Antimicrobial Lozenges

The present invention relates to therapeutic lozenges which contain a cationic antimicrobial effective against plaque and gingivitis and a nonionic lubricant. The lozenges of the present invention provide a convenient and effective way to apply the antimicrobial agent in the mouth.

The use of cationic antimicrobial agents to reduce plaque and gingivitis has been recognized for many years. Included among references disclosing, such compositions are U.S. Pat. No. 3,937,805, Feb. 10, 1976 to Harrison; U.S. Pat. No. 3,937,807, Feb. 10, 1976 to Haefele; U.S. Pat. No. 4,080,441, Mar. 21, 1978 to Gaffar et al.; U.S. Pat. No. 4,118,474, Oct. 3, 1978 to Gaffar et al.; U.S. Pat. No. 4,241,049, Dec. 23, 1980 to Colodney et al.; U.S. Pat. No. 3,925,543, Dec. 9, 1975 to Donohue; U.S. Pat. No. 4,256,731, Mar. 17, 1981 to Curtis et al.; U.S. Pat. No. 4,217,342, Aug. 12, 1980 to Gaffar; U.S. Pat. No. 4,259,316, Mar. 31, 1981 to Nakashima et al.; U.S. Pat. No. 4,309,409, Jan. 4, 1982 to Coll-Palagos et al.; and U.S. Pat. No. 4,169,885, Oct. 2, 1979 to Raaf et al. In addition lozenges containing cationic antimicrobials have been sold and the patents to Curtis et al. and Raaf et al. disclose lozenges but not of the type of the present invention.

Plaque is a term commonly used to describe the colonization and growth of microorganisms on both the surface and subsurface regions of the teeth. Antimicrobials have been shown to be able to interrupt this cycle and thereby reduce the level of plaque formed but have oftentimes caused unacceptable levels of staining. Maintaining a high level of efficacy and acceptable staining has proven to be difficult to achieve.

It has now been found with the present lozenges that concentration of the antimicrobial in the mouth as the lozenge dissolves can be minimized without compromising the level of active in saliva after dissolution of the lozenge, which is therapeutically effective against plaque and gingivitis.

It is therefore an object of the present invention to formulate effective antiplaque/antigingivitis compositions. By reducing plaque, caries may also be reduced.

It is a further object of the present invention to formulate antiplaque/antigingivitis compositions which have reduced staining.

These and other objects will become more apparent from the detailed description which follows. All percentages and ratios herein are by weight unless otherwise specified.

The present invention relates to therapeutic lozenges containing a safe and effective amount of a cationic antimicrobial agent and a nonionic lubricant. The lozenges in addition contain pharmaceutically acceptable lozenge materials which are not cariogenic and are compatible with the cationic antimicrobial agent. The necessary as well as optional ingredients are described in detail below.

The ingredients used in the present compositions are described below as well as certain terms.

By "safe and effective amount of cationic antimicrobial", as used herein, means a sufficient amount to reduce plaque while being safe to the hard and soft tissues of the oral cavity.

By "compatible with the cationic antimicrobial", as used herein, is meant that any material present in the lozenge will not form an insoluble precipitate with the cationic antimicrobial.

By the term "cariogenic", as used herein, is meant substances capable of increasing the natural caries rate in the mouth.

By the term "comprising", as used herein, is meant that various additional components can be conjointly employed in the compositions of this invention as long as the cationic antimicrobial can perform its intended function.

The antimicrobials used in the compositions of the present invention can be any of a wide variety of cationic antimicrobial agents such as quaternary ammonium compounds (e.g. cetyl pyridinium chloride), and substituted guanidines such as chlorhexidine and the corresponding compound alexidine. Mixtures of cationic antimicrobials may also be used in the present invention.

