Bioavailability of a commercial sustained-release quinidine tablet compared to oral quinidine solution

The bioavailability of quinidine sulfate after oral administration of a commercial sustained-release quinidine tablet was compared with that of oral quinidine sulfate solution in 18 normal subjects. Three hundred milligrams of each product was administered to each subject in standard cross-over fashion on separate occasions, with plasma quinidine levels measured for 46 h after each dose. Although peak plasma quinidine levels were lower, and occurred later, after tablet administration than after solution, analysis of the area under the plasma quinidine level-time curve (AUC) values for each product indicated that the products were equivalent, in terms of the extent of absorption, with the mean AUC (0-46 h) value for the tablet, 8744 . 4 ng x h ml-1, comparable to that of the solution, 9145 . 9 ng x h ml-1.