Alpha blocker

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Alpha blockers
α-blockers
Drug class
Class identifiers
Use  • hypertension
 • vasoconstriction
 • BPH
ATC code C02CA
Mechanism of action  • Receptor antagonist
 • Inverse agonist
Biological target α-adrenoceptors

Alpha-blockers or α-blockers are pharmacological agents that act as neutral antagonists or inverse agonists of α-adrenergic receptors (α-adrenoceptors).[1]

Classification[edit]

When the term "alpha blocker" is used without further qualification, it sometimes refers to α1-blockers, and sometimes refers to agents that act at both types of receptors.[citation needed]

Examples of non-selective α-adrenergic receptor antagonists include:

Selective α1-adrenergic receptor antagonists include:

Selective α2-adrenergic receptor antagonists include:

The agents carvedilol and labetalol are both α- and β-blockers.

Uses[edit]

α-Blockers are used in the treatment of several conditions, such as Raynaud's disease, hypertension, and scleroderma.[8]

α-Blockers can also be used to treat anxiety and panic disorders, such as generalized anxiety disorder, panic disorder, or posttraumatic stress disorder (PTSD). While most commonly used to treat hypertension (usually in conjunction with diuretics when other treatments are ineffective), they are also often used to treat the symptoms of BPH (benign prostatic hyperplasia).

Prazosin is a potent α1-adrenergic receptor inverse agonist.[4] Raskind and colleagues[9] studied the efficacy of prazosin for PTSD among Vietnam combat veterans in a 20-week double-blind crossover protocol with a two-week drug washout to allow for return to baseline.[9] The CAPS and the Clinical Global Impressions-Change scale (CGI-C) were the primary outcome measures. Patients who were taking prazosin had a robust improvement in overall sleep quality (effect size, 1.6) and recurrent distressing dreams (effect size, 1.9). In each of the PTSD symptom clusters the effect size was medium to large: 0.7 for reexperiencing or intrusion, 0.6 for avoidance and numbing, and 0.9 for hyperarousal. The reduction in CGI-C scores (overall PTSD severity and function at endpoint) also reflected a large effect size (1.4). Prazosin appears to have promise as an effective treatment for PTSD-related sleep disturbance, including trauma-related nightmares, as well as overall Anxiety and PTSD symptoms.

See also[edit]

References[edit]

  1. ^ alpha-Adrenergic Blockers at the US National Library of Medicine Medical Subject Headings (MeSH)
  2. ^ "Alfuzosin: Biological activity". IUPHAR. International Union of Basic and Clinical Pharmacology. Retrieved 3 June 2016. 
  3. ^ "Doxazosin: Biological activity". IUPHAR. International Union of Basic and Clinical Pharmacology. Retrieved 3 June 2016. 
  4. ^ a b "Prazosin: Biological activity". IUPHAR. International Union of Basic and Clinical Pharmacology. Retrieved 3 June 2016. 
  5. ^ "Tamsulosin: Biological activity". IUPHAR. International Union of Basic and Clinical Pharmacology. Retrieved 3 June 2016. 
  6. ^ "Terazosin: Biological activity". IUPHAR. International Union of Basic and Clinical Pharmacology. Retrieved 3 June 2016. 
  7. ^ "Silodosin: Biological activity". IUPHAR. International Union of Basic and Clinical Pharmacology. Retrieved 3 June 2016. 
  8. ^ "Alpha blockers - MayoClinic.com". 
  9. ^ a b Raskind MA, Peskind ER, Kanter ED, et al: Reduction of nightmares and other PTSD symptoms in combat veterans by prazosin: a placebo controlled study. American Journal of Psychiatry 160:371–373, 2003