Bioavailability of potassium from three dosage forms: suspension, capsule, and solution

A crossover study was performed in 28, healthy, male volunteers to determine the bioavailability of potassium from a suspension containing microencapsulated potassium chloride compared with that from a marketed microencapsulated potassium chloride capsule and a marketed potassium chloride solution. The 20-day study consisted of four, five-day periods. In three of the periods, a single, 40-mEq dose of one of the potassium formulations was administered; no drug treatment was given in the remaining period so that the amount of potassium contributed by dietary sources could be determined. Meals were served that provided controlled amounts of potassium and sodium. Bioavailability was represented by cumulative amount of K+ excreted in urine 24 and 48 hours after drug administration. The rate of absorption was calculated from excretion rates during each of the intervals of urine collection on Days 4. The pattern of excretion exhibited by the solution indicated rapid absorption and elimination. The potassium from the suspension and the capsules was excreted more slowly and over a longer period, indicating that the potassium content from these formulations was not being dumped. No statistically significant differences between the suspension and the capsules were found. The extent of absorption of K+ was similar from all three products, and the potassium from the suspension was found to be fully bioavailable when compared with the liquid and the capsule.