What are direct acting sympathomimetics?

Asked By: Abderraouf Romualdo | Last Updated: 29th April, 2020
Category: medical health hormonal disorders
4.8/5 (283 Views . 26 Votes)
Sympathomimetics are drugs that mimic the stimulation of the sympathetic nervous system. They are classified as directly acting (act directly on α or β receptors), indirectly acting (act by providing more norepinephrine to act on α or β receptors), or mixed acting (act by both mechanisms).

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Simply so, what are direct acting drugs?

The mechanisms of sympathomimetic drugs can be direct-acting (direct interaction between drug and receptor), such as α-adrenergic agonists, β-adrenergic agonists, and dopaminergic agonists; or indirect-acting (interaction not between drug and receptor), such as MAOIs, COMT inhibitors, release stimulants, and reuptake

Also, what does a sympathomimetic drug do? Sympathomimetic drugs are agents which in general mimic responses due to stimulation of sympathetic nerves. These agents are able to directly activate adrenergic receptors or to indirectly activate them by increasing norepinephrine and epinephrine (mediators of the sympathoadrenal system) levels.

Also asked, is ephedrine direct or indirect acting?

Ephedrine is one of the most commonly used noncatecholamine sympathomimetic drugs in the perioperative period. Ephedrine is a natural product of the ephedra plant (Ephedra sinica), and is a mixed-acting, noncatecholamine sympathomimetic with both direct and indirect stimulating effects on α- and β-adrenergic receptors.

What are the side effects of sympathomimetics?

The adverse effects of sympathomimetics include:

  • fine tremor, usually in the hands.
  • nervous tension.
  • headache.
  • peripheral vasodilation.
  • sinus tachycardia.
  • hypokalaemia after high doses - salbutamol.
  • hypersensitivity, including paradoxical bronchospasm.
  • impaired glucose tolerance in diabetics.

38 Related Question Answers Found

Is phenylephrine direct or indirect acting?

Phenylephrine. Phenylephrine is a noncatecholamine, direct-acting α receptor agonist that does not possess any significant β receptor activity. Phenylephrine has a slightly longer duration of action than norepinephrine.

What drugs block the sympathetic nervous system?

The main drugs that have been clearly shown to affect SNS function are beta-blockers, alpha-blockers, and centrally acting drugs. On the contrary, the effects of ACE inhibitors (ACE-Is), AT1 receptor blockers (ARBs), calcium channel blockers (CCBs), and diuretics on SNS function remain controversial.

What drugs increase adrenaline?

Examples of different vasopressors include:
  • ephedrine.
  • epinephrine.
  • dopamine.
  • phenylephrine.
  • pseudoephedrine.
  • oxymetazoline.

What drugs are alpha agonists?

Selected examples are:
  • Clonidine (mixed alpha2-adrenergic and imidazoline-I1 receptor agonist)
  • Dexmedetomidine.
  • Fadolmidine.
  • Guanfacine, (preference for alpha2A-subtype of adrenoceptor)
  • Guanabenz (most selective agonist for alpha2-adrenergic as opposed to imidazoline-I1)
  • Guanoxabenz (metabolite of guanabenz)

What do Alpha drugs do?

Alpha blockers are used in combination with other drugs to treat high blood pressure and can treat prostate problems in men. Alpha blockers lower blood pressure by keeping the hormone norepinephrine from tightening the muscles in the walls of smaller arteries and veins. As a result, the vessels remain open and relaxed.

What drugs affect the adrenergic system?

Examples of adrenergic drugs which only bind on alpha-1 receptors are phenylephrine, oxymetazoline. Selective alpha-2 receptor drugs include methyldopa and clonidine. The key beta-1 selective drug is dobutamine. Lastly, beta-2 selective drugs are bronchodilators, such as albuterol and salmeterol.

Does adrenaline increase systemic vasoconstriction?

As a hormone, adrenaline acts on nearly all body tissues. Its actions vary by tissue type and tissue expression of adrenergic receptors. Its actions are to increase peripheral resistance via α1 receptor-dependent vasoconstriction and to increase cardiac output via its binding to β1 receptors.

Where are alpha 2 receptors located?

Alpha 2 receptors are found both in the brain and in the periphery. In the brain stem, they modulate sympathetic outflow.

What does ephedrine do to your brain?

It is commonly used as a stimulant, appetite suppressant, concentration aid, decongestant, and to treat hypotension associated with anesthesia. Ephedrine stimulates the brain, increases the heart rate, increases blood pressure, expands bronchial tubes, increases metabolism, and increases body heat.

What drugs cause Tachyphylaxis?

To be specific, a high-intensity prolonged stimulus or often-repeated stimulus may bring about a diminished response also known as desensitization.
  • Molecular interaction.
  • Psychedelics.
  • Opioids.
  • Beta-2 agonists.
  • Nicotine.
  • Other examples.
  • Intranasal decongestants.

How long does IM ephedrine last?

Route Onset Duration
P.O. 15-60 min 3-5 hr
I.V. 5 min 1 hr
I.M., S.C. 10-20 min 1/2-1 hr
Nasal spray Unknown Unknown

What class of drug is ephedrine?

Ephedrine is a sympathomimetic amine and substituted amphetamine. It is similar in molecular structure to phenylpropanolamine, methamphetamine, and epinephrine (adrenaline). Chemically, it is an alkaloid with a phenethylamine skeleton found in various plants in the genus Ephedra (family Ephedraceae).

What are indirect acting sympathomimetics?

Indirectly acting sympathomimetic drugs. In addition to the agonists which stimulate directly adrenergic receptors, a certain number of compounds or drugs act indirectly via endogenous catecholamines by increasing their concentration in synaptic clefts and are called indirectly acting sympathomimetic drugs.

Why does ephedrine show Tachyphylaxis?

When given in repeated doses, tachyphylaxis occurs, probably because of depleted norepinephrine stores. Ephedrine causes an increase in systolic, diastolic, and MAPs. At higher doses, ephedrine causes hypertension and tachycardia. Because it crosses the blood-brain barrier, ephedrine can cause agitation and insomnia.

What is another name for ephedrine?

ephedrine systemic
Brand names: Akovaz, Corphedra. Drug class(es): decongestants, vasopressors.

How does ephedrine help you lose weight?

Ephedrine and How It Works
Ephedrine pills are stimulants that raise the metabolic rate of the user's body. This increases fat loss. Basically, ephedrine increases the energy expended by your body, most of which is from your body fat. The purpose of ephedrine pills is to improve breathing.

How does ephedrine work?

Ephedrine directly stimulates alpha and beta-adrenergic receptors and increases the release of norepinephrine. Its actions include relaxation of bronchioles, increased heart rate and contractility, and increased blood pressure. It also causes blood vessels in the nasal passages to shrink (vasoconstrict).