Safety and Efficacy of Oral Nifedipine versus Terbutaline Injection in Preterm Labor
Nisa Laohapojanart BPharm*,**, Suchada Soorapan PharmD, PhD**, Teera Wacharaprechanont MD***, Chaveewan Ratanajamit BPharm, PhD**
Affiliation : * Pharmacy Department, King Chulalongkorn Memorial Hospital, Bangkok ** Department of Clinical Pharmacy, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Hat Yai, Songkhla *** Department of Obstetrics and Gynecology, Faculty of Medicine, Chulalongkorn University, Bangkok
Objective : To compare the safety and tocolytic efficacy of oral nifedipine with intravenous terbutaline for the
management of threatened preterm labor.
Materials and Methods : Pregnant women between 24 and 36 completed weeks of single gestation with preterm
labor were randomized to either oral nifedipine (n = 20) or intravenous terbutaline (n = 20) treatment.
Nifedipine (immediate released capsule) 10 mg was crushed and swallowed, 10 mg every 20 minutes was
allowed if necessary with a maximum 40 mg in the first hour. After that 20 mg nifedipine every 4 hours was
given, up to 72 hours. Terbutaline was initially infused with the rate 10 µg/min with an increment 5 µg/min
every 10 minutes if required, until 25 µg/min was reached. Once the contractions had stopped for 2-6 hours,
the patients were switched to subcutaneous injection with 0.25 mg terbutaline every 4 hours for 24 hours. The
main safety outcome was the changes in maternal diastolic blood pressure from baseline and 1 hour after
starting the treatment (ΔDBP1hr). Secondary outcomes were the efficacy to delay delivery > 48 hours and 7
days, the adverse events and the birth outcomes.
Results : ΔDBP1hr was greater in the terbutaline group than that in the nifedipine group with no statistically
significant difference. Hypotension (defined as BP < 90/60 mmHg) was found in one patient of the nifedipine
group and two patients of the terbutaline group. Seventeen and 14 patients in the nifedipine group and 15 and
12 patients in the terbutaline group had delayed delivery > 48 hours and 7 days, respectively. Mothers in the
nifedipine group experienced fewer side effects than those in the terbutaline group. Maternal heart rate, at 1
hour after starting the treatment, increased significantly higher in the terbutaline group than in the nifedipine
group. Birth outcomes were measured in all nifedipine group patients, but in only 16 of the terbutaline group
patients. Six mothers in each group delivered after 37 weeks. Intraventricular hemorrhage (IVH) occurred in
three babies (gestational aged 25, 29 and 37 weeks) born to mothers treated with terbutaline. In one baby,
IVH related to trauma resulted from the delivery procedure.
Conclusion : The safety and efficacy of nifedipine compares with that of terbutaline for treatment of preterm
labor.
Keywords : Nifedipine, Terbutaline, Preterm labor, Efficacy, Safety, Tocolysis
