Vasodilators and Hypertension

Introduction[edit | edit source]

Vasoconstriction and Vasodilation.png

Vasodilators are medicines that dilate blood vessels allowing blood to flow more easily through eg nitroglycerin

Pharmacodynamics[edit | edit source]

The drug class of vasodilators treat hypertension by directly vasodilating blood vessels in the periphery.

  • Vasodilators decrease resistance in the blood vessels resulting in a decrease in blood pressure.[2]
  • Direct-acting vasodilators dilate arterioles specifically, without having a dilating effect on the venous system.[3]
  • Many antihypertensive drugs ultimately produce vasodilation through a cascade of events, this class antihypertensive drugs produce vasodilation by acting directly on the smooth muscle of the vasculature in the periphery.[4]
  • Specifically, direct-acting vasodilators stimulate intracellular components by activating phosphorylation of cyclic-adenosine monophosphate (cAMP) and cyclic-guanosine monophosphate (cGMP).[2] These cyclic second-messengers inhibit smooth muscle contraction, as well as platelet aggregation.[2]

Pharmacokinetics and Adverse Effects[edit | edit source]

Direct vasodilators are usually not the first in line in the treatment of hypertension.

This class of drugs

  • Have a fairly short half-life, which requires frequent doses throughout the day.[5]
  • Primarily metabolized by the liver and excreted via the kidneys.[3]

While vasodilators are successful in controlling hypertension, these medications possess a myriad of side effects.

  • Reflex tachycardia is the primary adverse effect of these drugs, as a consequence of the medication induced baroreflex response compensating for the sudden medication decrease in vascular resistance.
  • Other less serious side effects include orthostatic hypotension, dizziness, weakness, fluid retention and nausea.[6]

PTs should be mindful of potential implications of adverse effects of these drugs or contraindications to therapy in patients.

See also Pharmacological Management of Hypertension

References:[edit | edit source]

  1. Vasodilators Available from: (last accessed 20.6.2019)
  2. 2.0 2.1 2.2 Walter U, Waldmann R, Nieberding M. Intracellular mechanism of action of vasodilators. European Heart Journal. 1988;9(suppl H):1-6. doi:10.1093/eurheartj/9.suppl_h.1.
  3. 3.0 3.1 Cohn JN, Mcinnes GT, Shepherd AM. Direct-Acting Vasodilators. The Journal of Clinical Hypertension. 2011;13(9):690-692.
  4. Carter B, Saseen J. Hypertension. 5th ed. New York , NY: McGraw-Hill; 2002.
  5. Patel P, Jneid H. Interventional Pharmacology-Vasodilators. The Cardiology Advisor. Published September 17, 2018. Accessed October 10, 2018.
  6. Ciccone CD. Pharmacology in Rehabilitation. 5th ed. Philadelphia: F.A. Davis Company; 2016.