Adrenergic Agonists and Antagonists Practice Flashcards

Vocabulary-style flashcards covering adrenergic agonists and antagonists, including receptor types, physiological effects, specific drug indications, and adverse reactions.

Sympathomimetics

Adrenoceptor agonists that produce effects similar to those produced by the sympathetic nervous system.

$\alpha_1$-Adrenergic Receptors

Receptors located on postsynaptic effector cells, such as blood vessels, whose stimulation results in vasoconstriction and contraction of the uterus, bladder, and ciliary muscles.

$\alpha_2$-Adrenergic Receptors

Receptors located on presynaptic nerve terminals that inhibit the release of neurotransmitters like norepinephrine and acetylcholine.

$\beta_1$-Adrenergic Receptors

Receptors located primarily in the heart (myocardium, AV node, and SA node) that increase cardiac rate, force, and output when stimulated.

$\beta_2$-Adrenergic Receptors

Receptors located in the smooth muscle of the bronchioles, arterioles, and visceral organs that cause bronchodilation, vasodilation, and uterine relaxation.

Positive inotropic effect

An increase in the force of contraction of the heart muscle (myocardium).

Positive chronotropic effect

An increase in heart rate.

Positive dromotropic effect

An increase in the conduction of cardiac electrical impulses through the atrioventricular node.

L-Dopa

The precursor for dopamine used to treat patients with Parkinson's disease because dopamine itself is polar and cannot penetrate the blood-brain barrier (BBB).

Epinephrine (Adrenaline)

A non-selective adrenergic agonist that stimulates $\alpha_1$, $\alpha_2$, $\beta_1$, and $\beta_2$ receptors; it serves as the physiologic antidote of histamine in anaphylactic shock.

Dopamine

A potent vasoconstrictor with little effect on $\beta_2$ receptors, used for cardiogenic shock and hypotension; care must be taken to avoid extravasation which can lead to necrosis.

Clonidine

An $\alpha_2$ agonist and centrally acting sympatholytic agent used for hypertension and opiate withdrawal; it crosses the BBB and can cause rebound HTN if abruptly withdrawn.

Ritodrine

A $\beta_2$-selective agonist used as a tocolytic agent to prevent premature labor by causing uterine relaxation.

Phenylephrine

An $\alpha_1$ agonist used clinically as a nasal decongestant and as a mydriatic (to dilate pupils).

Sympatholytics

Adrenoceptor antagonists that inhibit the stimulation of the sympathetic nervous system, causing vasodilation or decreased cardiac output to reduce blood pressure.

$\alpha_1$ Blockers

Selective antagonists like prazosin and doxazosin used to treat hypertension and Benign Prostatic Hyperplasia (BPH) by causing vasodilation and improving urine flow.

Tamsulosin

A selective $\alpha_1$ blocker used specifically for the treatment of urinary flow obstruction in Benign Prostatic Hyperplasia (BPH).

Pheochromocytoma

A hypertensive condition caused by an adrenal gland tumor that secretes large amounts of catecholamines, treated with non-selective $\alpha$-antagonists like phentolamine.

Orthostatic hypotension

An adverse effect of selective $\alpha_1$ blockers often characterized by a strong "first-dose" hypotensive effect and syncope.

Propranolol

A nonselective $\beta$-blocker that antagonizes both $\beta_1$ and $\beta_2$ receptors, used for hypertension, migraine prophylaxis, and hyperthyroidism.

Cardioselective $\beta$ blockers

Drugs that primarily block $\beta_1$ receptors, such as atenolol, metoprolol, and bisoprolol.

Bronchospasm

A potentially lethal adverse effect of $\beta$-blockers in patients with asthma or COPD due to the antagonism of $\beta_2$ receptors.

Glycogenolysis

The conversion of glycogen into glucose in the liver, which is a metabolic effect of $\beta_2$ receptor stimulation.

Oliguria

A condition of low urine output that can be improved by using norepinephrine to cause vasodilation in the renal vascular beds.