Plasma and tissue concentrations of methylergometrine (methylergonovine) in the rabbit.

The concentrations of methylergometrine (M) (methylergonovine) in the plasma, uterus, liver, and kidneys of the rabbit were determined by a radioimmunoassay after a single 0.2 mg/kg intravenous injection and the drug response was studied in the uterus in situ. M disappeared quickly from the plasma with a mean distribution phase half-life of 0.91 min. According to the fast uterine tissue uptake of M the drug response in this effector organ began quickly. The stimulated concentrations in the peripheral compartment of the two-compartment open model can be useful in the understanding of the rapid drug effect, but they do not describe the real situation in any particular tissue.