Pre-operative oral erythromycin reduces residual gastric volume and acidity

We investigated whether low-dose erythromycin (200 mg) given as an oral premedicant altered the residual gastric volume and its acidity in fasted patients at induction of anaesthesia in a single-blinded study. Sixty patients were allocated randomly to receive either an erythromycin tablet (200 mg) or nothing with 10 ml water 3 h before induction of anaesthesia, and another 60 patients 1 h before induction of anaesthesia. Oral erythromycin significantly reduced residual gastric volume when it was given approximately 3 h (P<0.05; 95% CI for median difference: 0.1-17 ml) or 1 h (P<0.0005; 95% CI for median difference: 6-24 ml) before induction of anaesthesia. Erythromycin significantly reduced gastric acidity when it was given 1 h before induction of anaesthesia (P<0.02; 95% CI for median pH difference: 0.1-1.7). In contrast, when given 3 h before induction of anaesthesia, erythromycin did not significantly alter acidity.