1329838-45-0

Phenoxybenzamine-d₅ is intended for use as an internal standard for the quantification of phenoxybenzamine by GC- or LC-MS. Phenoxybenzamine is an antagonist of α-adrenergic receptors (α-ARs). It inhibits norepinephrine-induced inositol phosphate formation in HEK293 cells expressing α₁-ARs (EC₅₀s = 125.9-316.2 nM), as well as radioligand binding to α_2A-, α_2B-, and α_2C-ARs in CHO cell membranes (K_is = 60, 10, and 60 nM, respectively). Phenoxybenzamine (0.5-5 μM) decreases norepinephrine-, histamine-, and calcium-induced contractions in isolated rabbit aortic strips. It also inhibits proliferation of nine cancer cell lines, including lymphoma, breast, and lung cancer cells, with IC₅₀ values ranging from 29.5 to 99.8 μM. Phenoxybenzamine (3-1,000 μg/kg) reduces increases in diastolic blood pressure induced by the α-AR agonists cirazoline , St-587, Sgd 101/75, and B-HT 920 in pithed rats. It also decreases the time to find the platform in the Morris water maze, indicating restored spatial memory, in a rat model of fluid percussion-induced traumatic brain injury (TBI). Formulations containing phenoxybenzamine have been used in the treatment of hypertension and hyperhidrosis associated with pheochromocytomas, an adrenal medullary neuroendocrine tumor.

An irreversible α-antagonist. Used in the treatment of hypertension, it has a relatively slow onset and prolonged effect when compared to alternative α-blockers.

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