sympathomimetic drugs

(redirected from dipivefrine hydrochloride)

sympathomimetic drugs

agents that mimic the sympathetic nervous system, acting at alpha- or beta-adrenergic receptors within target tissues; vasoconstrictor sympathomimetics raise blood pressure by acting on alpha-adrenergic receptors, causing central vasoconstriction; beta receptor-active sympathomimetics dilate bronchi and peripheral blood vessels; beta-blockers block beta-receptor sites and promote peripheral vasoconstriction; adrenaline is a sympathomimetic drug that acts on both alpha- and beta-adrenergic receptors and is used to counter symptoms of anaphylaxis (it both raises blood pressure and dilates bronchi) Table 1
Table 1: Effects of stimulation of alpha, beta and dopamine receptors
ReceptorActionStimulating drug
Alpha-1 (α1); postsynapticVasoconstriction; positive inotropism; antidiuresisAdrenaline +
Noradrenaline +++
Alpha-2 (α2); presynapticVasodilatation; inhibition of noradrenaline releaseAdrenaline +
Noradrenaline +++
Dopamine +
Alpha-2 (α2); postsynapticConstriction of coronary arteries; promotion of salt and water excretionAdrenaline +
Noradrenaline +++
Dopamine +
Beta-1 (β1); postsynapticPositive inotropism; chronotropism; renin releaseAdrenaline ++
Noradrenaline ++
Isoprenaline ++
Dopamine +
Beta-2 (β2); presynapticNoradrenaline release accelerated; positive inotropism; chronotropismAdrenaline +
Isoprenaline +++
Beta-2 (β2); postsynapticVasodilatation; relaxation of bronchial smooth muscleAdrenaline +
Isoprenaline +++
Dopamine1; postsynapticVasodilatation; diuresisDopamine ++
Dopamine1; presynapticInhibits noradrenaline releaseDopamine +

Plus signs indicate degree of effect.

sympathomimetic drugs 

Drugs that produce an effect similar to that obtained by stimulation of the sympathetic nervous system. Some of these predominantly act on the adrenergic alpha-receptors (e.g. noradrenaline (norepinephrine)), while others act on the adrenergic beta-receptors (e.g. isoproterenol). Others have little direct effect on the adrenergic receptors but enhance the release of natural catecholamine from the sympathetic nerve terminals (e.g. amphetamine, phenylpropanolamine). Sympathomimetic drugs are used (1) in the treatment of open-angle glaucoma by decreasing aqueous humour secretion and increase the outflow through the trabecular meshwork thus reducing the intraocular pressure (e.g. adrenaline (epinephrine), apraclonidine, dipivefrine hydrochloride, brimonidine tartrate), (2) dilate the pupil without affecting accommodation (e.g. phenylephrine) and (3) constrict conjunctival blood vessels (e.g. naphazoline, tetrahydrozoline). Syn. adrenergic agonist; adrenergic stimulating agent. See alpha-adrenergic agonist; mydriatic.