Nifedipine, verapamil and cyclosporin A pharmacokinetics in children.

We report two paediatric renal transplant patients in whom interaction with the calcium channel blocking agent verapamil resulted in reduced cyclosporin A (CyA) elimination. Prior therapy with another calcium channel blocking agent, nifedipine, did not affect CyA pharmacokinetics. We speculate that verapamil reduced CyA elimination in children via an effect upon the microsomal oxidase system that is independent of calcium channel activity.