagonist, e.g., phentolamine or yohimbine, or (e) a dopaminergic agonist, e.g., apomorphine. Such a drug can be a compound of formula (I) below. Alternatively, a drug contained in the core of the tablet can be other than a drug useful in treatment and/or prevention of sexual dysfunction. As another alternative, a drug contained in the core of the tablet can be useful in treatment and/or prevention of sexual dysfunction but is other than a compound of formula (I) below.  
       [0078] In illustrative compositions a drug useful in treatment and/or prevention of sexual dysfunction is present in the core of the tablet in an amount of about 0.05 mg to about 10 mg per tablet and is a compound of formula (I)  
                 
 
       [0079] or a pharmaceutically acceptable salt thereof, wherein  
       [0080] R 1 , R 2  and R 3  are the same or different and are H, C 1-6  alkyl (optionally phenyl substituted), C 3-5  alkenyl or alkynyl or C 3-10  cycloalkyl, or where R 3  is as above and R 1  and R 2  are cyclized with the attached N atom to form pyrrolidinyl, piperidinyl, morpholinyl, 4-methylpiperazinyl or imidazolyl groups;  
       [0081] X is H, F, Cl, Br, I, OH, C 1-6  alkyl or alkoxy, CN, carboxamide, carboxyl or (C 1-6  alkyl)carbonyl;  
       [0082] A is CH, CH 2 , CHF, CHCl, CHBr, CHI, CHCH 3 , C═O, C═S, CSCH 3 , C═NH, CNH 2 , CNHCH 3 , CNHCOOCH 3 , CNHCN, SO 2  or N;  
       [0083] B is CH, CH 2 , CHF, CHCl, CHBr, CHI, C═O, N, NH or NCH 3 , and n is 0 or 1; and  
       [0084] D is CH, CH 2 , CHF, CHCl, CHBr, CHI, C═O, O, N, NH or NCH 3 .  
       [0085] It is preferred that the compound of formula (I) or salt thereof is water-soluble.  
       [0086] Pharmaceutically acceptable salts of a compound of formula (I) include without restriction salts of the following acids: hydrochloric, hydrobromic, sulfuric, methanesulfonic, phosphoric, nitric, benzoic, citric, tartaric, fumaric and maleic acids, and mono- and dicarboxylic acids of formula CH 3 —(CH 2 ) n —COOH and HOOC—(CH 2 ) n —COOH where n is 0 to 4, for example malonic acid.  
       [0087] Particularly preferred salts are the hydrochloride salt and the maleate, i.e., (Z)-2-butenedioate, salt.  
       [0088] Compounds of formula (I) and their salts can be prepared by processes known per se, including processes described in patent literature cited herein. However, the present invention is not restricted by the process used to prepare the therapeutic agent.  
       [0089] Preferred compounds of formula (I) are those disclosed generically or specifically in above-cited U.S. Pat. No. 5,273,975. Especially preferred compounds are those of formula (V)  
                 
