Preliminary evaluation of the efficacy and safety of brimonidine for deep sedation

Background: Although brimonidine is currently used in the clinical treatment of glaucoma and rosacea, research of the deep sedative effect on animals after systemic administration is reported firstly and has shown promising results. Methods: The median effective dose (ED50), the median lethal dose (LD50), and the therapeutic index of brimonidine for deep sedation and formalin stimulation assay were determined by various animal experiments. The effect of synergistic anesthesia in rabbits with brimonidine and chloral hydrate was preliminarily evaluated. Results: The ED50 of brimonidine for highly effective sedation by intraperitoneal injection in rats was calculated to be 2.05 mg kg(-1) with a 95% confidence interval (CI) of 1.87 to 2.25 mg kg(-1). The ED50 of brimonidine for deep sedation by intravenous and intrarectal injection in rabbits was calculated to be 0.087 mg kg(-1) with a 95% CI of 0.084 to 0.091 mg kg(-1) and 1.65 mg kg(-1) with a 95% CI of 1.43 to 1.91 mg kg(-1), respectively. The LD50 of intraperitoneal brimonidine injection in rats was calculated to be 468 mg kg(-1) with a 95% CI of 441 to 497 mg kg(-1) and a therapeutic index of 228. Brimonidine has a certain analgesic and heart rate lowering effects. Conclusion: The results confirmed that brimonidine has deep sedation and analgesic effects after systemic administration and has high safety. It can be used in combination with other types of sedative drugs to achieve better effects.