Effects of age on the pharmacokinetics of tramadol and its active metabolite, O‐desmethyltramadol following intravenous administration to foals

摘要: Summary Reasons for performing study Tramadol is an analgesic agent used in man and a number of veterinary species. The pharmacokinetics behavioural effects tramadol its active metabolite have been described mature horses, but not young foals. Objectives To characterise the pharmacokinetics, metabolism some induced physiological responses following i.v. administration same group foals on 4 different occasions, from few days after birth to age 43 days. Study design Experimental. Methods Tramadol was administered (3 mg/kg bwt) 8 separate occasions at ages 6–8, 13–15, 20–22 40–43 days. Blood samples were collected prior multiple times until 48 h post administration. analysed concentrations determined each age. Behavioural also assessed. Results The average volume distribution 5.10, 4.63, 4.02 3.84 l/kg bwt clearance 3.44, 3.08, 3.14 2.69 l/h/kg when aged days, respectively. There significant difference elimination half-life between groups (1.52, 1.73, 1.13 1.51 respectively). metabolites produced as horses; however, glucuronidation capability, appeared increase with increasing Tramadol well tolerated all studied sedation noted 3 older groups. Conclusions Tramadol appears be consistently 3 mg/kg ranging 1 6 weeks. Although yet established, results this study support further clinical use foals.