Erythromycin

Erythromycin: Uses, Dosage and Side Effects

Overview

• Time-dependent macrolide antibacterial that binds to the 50S ribosome (close to the binding site for chloramphenicol), inhibiting peptide bond formation.

Uses of Erythromycin

Not commonly used in dogs and cats.

• Has a similar antibacterial spectrum to penicillins.
• It is active against Gram-positive cocci (some Staphylococcus species are
  resistant), Gram-positive bacilli and some Gram-negative bacilli (Pasteurella).
• Some strains of Actinomyces, Nocardia, Chlamydophila and Rickettsia are also inhibited by erythromycin.
• Most of the Enterobacteriaceae (Pseudomonas, Escherichia coli, Klebsiella) are resistant.
• It may be considered to treat canine enteric Campylobacter, although isolation rates are similar between healthy dogs and those with diarrhoea.
• Being a lipophilic weak base, it is concentrated in fluids that are more acidic than plasma, including milk, prostatic fluid and intracellular fluid.
• Resistance to erythromycin can be quite high, particularly in staphylococcal organisms.
• Erythromycin acts as a GI prokinetic by stimulating motilin receptors.

Dose of Erythromycin in Dogs and Cats

Dogs, Cats:
• Antibiosis: 10–20 mg/kg p.o. q8–12h.
• GI prokinetic: 0.5–1 mg/kg p.o. q8h.

Side Effects of Erythromycin in Dogs and Cats

• The commonest adverse effect is GI upset.
• Care should be taken in cases of hepatic or renal impairment.

Contraindications of Erythromycin in Dogs and Cats

• Should be avoided in animals with hepatic dysfunction.

Some Notes:

• Erythromycin may enhance the absorption of digoxin from the GI tract and increase serum levels of ciclosporin, cisapride, methylprednisolone, theophylline and terfenadine.
• The interactions with terfenadine and cisapride proved particularly significant in human medicine, leading to fatal or near-fatal arrhythmias in some patients receiving both drugs.
• Erythromycin should not be used in combination with other macrolide, lincosamide or chloramphenicol antimicrobials as antagonism may occur.