Sympathomimetic

sympathomimetic [¦sim·pə·thō·mə′med·ik]

(pharmacology)

Having the ability to produce physiologic changes similar to those caused by action of the sympathetic nervous system.

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Sympathomimetic 

a pharmacological substance whose action basically coincides with the effects of the excitation of the sympathetic nervous system, including the constriction of blood vessels and the dilatation of bronchi. Inasmuch as sympathomimetics act on adrenergic receptors, that is, on receptor formations sensitive to norepinephrine and adrenaline, they are conventionally called adrenomimetics.

Sympathomimetics may be direct or indirect. Direct sympathomimetics act directly on adrenergic structures; they include norepinephrine, adrenaline, and Adrianol (also called sympa-thol). Indirect sympathomimetics either promote the release or block the capture of a mediator; they include Tyramine, Phena-mine (also called amphetamine), ephedrine, and imizin (also called imipramine). Indirect sympathomimetics cause the quantity of a mediator to increase and thereby produce sympathomimetic effects.

In clinical practice adrenaline, norepinephrine, and Adrianol are used locally to constrict blood vessels during hemorrhaging. They are also used to increase arterial pressure in cases of collapse. Ephedrine is used to arrest asthma attacks and to constrict peripheral vessels (for example, it is applied directly to the nose in cases of a cold). Phenamine is characterized by peripheral sympathomimetic action—for example, it constricts blood vessels and increases systole. It also exerts a stimulating effect on the central nervous system and consequently is used to excite nervous activity. Imizin is pharmacologically an antidepressant and is therefore used in the treatment of nervous and mental disorders accompanied by depression.

REFERENCES

Zakusov, V. V. Farmakologiia, 2nd ed. Moscow, 1966.
Anichkov, S. V. Izbiratel’noe deistvie mediatornykh sredstv. Leningrad, 1974.
Goodman, L. S., and A. Gilman. The Pharmacological Basis of Therapeutics, 3rd ed. New York-London-Toronto, 1965.

V. V. ZAKUSOV