Single-dose pharmacokinetics of the MAO-inhibitor moclobemide in man

The single-dose kinetics of the MAO-inhibitor p-chloro-N-(2-morpholinoethyl)-benzamide (moclobemide, Ro 11-1163) following oral and i.v. administration to six healthy subjects is described. The dosage was 50 mg throughout (1 tablet moclobemide orally, 2.0 ml ampoule moclobemide i.v.). The unchanged drug in plasma was measured by means of an HPLC-assay. The i.v. plasma level curves were analyzed assuming a two-compartment model. The drug was rapidly distributed into the tissue compartment and was then eliminated from the body with a mean half-life t 1/2 beta of about 1 h (range 0.79-1.34 h). The volume of distribution Vss was of medium size (range 0.81-1.25 l/kg). The oral bioavailability was reduced in consequence of the effect of the first passage through the liver and amounted to 44% on average (range 27-70%). As to the drug absorption from the intestinal tract the extent and rate of this process were shown to be large (more than 95% absorbed on average, tmax-values within 1 h).