norchlorpromazine

Norchlorpromazine, also known as N-desmethylchlorpromazine, is a major metabolite of chlorpromazine, a phenothiazine antipsychotic used in the treatment of schizophrenia and related psychoses. It is not marketed as a separate therapeutic drug.

In humans, norchlorpromazine is formed in the liver by N-demethylation of chlorpromazine. It is detectable in plasma and urine as a metabolite and is excreted primarily in conjugated forms. The exact pharmacokinetic properties can vary between individuals, reflecting differences in hepatic metabolism.

Pharmacologically, norchlorpromazine retains activity consistent with phenothiazine antipsychotics. In preclinical studies, it has demonstrated dopamine D2 receptor antagonism and associated antipsychotic-like effects, though its potency is generally lower than that of chlorpromazine. Its receptor profile may also overlap with other targets typical of this drug class, contributing to the overall therapeutic and side-effect patterns observed with chlorpromazine therapy.

Clinical relevance is primarily as a metabolite contributing to the total pharmacologic effect of chlorpromazine rather than as an independent treatment. Interindividual variability in hepatic demethylation can influence the clinical response and risk of adverse effects from chlorpromazine.

Chemistry and research use: Norchlorpromazine is described in pharmacological literature and serves as a useful compound in studies of phenothiazine metabolism, receptor binding, and pharmacodynamics.