Succinylcholine pharmacokinetics

Pharmacokinetics Succinylcholine is injected intravenously. Its brief duration of action (several minutes) results from rapid hydrolysis by plasma cholinesterase. It is therefore usually given by continuous infusion. 

Hug C G (eds) Pharmacokinetics of anaesthesia. Blackwell, Boston, MA, p. 157 Riedesel D H, Hildebrand S V 1985 Unusual response following use of succinylcholine in a horse anesthetized with halothane. Journal of the American Veterinary Medical Association 187 507-508 Robertson S A, Carter S W, Donovan M et al 1990 Effects of intravenous xylazine hydrochloride on blood glucose, plasma insulin and rectal temperature In neonatal foals. Equine Veterinary Journai 22 43-47 Roger T, Bardon T, Ruckebush Y 1994 Comparative effects of mu and kappa opiate agonists on the cecocolic motility In the pony. Canadian Journal of Veterinary Research 58 163-166... 

Age does not seem to alter the pharmacokinetics. Tests in patients with genetic deficiency of pseudocholinesterase also showed no significant difference in tm. The half-life of succinylcholine, on the other hand, increased from 2.6 minutes to 4 hours in patients devoid of this enzyme. It appears that the ester group activation of the Hofmann elimination reaction mutually promotes ester hydrolysis as well. The goal of chemical- over enzyme-catalyzed metabolism in vivo seems to have been achieved. The possibility that ester hydrolysis may be catalyzed by nonspecific esterases is likely that plasma cholinesterase is not utilized is established. 

Pharmacokinetics Succinylcholine is composed of two acetylcholine molecules linked end to end. Succinylcholine is metabolized by plasma cholinesterase (butyrylcholinesterase or pseudocholinesterase), which determines the amount of drug reaching the end plate. It has a duration of action of only a few minutes if given as a single dose. Blockade may be prolonged in patients with genetic variants of plasma cholinesterase that metabolize succinylcholine very slowly. Succinylcholine is not rapidly hydrolyzed by acetylcholinesterase. 

---