Bioavailability of indomethacin capsules in humans. (I): Bioavailability and effects of gastric acidity.

The bioavailabilities of five indomethacin capsules, two commercial and three experimental products, were studied in ten human subjects. The bioavailabilities of the products increased in proportion to their in vitro dissolution rates, although one of the commercial products provided a relatively lower bioavailability than was expected. Comparison of the bioavailabilities between high and low gastric acidity humans revealed that the serum levels of the drug during the absorption phase following oral administration of all the indomethacin products, except for one commercial product, were higher in the low acidity subjects than in the high acidity subjects. Also, the mean peak serum level of the most rapidly dissolving product was 1.6 times higher in the low acidity subjects than in the high acidity ones. These gastric acidity effects indicated enhanced dissolution of indomethacin from the capsules in the stomach of low acidity humans.