Beta Blockers - Clinical Indications, Adverse Effects, and Drug Interactions

Vocabulary practice flashcards covering clinical indications, adverse effects, contraindications, and drug interactions of beta blockers based on lecture materials.

Absolute Contraindications of Beta Blockers

Cardiogenic shock, decompensated HF, high-degree AV block (without pacemaker), severe bradycardia, and sick sinus syndrome.

Rebound HTN / Beta Blocker Withdrawal

Hypertensive crisis resulting from abrupt discontinuation due to upregulation of $\beta$ receptors; managed by tapering over $1\text{--}2$ weeks.

Lipophilic Beta Blocker CNS Effects

Fatigue, depression, nightmares, and insomnia caused by agents with high CNS penetration (propranolol > atenolol).

Peripheral Vascular Adverse Effects of Beta Blockers

Raynaud's phenomenon and cold extremities caused by $\beta_2$ blockade leaving $\alpha$ receptors unopposed; requires caution in peripheral arterial disease.

Metabolic Adverse Effects of Beta Blockers

Masking of hypoglycemia symptoms, worsening of insulin resistance, and $\uparrow$ triglycerides with $\downarrow$ HDL associated with older agents.

Beta Blocker Airway Adverse Effect

Bronchoconstriction caused by $\beta_2$ blockade in airways; non-selective agents should be avoided in severe asthma/COPD.

Heart Failure with Decreased Ejection Fraction Beta Blockers

Metoprolol succinate, Carvedilol, and Bisoprolol, which are specifically indicated for heart failure with $\downarrow$ EF.

Cardiovascular Indications for Beta Blockers

Hypertension, heart failure with $\downarrow$ EF, post-MI, angina pectoris ($\downarrow \text{O}_2$ demand), atrial fibrillation/flutter (rate control), hypertrophic obstructive cardiomyopathy, and aortic dissection (IV propranolol/esmolol).

Non-Cardiovascular Indications for Beta Blockers

Migraine prophylaxis (propranolol, timolol), essential tremor (propranolol), performance/situational anxiety, thyrotoxicosis/thyroid storm (propranolol), pheochromocytoma (after $\alpha$-blocker), glaucoma (topical timolol, betaxolol), and esophageal varices prophylaxis (propranolol, nadolol).

Pheochromocytoma Beta Blocker Precondition

Beta blockers must only be administered after initiating an $\alpha$-blocker to prevent unopposed $\alpha$-mediated vasoconstriction.

Beta Blockers + Verapamil / Diltiazem Interaction

Severe interaction caused by additive depression of SA/AV node conduction, resulting in complete heart block, severe bradycardia, or cardiac arrest; managed by avoiding the combination or giving IV calcium for toxicity.

Beta Blockers + Insulin / Oral Hypoglycemics Interaction

Moderate interaction where blunting of tachycardia (a warning sign of hypoglycemia) and impairment of glycogenolysis lead to prolonged, unrecognized hypoglycemia; managed by using cardioselective agents, monitoring blood glucose closely, and educating patients on diaphoresis as a warning sign.

Beta Blockers + Clonidine Discontinuation Interaction

Severe interaction where abrupt clonidine withdrawal causes $\uparrow$ NE while beta blockers leave $\alpha$ effects unopposed, resulting in hypertensive crisis with rebound HTN; managed by discontinuing the beta blocker first, then tapering clonidine.

Beta Blockers (Propranolol) + CYP1A2/2D6 Inhibitors Interaction

Moderate interaction where CYP1A2/2D6 inhibitors (e.g., amiodarone, fluoxetine, cimetidine) reduce hepatic metabolism, leading to $\uparrow$ propranolol plasma levels, bradycardia, and hypotension.

Non-selective Beta Blockers + Epinephrine Interaction

Moderate interaction where $\beta$-blockade leaves $\alpha_1$-mediated vasoconstriction unopposed, causing severe hypertension and reflex bradycardia; managed by using cardioselective agents when epinephrine may be needed.