Safety and efficacy of oral nifedipine versus terbutaline injection in preterm labor.
OBJECTIVE
To compare the safety and tocolytic efficacy of oral nifedipine with intravenous terbutaline for the management of threatened preterm labor.


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 g/min with an increment 5 microg/min every 10 minutes if required, until 25 microg/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 (deltaDBP(1hr)). Secondary outcomes were the efficacy to delay delivery > or =48 hours and 7 days, the adverse events and the birth outcomes.


RESULTS
deltaDBP(1hr) was greater in the terbutaline group than that in the nifedipine group with no statistically significant difference. Hypotension (defined as BP < or = 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 > or =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 I 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.


CONCLUSIONS
The safety and efficacy of nifedipine compares with that of terbutaline for treatment of preterm labor.
Laohapojanart
Nisa
N
Pharmacy Department, King Chulalongkorn Memorial Hospital, Bangkok.
Soorapan
Suchada
S
Wacharaprechanont
Teera
T
Ratanajamit
Chaveewan
C
D000284:Administration, Oral; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D005260:Female; D005865:Gestational Age; D006801:Humans; D007275:Injections, Intravenous; D009543:Nifedipine / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D007752:Obstetric Labor, Premature; D011247:Pregnancy; D011248:Pregnancy Complications; D013726:Terbutaline / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D013997:Time Factors; D015149:Tocolytic Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*
D015149:Tocolytic Agents; D009543:Nifedipine; D013726:Terbutaline