Pharmacokinetics of erythromycin after intravenous, intramuscular and oral administration to cats

• Published in: The veterinary journal (1997) Vol. 187; no. 1; pp. 129 - 132
• Main Authors: Albarellos, G.A., Montoya, L., Landoni, M.F.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 2011
• Subjects: Administration, Oral; Animals; Anti-Bacterial Agents - administration & dosage; Anti-Bacterial Agents - blood; Anti-Bacterial Agents - pharmacokinetics; Antibiotics; Antimicrobials; Area Under Curve; Cat Diseases - drug therapy; Cats; Cats - blood; Erythromycin; Erythromycin - administration & dosage; Erythromycin - blood; Erythromycin - pharmacokinetics; Female; Half-Life; Injections, Intramuscular - veterinary; Injections, Intravenous - veterinary; intramuscular injection; intravenous injection; Macrolides; Male; Metabolic Clearance Rate; oral administration; pharmacokinetics; Cats; Erythromycin; Antibiotics; Antimicrobials; Macrolides
• ISSN: 1090-0233; 1532-2971
• DOI: 10.1016/j.tvjl.2009.09.019

The aim of this study was to characterise the pharmacokinetic properties of different formulations of erythromycin in cats. Erythromycin was administered as lactobionate (4 mg/kg intravenously (IV)), base (10 mg/kg, intramuscularly (IM)) and ethylsuccinate tablets or suspension (15 mg/kg orally (PO)). After IV administration, the major pharmacokinetic parameters were (mean ± SD): area under the curve (AUC) (0–∞) 2.61 ± 1.52 μg h/mL; volume of distribution ( V z) 2.34 ± 1.76 L/kg; total body clearance ( Cl t) 2.10 ± 1.37 L/h kg; elimination half-life ( t ½ λ ) 0.75 ± 0.09 h and mean residence time (MRT) 0.88 ± 0.13 h. After IM administration, the principal pharmacokinetic parameters were (mean ± DS): peak concentration ( C max), 3.54 ± 2.16 μg/mL; time of peak ( T max), 1.22 ± 0.67 h; t ½ λ , 1.94 ± 0.21 h and MRT, 3.50 ± 0.82 h. The administration of erythromycin ethylsuccinate (tablets and suspension) did not result in measurable serum concentrations. After IM and IV administrations, erythromycin serum concentrations were above minimum inhibitory concentration (MIC) 90 = 0.5 μg/mL for 7 and 1.5 h, respectively. However, these results should be interpreted cautiously since tissue erythromycin concentrations have not been measured and can reach much higher concentrations than in blood, which may be associated with enhanced clinical efficacy.