Pharmacokinetics and effects of succinylcholine in African elephant (Loxodonta africana) and impala (Aepyceros melampus).
The phenomenon of slow onset of succinylcholine (Sch) effect in elephants was investigated by analyzing blood concentrations of Sch and its metabolite choline in elephant and impala. To assess whether the slow onset phenomenon is related to the pharmacokinetics of Sch following i.m. administration, we analyzed the time course of plasma concentrations of intact drug and its metabolite and determined its pharmacological effects. Blood samples were obtained from anaesthetized elephant (n=6) and impala (n=7) following i.m. administration of a lethal dose of Sch. Time from Sch injection to onset of apnoea and to death was significantly longer for elephant than impala (mean+/-S.D. apnoea 4.4+/-1.5 and 2.3+/-0.9 min, respectively; death 32.6+/-7.3 and 6.2+/-3.4 min, respectively). The C(max) was not different between elephants and impala (20.3+/-7.9 vs. 14.4+/-6.8 nmol ml-1, respectively) but the t(max) was significantly longer for elephants (23.0+/-7.6 vs. 3.7+/-2.2 min). Analysis of the plasma Sch and choline concentrations over time revealed that the relative amount of Sch entering the circulation within the first 30 s after i.m. injection is greater for impala than elephant. No greater rate in the plasma hydrolysis of Sch in elephant compared to impala was apparent.
Pitts
Neville Iain
NI
Department of Physiology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193 Johannesburg, South Africa. 057pitts@chiron.wits.ac.za
Mitchell
Graham
G
D000818:Animals; D000866:Antelopes / Q000097:blood / Q000378:metabolism*; D002794:Choline / Q000097:blood / Q000493:pharmacokinetics; D004606:Elephants / Q000097:blood / Q000378:metabolism*; D008297:Male; D009467:Neuromuscular Depolarizing Agents / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology; D013390:Succinylcholine / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology
D009467:Neuromuscular Depolarizing Agents; D013390:Succinylcholine; D002794:Choline