Actions of prednisolone acetate, pregnenolone-16alpha-carbonitrile, and triamcinolone upon drug resistance and metabolism: a comparative study.

In female rats, pretreatment with prednisolone acetate diminished the duration of zoxazolamine-induced paralysis as well as its plasma concentrations and increased significantly the in vitro metabolism of zoxazolamine and ethylmorphine. These actions of prednisolone were compared with those of equimolar amounts of pregnenolone-16alpha-carbonitrile (PCN) (a known microsomal enzyme inducer) and of triamcinolone (an agent that reduces the sensitivity of the body to drugs although not via microsomal enzyme induction). Prednisolone proved to be a strong drug-metabolizing enzyme inducer but it was less potent than PCN.