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

Abstract

Abstract Background Hypertensive disorders of pregnancy (HDP) may be managed with oral anti-hypertensives, however pregnancy induced changes in the hormonal milieu and volume of distribution make it difficult to determine optimal dosing regimens. Nifedipine is a first line therapy for treatment of HDP. The purpose of this study is to compare 60mg daily (QD) of extended released (XR) nifedipine to 30mg twice daily (BID) for blood pressure (BP) control antepartum and postpartum. Methods This is a retrospective chart review conducted at the Mount Sinai Health System. Patients admitted from 1/1/2015-4/30/2021, diagnosed with a hypertensive disorder of pregnancy and received nifedipine XR 30mg BID or 60mg QD for intrapartum or postpartum BP control were included. The primary outcome was need for up titration after reaching one of the study doses (30mg BID or 60mg QD), up titration was defined as either an increase in nifedipine dose or addition of another anti-hypertensive. Patients were excluded if they had preexisting renal disease or were already on oral anti-hypertensive medication. In a 1:1 ratio between single daily dosing group and twice daily dosing group, 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 calculation is based on a Pearson Chi-square test with a significance level of 0.05. Results 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 increase in nifedipine dose or addition of another oral anti-hypertensive agent between those receiving 30mg BID versus 60mg QD (33.8% vs 35.7%; aOR (95% CI): 0.90 (0.50–1.60); p = 0.71). Additionally, there was no difference in need for emergency hypertensive treatment after reaching study dose (p = 0.19) or readmission for BP control between the two groups (p > 0.99). Conclusions These findings suggest that BID dosing does not confer better blood pressure control in the antepartum or postpartum periods, thus daily dosing is reasonable and may be preferable for patient convenience and compliance.