 
       [0090] wherein X is O or S, and pharmaceutically acceptable salts thereof.  
       [0091] A “therapeutically effective amount” of a compound of formula (I) herein is an amount sufficient to improve sexual desire, interest or performance in a subject having a sexual dysfunction condition. A “sexual-stimulatorily effective amount” herein is an amount sufficient to improve sexual desire, interest or performance in a subject whether or not the subject has a sexual dysfunction condition. It is preferred that the amount of the compound of formula (I) or salt thereof be lower than an amount causing significant side-effects; in general it will be found that dosage amounts lower than about 5 mg, especially lower than about 3 mg, are relatively free of such side-effects.  
       [0092] Compounds of formula (I), in particular compounds of formula (V) and salts thereof, when formulated as described herein, can be effective at surprisingly low doses. At such low doses, despite the high aqueous solubility of compounds of formula (V) and in particular of their salts, there is generally no pronounced taste associated with the therapeutic agent. Even if a taste is detectable, it is relatively easily masked or balanced by excipients and encapsulation is normally not required.  
       [0093] Tablets of the invention containing a drug of formula (I) are adapted for discreet self-administration. By “discreet self-administration” herein is meant self-administration shortly prior to sexual activity in a way that does not draw attention of a sexual partner to, or emphasize, the existence of a sexual dysfunction, a need for therapy or a need or desire for enhancement of sexual performance. The combination of discreetness and rapid onset that is permitted by the present invention provides a benefit in spontaneity; by contrast, prior art compositions for treating sexual dysfunction can be seriously compromised in their effectiveness if their self-administration requires premeditation and/or cannot be done discreetly, such self-administration being thereby not conducive to spontaneity. In particular, the present invention does not involve self-injection, and does not require water or other drink as an aid to swallowing.  
       [0094] A tablet of the invention wherein the therapeutic agent is sumanirole, (R)-5,6-dihydro-5-(methylamino)-4H-imidazo[4,5-ij]-quinolin-2(1H)-one, preferably contains about 0.05 to about 5 mg, more preferably about 0.1 to about 5 mg, still more preferably about 0.2 to about 5 mg, even more preferably about 0.5 to about 5 mg, of sumanirole free base equivalent, as free base or as salt. In one embodiment the tablet contains about 0.25 to about 3 mg, for example about 1 to about 3 mg, of sumanirole free base equivalent, as free base or as salt. If desired, the sumanirole can be only partially neutralized with acid so that free base coexists with salt in the tablet.  
       [0095] A tablet of the invention wherein the therapeutic agent is (R)-5,6-dihydro-5-(methylamino)-4H-imidazo[4,5-ij]-quinoline-2(1H)-thione preferably contains about 0.05 to about 5 mg, more preferably about 0.1 to about 3 mg, and most preferably about 0.25 to about 2 mg, of (R)-5,6-dihydro-5-(methylamino)-4H-imidazo[4,5-ij]-quinoline-2(1H)-thione free base equivalent, as free base or as salt. In one embodiment the tablet contains about 0.1 to about 3 mg, for example about 0.25 to about 1 mg, of (R)-5,6-dihydro-5-(methylamino)-4H-imidazo[4,5-ij]-quinoline-2(1H)-thione free base equivalent, as free base or as salt. If desired, the (R)-5,6-dihydro-5-(methylamino)-4H-imdazo[4,5-ij]-quinoline-2(1H)-thione can be only partially neutralized with acid so that free base coexists with salt in the tablet.  
       [0096] In one embodiment a compound of formula (I) is present in a tablet of the invention in a therapeutically or sexual-stimulatorily effective amount of less than 1 mg, for example about 0.05 mg to about 0.75 mg. Surprisingly a tablet of the invention having such a low amount of the active agent can exhibit a desired degree of efficacy; further, any unpleasant taste resulting from intraoral interaction by the tablet is minimized or absent.  
       [0097] Tablet cores useful according to the invention can be prepared by any suitable process known in the art. Such cores are then coated with a coating composition comprising gellan gum, as more fully described below. The coating is typically present in an amount representing a weight gain of about 0.1% to about 5%, but greater or lesser amounts can be used if desired. Preferably the gellan gum constitutes about 25% to 100%, more preferably about 50% to 100%, by weight of the coating.  
       [0098] Any gellan gum can be used in the coating composition, but it is preferred to use a deacylated gellan gum such as that sold under the trademark Kelcogel™. Optionally one or more additional gums and/or biopolymers, for example alginates, can be present in the coating composition.  
       [0099] The coating composition comprises a sprayable vehicle, preferably water, having dissolved or dispersed therein a gellan gum and optionally one or more additional excipients. Preferably the coating composition has a total solids concentration of about 1% to about 10% by weight, and a gellan gum concentration of about 1% to about 5% by weight.  
       [0100] Additional excipients present in the coating composition can include one or more buffering agents, typically at a concentration of about 0.03% to about 3% by weight; one or more plasticizers, typically at a concentration of about 0.03% to about 3% by weight; and/or one or more dispersing and/or emulsifying agents, typically at a concentration of about 0.03% to about 3% by weight. An example of a suitable buffering agent is sodium citrate. An example of a suitable plasticizer is propylene glycol. An example of a suitable dispersing or emulsifying agent is lecithin. Flavoring and coloring agents can also be included in the coating composition if desired.  
       [0101] The coating composition can be prepared by any suitable process involving dissolving the gellan gum and other, optional, excipients in the vehicle, preferably water. Order of addition is not critical. The water is preferably heated, for example to a temperature of about 55° C. to about 85° C. Gellan gum and other excipients, if present, are added with stirring until all ingredients are homogeneously dispersed. The resulting coating liquid is preferably maintained at an elevated temperature during the stirring and subsequent spraying procedure.  
       [0102] Tablet cores to be coated are placed in a suitable coating apparatus, for example a coating pan, and are preferably preheated to a bed temperature of about 50° C. to about 70° C. The coating liquid is sprayed on to the tablets under conditions that will be readily optimized by one of skill in the art. Spraying is continued until an amount of coating solution equivalent to a weight gain of about 0.1% to about 5% has been applied. The resulting coated tablets are preferably cooled to ambient temperature, or about 20° C. to about 35° C., prior to discharge from the coating pan.  
       [0103] An illustrative sublingual tablet of the invention containing as active agent a salt, e.g., the maleate salt, of sumanirole or (R)-5,6-dihydro-5-(methylamino)-4H-imidazo[4,5-ij]-quinoline-2(1H)-thione has a core having the following composition:  
                                                          active agent   0.1-3%   free base equivalent           mannitol   50-90%           powdered sorbitol   10-40%           hydroxypropylcellulose   0-10%           xanthan gum   0-5%           flavoring agent   0-0.5%           coloring agent   0-0.5%           colloidal silicon dioxide   0-1%           magnesium stearate   0.5-5%                      
 
