(1173) Amlodipine Versus Nifedipine ER for Managing Postpartum Hypertension: Medication Continuation Beyond 6 weeks Postpartum

Despite being a leading cause of maternal morbidity, data on optimal management of postpartum (PP) hypertension (HTN) is limited. Our parent study demonstrated noninferiority of amlodipine for treatment of PP HTN in the immediate PP period when compared to nifedipine ER. In this secondary analysis, we sought to assess use of antihypertensives beyond 6 weeks PP. We hypothesized that the majority of patients using either medication would discontinue treatment prior to 6 weeks PP and that of those who continued treatment, participants assigned to amlodipine would be more likely to continue the assigned study drug than those assigned to nifedipine ER, as use of amlodipine is more common in the non-obstetric setting.

Study Design:

This was a secondary analysis of a randomized controlled noninferiority trial. 175 patients were enrolled in the parent study, with 120 patients started on either amlodipine or nifedipine ER in the per protocol cohort (n= 51 amlodipine, 69 nifedipine ER).  Charts of the per protocol cohort were abstracted to assess continuation of the initially assigned antihypertensive at 6 weeks, 12 weeks, and 12 months PP. Data was analyzed utilizing chi-squared and Fishers exact test.

Results:

Overall, forty percent of patients remained on antihypertensives at 6 weeks PP. No significant differences were found in rates of continuation of any antihypertensive at 6 weeks, 12 weeks, or 12 months PP. Those assigned to amlodipine were significantly more likely to be continued on their assigned study medication at 6 weeks and 12 weeks, but not 12 months, PP (Table 1).

Conclusion:

While the majority of patients discontinue antihypertensives by 6 weeks PP, some patients with hypertensive disorders of pregnancy will require prolonged treatment. In patients requiring prolonged treatment, patients assigned to amlodipine were significantly less likely to be changed to an alternative antihypertensive. Although this was not statistically significant at 12 months PP, this may be due to sample size. Our findings support that amlodipine should be considered for treatment of postpartum hypertension.