Asian Pacific journal of tropical medicine

Rifabutin reduces systemic exposure of an antimalarial drug 97/78 upon co-administration in rats: An in-vivo &in-vitro analysis.

PMID 26321516


To determine the potential drug-drug interactions between anti-malarial candidate 97/78 and anti-tubercular drug rifabutin in-vivo in rats followed by in-vitro investigation of the underlying mechanisms of drug interaction. Single oral dose study was conducted in male and female rats at 40xa0mg/kg and 70xa0mg/kg for 97/78 and rifabutin respectively. It was reported that rifabutin co-administration altered pharmacokinetics of 97/63 (active metabolite of 97/78). A significant decrease was reported in the systemic exposure of 97/63 by a factor of 3-4. The AUC0-last values were (4.03xa0±xa00.60) and (5.44xa0±xa01.15)xa0μgxa0hxa0mL(-1) upon 97/78 administration alone, while the values were decreased to (1.13xa0±xa00.10) and (1.23xa0±xa01.13)xa0μgxa0hxa0mL(-1) upon rifabutin co-administration in male and female rats respectively. Statistically significant differences were also reported in Cmax and Tmax values upon rifabutin co-administration. In-vitro drug metabolism study in rat liver microsomes has shown that the metabolism of 97/63 was increased by 10%-12% upon rifabutin co-incubation. The extent of plasma protein binding of 97/63 was found to be decreased from 54%-55% to 6%-8% upon rifabutin addition. It was concluded that rifabutin co-administration altered PK parameters of 97/63 in SD rats. However, no intersex influences were reported in the interaction pattern. The results obtained in the in-vivo study were well correlated with the in-vitro findings and can further be applied to explore other aspects of potential drug interactions between these two drugs.

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R3530 Rifabutin, >98% (HPLC), powder