U.S. Department of Health & Human Services Divider Arrow National Institutes of Health Divider Arrow NCATS

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Class (Stereo):
CHEMICAL (ABSOLUTE)



Silodosin is a selective antagonsit of alpha-1a adrenergic receptor which was developed by Kissei Pharmaceutical. The drug was approved by FDA under the name Rapaflo for the treatment of signs and symptoms associated with benign prostatic hyperplasia.
Prazosin (trade names Minipress, Vasoflex, Lentopres, and Hypovase) is a selective α-1-adrenergic receptor antagonist used to treat hypertension. Prazosin acts by inhibiting the postsynaptic alpha-1-adrenoceptors on vascular smooth muscle. This inhibits the vasoconstrictor effect of circulating and locally released catecholamines (epinephrine and norepinephrine), resulting in peripheral vasodilation. Prazosin is orally active and has a minimal effect on cardiac function due to its alpha-1 receptor selectivity. However, when prazosin is started, heart rate and contractility go up in order to maintain the pre-treatment blood pressures because the body has reached homeostasis at its abnormally high blood pressure. The blood pressure lowering effect becomes apparent when prazosin is taken for longer periods of time. The heart rate and contractility go back down over time and blood pressure decreases. The antihypertensive characteristics of prazosin make it a second-line choice for the treatment of high blood pressure. Prazosin is also useful in treating urinary hesitancy associated with prostatic hyperplasia, blocking alpha-1 receptors, which control constriction of both the prostate and urethra. Although not a first line choice for either hypertension or prostatic hyperplasia, it is a choice for patients who present with both problems concomitantly. Common (4–10% frequency) side effects of prazosin include dizziness, headache, drowsiness, lack of energy, weakness, palpitations, and nausea. Less frequent (1–4%) side effects include vomiting, diarrhea, constipation, edema, orthostatic hypotension, dyspnea, syncope, vertigo, depression, nervousness, and rash.
Status:
First approved in 1952
Source:
Regitine HCl by Ciba
Source URL:

Class (Stereo):
CHEMICAL (ACHIRAL)



Phentolamine (trade name Regitine) is a reversible nonselective α-adrenergic antagonist used for the control of hypertensive emergencies, most notably due to pheochromocytoma. Phentolamine produces its therapeutic actions by competitively blocking alpha-adrenergic receptors (primarily excitatory responses of smooth muscle and exocrine glands), leading to a muscle relaxation and a widening of the blood vessels. This widening of the blood vessels results in a lowering of blood pressure. The action of phentolamine on the alpha-adrenergic receptors is relatively transient and the blocking effect is incomplete. The drug is more effective in antagonizing responses to circulating epinephrine and/or norepinephrine than in antagonizing responses to mediator released at the adrenergic nerve ending. Phentolamine also stimulates β-adrenergic receptors and produces a positive inotropic and chronotropic effect on the heart and increases cardiac output. Phentolamine is indicated for the prevention or control of hypertensive episodes that may occur in a patient with pheochromocytoma as a result of stress or manipulation during preoperative preparation and surgical excision. Phentolamine is indicated for the prevention or treatment of dermal necrosis and sloughing following intravenous administration or extravasation of norepinephrine. Phentolamine is also indicated for the diagnosis of pheochromocytoma by the Phentolamine blocking test. Acute and prolonged hypotensive episodes, tachycardia, and cardiac arrhythmias have been reported. In addition, weakness, dizziness, flushing, orthostatic hypotension, nasal stuffiness, nausea, vomiting, and diarrhea may occur.
Status:
Other

Class (Stereo):
CHEMICAL (ACHIRAL)

Status:
US Previously Marketed
Source:
DAPIPRAZOLE HYDROCHLORIDE by WOODWARD
(2019)
Source URL:
First approved in 1990
Source:
DAPIPRAZOLE HYDROCHLORIDE by FERA PHARMS
Source URL:

Class (Stereo):
CHEMICAL (ACHIRAL)



Dapiprazole is an alpha-1 adrenergic receptors antagonist which was developed for for the treatment of drug induced mydriasis produced by adrenergic or parasympatholytic agents. The drug was marketed under the name Rev-Eyes, however it was withdrawn from market due to its slow effect.