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Serum erythromycin concentration in sheep fed two diets.
American Journal of Veterinary Research
|June 1, 1984
Summary
Dietary changes in sheep did not affect serum erythromycin levels. Forestomach fluid pH changes did not impact drug concentrations or half-life, suggesting no dosage adjustment is needed for erythromycin therapy.
Area of Science:
- Veterinary Pharmacology
- Animal Science
- Ruminant Physiology
Background:
- Erythromycin is a macrolide antibiotic used in veterinary medicine.
- Ruminant diets can significantly alter forestomach pH.
- The impact of dietary-induced pH changes on erythromycin pharmacokinetics in sheep is not well understood.
Purpose of the Study:
- To investigate the effect of different diets on serum erythromycin concentrations and half-life in sheep.
- To assess the influence of forestomach pH on erythromycin's pharmacokinetic profile.
- To determine if dietary modifications necessitate adjustments in erythromycin therapeutic dosage.
Main Methods:
- Six sheep were administered a single intravenous injection of erythromycin (12.5 mg/kg).
- Serum drug concentrations were measured during two dietary conditions: grass hay and concentrate feed.
- Forestomach fluid pH was monitored, and antibacterial activity was assessed.
Main Results:
- The concentrate diet decreased forestomach fluid pH by at least 1 unit.
- No significant alterations in serum erythromycin concentrations or elimination half-life were observed between diets.
- Antibacterial activity in forestomach fluid was detected early post-injection (1-2 hours).
Conclusions:
- Dietary-induced changes in forestomach pH do not significantly alter erythromycin pharmacokinetics in sheep.
- Ion-trapping in forestomach fluid is not a limiting factor for erythromycin efficacy with typical dietary variations.
- Therapeutic dosage adjustments for erythromycin are likely unnecessary in sheep based on common dietary changes.