Ability of nifedipine to prolong parturition in rats

Abstract

Summary. Rats were randomly assigned to treatments: (i) no surgery control; (ii) saline control; (iii) 0\m=.\25,0\m=.\5,1\ m=.\0or 2\m=.\0 \g=m\gnifedipine kg\m=-\1mi n\m=-\1; or (iv) 5\m=.\0 \g=m\g ritodrine kg\m=-\1 min\m=-\1. All drug treatments increased the interval between pup deliveries compared with the no surgery and saline controls. Apparent complete tocolysis was observed in 20, 60, 80 and 80% of the animals receiving 0\m=.\5, 1\m=.\0or 2\m=.\0 \ g=m\ gnifedipine kg\m=-\1 min\m=-\ 1 or 5 \ m=. \ 0\ g=m\ g ritodrine kg\ m=-\ 1 mi n\m=-\1, respectively. A positive pharmacodynamic relationship was observed for the nifedipine doses. Analysis of pup viability showed no statistically significant difference among treatments. Treatment with 2\m=.\0 \g=m\gnifedipine kg\m=-\1 min\m=-\ 1 gave a delay in pup delivery comparable to that with ritodrine.

Nifedipine in pregnancy

“…The action of the calcium channel blockers to inhibit smooth muscle contractility with apparent minimal side effects to the mother and fetus has resulted in their being evaluated as tocolytic agents. Animal studies have shown the ability of nifedipine to prolong pregnancy and prevent preterm delivery in both rats 74–76 and ewes 77 . Several studies in humans have evaluated the tocolytic action of nifedipine in preterm labour.…”