Daily versus Twice Daily Nifedipine for Blood Pressure Control in Pregnancy and Postpartum.

Objective:  The objective of this study was to compare 60 mg daily (QD) extended released (XR) nifedipine to 30 mg twice daily (BID) for blood pressure (BP) control antepartum and postpartum.

Study design:  This is a retrospective chart review conducted at the Mount Sinai Health System. Patients admitted from January 1, 2015, to April 30, 2021, diagnosed with a hypertensive disorder of pregnancy, who received nifedipine XR 30 mg BID or 60 mg QD for intrapartum or postpartum BP control were included. The primary outcome was the need for up-titration (i.e., the need for an increase in nifedipine dose or addition of another antihypertensive) after reaching one of the study doses (30 mg BID or 60 mg QD). Patients were excluded if they had preexisting renal disease or were already on oral antihypertensives. In a 1:1 ratio between single- and twice-daily dosing groups, the sample size needed to detect a 20% difference in up-titration rate to achieve 0.80 power is 97 patients per group, for a total of 194 patients. This is based on a Pearson chi-square test with a significance level of 0.05.

Results:  A total of 237 patients were included, 139 (59%) received 30 mg BID and 98 (41%) 60 mg QD. There was no statistically significant difference in the need for an increase in nifedipine dose or addition of another oral antihypertensive agent between those receiving 30 mg BID versus 60 mg QD (33.8 vs. 35.7%; adjusted odds ratio [aOR], 95% confidence interval [CI]: 0.90 [0.50-1.60]; p = 0.71). There was no difference in the need for emergency hypertensive treatment after reaching the study dose (p = 0.19) or readmission for BP control between groups (p > 0.99).

Conclusion:  These findings suggest that BID dosing does not confer better BP control in the antepartum or postpartum periods. Thus, daily dosing is reasonable and may be preferable for patient convenience and compliance.

Key points: · Nifedipine metabolism may increase in pregnancy.. · nifedipine 30 mg BID versus 60 mg QD were compared.. · There was no difference in the need for additional medication.. · There was no difference in the need for readmission.. · Daily dosing may be preferable for convenience..