Alpha/Beta Blockers

Alpha/Beta Blockers

General Overview

• Alpha/beta blockers are a category of sympatholytic medications.

• Used for treating:

  • Hypertension

  • Heart failure (commonly alongside digoxin, ACE inhibitors, and diuretics)

  • Prolong survival chance post-myocardial infarction (MI)

Prototype and Mechanism of Action

• Prototype Medication: Carvedilol

• Expected Pharmacologic Action:

  • Block both alpha and beta receptors in the heart, arterioles, and kidney.

  • Alpha Receptor Blockade:

    • Causes dilation of arterioles by blocking peripheral alpha1 receptors.

  • Beta1 Receptor Blockade:

    • Reduces heart rate and contractility by blocking cardiac beta1 receptors.

    • Decreases renin release by blocking kidney beta1 receptors.

  • Overall effects:

    • Decreased resistance in blood vessels

    • Decreased cardiac output

    • Increased excretion of water and sodium

Adverse Drug Reactions

• Common side effects include:

  • Dizziness

  • Hypotension

  • Bradycardia (especially from beta1 receptor blockade)

• Other potential reactions:

  • Postural hypotension

  • Exacerbation of asthma

Monitoring and Interventions

• Blood Pressure Monitoring:

  • Regularly monitor blood pressure; report hypotension.

• Heart Rate Monitoring:

  • Monitor heart rate; report rates below 60 beats per minute.

• Safety Alert:

  • Concurrent use with other antihypertensives can lead to bradycardia.

  • Ensure heart rate is above 60 before administration; hold if below and notify provider.

  • Prepare to administer atropine and isoproterenol for symptomatic clients.

Administration Guidelines

• Carvedilol is indicated for:

  • Oral use only

  • Administer with food to minimize orthostatic hypotension.

Client Instructions

• Advise clients to:

  • Report dizziness or syncope to the provider.

  • Move slowly from lying to standing to prevent falls.

  • Avoid hazardous activities (e.g., driving) until aware of medication effects.

  • Check pulse daily; report rates less than 60 beats per minute.

Contraindications and Precautions

• Do not administer to clients with:

  • Severe, unstable heart failure

  • Asthma/bronchospastic disorders

  • Heart block or severe bradycardia

  • Cardiogenic shock

  • Pregnancy/lactation

• Caution with:

  • Children under 18

  • Clients with diabetes, renal/hepatic disorders, peripheral vascular disease

Interactions

• Carvedilol interactions:

  • Concurrent use with insulin/oral hypoglycemics may alter hypoglycemic effects.

  • Higher risk of bradycardia when taken with digoxin.

  • Co-administration with MAO inhibitors may lead to bradycardia or hypotension.

  • Cimetidine can increase blood levels of alpha/beta blockers.

  • Increased risk for hypotension when combined with other antihypertensives.