The Efficacy and Safety of Intravenous Emulsified Isoflurane in Rats

Abstract

Although direct IV injection of liquid volatile anesthetics is usually lethal, anesthesia using emulsified halothane and isoflurane without adverse effects has been safely induced in animals. We identified the safe concentration of emulsified volatile anesthetic preparations and determined the dose-response relationship of IV emulsified isoflurane and propofol in rats. Liquid/gas partition coefficients of desflurane, sevoflurane, isoflurane, enflurane, and halothane in 20% and 30% Intralipid were measured and used to calculate their saturated concentrations. Unsaturated emulsified isoflurane was prepared by adding liquid isoflurane to 30% Intralipid. The loss of forepaw righting reflex was taken as induction of anesthesia, and disappearance of electrocardiogram was taken as death. The median effective induction dose (ED50) and median lethal dose (LD50) of emulsified isoflurane were 0.072 and 0.216 mL/kg liquid isoflurane, respectively. The ED50 and LD50 of propofol were 5.89 mg/kg and 18.19 mg/kg, respectively. Time to return of forepaw righting reflex after injection of emulsified isoflurane (38 +/- 18 s) was significantly shorter than with propofol (101 +/- 62 s; P < 0.05). Anesthesia was successfully induced in rats by IV emulsified isoflurane with a comparable safety index and certain safety factor as propofol. Recovery of anesthesia after IV emulsified isoflurane was faster than with propofol.

Involvement of 5-hydroxytryptamine type 3 receptors in sevoflurane-induced hypnotic and analgesic effects in mice

“…This preparation may be clinically useful to produce anesthesia [4]. Previous studies support the efficacy and safety of the iv administration of emulsified inhalation anesthetics in animals [34,35]. According to drug pharmacokinetics and our preliminary experiments [6,7], we confirmed that ip and sc injection of emulsified inhalation anesthetics can achieve hypnosis and analgesia similar to that produced by inhalation.…”

Comparison between emulsified isoflurane and propofol/isoflurane combination on plasma thyroid hormones, insulin, glucose, and glucagon in dogs

“…Emulsified isoflurane (EI) is an unsaturated lipid emulsion preparation of isoflurane; commercially available preparation is 30% Intralipid, a sterile, non-pyrogenic fat emulsion prepared for IV administration. Several studies have demonstrated that IV administration of 8% emulsified isoflurane is safe and effective without adverse effects in rats and dogs (Zhang et al 2005;Yang et al 2006;Zhou et al 2006). An ideal anaesthetic should be predictable, maintain a sufficient duration, provide adequate postoperative analgesia, and importantly, should not interfere with the endocrine system.…”

Protective Effect of Emulsified Isoflurane Preconditioning on Cardiac Toxicity Induced by Bupivacaine in Rats

“…All animal studies were performed between 09: 00-16: 00. Emulsified isoflurane was prepared as previously reported (9). Briefly, liquid isoflurane (Abbott Laboratories, Shanghai) was dissolved into 30% Intralipid (Jiangsu Huarui pharmaceutical companies) at the volume ratio of 1:11.5, which presents an isoflurane concentration of 8% (vol/ vol).…”

“…Phase I clinical trial has demonstrated that emulsified isoflurane is a safe intravenous anesthetic in human, which produced rapid onset and short lasting anesthesia in volunteers in a dose-dependent manner (9). In previous animal study, EISO had a significantly shorter recovery time than propofol after single injection, with a similar onset time, which suggested that EISO was more adjustable.…”