Treatment of experimental schistosomiasis mansoni with praziquantel alone and combined with cimetidine.

In this work, praziquantel (EMBAY 8440, CAS 55268-74-1), an oral antihelminthic drug effective against the three species of schistosomes pathogenic to man, was tested alone and in combination with cimetidine (CAS 51481-61-9), aH2-receptor antagonist having a known potentiative power when combined with other drugs. Both drugs were tested in different doses and regimen either alone or in combination by giving them to S. mansoni infected Swiss albino mice (100 cercariae/mouse) 7 weeks post infection. Cimetidine was tested in doses of 50, 100 and 200 mg/kg for 2 consecutive days; praziquantel was given in doses of 100 and 500 mg/kg for 2 consecutive days. It was found that the best regimen was that of cimetidine and praziquantel when given simultaneously. Both drugs when given in a dose of 100 mg/kg for 2 consecutive days reduced the total worm load by 84.61%, while a percent reduction of 75.1% and 88.9% was recorded in hepatic and intestinal tissue egg load, respectively. Maximum efficacy was recorded when both drugs were given simultaneously at 200 mg/kg for 2 consecutive days. This regimen completely eradicated all schistosome worms and resulted in the maximum reduction in total tissue egg load (92%). The efficacy of this regimen was nearly the same as that of the full dose of praziquantel (500 mg/kg for 2 consecutive days), gave 100% worm eradication and 95% reduction in total tissue egg load.