Combination of pentamidine and trimethoprim-sulfamethoxazole in therapy of Pneumocystis carinii pneumonia in rats.
Treatment with either pentamidine isethionate or trimethoprim-sulfamethoxazole significantly reduces the mortality of Pneumocystis carinii pneumonia. It is not known whether a combination might act in an additive, synergistic, or antagonistic manner. We studied the interaction of these two agents in the steroid-conditioned rat model of pneumocystosis. Of animals receiving pentamidine alone, 48% died and 45% had P. carinii cysts at autopsy. Trimethoprim-sulfamethoxazole alone resulted in 21% mortality, and cysts were found in 28%. Both agents in full doses resulted in 45% deaths and cysts in 37%. Animals treated with half-dosages of pentamidine plus trimethroprim-sulfamethoxazole had mortality of 35%, and 21% had cysts. Trimethoprim alone, in two dosages, was ineffective in eradicating P. carinii cysts. The data suggest that combination therapy is no more effective than trimethoprim-sulfamethoxazole alone in the treatment of P. carinii pneumonia.
D000578:Amidines / Q000627:therapeutic use*; D000818:Animals; D003560:Cysts / Q000473:pathology; D004359:Drug Therapy, Combination; D008297:Male; D010419:Pentamidine / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D011020:Pneumonia, Pneumocystis / Q000188:drug therapy* / Q000473:pathology; D051381:Rats; D013420:Sulfamethoxazole / Q000008:administration & dosage / Q000627:therapeutic use*; D014295:Trimethoprim / Q000008:administration & dosage / Q000627:therapeutic use*
D000578:Amidines; D010419:Pentamidine; D014295:Trimethoprim; D013420:Sulfamethoxazole