Alpha (α)-adrenergic blockers

Alpha (α)-adrenergic blockers, also known as alpha-blockers, are a class of drugs that block the action of the alpha-adrenergic receptors in the body. These receptors are found in various tissues, including blood vessels, the bladder, and the prostate gland.

Alpha (α)-blockers are commonly used to treat conditions such as high blood pressure, benign prostatic hyperplasia (BPH), and Raynaud’s disease. By blocking the action of alpha receptors, these drugs relax smooth muscle in blood vessels and other tissues, leading to a decrease in blood pressure and improved blood flow.


Alpha-adrenergic blockers are a class of drugs that are primarily used to treat conditions related to the overactivity of the sympathetic nervous system, which is responsible for the “fight or flight” response in the body. Here are some of the most common uses of alpha-adrenergic blockers:

  1. High blood pressure: Alpha-adrenergic blockers can help lower blood pressure by relaxing the smooth muscle in the walls of blood vessels, allowing them to dilate and increase blood flow. Selective alpha-1 blockers like Prazosin, Terazosin, Doxazosin, and Tamsulosin are commonly used to treat high blood pressure.
  2. Benign prostatic hyperplasia (BPH): Alpha-adrenergic blockers can help reduce the symptoms of BPH, which is a non-cancerous enlargement of the prostate gland that can cause difficulty urinating. Selective alpha-1 blockers like Tamsulosin are commonly used to treat BPH.
  3. Raynaud’s disease: Alpha-adrenergic blockers can help improve blood flow to the fingers and toes in patients with Raynaud’s disease, a condition in which blood vessels in the fingers and toes constrict in response to cold or stress. Selective alpha-1 blockers like Prazosin, Terazosin, Doxazosin, and Tamsulosin, and non-selective alpha-blockers like Phenoxybenzamine and Phentolamine, are used to treat Raynaud’s disease.
  4. Pheochromocytoma: Non-selective alpha-blockers like Phenoxybenzamine and Phentolamine are used to treat pheochromocytoma, a rare tumor of the adrenal gland that can cause high blood pressure and other symptoms.


(α) Alpha ADRENERGIC BLOCKERS  classification KD Tripathi
classification of Alpha ADRENERGIC BLOCKERS


  1. Non equilibrium type– B-haloalkylamine, Phenoxybenzamine
  2. Equilibrium type (Competitive antagonists)
    • Non selective
      • Ergot alkaloids– Ergotamine, Ergotoxine
      • Imidazoline– Phentolamine
      • Chlorpromazine– Chlorpromazine
      • Hydrogenated ergot alkaloids– Dihydroergotamine (DHE), Dihydroergotoxine (Codergocrine)
    • α.1 Selective– Prazosin, Terazosin, Alfuzosin, Doxazosin, Tamsulosin
    • α.2 Selective-Yohimbine

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