Stabilized photoprotective composition

Abstract

Sunscreen compositions contain the active ingredients avobenzone, zinc oxide and phenylbenzimidazole sutfonic acid. The phenylbenzimidazole sulfonic acid protects avobenzone against photodegradation.

1 - 16 . (canceled)  
   
   
       17 . A sunscreen composition comprising avobenzone and sufficient phenylbenzimidazole sulfonic acid to stabilize the avobenzone against photodegradation, wherein the composition does not contain a diester or polyester of a naphthalene dicarboxylic acid.  
   
   
       18 . The composition of  claim 17 , wherein the concentration of avobenzone is about 1 to about 3 weight percent, and the concentration of phenylbenzimidazole sulfonic acid is about 0.5 to about 4 weight percent.  
   
   
       19 . The composition of  claim 17 , further containing zinc oxide  
   
   
       20 . The composition of  claim 17 , wherein in the zinc oxide is present in an amount of about 3 weight percent.  
   
   
       21 . The composition of  claim 17 , wherein the concentration of phenylbenzimidazole sulfonic acid is about 1 weight percent.  
   
   
       22 . The composition of  claim 17 , which is in the form of an emulsion.  
   
   
       23 . The composition of  claim 22 , wherein the emulsion is an oil-in-water emulsion.  
   
   
       24 . A method for protecting the skin against ultraviolet radiation, comprising applying to the skin an effective amount of the composition of  claim 17 .  
   
   
       25 . A method for protecting the skin against ultraviolet radiation, comprising applying to the skin an effective amount of the composition of  claim 19 .  
   
   
       26 . A method for increasing the SPF value of a sunscreen composition comprising avobenzone, the method comprising adding to the composition an amount of phenylbenzimidazole sulfonic acid sufficient to photostabilize avobenzone, thereby increasing the SPF value, wherein the composition does not contain a diester or polyester of a naphthalene dicarboxylic acid.  
   
   
       27 . The method of  claim 26 , wherein the composition further comprises zinc oxide.  
   
   
       28 . The method of  claim 27 , wherein zinc oxide is present in the composition in an amount of about 3 weight percent.  
   
   
       29 . The method of  claim 26 , wherein the concentration of avobenzone is about 1 to about 3 weight percent, and the concentration of phenylbenzimidazole sulfonic acid is about 0.5 to about 4 weight percent.  
   
   
       30 . The method of  claim 26  wherein the amount of phenylbenzimidazole sutfonic acid is about 1 weight percent.  
   
   
       31 . A method for improving the photostability of avobenzone in a sunscreen composition, the method comprising adding to the composition an amount of phenylbenzimidazole sulfonic acid sufficient to photostabilize avobenzone, wherein the composition does not contain a diester or polyester of a naphthalene dicarboxylic acid.  
   
   
       32 . The method of claim  3   1 , wherein the composition further comprises zinc oxide.  
   
   
       33 . The method of  claim 32 , wherein zinc oxide is present in the composition in an amount of about 3 weight percent.  
   
   
       34 . The method of  claim 31 , wherein the concentration of avobenzone is about 1 to about 3 weight percent, and the concentration of phenylbenzimidazole sulfonic acid is about 0.5 to about 4 weight percent.  
   
   
       35 . The method of  claim 31 , wherein the amount of phenylbenzimidazole sulfonic acid is about 1 weight percent.