Gastrointestinal side effects after intravenous erythromycin lactobionate.

Ten healthy normal volunteers received an intravenous infusion of erythromycin lactobionate over 60 min to a total dose of 800 mg (n = 9), and 524 mg (n = 1). Blood samples were collected at 10 min intervals for 100 min and gastric contents aspirated, via a nasogastric tube, from pre-dose to 105 min after start of infusion. Incidence and severity of three gastrointestinal symptoms (nausea, stomach discomfort and feelings of hunger), two CNS symptoms (dizziness and faintness) and a 'control' symptom (back pain) were measured using 100 mm visual analogue scales. Rate of infusion and plasma erythromycin concentration correlated with nausea (P less than 0.001) and stomach discomfort (P less than 0.001); plasma erythromycin concentration was also correlated with dizziness (P less than 0.05). Concentrations of active erythromycin in the aspirate were pH dependent. In one subject the concentration of erythromycin in the aspirate exceeded that in the plasma by 100 fold. Bile staining of samples containing the highest levels of microbiologically active erythromycin makes the origin of the erythromycin in these samples uncertain.