An evaluation of maprotiline intravenous kinetics and comparison of two oral doses

The kinetics of maprotiline have been evaluated in six normal volunteers following rapid intravenous administration of 75 mg. Blood levels could be resolved using a biexponential equation. Mean estimates of half-life, volume of distribution and systemic clearance were 40 +/- 15 h, 51.7 +/- 18.01/kg and 0.92 +/- 0.24/kg/h, respectively. Blood/plasma concentrations varied between subjects from 0.77 to 1.64. A comparison of the bioavailability of two oral doses (a 75 mg tablet and three 25 mg tablets) was carried out in the same volunteers. No significant difference was observed between the maprotiline concentrations obtained for the two doses at sampling times up to 26 h. No significant difference was found in the area under the concentration vs. time curves for the two doses. Equivalent bioavailability can be assumed. On the basis of the intravenous injection study, systemic bioavailability averaged 66% and 70% for the 75 mg and three 25 mg tablets respectively.