ICI-118,551 is a selective ò<sub>2</sub> adrenergic receptor (adrenoreceptor) antagonist or beta blocker. ICI binds to the ò<sub>2</sub> subtype with at least 100 times greater affinity than ò<sub>1</sub> or ò<sub>3</sub>, the two other known subtypes of the beta adrenoceptor. The compound was developed by Imperial Chemical Industries, which was acquired by AkzoNobel in 2008.
ICI-118,551 has no known therapeutic use in humans although it has been used widely in research to understand the action of the ò<sub>2</sub> adrenergic receptor, as few other specific antagonists for this receptor are known. ICI-118,551 has been used in pre-clinical studies using murine models. When dissolved in saline, the compound crosses the bloodâÂÂbrain barrier. Common systemic doses used in rodent research are 0.5 or 1 mg/kg although efficacy has been demonstrated at doses as low as 0.0001 mg/kg (100 ng/kg) in rhesus monkeys. Doses up to 20 mg/kg have been used without toxicity. At room temperature in saline, the ICI 118,551 hydrochloride is soluble to at least 2.5 mg/mL.