Pharmacokinetic differences in exposure to camphor after intraruminal dosing in selectively bred lines of goats

A pharmacokinetic dosing study with camphor was used to determine whether selection lines of high-juniper-consuming goats (HJC, n = 12) and low-juniper-consuming goats (LJC, n = 12) differed in their respective disposition kinetics. Postdosing plasma camphor concentrations were used to examine whether a timed single blood sample collected after intraruminal administration of camphor would be a useful screening test to aid in the identification of HJC. Yearling female Boer x Spanish goats (n = 24) received a single intraruminal dose of monoterpene cocktail (0.270 g/kg of BW) containing 4 different monoterpenes that represented their composition previously reported for Ashe juniper (Juniperus ashei). Camphor, the predominant monoterpene in Ashe juniper, was 49.6% of the mix and was the monoterpene analyzed for this study. Blood samples were taken at 15 time points from 0 to 8 h after dosing. Concentrations of camphor were measured in plasma using solid phase extraction and gas chromatography/flame-ionization detection analysis. Maximal plasma concentration of camphor was greater for LJC than HJC (P = 0.01), and area under the curve extrapolated to infinity was greater for LJC than HJC (P < 0.01). Total systemic exposure (area under the curve) to camphor was 5 times less in HJC goats. We conclude that 1) HJC goats possess internal mechanisms to reduce the bioavailability of camphor, and 2) a blood sample taken at 45 min or at 60 min after intraruminal administration of camphor may be useful for identifying HJC individual animals from within large populations of goats.