MEDROXYPROGESTERONE ACETATE (MAP) RELATIVE BIOAVAILABILITY AFTER SINGLE HIGH-DOSE ADMINISTRATION IN CANCER-PATIENTS

  • 1 January 1982
    • journal article
    • research article
    • Vol. 66  (12) , 2043-2049
Abstract
A pharmacokinetic evaluation of medroxyprogesterone acetate (MAP; 6.alpha.-methyl-17.alpha.-hydroxyprogesterone acetate) was undertaken in 70 patients with advanced cancer treated orally or i.m. with single high doses. MAP plasma levels were determined by gas chromatography (63Ni electron capture detector) after derivatization with heptafluorobutyric anhydride, using 17.alpha.-hydroxyprogesterone caproate as internal standard. Plasma levels after oral administration can be approximated by a triexponential function in agreement with a pharmacokinetic 2-compartment open model with 1st-order absorption; peak levels are dose-related, but high interindividual variance is present. Following i.m. administration, both decay phases are masked by prolonged absorption; peak levels are lower than after oral administration, but long-term bioavailability is higher, as demonstrated by comparison of the values for areas under curves in the 0-146 h interval. The high interindividual ranges in the observed MAP plasma levels indicate that if any significant clinical evaluation is to be made, routine analysis of plasma MAP is mandatory.

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