Antimicrobial quaternary ammonium compounds include those in which one or two of the substituents on the quaternary nitrogen has a carbon chain length (typically alkyl group) of some 8 to 20, typically 10 to 18 carbon atoms while the remaining substituents (typically alkyl or benzyl group) have a lower number of carbon atoms, such as 1 to 7 carbon atoms, typically methyl or ethyl groups. Dodecyl trimethyl ammonium bromide, tetradecyl pyridinium chloride, tetradecyl ethyl pyridinium chloride, dodecyl dimethyl(2-phenoxyethyl)ammonium bromide, benzyl dimethylstearyl ammonium chloride, cetyl pyridinium chloride, quaternized 5-amino-1,3-bis(2-ethyl-hexyl)-5-methyl hexa hydropyrimidine and benzethonium chloride are exemplary of typical quaternary ammonium antibacterial agents. Other compounds are the bis[4-(R-amino)-1-pyridinium]alkanes as disclosed in U.S. Pat. No. 4,206,215, June 3, 1980 to Bailey incorporated herein by reference. The pyridinium compounds are the preferred quaternary ammonium compounds.

The substituted guanidines of this invention include bisbiguanide compounds having the generic formula ##STR1## wherein A and A' each represent either (1) a phenyl radical which optionally is substituted by an alkyl or alkoxy group containing from 1 to about 4 carbon atoms, a nitro group, or a halogen atom; (2) an alkyl group containing from about 1 to about 12 carbon atoms; or (3) alicyclic groups containing from 4 to about 12 carbon atoms; wherein X and X' each represent an alkylene radical containing from 1 to 3 carbon atoms; wherein Z and Z' each can be either 0 or 1; wherein R and R' each represent either hydrogen, an alkyl radical containing from 1 to about 12 carbon atoms, or an aralkyl radical containing from 7 to about 12 carbon atoms; wherein n is an integer from 2 to 12 inclusive; wherein the polymethylene chain (CH.sub.2).sub.n may optionally be interrupted by oxygen or sulfur atoms, aromatic nuclei, etc. The water soluble salts of the above compounds are preferred for use herein. Suitable water soluble salts include the chloride, the fluoride, and especially the acetate salt. The preferred substituted guanidine is chlorhexidine-[1,6-di(-N.sup.5 -pchlorophenyl-N-diguanido)hexane].

The cationic antimicrobial is generally used in the present compositions at a level of from about 0.02% to about 1%, preferably from about 0.3% to about 0.7% most preferably from about 0.3% to about 0.5%.

The use of a lubricant in the manufacture of compressed lozenges is to facilitate the release of the lozenge from the die in which it is formed. This function is described in detail in Pharmaceutical Dosage Forms: Tablets, Volume 1 edited by H. A. Lieberman and L. Lochman, New York; Marcel Dekker, Inc., 1980 incorporated herein by reference.

The lubricant used in the present invention is a solid material which is not charged and which will not interfere (e.g. complex) with the cationic antimicrobial. The material should preferably be water insoluble. One type of suitable material meeting these requirements is a non-toxic hydrocarbon fat or derivative. Examples include hydrogenated tallow and hydrogenated vegetable oil. Polyethylene glycols may also be used as a lubricant so long as they are solid materials which generally means having a molecular weight in the 4000 to 6000 range. These materials can also be used as a filler as noted below.

Mixtures of lubricants may also be used in the present invention. The lubricant is used at a level of from about 0.1% to about 4.0% preferably from about 0.5% to about 2%.

The "vehicle" as the term is used herein is the material(s) which carries the cationic antimicrobial and the nonionic lubricant. These materials are also known as "fillers". Since the vehicle is non-cariogenic the vehicle should be free of sucrose and similar materials. Acceptable filler materials include mannitol, sorbitol, xylitol, polyethylene glycol and non-cariogenic dextrans. The fillers may be used alone or in combination.

Mannitol is a naturally occurring sugar alcohol and is available as a fine powder. It has a sweetness of only about 50% of that of sucrose. However, mannitol's negative heat of solution enables it to impart a pleasant, cooling sensation in the mouth as the lozenge dissolves.

Sorbitol is a chemical isomer of mannitol and possesses a similar degree of sweetness. Its heat of solution, being negative, also provides for a pleasant, cooling sensation in the mouth. Sorbitol is available either as free flowing granules or as a crystalline powder.

