High performance liquid chromatographic method for routine monitoring of amiodarone and desethylamiodarone plasma levels.

The authors describe a normal phase liquid-chromatographic assay suitable for therapeutic monitoring of amiodarone and desethylamiodarone in human plasma. The compounds were extracted at pH 3.8 into methyl tert-butyl ether containing [2-ethyl-3-3.5-dibromo-4-dipropylaminoproxybenzoyl)benzothiophe ne] as internal standard. The separation was obtained by using a mobile phase of methanol-methyl tert butyl ether-sulfuric acid (60-40-0.015; v/v/v). The absorbance of the compounds was monitored at 254 nm with a sensitivity limit of 0.05 mg/l for amiodarone and 0.02 mg/l for desethylamiodarone. The mean overall recovery from plasma samples was greater than 90 p. cent for both compounds. This method was applied to therapeutic and pharmacokinetic studies.

Rapid quantitative determination of doxorubicin and its metabolites in biological samples.

A rapid sensitive and selective method is developed for the plasma analysis of doxorubicin and its metabolites, doxorubicinol and doxorubicinone with daunorubicin as the internal standard, by using high performance liquid chromatography (HPLC) with fluorescence detection and a "zorbax ODS" column. An eluent containing tetrahydrofuran and trietylamine afforded improved efficiency and resolution and was used to resolve the four anthracycline derivatives in a sole isocratic run. An example of the plasma levels obtained in a cancerous patient after two different administrations is shown.

Pharmacokinetic and pharmacodynamic study of amodiaquine and its two metabolites after a single oral dose in human volunteers.

The pharmacokinetics of amodiaquine (AQ, Flavoquine, CAS 6398-98-7) and its metabolites, mono (AQml) and bis-desethyl amodiaquine (AQm2) were investigated in 8 healthy volunteers after an oral dose of 306.2 mg of AQ. Metabolic clearance was the main AQ elimination pathway. AQ disappeared rapidly, from the plasma and blood, whereas AQml appeared rapidly in keeping with a hepatic first-pass effect. By contrast, AQ was little excreted in urine and AQm2 formation from AQm1 was low. Blood AQm1 concentrations were higher than plasma levels, with an AQm1/AQ concentration ratio of 5 to 10. This result was related to strong uptake of AQm1 by white blood cells, as shown by an in vitro study. On the basis of plasma concentrations, there was no preferential uptake by red blood cells, the pharmacological target cells; effective AQ concentrations should thus be analyzed in plasma rather than in whole blood. The inhibitory activity of patients' sera on Plasmodium falciparum growth in vitro appears to be directly related to the AQm1 concentration.