Composition and method for treatment of acne
RELATIONSHIP TO EARLIER FILED APPLICATIONS 
     This application is a Continuation-in-Part of U.S. Ser. No. 533,617 filed Dec. 19, 1974 now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates generally to topical treatment of acne. More particularly, the invention relates to a method for the topical treatment of acne vulgaris with antibiotics of the lincomycin family. 
     Acne is the name commonly applied to any inflammatory disease of the sebaceous glands; also acne vulgaris. Acne vulgaris is a common inflammatory disorder of the skin first appearing in early adolescence. Endocrinological factors are thought to be of prime importance in producing a hyperactivity of the sebaceous glands which leads to the condition. Acne lesions contain no pathogenic organisms, despite the presence of pus. Sebum, a liquid secreted by the sebaceous glands, is thought to contain an irritant factor that results in the production of comedones which form an integral part of the disease. Corynebacterium acnes, ordinarily a member of the normal flora of the skin, is found in quantity in some acne lesions. Some observers believe that C. acnes plays a part in the pathogenesis of the acne lesion. For example, it is known that oral administration of antibiotics such as tetracycline reduce the population of C. acnes in the skin. 
     Various therapeutic methods for treating acne have been attempted including topical antibacterials, e.g. hexachlorophene, and systemic antibiotics such as tetracycline and clindamycin. While the systemic antibiotic treatment have been effective, the topical antibacterial treatments have not been effective. 
     It has long been known that systemic treatment of acne is not preferred because of side effects resulting from saturation of the entire body with antibiotics and the fact that only the affected skin need be treated. However, despite a long-felt need for a topical treatment for acne, antibiotics generally have been used only sytemically to treat acne because it was not heretofore believed that antibiotics could be used effectively in the topical treatment of acne. 
     SUMMARY OF THE INVENTION 
     It has now unexpectedly been discovered that certain active antibiotics may be used topically in the treatment of acne. 
     The invention relates to a method for temporarily alleviating the signs and symptoms of acne by topically administering to humans or animals antibiotics of the lincomycin family. The foregoing method is carried out by topically administering to a human or animal an effective amount of a composition containing about 0.1 to about 10% by weight of an antibiotic of the lincomycin family. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The term &#34;antibiotic of the lincomycin family&#34; is used herein to refer to a class of antibiotic originally elaborated by an actinomycete Streptomyces lincolnensis. These compounds and their methods of synthesis are shown in U.S. Pat. Nos. 3,086,912 and 3,155,580. The structural formula of lincomycin is as follows: ##SPC1## 
     Lincomycin 
     Clindamycin is the 7-deoxy, 7-chloro derivative of lincomycin. Typical examples of antibiotics of the lincomycin family include lincomycin, mirincamycin, clindamycin, N-demethyl clindamycin and their pharmaceutically acceptable salts, e.g. clindamycin free base, clindamycin phosphate, clindamycin HCl, etc. 
     The amount of antibiotic of the lincomycin family which may be used in the present invention ranges from about 0.1 to about 10 percent by weight and preferably about 0.5 to about 5 percent by weight of the composition. 
     An effective amount of the composition, as the term is used herein, refers to that amount of composition which is effective therapeutically in the treatment of acne, especially acne vulgaris. The composition is generally applied about 1-4 times daily in conventional amounts, that is, amounts sufficient to thinly spread over the affected areas. The treatment is continued until or after all of the manifestations of acne have disappeared. 
     The antibiotics of the lincomycin family described herein may be dissolved in a suitable topical formulation and topically applied to affected areas of the skin in any convenient form, e.g. cream, lotion, spray, solution, etc. 
     Ingredients which may be used in these formulations include conventional formulating ingredients, such as, for example, Freons, ethyl alcohol, isopropyl alcohol, acetone, polyvinyl pyrrolidone, propylene glycol, fragrances, gel-producing materials, mineral oil, water, stearyl alcohol, stearic acid, spermaceti, sorbitan monooleate, Polysorbate 80, Tween 60, sorbital solutions, methylcellulose. Preferred ingredients include alcohols and other materials which enhance percutaneous absorption of antibiotics of the lincomycin family, including 2-pyrrolidone and N-lower alkyl substituted-2-pyrrolidones, e.g. N-methyl-2-pyrrolidone. 
     2-Pyrrolidone and N-lower alkyl-2-pyrrolidones are available commercially and are made by a number of methods known to those of skill in the art as exemplified by U.S. Pat. Nos. 2,555,353 and 2,267,757. N-lower alkyl-2-pyrrolidones include the straight and branch chain lower alkyl groups having 1-4 carbon atoms. N-methyl-2-pyrrolidone is preferred. 
     The amount of 2-pyrrolidone or N-lower alkyl-2-pyrrolidone which may be used in the present formulation ranges from about 5 to about 99.9 percent and preferably 10-50 percent by weight of the composition. 
    
