Bioavailability of levamisole after intramuscular and oral administration in sheep

Authors: Garcia JJ, Teran MT, Diez MJ, Fernandez M, Sierra M
Publication: New Zealand Veterinary Journal, Volume 46, Issue 5, pp 173-176, Oct 1998
Publisher: Taylor and Francis

Animal type: Livestock, Production animal, Ruminant, Sheep
Subject Terms: Alimentary system/gastroenterology, Animal remedies/veterinary medicines, Anthelmintics, Parasite control, Parasites - internal, Treatment/therapy, Nematode
Article class: Scientific Article

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Abstract: AIMS: To determine the bioavailability of levamisole in sheep.
METHODS: Levamisole was administered to three groups of six Merino sheep orally and intramuscularly at three dose levels of 5, 7.5 and 10 mg/kg. There was a washout period of 1 week between treatments. Blood samples were collected by jugular venepuncture and plasma was separated immediately by centrifugation and stored at 20°C until analysed. The levamisole concentration in plasma was determined by high performance liquid chromatography with a U.V. detection method. Individual plasma levamisole concentration-time data were analysed using the compartmental method.
RESULTS: The values obtained for k_a, C_max, t_max and F show a moderate rate and extent of absorption after oral administration of levamisole while, after intramuscular administration, these values demonstrate a high rate and extent of absorption of levamisole. The intramuscular bioavailability was higher than the oral bioavailability (rate of absorption three-fold faster, extent of absorption 25 -33% higher and C_max two-fold higher). The Friedman test involving dose and route of administration showed that the route of administration affects k_a, C_max, t_max and F; significant differences were found in these parameters.
CLINICAL RELEVANCE: On the basis of these data, the recommended routes for the administration of levamisole in sheep are oral for gastro-intestinal nematodiasis and intramuscular for extragastric nematodiasis.
KEY WORDS: Levamisole, bioavailability, sheep.

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