2 - Sympathoplegic Agents (Beta-Blockers)

Which class are sympathoplegic agents?

• beta-blockers

• alpha-1 blockers

• centrally acting alpha-2 agonists

What is the MOA of beta-blockers?

binds and inhibits beta-receptors, decreasing HR and stroke volume

What are the major ADE of beta-blockers?

• bradycardia

• worsening HF

• bronchoconstriction

• hypoglycemia

• fatigue

• depression

• sexual dysfunction in males

What are the clinical cautions of beta blockers?

• asthma/COPD

• HF

• diabetes

• abrupt withdrawal → taper over 2-3 weeks

Is propanolol selective or nonselective?

nonselective

Which agent was the first beta blocker and is available in ER?

propranolol

Is metoprolol selective or nonselective?

β₁ selective

What are the potential drug interactions of metoprolol, betaxolol, & bisoprolol?

CYP2D6

• SSRIs

• bupropion

• H2-antagonist

What are the dosage forms of metoprolol?

• tartrate = IR

• succinate = ER

Is atenolol selective or nonselective?

β₁ selective

How are atenolol, nadolol, & carteolol primarily excreted?

unchanged in urine

Are nadolol & carteolol selective or nonselective?

nonselective

Are betaxolol & bisoprolol selective or nonselective?

β₁ selective

What is notable about betaxolol & bisoprolol?

long half life → once daily dosing

What is the MOA of pindolol, acebutolol, & penbutolol?

partial agonist at beta-receptors, less activity than full agonist

Which beta-blocker agents are vasodilating?

labetolol, carvedilol, nebivolol

What is notable about labetalol?

racemic mixture of 4 isomers

• SR - potent alpha-blocker

• RR - potent non-selective beta-blocker

What is notable about carvedilol?

racemic mixture of 2 isomers

• S(-) - nonselective

• R(+) - alpha-blocker

What are the potential drug interactions of carvedilol?

CYP2C9 & 2D6

• SSRIs

• antifungals

• valproic acid

What is notable about nebivolol?

racemic mixture of 2 isomers

• D - β₁

• L - increased nitric oxide production

t_1/2 = 10 hours

Is esmolol selective or nonselective?

β₁ selective

What is notable about esmolol?

• rapidly metabolized by RBC esterases

• t_1/2 = 9-10 minutes

• continuous IV infusion

What are the uses of esmolol?

• intra-/postoperative hypertension

• HTN emergency w/ tachycardia

What is the use of timolol?

absorbed orally to treat glaucoma