Human pharmacokinetics, excretion, and metabolism of the anthracycline antibiotic menogaril (7-OMEN, NSC 269148) and their correlation with clinical toxicities

Abstract

In a Phase I study, menogaril (7-OMEN) was administered daily for 5 days/course, every 21-28 days. Dosages of 3.5, 7, 11.5, 17, and 31.5 mg/m2 were infused over 1 h, and dosages of 42, 50, and 56 mg/m2 were infused over 2 h. Pharmacokinetics was studied at all dosages. Plasma and urine samples were collected from 24 patients, and bile samples were also collected from 2 patients. 7-OMEN and metabolites were measured by high performance liquid chromatography. 7-OMEN was the major plasma fluorescent species at all times, with only trace amounts of N-demethyl menogaril observed. 7-OMEN disappeared from plasma biexponentially with t1/2 alpha 0.19 +/- 0.04 (mean +/- SE) h and t1/2 beta 13.22 +/- 1.54 h. Plasma pharmacokinetics of 7-OMEN was linear from 3.5-56 mg/m2; area under the curve increased proportionally with dosage. Total body clearance of 7-OMEN was 28.18 +/- 3.33 liter/m2/h, Vc was 224 +/- 30.8 liter/m2, and Vss was 370 +/- 25.7 liter/m2. Plasma pharmacokinetics of 7-OMEN studied on multiple days of a given course were similar. Urinary excretion of 7-OMEN and fluorescent metabolites accounted for 5.4 +/- 0.4% of the daily dose. Parent compound still represented greater than or equal to 80% of urinary drug fluorescence after 24 h. N-demethyl menogaril was the only other fluorescent drug species detected in urine. In two patients with biliary tract drains, biliary excretion of drug fluorescence accounted for 2.2-4.2% of the daily dose. Only 7-OMEN and N-demethyl menogaril were detected in bile by high performance liquid chromatography and thin layer chromatography. 7-OMEN was the major fluorescent biliary species, but, by 24 h, N-demethyl menogaril accounted for approximately 40% of biliary drug fluorescence. When considered in light of each patient's observed toxicities, excellent relationships were observed between the plasma area under the curve of 7-OMEN and the percentage of decreases in WBC and absolute neutrophil count. These latter findings should be useful in developing more precise and intelligent dosing schemes for 7-OMEN.