BALTIMORE – , according to research presented at the annual clinical and scientific meeting of the American College of Obstetricians and Gynecologists.*
Isabelle Band
Ms. Isabelle Band
The findings suggest that starting patients on a once-daily 60-mg dose is therefore reasonable, Isabelle Band, BA, a medical student at the Icahn School of Medicine at Mount Sinai, New York, told attendees. Ms. Band said in an interview that there does not appear to be a consensus on the standard of care for nifedipine dosing regimen in this population but that previous in vitro studies have shown increased metabolism of nifedipine in a physiologic state that mimics pregnancy.
“I’ve spoken to some colleagues here who say that they frequently have this debate of which dosing regimen to go with,” Ms. Band said. “I was pleasantly surprised that there was no significant difference between the two dosing regimens because once-daily dosing is less burdensome for patients and will likely improve compliance and convenience for patients.” An additional benefit of once-daily dosing relates to payers because anecdotal reports suggest insurance companies do not tend to approve twice-daily dosing as readily as once-daily dosing, Ms. Band added.
Ms. Band and her colleagues conducted a retrospective chart review of all patients with hypertensive disorders of pregnancy who were admitted to the Mount Sinai Health System between Jan. 1, 2015, and April 30, 2021, and were prescribed nifedipine in a once-daily (60-mg) or twice-daily (two 30-mg) dose. They excluded patients with renal disease and those already taking hypertensives prior to admission.
Among 237 patients who met the criteria, 59% received 60 mg in a twice-daily 30-mg dose, and 41% received 60 mg in a once-daily dose. Among patients requiring an up titration, two-thirds (67%) needed an increase in the nifedipine dose – the most common adjustment – and 20.7% needed both an increase in nifedipine and an additional medication.
The researchers observed no statistically significant differences in the proportion of patients who required a dose increase or an additional antihypertensive in the group taking the twice-daily dose (33.8%) or those receiving the once-daily dose (35.7%). This finding remained statistically insignificant after controlling for gestational diabetes, delivery mode, administration of Lasix, and receipt of emergency antihypertensive treatment (P = .71). The time that passed before patients needed a dose increase was also statistically similar between the groups: 24.3 hours in the twice-daily group and 24 hours in the once-daily group (P = .49).
There were no statistically significant differences in the need for a dose increase or an additional hypertensive agent based on race, ethnicity, body mass index, or history of preeclampsia as well. However, 24.5% of those taking the once-daily dosage had a history of preeclampsia, compared with 7.2% of those taking the twice-daily dosage (P < .001). Further, the median number of prior pregnancies was two in the twice-daily group versus three in the once-daily group (P = .002).
The authors found no significant difference between the two dosing groups in the need for emergency hypertensive treatment after reaching the study dose or in readmission for blood pressure control. In the twice-daily group, 21.6% of patients needed emergency antihypertensive treatment, compared with 14.3% in the once-daily group (P = .19). Readmission was necessary for 7.2% of the twice-daily group and 6.1% of the once-daily group (P > .99).
A subgroup analysis compared those who started nifedipine antepartum and those who started it post partum, but again, no significant difference in the dosing regimens existed.
Michael Ruma, MD, a maternal-fetal medicine specialist at Perinatal Associates of New Mexico in Albuquerque, was not involved in the study and said he welcomed the results.
“We have too many choices in medicine, so we need to just simplify the plan of attack,” reducing the number of things that clinicians need to think about, Dr. Ruma said in an interview. “A singular dose is always easiest for the patient, always easier for nursing staff, and usually, if you can optimize the dosing, that’s the best approach.”
Annabeth Brewton, MD, a resident at University of Tennessee, Knoxville, agreed, adding that new parents already have a lot going on immediately post partum.
“They’re going to be breastfeeding, they’re not sleeping, they’re going to forget to take that [second] dose,” Dr. Brewton said.
Ms. Band and Dr. Brewton had no disclosures. Dr. Ruma reported consulting and speaking for Hologic and consulting for Philips Ultrasound.
Correction, 5/24/23: An earlier version of this article misstated the daily doses of nifedipine. The study compared a