Bioavailability of hydrocortisone retention enemas in relation to absorption kinetics

The rate and extent of absorption of hydrocortisone from two commercial formulations of rectal enemas were determined in 12 normal subjects. The bioavailability of the enema was related to its absorption rate constant. Four subjects absorbed hydrocortisone slowly from both enemas at a mean rate of 0.361 hr-1 and five subjects absorbed hydrocortisone rapidly from both preparations at a mean rate of 1.05 hr-1 (p < 0.001). The bioavailability of hydrocortisone retention enemas ws 0.810 and 0.502 in slow and rapid absorbers (p < 0.01).