III - Symphathomimetics

Question 1

Norepinephrine - primary transmitter at the symphathetic postganglionic neuron-effector cell synapse in most tissues.

Answer 1

Dopamine/Norepinephrine: Dopamine vasDILATES renal blood vessels while Norepinephrine vasCONTRICTS them.

Question 2

Epinephrine is a Sympathomimetic (non-selective, direct-acting). MOA: Activates alpha and beta adrenergic receptors. A1: vasoconstriction, B1 increased HR, conduction and contractility, B2: bronchodilation

Answer 2

Uses: Cardiac arrest, Anaphylaxis, Asthma. SE: Hypertension, Tachycardia

Question 3

Norepinephrine is a Sypathomimetic (non-selective, direct acting). MOA: Activates alpha and beta receptors. A1: vasoconstriction, B1 increased HR, conduction and contractility, B2: bronchodilation

Answer 3

Uses: Neurogenic shock, Cadiogenic shock (last resort). SE: Excessive blood pressure increase, Reflex bradycardia, Extreme vasospasm, Arrhythmias

Question 4

Dopamine is a Sympathomimetic (non-selective, direct-acting). MOA: Activates alpha and beta receptors. A1: vasoconstriction, B1 increased HR, conduction and contractility, B2: bronchodilation

Answer 4

Uses: Shock, Heart failure. SE: Cardiovascular disturbance, Arrhythmias

Question 5

Dose-Dependent Actions of Dopamine

Answer 5

Low Dose (1-5 mcg/kg/min) - renal protective dose. Vasodilation in the splanchnic and renal vascular beds via D1 receptors. Medium Dose (5-15 mcg/kg/min) - inc. renal blood flow, heart rate,cardiac output via B1 receptors. High Dose (>15 mcg/kg/min) - vasoconstriction and inc BP via A receptors.

Question 6

Isoproterenol is a Sympathomimetic (beta-nonselective). MOA: Non-selectively activates B adrenergic receptors. B1: inc HR, conduction, contractility, B2: bronchodilation

Answer 6

Uses: Asthma

Question 7

Phenylephrine is a sympathomimetic (alpha 1-selective). MOA: Selectively activates A1 adrenergic receptors. A1: vasoconstriction, Inc BP

Answer 7

Uses: Decongestant, Mydriatic. SE: Rebound nasal congestion, Hypertension, Stroke. Notes: Ocular administration causes mydriasis WITHOUT cyclopegia

Question 8

Clonidine is a sympathomimetic (alpha 2-selective). MOA: Activates Alpha 2 receptors. A2: decreases central sympathetic outflow.

Answer 8

Uses: Hypertension, Cancer pain. SE: Rebound Hypertension, Sedation. Notes: Taper use prior to discontinuation to avoid rebound hypertension. Treat with Phentolamine.

Question 9

Methyldopa is a sympathomimetic (alpha 2-selective). MOA: Activates alpha 2 adrenergic receptors. A2: decreases central sympathetic outflow.

Answer 9

Uses: Pre-eclampsia. SE: Hemolytic anemia (positive Coomb’s test), Sedation.

Question 10

Apraclonidine is a sympathomimetic (alpha 2-selective). MOA: Activates alpha 2 adrenergic receptors A2: decreases secretion of aqueous humor

Answer 10

Uses: Glaucoma. SE: Blurring of vision, Conjunctivitis, Dry mouth

Question 11

Dobutamine is a sympathomimetic ( beta 1-selective). MOA: Activates Beta 1 adrenergic receptors. B1: increases HR and contractility

Answer 11

Uses: Acute heart failure, Cardiogenic shock, Tachyphylaxis - lower response due to rapid administration. Notes: use also in cardiac stress testing.

Question 12

Albutamol are sympathomimetic (beta 2-selective). MOA: Activates beta 2 receptors in bronchial smooth muscle. Causes bronchodilation.

Answer 12

Uses: Acute asthma attacks (drug of choice), Tocolysis for preterm labor. Notes: May precipaitate arrhythmias in patient with concurrent COPD and heart disease.