Phenoprolamine Hydrochloride is an adrenergic α1 receptor antagonist with potent antihypertensive, neuroprotective and cardioprotective effects. Phenoprolamine Hydrochloride inhibits CYP2D and CYP3A activities and down-regulates their mRNA transcription and protein expression. Phenoprolamine Hydrochloride can efficiently penetrate through blood brain barrier and inhibit the contraction of vascular smooth muscle in the brain.