Effect of allopurinol on tolbutamide pharmacokinatics and hypoglycaemic activity in rabbits

The effect of allopurinol on pharmacokinetic parameters and hypoglycemic activity of tolbutamide was assessed in fasted rabbits. Pretreatment of animals with allopurinol [30 mg/kg orally] 2 hours before tolbutamide injection [50 mg/kg i.v.] resulted in a significant increase in plasma tolbutamide levels compared to those of rabbits received tolbutamide alone. The plasma half life [t1/2] of tolbutamide increased from 6.60 to 12.83 hours by allopurinol pretreatment. The hypoglycemic activity of tolbutamide was also significantly enhanced in rabbits received allopurinol. These results suggested the importance of tolbutamide dosage adjustment when allopurinol is given concurrently

Competitive binding of digitoxin and frusemide to bovine serum albumin

The binding of digitoxin [DG] and frusemide [FR], each alone and in combination, to bovine serum albumin [BSA] was investigated by ultrafiltration technique. The results obtained were used to construct Scatchard plots revealing that there are marked differences in the binding characteristics of both drugs. In the presence of FR, the extent of binding of DG to BSA was significantly reduced with the appearance or a secondary class of binding sites for DG, in addition to the primary class, but with lower affinities and capacities. On the other h and, DG had insignificant effect on the binding characteristics of FR. The results indicated that the interactions between FR and DG for binding sites on BSA are competitive