Pharmacokinetics of M100240 and MDL 100,173, a dual angiotensin-converting enzyme/neutral endopeptidase inhibitor, in healthy young and elderly volunteers.

M100240 is an acetate thioester of MDL 100,173-a dual angiotensin-converting enzyme (ACE)/neutral endopeptidase (NEP) inhibitor-in phase II development. The pharmacokinetics of M100240 and MDL 100,173 were compared in young and elderly subjects. Pharmacokinetic data were obtained from 12 young (ages 18-45 years, 10 male, 2 female) and 12 elderly (ages 65-85 years, 7 male, 5 female) healthy subjects in a parallel-group, open-label study. Following an overnight fast, subjects received a single 25-mg oral dose of M100240. Serial plasma concentrations of M100240 and MDL 100,173 were determined using a validated liquid chromatography/tandem mass spectrometry (LC/MS/MS) method, and pharmacokinetic parameters were calculated with noncompartmental methods. Single-dose treatment with M100240 was well tolerated in both groups of subjects, with no clinically significant changes in vital signs, ECG recordings, or laboratory safety parameters. M100240 was rapidly absorbed and converted to MDL 100,173, with M100240 concentrations no longer detectable at 3 to 4 hours postdose in both groups. The pharmacokinetics of the pharmacologically active MDL 100,173 were similar for both groups. Although maximum concentrations of M100240 were generally higher in elderly versus young subjects (C(max) 0.48 ng/mL vs. 0.17 ng/mL), systemic availability of M100240 was quite low and variable with plasma, and this apparent difference in parent drug exposure is unlikely to have important clinical implications. No age-related differences in the pharmacokinetic parameters of MDL 100,173 (C(max) 8.16 vs. 9.62 ng/mL, t(max) 1.25 vs. 1.5 h, AUC((0-last)) 81.6 vs. 72.2 ng x h/mL) were observed between young and elderly subjects, respectively. In conclusion, there are no age-related differences in the pharmacokinetics of MDL 100,173 between young and elderly subjects.