The effect of aluminum hydroxide gel on quinidine gluconate bioavailability was studied in eight nonsmoking healthy male volunteers. Subjects were randomized to receive quinidine gluconate 648 mg with and without 30 mL of aluminum hydroxide gel. The mean area under the concentration-time curve (AUC) (23.11 +/- 5.21 mg.h/L), time to reach maximum concentration (tmax) (3.13 +/- 0.64 h), maximum serum concentration (1.44 +/- 0.41 mg/L), and elimination rate constant (0.069 +/- 0.010-h) observed during the control phase of the trial did not differ significantly (p greater than 0.05) from values obtained during the coadministration of aluminum hydroxide with quinidine gluconate (23.91 +/- 4.48 mg.h/L, 4.13 +/- 2.12 h, 1.53 +/- 0.34 mg/L, and 0.077 +/- 0.013-h, respectively). There was considerable individual variation in AUC with one subject demonstrating an increase of 35 percent and one subject demonstrating a decrease of 18 percent. There was a trend toward aluminum hydroxide delaying tmax with only one subject experiencing an earlier tmax with the coadministration of aluminum hydroxide. The results of this single-dose trial suggest that, although statistically the concurrent administration of aluminum hydroxide gel with quinidine gluconate does not significantly alter the extent of quinidine absorption, clinically significant individual variations may occasionally occur.