Pharmacokinetics residues and safety

Pharmacokinetic evaluation of subcutaneously administered (200 |g kg-1) ivermectin or moxidectin levels following treatment in plasma and milk of lactating camels (Oukessou et al., 1999) and for ivermectin in plasma of non-lactating camels (Oukessou et al., 1996) yielded area under the curve (AUC), Cmax and Tmax values that generally suggested dramatically reduced bioavailability of the two drugs in camels relative to published literature on cattle, but more comparable bioavailability relative to published information on sheep and goats for the respective compound. The plasma AUC (ng ml-1 day-1), Cmax (ng ml-1) and Tmax (days) values, respectively, observed for ivermectin were approximately 30, 2 and 12 (lactating camels) and 66, 3 and 6 (non-lactating camels), and for moxidectin were 71, 9 and 1 (non-lactating camels). Respective values observed in milk of lactating camels for ivermectin were 38,3 and 17, and for moxidectin were 291, 29 and 4. In general, the data from lactating camels suggest a greater bioavailability for moxidectin than for ivermectin in this species.

A 28-day withdrawal period has been established by the FDA for ivermectin administered subcutaneously at 200 | g kg-1 in camels. Transitory discomfort has been observed in some camels following subcutaneous administration, and a low incidence of soft tissue swelling, which resolved without treatment, has been seen at the injection site (Hashim and Wasfi, 1986; Robin et al., 1989; Maqbool et al., 1994). Radwan et al. (1987) found no adverse effects on pregnancy or resulting offspring following monthly subcutaneous treatments with ivermectin at 600 | g kg-1 during the second and third trimesters in camels.

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