       [0104] all percentages being by weight.  
       [0105] Another illustrative sublingual tablet of the invention containing as active agent a salt, e.g., the maleate salt, of sumanirole or (R)-5,6-dihydro-5-(methylamino)-4H-imidazo[4,5-ij]-quinoline-2(1H)-thione has a core having the following composition:  
                                                          active agent   0.1-3%   free base equivalent           lactose monohydrate   50-85%           pregelatinized starch   10-45%           xanthan gum   0-5%           flavoring agent   0-0.5%           coloring agent   0-0.5%           colloidal silicon dioxide   0-1%           magnesium stearate   0.5-5%                      
 
       [0106] all percentages being by weight.  
       [0107] Yet another illustrative sublingual tablet of the invention containing as active agent a salt, e.g., the maleate salt, of sumanirole or (R)-5,6-dihydro-5-(methylamino)-4H-imidazo[4,5-ij]-quinoline-2(1H)-thione has a core having the following composition:  
                                                          active agent   0.1-3%   free base equivalent           microcrystalline cellulose   30-70%           pregelatinized starch   25-65%           croscarmellose sodium   0-10%           xanthan gum   0-5%           flavoring agent   0-0.5%           coloring agent   0-0.5%           colloidal silicon dioxide   0-1%           magnesium stearate   0.5-5%                      
 
       [0108] all percentages being by weight. 
     
    
    
     EXAMPLES  
     [0109] The following examples illustrate aspects of the present invention but should not be construed as limitations. In these examples “compound Z” refers to (R)-5,6-dihydro-5-(methylamino)-4H-imidazo[4,5-ij]-quinoline-2(1H)-thione, maleate salt. All percentages are by weight unless otherwise indicated.  
     [0110] Example 1  
     [0111] A sublingual tablet formulation was prepared having the following composition:  
                                                      compound Z   1.11%           Avicel ™ PH-101 (microcrystalline cellulose)   46.71%           Starch 1500 of Colorcon (pregelatinized starch)   44.00%           croscarmellose sodium NF   5.00%           colloidal silicon dioxide NF   0.50%           cinnamon flavor   0.14%           mint flavor   0.04%           color (cherry shade #1632, Crompton &amp; Knowles)   0.50%           magnesium stearate   2.00%                      
 
