Methylergometrine (methylergonovine) concentrations in the human plasma and urine.

There were no significant differeneces in the radioimmunologically determined plasma concentrations of methylergometrine, nor in its 32-hour cumulative urinary excretion after a sinlge 0.250-mg p.o. dose of Methergin (Sandoz) or Myomergin (Leiras). Peak plasma concentrations were obtained as early as 0.5 hours after the drug administration. Approximately 3% of the 0.250-mg p.o. dose was excreted in the urine during a period of 32 hours. In two subjects, after a single 0.20-mg i.v. injection, the beta phase half-life in the plasma was 1.9 hours. From the ratio of the area under the plasma curve after p.o. and i.v. administration in these two subjects, it was estimated that 64% and 63% of the p.o. dose reached the systemic circulation. No cumulation in the plasma was observed after repeated p.o. doses of 0.125 mg of methylergometrine given thrice daily to the two subjects.