Cl. Wrzesinski et al., DERMAL PENETRATION OF 4''-(EPI-METHYLAMINO)-4''-DEOXYAVERMECTIN B-1A BENZOATE IN THE RHESUS-MONKEY, Food and chemical toxicology, 35(10-11), 1997, pp. 1085-1089
The dermal absorption of the experimental avermectin insecticide emame
ctin benzoate was studied in the Rhesus monkey. Dermal absorption was
calculated by comparing radioactivity levels in excreta following derm
al application of the compound with those following administration of
an equivalent intravenous dose. After iv administration of 300 mu g [H
-3]MAB1a (prepared as a 1:1 solution of propylene glycol:saline) to th
ree monkeys, plasma levels decreased biphasically with a rapid decline
in radioactivity during the first 15 min followed by a slower decline
to background. By 7 days post-dose, approximately 90% and 5% of the a
dministered radioactivity was recovered in the faeces and urine, respe
ctively. After a washout period, 300 mu g [H-3]MAB1a (dissolved in emu
lsifiable concentrate) was applied topically to the shaved forearm of
the same monkeys. Following a IO-hr exposure period, approximately 90%
of the radioactivity was recovered in a soap and water wash of the ex
posed forearms. Although plasma radioactivity levels generally remaine
d below background levels, approximately 1.5% of the applied dose was
recovered in the excreta. Dermal absorption of [H-3]emamectin benzoate
was calculated as 1.6%. The low dermal penetration of emamectin benzo
ate indicates that minimal actual exposure of agricultural workers to
this compound will occur. (C) 1997 Elsevier Science Ltd. All rights re
served.