Pharmacokinetics, efficacy, and adverse effects of selamectin following topical administration in flea-infested rabbits.

Abstract

OBJECTIVE:

To determine pharmacokinetics, efficacy, and adverse effects of topically administered selamectin in flea-infested rabbits.

ANIMALS:

18 healthy 5-month-old New Zealand White rabbits.

PROCEDURES:

On day 0, rabbits (n = 6/group) received topically applied selamectin at doses of 10 or 20 mg/kg or received no treatment. Each rabbit was infested with 50 fleas (Ctenocephalides felis) on days -1, 7, and 14. Live and dead flea counts were performed on days 2, 9, and 16, and treatment efficacy was calculated. Blood samples were collected prior to drug administration and at 6 and 12 hours and 1, 2, 3, 5, 7, 10, 14, 21, and 28 days after treatment for determination of plasma selamectin concentrations via high-performance liquid chromatography with mass spectrometry. Pharmacokinetic parameters were determined.

RESULTS:

On day 2, efficacy of selamectin against flea populations of rabbits in the 10 and 20 mg/kg treatment groups was 91.3% and 97.1%, respectively, but by day 9, these values decreased to 37.7% and 74.2%, respectively. Mean terminal half-life and maximum plasma concentrations of selamectin were 0.93 days and 91.7 ng/mL, respectively, for rabbits in the 10 mg/kg group and 0.97 days and 304.2 ng/mL, respectively, for rabbits in the 20 mg/kg group. No adverse effects were detected.

CONCLUSIONS AND CLINICAL RELEVANCE:

Selamectin was rapidly absorbed transdermally and was rapidly eliminated in rabbits. Results suggested that topical administration at a dosage of 20 mg/kg every 7 days is efficacious for treatment of flea infestation in rabbits. Further studies are needed to assess long-term safety in rabbits following repeated applications.

• Authors: James W Carpenter, Michael W Dryden, Butch Kukanich
• Journal: American journal of veterinary research (Am J Vet Res) Vol. 73 Issue 4 Pg. 562-6 (Apr 2012) ISSN: 1943-5681 [Electronic] United States
• PMID: 22452505 (Publication Type: Clinical Trial, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antiparasitic Agents
• Ivermectin
• selamectin

Topics

• Administration, Topical
• Animals
• Antiparasitic Agents (administration & dosage, blood, pharmacokinetics, therapeutic use)
• Area Under Curve
• Ectoparasitic Infestations (drug therapy, veterinary)
• Female
• Half-Life
• Ivermectin (administration & dosage, analogs & derivatives, blood, pharmacokinetics, therapeutic use)
• Male
• Rabbits
• Siphonaptera