Effects of isradipine, a new calcium antagonist, on postpartum uterine activity.
The effects of a new calcium antagonist, isradipine (PN 200-110) on postpartum uterine activity and the maternal cardiovascular system were investigated. Uterine activity was recorded by a microtip transducer catheter inserted transcervically within 45 min of normal vaginal delivery. 0.5 mg of isradipine was given as a bolus injection during 5 min to 7 women with spontaneous uterine activity and 1 mg was given during a 15-min period to another 8 women with oxytocin-stimulated uterine activity. Matched controls with similar pre-injection activity (+/- 5%) but not given the drug were selected for comparison. The effects of the drug in 3 women (given 1 mg of isradipine) were compared with those in matched controls and in women given 0.25 mg of terbutalin i.v. as a bolus injection. Isradipine had a marked inhibitory effect on both spontaneous and oxytocin-stimulated uterine activity. The inhibitory effect of 1 mg of isradipine seemed comparable to that of 0.25 mg of terbutalin. The inhibition occurred within 1-2 min after the injection and was sustained throughout the study period (2 h). A transient reduction of the systolic (mean maximum decrease 10-15%) and diastolic blood pressure (mean maximum decrease 15-20%) was seen, particularly during the injection period. Hypotension (systolic blood pressure less than 80 mmHg) was not recorded. A moderate increase in pulse rate (mean maximum increase 22-27%) was seen in all cases. The results show that isradipine given as a bolus injection can inhibit early postpartum uterine activity, with minimal side effects.
Ingemarsson
I
I
Department of Obstetrics and Gynaecology, University Hospital, Lund, Sweden.
Arulkumaran
S
S
Wide-Swensson
D
D
Forman
A
A
Andersson
K E
KE
Ratnam
S S
SS
D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000008:administration & dosage*; D002986:Clinical Trials as Topic; D005260:Female; D006801:Humans; D017275:Isradipine; D049590:Postpartum Period / Q000187:drug effects; D011247:Pregnancy; D011725:Pyridines / Q000008:administration & dosage*; D014590:Uterine Contraction / Q000187:drug effects*
D002121:Calcium Channel Blockers; D011725:Pyridines; D017275:Isradipine