Analysis of amoxapine, 8-hydroxyamoxapine, and maprotiline by high-pressure liquid chromatography

Two high-pressure liquid chromatography procedures are presented for the routine analysis of two new antidepressant drugs, amoxapine (Asendin) as well as its active metabolite and maprotiline (Ludiomil). Recovery rates were excellent with both methods of extraction. Method 1, for amoxapine and its metabolites, was linear up to 1,000 ng/ml. Sensitivity for the parent drug was 10 ng/ml and, for the active metabolite, 25 ng/ml. Within-run coefficients of variation (CV) were 4.57% for 8-hydroxyamoxapine and 3.84% for amoxapine. Method 2, for maprotiline, was linear from 10 to 1,000 ng/ml. Intraassay CV was 3.2%. Reliable, yet simple, methods for monitoring these drugs are needed in order to establish firmly the pharmacological data important to appropriate patient therapy.