Enhancing the toxicity of warfarin in rodents

Abstract

The presence of a small amount of an antibiotic, such as metronidazole or a salt or derivative thereof, in warfarin-containing rodent baits enhances the toxicity of warfarin against rodents which have heretofore shown apparent resistance to warfarin.

I claim:  
     
         1 . A method of enhancing the efficiency of warfarin in a rodenticide which comprises adding to a warfarin-containing rodenticidal composition an antibiotic selected from the group consisting of cotrimoxazole, metronidazole, erythromycin, fluconazole, isoniazid, miconazole, ciprofloxacin, and itraconazole, or a salt of said antibiotic, the amount of antibiotic being sufficient to inhibit the action of bacteria present in the gastrointestinal tract of a rodent.  
     
     
         2 . A method according to    claim 1    in which the antibiotic is metronidazole.  
     
     
         3 . A method for killing rodents which comprises causing the rodents to ingest a composition comprising a rodenticidally effective amount of warfarin and an antibiotic selected from the group consisting of cotrimoxazole, metronidazole, erythromycin, fluconazole, isoniazid, miconazole, ciprofloxacin, and itraconazole, or a salt of said antibiotic, in an amount sufficient to inhibit the action of bacteria present and to reduce the amount of vitamin K in the gastrointestinal tract of said rodents.  
     
     
         4 . A method according to    claim 3    in which the antibiotic is metronidazole or a salt thereof.  
     
     
         5 . A composition for killing rodents comprising (a) a rodenticidally effective amount of warfarin and (b) an antibiotic selected from the group consisting of cotrimoxazole, metronidazole, erythromycin, fluconazole, isoniazid, miconazole, ciprofloxacin, and itraconazole, or a salt of said antibiotic, in an amount sufficient to inhibit the action of bacteria present in the gastrointestinal tract of the rodent.  
     
     
         6 . A composition according to    claim 5    in which said composition comprises the antibiotic or a salt of the antibiotic suspended in a solid carrier.  
     
     
         7 . A composition according to    claim 6    in which the antibiotic or salt thereof is present in an amount of from about 0.05 to 1.0 percent based on the weight of the composition.  
     
     
         8 . A composition according to    claim 7    in which warfarin is present in an amount of from about 50 to about 300 ppm.  
     
     
         9 . A composition according to    claim 5    in which the antibiotic is metronidazole or a salt thereof.