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Pharmacokinetics of ivermectin in zebu Gobra (Bos indicus)

https://doi.org/10.1016/j.vetpar.2004.11.014Get rights and content

Abstract

Plasma disposition kinetics of ivermectin was evaluated in a West African cattle breed. Five clinically healthy zebu Gobra cattle (Bos indicus) weighing 220–270 kg were treated (0.2 mg kg−1) with a commercially available ivermectin formulation for cattle. Blood samples were collected by jugular puncture at different times between 0.5 h and 40 days post-treatment. After plasma extraction and derivatization, samples were analysed by HPLC with fluorescence detection. Ivermectin was detected in plasma between 30 min and 20 days post-treatment. The observed peak plasma concentration (Cmax) was 46.3 ± 13.8 ng ml−1 and the time to reach Cmax (tmax) was 0.9 ± 0.2 day. The values for the absorption half-life (t1/2ab) and the elimination half-life (t1/2el) were 0.3 ± 0.2 and 2.8 ± 0.7 days, respectively. The calculated area under the concentration–time curve (AUC) was 185.2 ± 12.1 ng day ml−1 and the mean residence time (MRT) was 4.2 ± 1.3 days. The availability of ivermectin is low in zebu Gobra in comparison to other breeds cattle but equivalent to that reported in the yak and is likely to be due to physiological characteristics of this breed.

Introduction

Zebu Gobra is a West African domestic cattle which shows marked adaptation to arid environments and predominates in those areas of the world with Sudano-Sahelian pasture ecologies. This breed cattle represents an important nutritional source of milk and meat in these desert regions, but possesses little or no adaptation to the tsetse fly-transmitted disease, trypanosomiasis. Livestock in the Sahelian regions harbour several species of gastrointestinal nematodes, including Haemonchus spp. often considered to be the most prevalent species in the region, H. placei (Jacquiet et al., 1998) and H. contortus (Belem et al., 2001). Different tick species are also present including Hyalomma truncatum, H. marginatum rufipes, Rhipicephalus evertsi, R. guilhoni, Amblyomma variegatum, Boophilus decoloratus (Gueye et al., 1994).

To control these parasitic infections, chemotherapic remedies are applied including anthelmintic drugs as albendazole (Mattioli et al., 1999), fenbendazole (Zinsstag et al., 1997), organophosphorous and macrocyclic lactones (Soll et al., 1990, Talabi et al., 2003). Among the various anthelmintics, ivermectin is a potent agent active against many external and internal parasites of domestic animals.

The rational use of a drug requires knowledge of its basic pharmacokinetic parameters and, in food animals, residue concentrations in edible tissues and withdrawal times. Although ivermectin pharmacokinetic data from cattle have been reported, these data have not been described in African species. Due to the physiological adaptations of these species to their environment, drug pharmacokinetics may be different in comparison with other ruminants. The purpose of the present study was to describe the pharmacokinetics of ivermectin in zebu Gobra under field conditions following a single subcutaneous administration and to compare the results to other bovine species.

Section snippets

Animals

Five clinically healthy zebu Gobra cattle weighing 220–270 kg and identified by ear tags were selected for this study which was conducted from August to September 2003. The animals were maintained in the experimental station of Dahra (Senegal). They were kept in field conditions and no additional feed was supplied except hay and fresh water.

Treatment and sampling

Treatments were given by subcutaneous injection in the neck region at the recommended dose for cattle (0.2 mg kg−1) using a commercially formulation of

Results

The analytical method used to extract, derivatize and quantify the plasma concentration of ivermectin by chromatographic analysis using fluorescence detector was validated adequately. Calibration graphs were prepared using pooled zebu Gobra drug free plasma in the range 0.1–50 ng ml−1. Pooled plasma was taken through the procedure. The regression line between peak area and drug concentration showed correlation coefficient of 0.995. The mean extraction recovery from plasma was 95%. The interassay

Discussion

The pharmacokinetic behaviour of ivermectin has not been previously investigated in West African breeds cattle. The results of the current study showed marked differences between zebu Gobra and other bovine species. Cmax (46.3 ± 13.8 ng ml−1) was equivalent to that reported for cattle by several authors (Toutain et al., 1988, Lanusse et al., 1997, Lifschitz et al., 1999) and for the yak (Dupuy et al., 2003). It is higher than those obtained by Echeverria et al. (1997) and Toutain et al. (1997) at

Acknowledgements

This work was supported by AUF (Agence Universitaire de la Francophonie, Bureau Afrique de l’Ouest). We would like to think Mr. Bonaventure Mvé-Ondo for encouragement.

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