    
     Following are specific examples which demonstrate the effectiveness of various forms of this invention. 
     EXAMPLE I 
     A clinical and microbiological study was carried out to show the effectiveness of the composition of the present invention in the treatment of acne. 5-6 human subjects with acne vulgaris were used in each determination. Formulations A, B and C (Table 1) were applied to each patient&#39;s face twice daily in an amount of about 0.5 cc per day. Comedones were removed with an extractor and put into a gelatin capsule. The capsule was dissolved in warm phosphate buffer and an aliquot plated on a special medium in dilutions which were cultured anaerobically for 7 days. The counts of C. acnes are expressed as the number of C. acnes per milligram of comedone material. Clinical appraisal was carried out at biweekly intervals. The results of the study are shown in Table 2 and 3 below. 
     
                       Table 1                                                     
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 Ingredients       A        B        C                                    
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Tetracycline HCl    1%      --       --                                   
Clindamycin phosphate                                                     
                   --       1%       --                                   
N-methyl-2-pyrrolidone                                                    
                   99%       99%     100%                                 
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                       Table 2                                                     
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Antibacterial Evaluation of Antibiotics                                   
Active Against C. acnes in the Treatment of Acne                          
       Comedone Bacterial (C. acnes) Count, No./mg                        
       Evaluation time, weeks                                             
Preparation                                                               
         0       2        4      6      8                                 
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A        3×10.sup.7                                                 
                 1×10.sup.7                                         
                          3×10.sup.6                                
                                 6×10.sup.6                         
                                        3×10.sup.7                  
B        3×10.sup.6                                                 
                 2×10.sup.5                                         
                          2×10.sup.3                                
                                 2×10.sup.1                         
                                        3×10.sup.1                  
C        2×10.sup.6                                                 
                 3×10.sup.6                                         
                          7×10.sup.5                                
                                 2×10.sup.6                         
                                        3×10.sup.7                  
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                       Table 3                                                     
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Clinical Evaluation in the Treatment of Acne.sup.a                        
         Evaluation time, weeks                                           
Preparation                                                               
           0      2        4      6      8                                
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A          --     0.7      1.0    0.8    1.1                              
B          --     2.2      3.1    3.5    3.5                              
C          --     0.5      0.6    0.7    0.9                              
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 .sup.a) Appraisal based upon following scale:                            
 0 = no response                                                          
 1 = slight improvement                                                   
 2 = good improvement                                                     
 3 = very good improvement                                                
 4 = dramatic improvement                                                 
 
    
     The results of the foregoing tests show that formulation A (tetracycline) is essentially ineffective as is formulation C (a penetrating vehicle) alone. However, the results of the foregoing tests show a dramatic improvement with formulation B (a clindamycin together with a penetrating vehicle). 
     EXAMPLE II 
     Additional studies were performed with a clindamycin alone and with a clindaymcin with various vehicles to enhance percutaneous absorption. Each of the formulations shown in Table 1 was clinically tested in 15 acne patients over an 8-week period. 
     
