Hypotension in normotensive pregnant women treated with nifedipine as a tocolytic drug

Cardiogenic Shock after Nifedipine Administration in a Pregnant Patient: A Case Report and Review of the Literature

We present a case of a 21-year-old Caucasian woman at 27 weeks of pregnancy who was admitted to the obstetric department for pre-term labor. She received 10 mg of nifedipine 4 times in 1 h, according to the internal protocol. Shortly after, she brutally deteriorated with pulmonary edema and hypoxemia requiring transfer to the intensive care unit (ICU) for mechanical ventilation. She finally improved and was successfully extubated after undergoing a percutaneous valvuloplasty of the mitral valve. This case illustrates a severe cardiogenic shock after administration of nifedipine for premature labor in a context of unknown rheumatic mitral stenosis. Nifedipine induces a reflex tachycardia that reduces the diastolic period and thereby precipitates pulmonary edema in case of mitral stenosis. This case emphasizes the fact that this drug may be severely harmful and should never be used before a careful physical examination and echocardiography if valvular heart disease is suspected.

An effect of maternal nifedipine therapy on fetoplacental blood flow: a prospective study

PURPOSE

The aim of this study is to assess the effects of maternal nifedipine administration on placental and fetal blood flow.

METHODS

A total of 29 patients with preterm labor diagnosis admitted to the tertiary care center, Zeynep Kamil Hospital, were evaluated. Before and 24-48 h after administration of oral nifedipine, Doppler ultrasound scan was carried out to measure fetal middle cerebral artery, ductus venosus, umbilical artery, and maternal uterine artery blood flow.

RESULTS

After 24 and 48 h of therapy, there were no changes in mean PI and RI in the umbilical arteries and ductus venosus (p > 0.05). Fetal middle cerebral artery and maternal uterine artery PI and RI values showed a significant reduction 24-48 h after oral nifedipine therapy (p < 0.05).

CONCLUSIONS

Our study showed that 24 and 48 h after oral nifedipine therapy, there is a significant increase in fetal MCA and maternal uterine artery blood flow, while fetal umbilical artery and ductus venosus Doppler values do not change.

Pharmacokinetics, safety and tolerability of OBE022, a selective prostaglandin F2α receptor antagonist tocolytic: A first-in-human trial in healthy postmenopausal women

AIMS

Preterm birth remains a significant risk for later disability. The selective inhibition of the prostaglandin F_2α receptor has significant advantages for a tocolytic. The prodrug OBE022 and its metabolite OBE002 are novel prostaglandin F_2α receptor antagonists under development for treating preterm labour.

METHODS

We performed a prospective, first in human, Phase I, dose escalation, placebo-controlled, randomized trial at a clinical trial site in the UK. Placebo, single ascending doses of 10, 30, 100, 300, 1000 or 1300 mg, and multiple ascending doses over 7 days of 100, 300 or 1000 mg day^-1 ; were administered to postmenopausal female volunteers. Food interaction was additionally evaluated.

RESULTS

Subjects tolerated OBE022 well at all single and multiple doses. No clinically relevant changes in safety parameters were shown and there were no serious adverse events. Observations showed that prodrug OBE022 was readily absorbed and rapidly converted into its equally active stable metabolite OBE002. The plasma level of OBE002 rose with increasing doses, reaching exposure levels that were anticipated to be clinically relevant within 1 h following administration. There was no clinically significant food interaction, with peak exposures reduced to 80% and area under the curve staying bioequivalent. The mean half-life of OBE002 ranged between 8 and 11 h following administration of a single dose and 22-29 h after multiple doses.

CONCLUSIONS

Administration of OBE022 was safe and had favourable pharmacokinetic characteristics and no clinically relevant interaction with food. Our results allow further investigation of OBE022 in preterm labour patients.

Hemodynamic effects of nifedipine tocolysis

AIM

To describe the effects of nifedipine tocolysis on blood pressure and heart rate in non-hypertensive women.

METHODS

This was a retrospective study from 2001 to 2011 to compare blood pressures and heart rates among non-hypertensive women on nifedipine tocolysis up to 8 h after nifedipine initiation. Measurements at 20-60 and 61-120 min were compared to assess the differential effects of dosing on hemodynamics and reflected the effects of the initial and complete loading doses, respectively. Charts were reviewed for hypotension-related emergent delivery.

RESULTS

One hundred and thirty-eight patients were included. Over the 8-h study interval, mean systolic blood pressure (P < 0.001) and mean diastolic blood pressure (P < 0.001) decreased by 5 mmHg and heart rate increased by 4 b.p.m. (P < 0.001). Systolic and diastolic blood pressures were unchanged from baseline up to 120 min at all doses. Heart rate increased at both 20-60 and 61-120 min when all doses were considered (P < 0.001), but differential dosing effects were not observed. Rates of tachycardia increased (P < 0.001), but rates of hypotension were unchanged. No hypotension-related emergent deliveries occurred.

CONCLUSION

Nifedipine tocolysis was associated with hemodynamic changes in non-hypertensive women. Tachycardia was increased but hypotension was unaffected, supporting the general safety of nifedipine in this setting.

Maternal hypotension during fetoscopic surgery: incidence and its impact on fetal survival outcomes

In this retrospective cohort study, we aimed to determine the incidence of intraoperative maternal hypotension during fetoscopic surgery for twin-twin transfusion syndrome (TTTS) and to evaluate the impact of intraoperative hypotension on fetal survival. A total of 328 TTTS patients with recipient twin cardiomyopathy who underwent fetoscopic surgery under epidural anesthesia were included. The exposure of interest was maternal medical therapy with nifedipine for the treatment of fetal cardiomyopathy. We found that intraoperative hypotension occurred in 53.4% (175/328 patients). There was no statistically significant difference in incidence of hypotension between nifedipine exposure and nonexposure groups (54.8% versus 50.8%, P = 0.479). However, the nifedipine exposure group received a statistically significant higher dose of phenylephrine (7.04 ± 6.38 mcg/kg versus 4.70 ± 4.14 mcg/kg, P = 0.018) and higher doses of other vasopressor, as counted by number of treatments (6.06 ± 4.58 versus 4.96 ± 3.42, P = 0.022). There were no statistically significant differences in acute fetal survival rate (within 5 days) and fetal survival rate at birth between hypotensive and nonhypotensive patients. We concluded that preoperative exposure to nifedipine resulted in increased intraoperative maternal vasopressor requirement during fetoscopic surgery under epidural anesthesia. In patients who had intraoperative maternal hypotension, there was no correlation between the presence of maternal hypotension and postoperative fetal survival.