What Are Vasoconstrictor Drugs?

Jillian O Keeffe
Jillian O Keeffe
Excessive vasodilation can trigger low blood pressure, a condition also known as hypotension.
Excessive vasodilation can trigger low blood pressure, a condition also known as hypotension.

Vasoconstrictor drugs are medicines that cause the blood vessels of the body to narrow. These vessels naturally have the capability to relax and contract as the blood pumps through them, and constricting drugs simply make the vessels narrower than they would otherwise be. Drugs of this class can be useful for people with conditions like shock and low blood pressure. Vasoconstrictor drugs, which are also called vasopressors, are split into two major groups, which are the vasopressin analogs and the alpha-adrenoreceptor agonists.

Vasoconstrictor drugs cause the blood vessels of the body to narrow.
Vasoconstrictor drugs cause the blood vessels of the body to narrow.

In a person with a healthy circulatory system, the heart pumps blood through veins and arteries in a heartbeat pattern, which alternates high pressure with low pressure. In order to accommodate the changes in pressure, the blood vessels are covered in muscle, which allows the channel to expand and contract. Vasoconstriction is the scientific term for the contraction of the vessels, which reduces the internal diameter of the hollow vessel. As well as responding to the natural pressure variations of traveling blood, the blood vessels can also constrict in response to environmental factors such as cold, stress and even nicotine from cigarette smoke.

The side effects of some vasoconstrictor drugs can be especially dangerous for seniors.
The side effects of some vasoconstrictor drugs can be especially dangerous for seniors.

Some medical conditions cause problems with efficient movement of blood around the body. Shock, for example, is a serious condition that can be lethal. Hypotension, which is low blood pressure, can also be dangerous to health. Vasoconstrictor drugs can therefore be a useful tool in treating these conditions. Sometimes, the constricting effect of the drug can be complemented by administration of an additional drug of the inotrope class, which increase the strength of heart contractions.

The nicotine from cigarette smoke may cause blood vessels to constrict.
The nicotine from cigarette smoke may cause blood vessels to constrict.

Two options for vasoconstrictor drugs are available to doctors. One type of medication are drugs that stick to certain receptors on the muscle of the vessels to prevent them from doing the job of expanding the vessel. These receptors are called alpha-adrenoreceptors, and the drugs are therefore called alpha-adrenoreceptor agonists. Examples of specific drugs in this group are methoxamine, tetrahydralazine and clonidine. Possible side effects of this group of drugs include abnormal heartbeat, headache and fluid retention.

Side effects of vasoconstrictor drugs may include headache.
Side effects of vasoconstrictor drugs may include headache.

The second major type of vasoconstrictor is a molecule similar to a natural hormone called vasopressin. This hormone, and the copy of it present in the drug products, block receptors in the muscle called V1 receptors, and thereby prevent expansion of the vessel. A significant effect of these hormone analogs, as well as vasoconstriction, is water loss from the body. Possible side effects include headache, a feeling of nausea, and elecrolyte deficiency due to excess water loss.

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    • Excessive vasodilation can trigger low blood pressure, a condition also known as hypotension.
      By: Monkey Business
      Excessive vasodilation can trigger low blood pressure, a condition also known as hypotension.
    • Vasoconstrictor drugs cause the blood vessels of the body to narrow.
      By: Balint Radu
      Vasoconstrictor drugs cause the blood vessels of the body to narrow.
    • The side effects of some vasoconstrictor drugs can be especially dangerous for seniors.
      By: krutoeva
      The side effects of some vasoconstrictor drugs can be especially dangerous for seniors.
    • The nicotine from cigarette smoke may cause blood vessels to constrict.
      By: Rui Vale de Sousa
      The nicotine from cigarette smoke may cause blood vessels to constrict.
    • Side effects of vasoconstrictor drugs may include headache.
      By: Sandor Kacso
      Side effects of vasoconstrictor drugs may include headache.
    • Nicotine exposure may actually exacerbate symptoms of stress, including vasoconstriction.
      By: Vladimir Jovanovic
      Nicotine exposure may actually exacerbate symptoms of stress, including vasoconstriction.
    • Side effects of vasoconstrictor drugs may include nausea.
      By: BlueSkyImages
      Side effects of vasoconstrictor drugs may include nausea.