Twenty-five studies (n=2,107 women) were included in the review. Three were controlled studies; two of the controlled studies were described as double blind. Eleven studies provided individual patient data (IPD) on 479 patients. Sample size ranged from 12 to 338.
The two double-blind studies found an overall positive effect of isoxsuprine in 92% of patients compared with 44.5% for placebo control (p<0.001). For women at risk of premature delivery, the figures were 94.7% for isoxsuprine compared with 41.2% for placebo (p<0.001). For those at risk of abortion, 92.5% of those treated with isoxsuprine showed a positive outcome, while 46.4% of those in the placebo groups did so (P<0.001).
The 11 studies providing IPD showed a beneficial effect of isoxsuprine in prolonging pregnancy in 54.5% of women at risk of abortion and in 82.3% of those at risk of premature delivery.
Analysis of all studies showed a beneficial effect of isoxsuprine in 77.3% cases at risk of abortion and 89% at risk of premature delivery.
Only four studies (n=209 women) reported the incidence of adverse events. Twenty-one percent of women (n=44) reported a total of 62 adverse events. These included tachycardia (13.9%), hypotension (5.7%), nausea (5.3%) and constipation (2.4%).