What is the dosage form specified for the prokinetic erythromycin used in vagal indigestion management?

• A. 10 mg/kg IM
• B. 5 mg/kg IV
• C. 20 mg/kg PO
• D. 1 mg/kg SC

Answer: (A)

Erythromycin acts as a prokinetic by stimulating motilin receptors in the GI tract, which increases migrating motor complex activity and enhances gastric/abomasal emptying. For managing vagal indigestion, the recommended dosage form is intramuscular injection at 10 mg/kg. The IM route provides reliable, predictable absorption to achieve a timely prokinetic effect in field settings, without the rapid peaks and broader monitoring needs of intravenous dosing. Oral administration tends to be unreliable in ruminants due to rumen degradation and variable bioavailability, while subcutaneous dosing is less commonly used because of variable absorption. This combination—IM delivery at 10 mg/kg—balances effectiveness with practicality for short-term management of vagal indigestion.