     [0112] Pregelatinized starch and color were blended in a high-shear mixer for 2 minutes or until homogeneously mixed. The following ingredients were then individually layered over the resulting mixture in the high-shear mixer: compound Z; microcrystalline cellulose; colloidal silicon dioxide; croscarmellose sodium. Mixing in the high-shear mixer was resumed for a further 2 minutes. If the color was not adequately dispersed throughout the resulting mixture, mixing continued in 1 minute increments until good dispersion of color was observed. A small portion of the mixture was then removed and hand-mixed with magnesium stearate to form a magnesium stearate premix. This premix, together with the flavors, was added to the high-shear mixer and mixed for 1 minute to form a lubricated tablet stock.  
     [0113] The lubricated tablet stock was discharged from the high-shear mixer and stored in desiccated hermetically sealed containers until ready for tableting. Tablets were prepared by compression using {fraction (12/32)} inch (approximately 9 mm) Plain/Plain tooling with slight curvature to the following specifications:  
                                                          tablet weight   180   mg           hardness   3-4   SCU           friability   &lt;0.5%                      
 
     [0114] Example 2  
     [0115] Sublingual tablets prepared as in Example 1 were coated with a gellan gum coating according to the following procedure.  
     [0116] A coating liquid having the following composition was prepared:  
                                                      gellan gum (Kelcogel ™)   2.00%           sodium citrate   0.13%           propylene glycol   0.40%           lecithin   0.20%           deionized water   97.27%                      
 
     [0117] Deionized water was heated to 70° C. The other ingredients were added with stirring until all ingredients were homogeneously dispersed. The resulting coating liquid having a solids content of 2.73% was maintained at a temperature of 70° C. during the stirring and subsequent spraying procedure.  
     [0118] Tablets of Example 1, in an amount of 700 g, were placed in a 12 inch (approximately 300 mm) coating pan and preheated to a bed temperature of 60° C. The coating liquid was sprayed on to the tablets under the following conditions:  
                                                          outlet air temperature   50-60°   C.           pan speed   16   rpm           air flow   30-35   cfm (0.84-0.98 m 3 /minute)           atomizing air pressure   10   psi (69 kPa)           peristaltic pump setting   15-20   g/minute                      
 
     [0119] Spraying was continued until an amount of coating solution equivalent to a weight gain of 1.2% had been applied. The resulting coated tablets were cooled to 30° C. prior to discharge from the coating pan.  
     [0120] Example 3  
     [0121] A sublingual tablet formulation was prepared having the following composition:  
                                                      compound Z   1.05%           mannitol, granular   70.00%           sorbitol   16.57%           hydroxypropylcellulose, type LH-11   7.00%           xanthan gum   2.50%           colloidal silicon dioxide NF   0.50%           cinnamon flavor   0.14%           mint flavor   0.04%           color (cherry shade #1632, Crompton &amp; Knowles)   0.20%           magnesium stearate   2.00%                      
 
     [0122] Mannitol and color were blended in a high-shear mixer for 2 minutes or until homogeneously mixed. The following ingredients were then individually layered over the resulting mixture in the high-shear mixer: compound Z; sorbitol; hydroxypropylcellulose; xanthan gum; colloidal silicon dioxide. Mixing in the high-shear mixer was resumed for a further 2 minutes. If the color was not adequately dispersed throughout the resulting mixture, mixing continued in 1 minute increments until good dispersion of color was observed. A small portion of the mixture was then removed and hand-mixed with magnesium stearate to form a magnesium stearate premix. This premix, together with the flavors, was added to the high-shear mixer and mixed for 1 minute to form a lubricated tablet stock.  
     [0123] The lubricated tablet stock was discharged from the high-shear mixer and stored in desiccated hermetically sealed containers until ready for tableting. Tablets were prepared by compression using {fraction (12/32)} inch (approximately 9 mm) Plain/Plain tooling with slight curvature to the following specifications:  
                                                          tablet weight   190   mg           hardness   3-4   SCU           friability   &lt;0.5%                      
 
     [0124] Example 4  
     [0125] Sublingual tablets prepared as in Example 3 were coated with a gellan gum coating according to the following procedure.  
     [0126] A coating liquid having the following composition was prepared:  
                                                      gellan gum (Kelcogel ™)   2.00%           sodium citrate   0.13%           propylene glycol   0.40%           lecithin (Lipoid ™ LS-100)   0.20%           flavor   0.30%           deionized water   96.97%                      
 
