Premium
Nifedipine trials: effectiveness and safety aspects
Author(s) -
Geijn Herman P.,
Lenglet Joris E.,
Bolte Annemieke C.
Publication year - 2005
Publication title -
bjog: an international journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.157
H-Index - 164
eISSN - 1471-0528
pISSN - 1470-0328
DOI - 10.1111/j.1471-0528.2005.00591.x
Subject(s) - nifedipine , medicine , calcium
Nifedipine (Adalat) is marketed as an anti‐hypertensive agent. Nifedipine inhibits voltage‐dependent L‐type calcium channels, which leads to vascular (and other) smooth muscle relaxation and negative inotropic and chronotropic effects on the heart. Vasodilation, followed by a baroreceptor‐mediated increase in sympathetic tone then results in indirect cardiostimulation. Nifedipine was introduced as a tocolytic agent at a time when β‐agonists and magnesium sulphate dominated the arena for the prevention of preterm birth. The oral administration route, the availability of immediate and slow‐release preparations, the low incidence of (mild) side effects, and its limited costs explain the attraction to this medication from the obstetric field and its rapid and widespread distribution. Currently, over 40 studies have been published on nifedipine's tocolytic effectiveness, including seven meta‐analyses. The quality of the studies suffers particularly from performance bias because the majority of them failed to ensure adequate blinding to treatment both for providers and patients. Concerns about other methodological flaws include measurements, outcome assessment and attrition bias. In particular, the safety aspects of nifedipine for tocolysis have been underassessed. Conclusions from the meta‐analyses, favouring the use of nifedipine as a tocolytic agent, are not supported by close examination of the data. The tocolytic effectiveness and ‘safety’ of nifedipine has been studied primarily in normal pregnancies. Based on its pharmacological properties, one should be cautious to administer nifedipine when the maternal cardiovascular condition is compromised, such as with intrauterine infection, twin pregnancy, maternal hypertension, cardiac disease, etc. Life‐threatening pulmonary oedema and/or cardiac failure are definite risks and have been reported. Under such circumstances, the baroreceptor‐mediated increase in sympathetic tone may not balance the cardiac‐depressant activity of nifedipine.