Adrenergic agents – how do they work?

In the previous two blogs, we discussed alpha-adrenergic and beta-adrenergic drugs, drugs that inhibit various actions of the sympathetic nervous system. In this blog we are going to take a look at adrenergic drugs, often called sympathomimetic agents, which have the other effect. Let’s take a take a look at how they work.

Basic overview

Adrenergic drugs are substances that may simulate or hinder the functioning of the sympathetic nervous system. They achieve this by influencing the discharge or activity of the hormones norepinephrine (norepinephrine) and epinephrine (adrenaline) (Brittanica, 2018). These hormones, secreted by the adrenal glands, are chargeable for the body’s “fight or flight” response, causing blood vessels to constrict, blood pressure to extend, and heart rate and strength to extend. heart contractions. Sympathomimetic agents simulate and enhance the results of the sympathetic nervous system.

Action mechanism

In the conventional physiology of the sympathetic nervous system, impulses travel along the presynaptic neuron, where cellular changes occur. Neurotransmitters are released on the synapse and activate adrenergic receptors positioned on the postsynaptic nerve. Adrenergic agonists have three mechanisms of motion: direct motion, indirect motion, or dual motion. Sympathomimetics mimic normal physiology and directly activate adrenergic receptors. They are classified based on their activity on specific adrenergic receptors: alpha-1, alpha-2, beta-1 and beta-2.

• Alpha-1 (α₁) agonists contract most vascular smooth muscles
• Alpha-2 (α₂) agonists contract mixed smooth muscles
• Beta-1 (β₁) agonists increase heart rate
• Beta-2 (β₂) agonists chill out the graceful muscles of the respiratory tract and uterus

Adrenergic agonists work in three alternative ways. They can 1. stimulate and increase the discharge of neurotransmitters reminiscent of noradrenaline from nerve endings to synapses; 2. reduce the reuptake of neurotransmitters into the presynaptic nerve; and three. reduce the enzymatic metabolism of neurotransmitters. Indirect-acting sympathomimetics include drugs reminiscent of amphetamines and cocaine (Farzam, Kidron, & Lakhkar, 2022).
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or adrenergic stimulate each adrenergic receptor sites and the discharge of norepinephrine from nerve endings. Dual-acting medications include ephedrine and pseudoephedrine.

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Nursing considerations

When administering adrendergic agonists, monitor for adversarial effects reminiscent of hypertension and reflex bradycardia (±₁); hypotension, dry mouth and sedation (±₂); tachycardia, palpitations, tachyarrhythmia and anxiety (β₁); tremor and tachycardia (β₂). Patients taking alpha-2 agonists are in danger for substance abuse, and patients taking beta-2 agonists must be monitored for paradoxical bronchospasm.
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Full details could be present in the leaflet that comes with the drugs or within the Nursing2022 Medicines Manual + medicines updates.
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Britannica, T. Editors of Encyclopaedia (2018, July 13). https://www.britannica.com/science/adrenergic-drug

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Farzam, K., Kidron, A., & Lakhkar, A. D. (2022, July 3). Adrenergic drugs. https://www.ncbi.nlm.nih.gov/books/NBK534230/#:~:text=Adrenergic%20drugs%20are%20a%20broad,to%20induce%20various%20physiologic%20effects.

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