Direct vasodilation

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Vasodilators are drugs causing blood vessels dilatation.

Classification of vasodilators[edit | edit source]

1. Myotropic

  • coronary – nitrates, nitrites, molsidomine;
  • others – Ca2+ Channel blockers, hydralazines, nitroprusside , minoxidil, diazoxide, purines, nicotine derivatives, others.


  • non-selective – phentolamine, phenoxybenzamine;
  • selective – prazosin, doxazosin, metazosin.


It is advisable to divide the individual drugs according to the site of action
  • mainly for arterioles – hydralazines, Ca2+ antagonists , phentolamine, purines, nicotinic acid derivatives, others;
  • mainly for veins – nitrates, molsidomine (at higher doses also arterioles);
  • for arterioles and veins – selective α1-lytic, ACEI, nitroprusside.

Direct vasodilation[edit | edit source]

They reduce blood pressure by dilating the effect on vascular smooth muscle - thereby reducing peripheral vascular resistance while maintaining compensatory mechanisms mediated by baroreceptors, sympathetic nerves and the renin-angiotensin-aldosterone system ( RAAS ). This fact has its advantages and disadvantages.

  • The advantage is that the vasodilators are not hypotensive , they dilate the renal arterioles, so they do not restrict renal flow . They do not affect sexual function . They can be given during pregnancy.
  • The disadvantages are fluid retention by RAAS activation and the subsequent possible expansion of extracellular volume, undesired reflex tachycardia, and a decrease in the antihypertensive effect due to compensatory effects. The mentioned disadvantages can be balanced by combination with β-lytics (in case of contraindication β-lytics they can be combined with methyldopa , clonidine ). The risk of fluid retention can be avoided by concomitant administration of diuretics .
  • Dihydralazine
  • Endralazine
  • Minoxidil
  • Sodium nitroprusside

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