     [0127] Deionized water was heated to 70° C. The other ingredients were added with stirring until all ingredients were homogeneously dispersed. The resulting coating liquid having a solids content of 3.03% was maintained at a temperature of 70° C. during the stirring and subsequent spraying procedure.  
     [0128] Tablets of Example 1, in an amount of 700 g, were placed in a 12 inch (approximately 300 mm) coating pan and preheated to a bed temperature of 60° C. The coating liquid was sprayed on to the tablets under the following conditions:  
                                                          outlet air temperature   50-60°   C.           pan speed   16   rpm           air flow   30-35   cfm (0.84-0.98 m 3 /minute)           atomizing air pressure   10   psi (69 kPa)           peristaltic pump setting   15-20   g/minute                      
 
     [0129] Spraying was continued until an amount of coating solution equivalent to a weight gain of 1.36% had been applied. The resulting coated tablets were cooled to 30° C. prior to discharge from the coating pan.  
     [0130] Example 5  
     [0131] A sublingual tablet formulation was prepared having the following composition:  
                                                      compound Z   0.43%           Avicel ™ PH-101 (microcrystalline cellulose)   47.39%           Starch 1500 of Colorcon (pregelatinized starch)   44.00%           croscarmellose sodium NF   5.00%           colloidal silicon dioxide NF   0.50%           cinnamon flavor   0.14%           mint flavor   0.04%           color (cherry shade #1632, Crompton &amp; Knowles)   0.50%           magnesium stearate   2.00%                      
 
     [0132] Pregelatinized starch and color were blended in a high-shear mixer for 2 minutes or until homogeneously mixed. The following ingredients were then individually layered over the resulting mixture in the high-shear mixer: compound Z; microcrystalline cellulose; colloidal silicon dioxide; croscarmellose sodium. Mixing in the high-shear mixer was resumed for a further 2 minutes. If the color was not adequately dispersed throughout the resulting mixture, mixing continued in 1 minute increments until good dispersion of color was observed. A small portion of the mixture was then removed and hand-mixed with magnesium stearate to form a magnesium stearate premix. This premix, together with the flavors, was hand screened through a #20 mesh pharmaceutical screen, then added to the high-shear mixer and mixed for 1 minute to form a lubricated tablet stock.  
     [0133] The lubricated tablet stock was discharged from the high-shear mixer and stored in desiccated hermetically sealed containers until ready for tableting. Tablets were prepared by compression using {fraction (12/32)} inch (approximately 9 mm) Plain/Plain tooling with slight curvature to the following specifications:  
                                                          tablet weight   180   mg           hardness   3.5-4   SCU           friability   &lt;0.8%                      
 
     [0134] Example 6  
     [0135] Sublingual tablets prepared as in Example 5 were coated with a gellan gum coating according to the following procedure.  
     [0136] A coating liquid having the following composition was prepared:  
                                                      gellan gum (Kelcogel ™)   2.00%           sodium citrate   0.13%           propylene glycol   0.40%           lecithin (Lipoid ™ LS-100)   0.20%           hot cinnamon flavor   0.30%           deionized water   96.97%                      
 
     [0137] Deionized water was heated to 70° C. The other ingredients were added with stirring until all ingredients were homogeneously dispersed. The resulting coating liquid having a solids content of 3.03% was maintained at a temperature of 70° C. during the stirring and subsequent spraying procedure.  
     [0138] Tablets of Example 5, in an amount of 7000 g, were placed in a 24 inch (approximately 600 mm) coating pan and preheated to a bed temperature of 60° C. The coating liquid was sprayed on to the tablets under the following conditions:  
                                          outlet air temperature   48-55°   C.       pan speed   10-14   rpm, preferably 14 rpm       air flow   300-400   cfm (8.5-11.3 m 3 /minute)       atomizing air pressure   20-35   psi (138-242 kPa),               preferably about 20 psi       peristaltic pump setting   15-40   g/minute/gun (2 gun spray system),               preferably 30-40 g/minute/gun       tablet bed temp   37-50°   C., preferably about 40° C.                  
 
     [0139] Spraying was continued until an amount of coating solution equivalent to a weight gain of 2.04% had been applied. The resulting coated tablets were cooled to 30° C. prior to discharge from the coating pan.