Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 29.10.2020

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4-Amino-2-[4-(2-furoyl)-1-piperazinyl]-6,7-dimethoxychinazolin; CAS number: 19216-56-9

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Prazosin is a drug from the group of α1-adrenoceptor antagonists (α1-blockers). The pharmacon has the molecular formula C19H21N5O4 and the molar mass of 383.40 g-mol-1.

Spectrum of action
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The alpha1-adrenoreceptors belong to the adrenoreceptors (G-protein-coupled receptors) and can be detected mainly in the presynaptic membrane of sympathetic and also parasympathetic neurons. They are activated by accumulation of catecholamines (adrenaline and noradrenaline). α 1-Arenoreceptors contribute to the regulation of sympathetic nervous system activity and influence a number of sympathetic reactions, for example to smooth muscles in vessels, bronchia, hair follicles (goose bumps), the urogenital tract and the gastrointestinal tract. They unfold their effect via the Gq protein (see below G-protein coupled receptors; see also adrenoreceptors). α 1-receptor antagonists can only be effective if the corresponding receptor is tonic activated. This applies to the α 1-receptors of the resistance vessels.

However, all α 1-receptor antagonists do not belong to the first-line antihypertensives, as they promote rather than prevent the development of cardiovascular secondary diseases (secondary disease of hypertension = heart failure) (Graefe KH et al. 2016).

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Treatment of arterial hypertension (no first-line therapy); Raynaud's syndrome, benign prostatic hyperplasia (BPH)

Undesirable effects
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Frequent (may affect up to 1 in 10 people treated)

  • Respiratory infections, urinary tract infection; drowsiness, headache, pronounced drowsiness (somnolence); dizziness; tachycardia; hypotension; bronchitis, cough, dyspnoea, rhinitis; dyspepsia, dry mouth.
  • Occasional (may affect up to 1 in 100 people treated)
  • Allergic drug reactions; loss of appetite, depression, insomnia.

Rare (may affect up to 1 in 1,000 people treated)

  • Inhibition of the gastrointestinal passage.

Very rare (can affect up to 1 in 10,000 people treated)

  • Leukopenia, thrombocytopenia;

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Diuretics Antihypertensives Vasodilators Nitrates Antidepressants Neuroleptics General anaesthetics Nonsteroidal anti-inflammatory drugs Oestrogen-containing preparations Sympathomimetics

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Minipress®; Cardular PP®

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Prazosin was patented by Pfizer in 1969 and marketed under the brand name Minipress®.


Last updated on: 29.10.2020