Polyethylene glycols (PEG's) can also be used in the present compositions. These materials are polymers of ethylene oxide with the generalized formula HOCH.sub.2 (CH.sub.2 OCH.sub.2).sub.n CH.sub.2 OH. The use of PEG's alone is not favored but their use in combination with other fillers is acceptable. The molecular weights found most desirable are between 4000 and 6000.

Fillers are generally used in the present invention at a level of from about 85% to about 99.8%, preferably from about 90% to about 98%, most preferably from about 94% to about 97%.

Acceptable lozenges may be manufactured using just the active ingredient, the lubricant and the filler material as outlined above. However, in order to make the lozenges more acceptable from an aesthetic viewpoint, generally included are materials such as spray-dried or encapsulated flavors or liquid flavors adsorbed onto a suitable diluent. Spray dried or encapsulated flavors are preferred. Suitable flavors include oil of peppermint, oil of wintergreen, oil of sassafras, oil of spearmint and oil of clove.

Sweetening agents are also acceptable for use in the present compositions. Suitable agents include aspartame, acesulfame, saccharin, dextrose and levulose. Sweetening and flavoring agents are generally used in the compositions of this invention at levels of from about 0.1% to about 2%, preferably from about 0.25% to about 1.5%.

It is also acceptable to have a solid form of a water-soluble fluoride compound present in the present lozenges in an amount sufficient to give a fluoride concentration of from about 0.0025% to about 0.5% by weight, preferably from about 0.005% to about 2.0% by weight, to provide additionally anticaries effectiveness. Preferred fluorides are sodium fluoride, stannous fluoride, indium fluoride, and sodium monofluorophosphate. Norris et al., U.S. Pat. No. 2,946,735, issued July 26, 1960 and Widder et al., U.S. Pat. No. 3,678,154, issued July 18, 1972 disclose such salts as well as others.

The size and shape of the present lozenges are not critical so long as the lozenge can be easily dissolved in the mouth. Exemplary shapes, weighing from about one to four grams, include cubes, spheres, saucer shapes, cones, cylinders and rectangular parallelopipeds among many others. A convenient shape is a rectangular parallelopiped measuring 1.5 cm.times.1.5 cm.times.0.5 cm.

A method for manufacturing the lozenges of the present invention is given in Example I

The lozenges of the present invention are dissolved in the mouth thereby releasing the antimicrobial agent.

The following examples further describe and demonstrate preferred embodiments with the scope of the present invention. The examples are given solely for illustration and are not to be construed as limitations of this invention as many variations thereof are possible without departing from the invention's spirit and scope.

The following are chlorhexidine lozenges of the present invention.

These compositions are prepared by mixing the active, sweetener, flavor and filler together in a Patterson-Kelley 16-quart, Model LB-16P, Liquid-Solids Laboratory Twin Shell Blender and mixing for about 45 minutes. The lubricant is then added and an additional 45 minutes of mixing is carried out. The powder is then transferred to a tablet press and the tablets are formed using 70 kN of pressure.

These compositions possess effective antiplaque activity and good consumer properties. In the compositions chlorhexidine may be replaced by other substituted guanidines such as alexidine or quaternary compounds such as cetyl pyridinium chloride, tetradecyl pyridinium chloride, tetradecyl ethyl pyridinium chloride and benzethonium chloride. Likewise sorbitol may be replaced in whole or in part by mannitol or in part by polyethylene glycols or a mixture of mannitol and polyethylene glycols or mixtures of all three.

The biocidal activity of chlorhexidine in lozenges containing either magnesium stearate or Sterotex lubricant (as described in the preceding examples). The Sterotex product was as set forth in Example I while the magnesium stearate product had the following composition.

A representative lozenge of each type was ground to a fine powder and sufficient powder was weighed into a glass vial to yield a final concentration of 200 ppm chlorhexidine in 10 ml. Nine ml of water was added to the vial after which the vial was shaken well to dissolve the powder. Test bacteria, E. coli, in an amount of one ml of log 7.4/ml concentration was introduced into the vial one minute after the water was added. Survival of the bacteria was then monitored over time with the following results.

The composition of this invention clearly demonstrates superiority over a composition using a lubricant not within the scope of the claimed invention.