Effect of hepatic and renal dysfunction on disposition of bupropion in rats

Disposition of bupropion after oral administration was investigated in carbon tetrachloride (CCl4) and gentamicin treated rats. Bupropion exhibits extensive first-pass effect and is mainly cleared by hepatic route. In rats with hepatic damage, maximum plasma concentration (Cmax) was approximately 3 times higher and area under the plasma concentration-time curve up to 6 h (AUC 0-6) and AUC 0-infinity increased on an average 4 and 5 times respectively compared to the control. The half-life was doubled with hepatic dysfunction. These findings suggest that hepatic impairment in rats causes a decrease in first pass effect as well as an increase in the half-life of the drug. Rats with renal impairment, exhibited a significant increase in Cmax, AUC 0-6 and AUC 0-infinity of bupropion approximately 3-fold as compared to the control, no change in half life of the drug was observed. This indicates that rats with renal impairment show less efficient first-pass effect which may lead to increase in systemic bioavailability. The time to peak observed in all treated animals was not significantly different from the control. The percentage of bound bupropion did not differ either in CCl4 or gentamicin treated plasma as compared to the control.