(288) Amlodipine Versus Nifedipine ER for the Management of Postpartum Hypertension: A Noninferiority Randomized Controlled Trial

Hypertensive disorders of pregnancy (HDP) are a leading cause of maternal morbidity, yet data comparing postpartum hypertension (PPHTN) medications are limited. We sought to compare the effectiveness of 2 dihydropyridine calcium channel blockers: amlodipine, which is often used as first-line monotherapy for non-obstetric hypertension, and nifedipine ER, which is frequently used for PPHTN. We hypothesized that amlodipine is non-inferior to nifedipine ER for PPHTN control, as defined by time from delivery until discharge (PPLOS).

Study Design:

This was a pragmatic, noninferiority RCT at a single regional perinatal center. Patients with unmedicated HDP were randomized 1:1 to postpartum treatment with amlodipine or nifedipine ER, stratified by underlying chronic hypertension (CHTN). The primary outcome was PPLOS with a non-inferiority limit of 24 hrs. Secondary outcomes included readmission rate, side effects, and medication discontinuation. Primary analysis was intent-to-treat; secondary analysis was performed on an as-treated cohort (AT). Wilcoxon rank sum, ANOVA, and logistic regression were utilized as appropriate.

Results:

175 patients met inclusion criteria and were randomized, 87 to amlodipine and 88 to nifedipine ER. 120 were evaluated in the AT cohort. Baseline characteristics were balanced (Table). Median PPLOS was 73.5 hrs. for amlodipine and 72 hrs. for nifedipine ER, consistent with noninferiority (p< 0.001). Noninferiority was maintained in the AT cohort and in those with CHTN. There was no difference in readmission (4.1% amlodipine vs 5.1% nifedipine ER, p=0.77). Patients exposed to nifedipine ER experienced more hypotension (OR 4.6, 95% CI 1.72-14.63) and tachycardia (OR 2.25, 95% CI 1.08-4.78) compared to patients exposed to amlodipine. Seven patients (10%) exposed to nifedipine ER discontinued medication due to side effects, compared to none exposed to amlodipine.

Conclusion:

Amlodipine is non-inferior to nifedipine ER in managing PPHTN as measured by PPLOS. Readmission rates were similar and amlodipine discontinuation was lower. Amlodipine should be considered for PPHTN management.