Further investigations of omeprazole in obstetric patients

The routine use of antacid therapy during labour is controversial but most anaesthetists would agree that patients requiring regional or general anaesthesia should be treated. A recent survey’ has shown that suppression of acid secretion by Hz receptor blockade, supplemented by a saline antacid if operative obstetrics becomes necessary, is being widely used. Nevertheless H, receptor blockers by inhibiting liver enzymes and reducing hepatic blood flow could influence the pharmocokinetic pattern of other drugs. Omeprazole inhibits the proton pump of the parietal cell by way of a metabolite which is produced only in the highly acid milieu existing there.’ The parent drug in clinical doses has been shown to have no discemable effects elsewhere and the active metabolite has a very short half-life when absorbed. Nonobstetric studies indicated that a single dose provided a marked reduction in acid output for periods up to 24 h.3 Investigation of its effects as pre-anaesthetic antacid therapy was indicated and two investigations of its efficacy, side-effects and placental transfer in patients undergoing elective caesarean section were carried out.