22 The effect of labetalol and nifedipine MR on blood pressure in women with chronic hypertension in pregnancy

• Published in: Pregnancy hypertension 2016-07, Vol.6 (3), p.147-148
• Main Authors: Shawkat, Emma, Mistry, Hitesh, Chmiel, Catherine, Johnstone, Edward, Myers, Jenny
• Format: Article
• Language: English
• Subjects: Cardiovascular; Obstetrics and Gynecology
• ISSN: 2210-7789
• DOI: 10.1016/j.preghy.2016.08.023

Introduction Labetalol and modified release (MR) nifedipine are recommended for the treatment of hypertension in pregnancy. However, there is limited data on the blood pressure (BP) lowering effects of these drugs in the pregnant population. Objectives To determine and compare the effects of labetalol and nifedipine MR on the systolic (S) and diastolic (D) BP in a high-risk pregnant cohort. Methods Pregnant women already prescribed labetalol or nifedipine MR for chronic hypertension were offered 24-h ambulatory blood pressure monitoring (ABPM). The pre-dose BP was taken as baseline. The BP was measured every 30 min between 8 am and 10 pm. The time of drug ingestion was self-reported. For labetalol, the BP time series data were binned into quartiles; 0–25th (0–2.5 h(h)), 25th–50th (2.5–4 h), 50th–75th (4–6.4 h) and 75th–100th (6.4-end). For nifedipine the quartiles represented the following times post drug ingestion: 0–3 h, 3–5.7 h, 5.7–8.5 h and 8.5-end respectively. A statistical model was fitted to investigate the drug effect on systolic and diastolic BP: BP(t) = BP(0)∗ exp(−d∗ t) + g∗ t where d was the drug effect which decays over time and g was the change in BP as a function of time. Results Data was available for 41 women; labetalol n = 22 and nifedipine n = 19. In the labetalol group the median total daily dose was 400 mg (IQR: 300–600 mg). In the nifedipine group the median total daily dose was 35 mg (IQR: 20–55 mg). The median gestation was 175 days (IQR: 112–188) for labetalol and 162 days (126–219) for nifedipine. Baseline SBP and DBP was different between the 2 groups p -value