Overview
Atenolol is a cardioselective beta-1 adrenergic blocker used primarily for hypertension and angina pectoris. It reduces heart rate, cardiac output, and blood pressure through competitive antagonism of catecholamines at cardiac adrenergic sites. The drug is also indicated for acute myocardial infarction management to reduce cardiovascular mortality.
Mechanism of Action
Atenolol selectively blocks beta-1 adrenergic receptors in the heart, reducing sympathetic stimulation. This decreases heart rate, myocardial contractility, and cardiac output, leading to reduced blood pressure and myocardial oxygen demand. Unlike non-selective beta-blockers, it has minimal effect on beta-2 receptors in bronchial and vascular smooth muscle at therapeutic doses.
Indications
- Hypertension
- Angina pectoris
- Acute myocardial infarction (to reduce cardiovascular mortality)
Common Doses
- 25 mg
- 50 mg
- 100 mg
Dosage
Typically initiated at 25-50 mg once daily for hypertension or angina, titrated to 100 mg once daily maximum. For acute MI: 5 mg IV over 5 minutes, followed by 50 mg orally 10 minutes later, then 50 mg twice daily or 100 mg once daily.
Contraindications
- Sinus bradycardia
- Heart block greater than first degree
- Cardiogenic shock
- Overt cardiac failure
- History of hypersensitivity to atenolol or any component
Side Effects
- Bradycardia
- Cold extremities
- Fatigue
- Dizziness
- Depression
- Nausea
- Diarrhea
- Dyspnea
- Postural hypotension
- Lethargy
- Dream disturbances
Interactions
- Catecholamine-depleting drugs (reserpine) - additive hypotension/bradycardia
- Calcium channel blockers - additive cardiac effects
- Disopyramide - severe bradycardia/heart failure
- Clonidine - rebound hypertension on withdrawal
- Digitalis glycosides - increased bradycardia risk
- NSAIDs (indomethacin) - decreased antihypertensive effect
Counseling Points
- Do not stop abruptly - taper under medical supervision
- Monitor pulse rate regularly
- Report dizziness, shortness of breath, or excessive fatigue
- May cause cold hands/feet
- Can mask hypoglycemia symptoms in diabetics
- Take at same time daily