Vasodilators
Introduction[edit | edit source]
Vasodilators are medicines that dilate blood vessels thus blood to flow more easily through. Some act directly on the smooth muscle cells lining the blood vessels. Other have a central effect, and regulate blood pressure most likely through the vasomotor center located within the medulla oblongata of the brain.[1]
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] Although, 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]
However, 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] This class of drugs are 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]
- ↑ Drugs.com Vasodilators Available from: https://www.drugs.com/drug-class/vasodilators.html (last accessed 20.6.2019)
- ↑ 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.
- ↑ 3.0 3.1 Cohn JN, Mcinnes GT, Shepherd AM. Direct-Acting Vasodilators. The Journal of Clinical Hypertension. 2011;13(9):690-692.
- ↑ Carter B, Saseen J. Hypertension. 5th ed. New York , NY: McGraw-Hill; 2002.
- ↑ Patel P, Jneid H. Interventional Pharmacology-Vasodilators. The Cardiology Advisor. https://www.thecardiologyadvisor.com/cardiology/interventional-pharmacologyvasodilators/article/583886/. Published September 17, 2018. Accessed October 10, 2018.
- ↑ Ciccone CD. Pharmacology in Rehabilitation. 5th ed. Philadelphia: F.A. Davis Company; 2016.
