Comparative Pharmacokinetics of Metronidazole in Camels, Sheep and Goats

Ali, B. H. , B. G. Charles, M. Al-Yousif , A. K. Bashir : Comparative Pharmacokinetics of Metronidazole in Camels, Sheep and Goats. Acta Vet Brno 2002, 71: 49-53. The pharmacokinetics of metronidazole was determined after a single intramuscular (i.m.) dose of 30 mg⋅kg-1-body weight in five camels, sheep and goats. Marked differences were found between the three species in some of the kinetic parameters. For example, the elimination half-lives (t1/2; h) in camels, sheep and goats were 10.0, 6.21 and 5.87, respectively. The drug maximum concentrations in plasma, Cmax (mg⋅ml-1), were 28.3, 54.6 and 54.4 in camels, sheep and goats, respectively. The time to reach Cmax, tmax (h), were 5, 4 and 2 in camels, sheep and goats, respectively. The mean residence times (MRT; h) in camels, sheep and goats were 16.7, 10.8 and 8.64, respectively. In the light of the present kinetic data and known microbial sensitivities of metronidazole, we recommend an i.m. dose of 15 mg⋅kg-1 in camels and 10 mg⋅kg-1 in sheep and goats, every 12 h. Ruminants, kinetics, metronidazole, antiprotozoals, antibacterials Metronidazole (2-methyl-5-nitroimidazole-1-ethanol) is a synthetic bactericidal and antiprotozoal agent that is used to treat certain urogenital diseases such as trichomoniasis, giardiasis, Balantidium coli, and intestinal and extraintestinal amoebiasis. It is also effective against bacterial anaerobes. The drug is also considered a reliable marker or probe for studying liver function in vivo (Muscar et al. 1995). The pharmacokinetics of this drug has been reported previously following intravenous (i.v.), oral or rectal administration to humans (Jensen and Gugler 1983; Loft et al. 1986), horses (Baggot et al. 1988; Specht et al. 1992), calves (Bhavsar and Malik 1994), dogs (Neff-Davis et al. 1981), birds (Cybulski et al. 1996) and rats (Tu et al. 1990). Intramuscular (i.m.) administration of drugs to animals, particularly larger grazing animals, may often be more convenient than by other routes particularly in chronic treatment. There have been no pharmacokinetic data reported for i.m. administration of metronidazole, and this was the purpose of the current study in which a single 30 mg⋅kg-1 i.m. dose was administered to camels, sheep and goats. These species are susceptible to the bacterial and protozoal infections treatable with metronidazole. Materials and Methods Animals and procedures The protocol received prior approval from the Animal Research Ethics Committee of the Desert and Marine Environment Research Center. Animals used in this study were healthy, male Dromedary camels (Camelus dromedarius) aged 3-4 years and weighing 270-350 kg, Desert sheep (Ovis aries ) aged 2-3 years and weighing 27-33 kg and Nubian goats (Capra hircus) aged 2-3 years and weighing 22-27 kg (n = 5 of each species). When used, they have been housed for at least two years in shaded pens at the University farm, where they were given hay and water ad libitum, and the diet was supplemented with pelleted concentrates and mineral blocks. The animals were given a single i.m. dose of metronidazole (Torgyl-Forte, Rhone-Merieux, Harlow, Essex, U.K.) into the lower third region of the neck muscles. Blood (5 ml per sample) was collected into heparinized tubes just before, then after metronidazole administration at the following times: 10, 20, 40, 60, 90, 120, 240, 300, 360, 420, ACTA VET. BRNO 2003, 72: 49–53 Address for correspondence: B.H. Ali P. O. Box 10158 Buraydah, Al Gaseem 81999, Saudi Arabia Fax 966-63813372 e-mail: [email protected] http://www.vfu.cz/acta-vet/actavet.htm