Oral administration of methylergometrine shows a late and unpredictable effect on the non-pregnant human menstruating uterus.
OBJECTIVE
To study the pharmacodynamic and pharmacokinetic properties of oral and intravenous methylergometrine upon uterine motility during menstruation.


METHODS
Intra-uterine pressure was measured in six volunteers with a fluid-filled sponge-tipped catheter during menstruation. Methylergometrine was given orally (0.5 mg) or intravenously (0.2 mg) in a cross-over design.


RESULTS
After intravenous administration, a fast increase of the frequency of uterine contractions and basal tone occurred with a decrease of amplitude, lasting at least 30 min. Oral administration had a late and less marked effect on uterine motility. An intravenous dose administered 24 h after an oral dose had no effect on uterine motility. Pharmacokinetic data, such as the maximum plasma concentration (Cmax), the time at which Cmax is reached (tmax) and the half-life of absorption (t1/2abs) also demonstrated large individual variations after oral administration.


CONCLUSIONS
Oral administration of methylergometrine had an unpredictable and late effect on uterine motility on the menstruating uterus, probably due to an unpredictable bioavailability, in contrast with the fast and predictable effect after intravenous administration.
de Groot
A N
AN
Department of Obstetrics & Gynaecology, University Hospital Nijmegen, The Netherlands.
van Dongen
P W
PW
Vree
T B
TB
Eskes
T K
TK
D000284:Administration, Oral; D000328:Adult; D005260:Female; D006207:Half-Life; D006801:Humans; D007275:Injections, Intravenous; D007700:Kinetics; D008598:Menstruation; D008755:Methylergonovine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000494:pharmacology; D011312:Pressure; D014590:Uterine Contraction / Q000187:drug effects; D014599:Uterus / Q000187:drug effects* / Q000502:physiology
D008755:Methylergonovine