Plasma concentrations and bioavailability of clofibric acid from its calcium salt in humans.

The bioavailability of clofibric acid from formulations containing calcium clofibrate along and mixed with calcium carbonate (1:1 w/w) was compared to that from a standard clofibrate formulation in a crossover study in 12 human subjects. The 95% confidence intervals of bioavailability differences were such that they were unlikely to be detected in clinical practice; all three formulations may be considered bioequivalent, although the bioavailability rate was probably greater from the formulation containing calcium clofibrate alone. Peaks of mean concentrations of 80 +/- 13,67 +/- 16, and 64 +/- 18 microgram/ml +/- SD occurred after administration of 853 mg of clofibric acid calcium salt alone, 809 mg of clofibric acid calcium salt mixed with calcium carbonate, and 885 mg of clofibrate, respectively; mean concentrations declined from peak levels with half-lives of 15-17 hr.