N-desmethyl Diltiazem is an active metabolite of the calcium channel inhibitor diltiazem.¹It is formed from diltiazem by the cytochrome P450 (CYP) isoforms CYP3A4, CYP3A5, and CYP3A7.²N-desmethyl Diltiazem binds to isolated rat cerebral cortex homogenates (IC₅₀= 323 nM) and inhibits spontaneous contractions in isolated rat portal veins (IC₅₀= 489 nM).¹It has been found as a contaminant in fresh water.³

1.Schoemaker, H., Hicks, P.E., and Langer, S.Z.Calcium channel receptor binding studies for diltiazem and its major metabolites: Functional correlation to inhibition of portal vein myogenic activityJ. Cardiovasc. Pharmacol.9(2)173-180(1987) 2.Williams, J.A., Ring, B.J., Cantrell, V.E., et al.Comparative metabolic capabilities of CYP3A4, CYP3A5, and CYP3A7Drug Metab. Dispos.30(8)883-891(2002) 3.Marshall, M.M., and McCluney, K.E.Mixtures of co-occurring chemicals in freshwater systems across the continental USEnviron. Pollut.268(Pt. B)115793(2021)