Erythromycin enhances solid-phase gastric emptying in induced-hyperglycemia in patients with truncal vagotomy and pyloroplasty.

Abstract

Erythromycin has been found to be a gastrointestinal prokinetic agent while acute hyperglycemia has been associated with delayed gastric emptying in healthy controls and diabetics. The aim of this study was to investigate whether hyperglycemia, per se, alters gastric motility, during erythromycin-induced acceleration of gastric emptying of solids in patients with truncal vagotomy and pyloroplasty (TVP) and the role of vagus nerves. Eight TVP patients and six controls underwent scintigraphic measurement of gastric emptying of a solid meal, during placebo in normoglycemia (5-8.9 mmol/liter glucose) or 200 mg intravenous erythromycin lactobionate in normo- or hyperglycemia (16-19 mmol/liter glucose) induced by intravenous glucose infusion, on separate days in random order. In the TVP patients during normoglycemia, the erythromycin compared to placebo accelerated the meal gastric half-emptying time (T1/2), (37.12 +/- 6.87 vs 91.88 +/- 11.53, P < 0.001) and decreased the lag-phase duration (P < 0.001) and the percentage of meal retained in the stomach at 120 min (P < 0.001). Erythromycin in hyperglycemia compared to normoglycemia increased T1/2 (61.25 +/- 10.67 vs 37.12 +/- 6.87, P < 0.001), prolonged lag-phase duration (P < 0.001), and the percentage of isotope retained in the stomach at 120 min (P < 0.001). The T1/2, the lag phase duration, and the meal retained in the stomach at 120 min, after giving placebo was significantly increased, compared to erythromycin administration in hyperglycemia (P < 0.001). Significant differences among patients and controls were found during gastric emptying after giving placebo and after erythromycin in hyperglycemia (P = 0.04 and P = 0.007, respectively), while nonsignificant differences were found after giving erythromycin in normoglycemia. We conclude that the effect of erythromycin-induced acceleration on gastric emptying is related to the plasma glucose level. Hyperglycemia reduces the erythromycin-induced acceleration of gastric emptying of solids in both controls and TVP patients. A significant increase in the delay of gastric emptying was achieved in TVP patients compared to controls after giving erythromycin in hyperglycemia and after placebo. Despite the inhibitory effect of induced hyperglycemia on gastric emptying, erythromycin is still able to accelerate the emptying rate and could prove to be a useful prokinetic agent under hyperglycemic conditions. Hyperglycemia may indicate a cholinergic-antagonist pathway that delays the erythromycin-induced acceleration of gastric emptying of solids and is more evident in vagotomized patients than controls, who retain the functional integrity of the vagus nerves.