Abstract
BackgroundTo determine the hypnotic and analgesic effects of brimonidine, and evaluate its efficacy and safety for general anesthesia. Potentiation of pentobarbital sleeping time following brimonidine administration was observed in mice, as was the analgesic activity of brimonidine.MethodsThe median effective dose (ED50) and lethal dose (LD50) of intraperitoneally injected brimonidine were determined in hypnotized mice. In addition, the LD50 of intravenously injected brimonidine, and ED50 of intravenously, intramuscularly, and intrarectally injected brimonidine in hypnotized rabbits were determined. Finally, the synergistic anesthetic effect of brimonidine and chloral hydrate was evaluated in rabbits.ResultsIntraperitoneal injection of 10 mg/kg brimonidine enhanced the hypnotic effect of a threshold dose of pentobarbital. Intraperitoneally injected brimonidine produced dose-related analgesic effects in mice. The ED50 of intraperitoneally administered brimonidine in hypnotized mice was 75.7 mg/kg and the LD50 was 379 mg/kg. ED50 values of intravenous, intramuscular, and intrarectal brimonidine for hypnosis in rabbits were 5.2 mg/kg, 8.8 mg/kg, and 8.7 mg/kg, respectively; the LD50 of intravenous brimonidine was 146 mg/kg. Combined intravenous administration of 0.6 mg/kg brimonidine and 0.03 g/kg chloral hydrate had a synergistic anesthetic effect.ConclusionsBrimonidine elicited hypnotic and analgesic effects after systemic administration and exhibited safety. Moreover, brimonidine enhanced the effects of other types of narcotics when combined.
Highlights
To determine the hypnotic and analgesic effects of brimonidine, and evaluate its efficacy and safety for general anesthesia
Tianjin Institute of Medical & Pharmaceutical Sciences, No 79 Duolun Road, Heping District, Tianjin 300020, China α2 Adrenergic receptor agonists, such as dexmedetomidine, are often used as adjuncts to clinical general anesthesia, but can be used as a basic anesthetic in combination with local anesthetics for surgery. Such anesthetics act as both sedatives and analgesics, and may have hypnotic, anti-anxiety, anti-sympathetic, and muscle relaxation effects. These anesthetics protect organs, have good safety profiles, are not addictive.α2 adrenergic receptor agonists are often used in combination with other anesthetics to meet the anesthesia needs of various surgical settings during the induction period, maintenance period, and awakening period
No previous study has investigated the induction or maintenance of general anesthesia with brimonidine; a report of brimonidine is used for pre-anesthetic administration for animals, such as intraperitoneal injection of 30 μg/kg brimonidine, diminished the sympathetic nerve effect of ketamine general anesthesia in rats [1]
Summary
To determine the hypnotic and analgesic effects of brimonidine, and evaluate its efficacy and safety for general anesthesia. General anesthesia involves drugs that widely inhibit the central nervous system to temporarily inhibit consciousness and nerve response activities, such that the body has no response or memory to pain and noxious stimulation Such effects may be accompanied by a decrease of muscle tension caused by central mechanisms, but the important central functional state of the medulla oblongata is maintained. Α2 Adrenergic receptor agonists, such as dexmedetomidine, are often used as adjuncts to clinical general anesthesia, but can be used as a basic anesthetic in combination with local anesthetics for surgery Such anesthetics act as both sedatives and analgesics, and may have hypnotic, anti-anxiety, anti-sympathetic, and muscle relaxation effects. Their characteristics include good hypnotic and analgesic effects, as well as the abilities to strengthen
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