A fresh look at magnesium trisilicate.

Confusion exists about the correct way to use magnesium trisilicate as an antacid prior to inducing general anaesthesia in the pregnant woman. The effectiveness of two-hourly doses of antacid is discussed with special reference to the rate at which the stomach empties. Consequently, it is important to know whether the patient is in labour and if so the type of analgesic used. Some of the chemical characteristics of Mist. Mag. Trisil. B.P.C. are discussed. It is shown that it is capable of raising the pH of the stomach contents above 3.0 within two minutes in comparatively small doses. Clinically it is shown to be almost completely effective in a large series of patients. Inadequate mixing of the alkali with the stomach contents when it is given as an immediate pre-induction dose leads to a hazard of acid regurgitation when anaesthesia is induced in these patients.