                       Table 1                                                     
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             Formulation (%)                                              
 Ingredient    A        B        C     D                                  
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Clindamycin phosphate                                                     
               1.3      1.3      --    --                                 
Clindamycin base                                                          
               --       --        1     1                                 
N-methyl-2-pyrrolidone                                                    
                34      --        34   --                                 
Adjuvant solvent                                                          
topical solution qs. ad                                                   
               100      100      100   100                                
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     The results of the study showed substantial improvement in most patients as shown in Tables 2 and 3 below. Table 2 describes the results in terms of clinical evaluation of the patients. 
     
                       Table 2                                                     
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            Clinical Evaluation:                                          
            Initial vs Final                                              
Formulation   Improved   Same     Worse                                   
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A             13         2        0                                       
B             12         2        0                                       
C             13         2        0                                       
D              7         8        0                                       
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     Table 3 describes the results in terms of the bacterial count of the comedones at the end of the two-month study. 
     
                       Table 3                                                     
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          Bacterial Count                                                 
                           Not decreased                                  
Formulation Decrease to 0  to 0                                           
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A           11             3                                              
B           6              7                                              
C           6              9                                              
D           5              7                                              
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     The foregoing study demonstrates the effectiveness of the formulations tested in the treatment of acne. 
     EXAMPLE III 
     The studies of Example II are repeated using clindamycin HCl, lincomycin, N-demethyl clindamycin and mirincamycin in the place of clindamycin phosphate. Comparable results are obtained. 
     EXAMPLE IV 
     Example III is repeated, except that the N-methyl-2-pyrrolidone is replaced by each of 2-pyrrolidone, N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone and N-isobutyl-2-pyrrolidone. Comparable results are obtained. 
     EXAMPLE V 
     The following cream formulations are prepared: 
     
                        Creams (%)                                                 
               A     B       C       D                                    
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Clindamycin       1       1       1     1                                 
N-methyl-2-pyrrolidone                                                    
                  25      20      34    42                                
Stearyl alcohol   12     --      --     10                                
Stearic acid     --       19      18    6                                 
Synthetic spermaceti                                                      
                 7.5     --      2      4                                 
Sorbitan monooleate                                                       
                 1.0     --      --    --                                 
Polysorbate 80   5.5     --      --    --                                 
Tween 60         --      3.5     3.5   3.5                                
Arlacel 60       --      3.5     3.5   1.5                                
Sorbitol solution                                                         
                 5.5     19.4    14    10.5                               
Mineral oil      --      2       --    --                                 
Methocel 90 HG:100                                                        
                 --      0.2     0.2   0.2                                
Fragrances       0.2     --      --    --                                 
Sodium citrate   0.5     --      --    --                                 
Water qs. ad     100     100     100   100                                
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     EXAMPLE VI 
     The following solution formulations are prepared: 
     
                      Solutions (%)                                                
             A     B        C        D                                    
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N-demethyl clindamycin                                                    
               --      --       1      --                                 
Clindamycin phosphate                                                     
               1       --       --     1                                  
Mirincamycin   --      1        --     --                                 
N-methyl-2-pyrrolidone                                                    
               --      --       --     25                                 
Isopropyl myristate                                                       
               5       5        5      --                                 
Propylene glycol                                                          
               --      --       --     33                                 
Fragrance      0.1     0.1      0.1    0.1                                
Adjuvant solvent                                                          
               ethanol iso-     acetone                                   
                                       iso-                               
qs. ad 100%            propyl          propyl                             
                       alcohol         alcohol                            
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     EXAMPLE VII 
     An aerosol form of formulation A of Example VI is prepared by preparing the following mixture: 
     
         formulation B            25%                                              
Freon.sup.1              75%                                              
 .sup.1 Freon is 75/25 Freon 114/12.                                      
 
    
     EXAMPLE VIII 
     The following gel formulations are prepared: 
     
                        Gel (%)                                                    
               A         B                                                
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Lincomycin base   1          --                                           
Clindamycin phosphate                                                     
                 --          1                                            
Carbopol 934      1          --                                           
Carbopol 940     --          0.75                                         
Ethanol          50          50                                           
Ethoxyl 16R      --          2                                            
Diethanolamine   --          0.5                                          
di-2(ethylhexyl)amine                                                     
                 --          0.5                                          
Water qs. ad     100         100                                          
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