Effect of combined low dose praziquantel and oxamniquine on different stages of schistosome maturity.

Combined low doses of praziquantel and oxamniquine were tested against different stages of Schistosoma mansoni in infected Swiss albino mice. The effect of combination therapy (1/3 the curative dose of praziquantel plus 1/3 the curative dose of oxamniquine) was compared with the effect of each drug alone, in reduced or full dose. Comparison with infected untreated controls was also made. Drug effects were evaluated on different growth stages of schistosomes by administering the drugs 24 h before infection and 4 h, 1, 2, 3, 4 and 5 weeks after infection. Animals were killed 8 weeks after infection. Worm burden, distribution, tissue egg load and oogram pattern were used in assessing drug efficacy. A potentiating effect was observed in animals receiving combination therapy. The combination regimen was most effective 4 h after infection, producing 96% worm reduction; eggs were not detected in the liver or intestine. Five weeks after infection the same regimen resulted in 98% reduction in the tissue egg load.

Pharmacological effects of althesin and its steroidal components on the cardiovascular system.

Althesin and its two steroidal components elicited, despite a deficit vasopressor effect by their solvent vehicle Cremophor El, a well-marked hypotensive activity appearing abruptly after i.v. injection in chloralosed cats. This vasodepressor effect which was weaker and shorter lasting with alphadolone acetate than alphaxalone proved to be one-cholinergic, nonhistaminergic, not mediated via any ganglionic blocking activity and ;mostly attributable to central depressant action on vasomotor tone. An appreciable direct myocardial inhibition and a much weaker direct peripheral vasodilatation were shown to be contributory factors to the hypotension. ECG studies in chloralosed cats indicated the occurrence of mild grade bradycardia or else no evident change in the heart rate under the influence of althesin and its steroidal components. A definite protective influence for althesin mainly due to alphaxalone against adrenaline induced arrhythmia in chloralosed cats was also demonstrated.