title: Ketamine infusions: pharmacokinetics and clinical effects.
abstract: The clinical effects and pharmacokinetics of ketamine, administered as an i.v. infusion, were studied in 31 patients. Anaesthesia was induced with ketamine 2 mg kg-1 i.v. and maintained using an i.v. infusion of ketamine, supplemented by nitrous oxide. The plasma concentrations of ketamine, nor-ketamine and dehydro-nor-ketamine were analysed using gas-liquid chromatography. The average maintenance dose of ketamine was 41 +/- 21 microgram kg-1 min-1, but there was an obvious decrease in the dose required as anaesthesia progressed. This dose gave a stable plasma concentration of ketamine of 9.3 +/- 0.8 mumol litre-1. Patients recovered at 2.7 +/- 0.9 mumol litre-1. Plasma half-life of ketamine was 79 +/- 8 min. Maximum concentration of nor-ketamine was 4.7 +/- 2.4 mumol litre-1 and of dehydro-nor-ketamine 3.2 +/- 1.9 mumol litre-1. There were transient increases (15-30% of pre anaesthetic values) in arterial pressure, heart rate and cardiac output during operation. No post-operative respiratory depression was seen.
mesh_terms: D000328:Adult; D000368:Aged; D000771:Anesthesia, Intravenous; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007649:Ketamine / Q000097:blood / Q000378:metabolism* / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D012119:Respiration / Q000187:drug effects
chemical_list: D007649:Ketamine