Study of serum levels, venous irritation and gastrointestinal side-effects with intravenous erythromycin lactobionate in patients with bronchopulmonary infection.

Sixteen patients with bronchopulmonary infection received 500 mg erythromycin lactobionate by intravenous infusion every 8 h for 2 days. The duration of infusion was either 30 (8 patients) or 60 min (8 patients). An inline filterset (0.22 micrometer) was included in the intravenous administration set in 4 patients of each infusion group. Serum erythromycin levels were obtained before and at various times for 8 h after the first and fourth doses and before and immediately after the other doses. The incidence and severity of venous irritation and gastrointestinal side-effects were assessed. Mean (S.D.) peak erythromycin levels for the 30 min infusion were 26.31 (6.89) micrograms/ml (first dose) and 26.85 (6.11) micrograms/ml (fourth dose) and for the 60 min infusions, 23.96 (7.91) micrograms/ml (first dose) and 23.65 (6.55) micrograms/ml (fourth dose). Venous irritation was experienced by 12 patients, ranging from localized discomfort to thrombophlebitis, but the severity was significantly reduced by inline filtration (P less than 0.005). Gastrointestinal side-effects were reported by 8 patients and 1 patient withdrew because of severe abdominal pain and nausea. These symptoms were usually relieved by spasmolytic agents and possibly could be explained by high concentrations reaching the gut wall either by biliary excretion or direct transport from blood and stimulating smooth muscle motility.