Nurses Compass
Drug Guide
Atenolol and Chlorthalidone
Classification
Therapeutic: Antihypertensive
Pharmacological: Beta-adrenergic blocker and Thiazide-like diuretic
FDA Approved Indications
- Hypertension
- Angina pectoris
Mechanism of Action
Atenolol blocks beta-1 adrenergic receptors, reducing heart rate and cardiac output; Chlorthalidone inhibits sodium reabsorption in the distal tubules, promoting diuresis — together lowering blood pressure.
Dosage and Administration
Adult: Typically 50 mg once daily, may be increased to 100 mg. Chlorthalidone 12.5-25 mg once daily.
Pediatric: Not approved for pediatric use.
Geriatric: Start at lower doses due to increased sensitivity and comorbidities.
Renal Impairment: Use with caution, dosage adjustments may be necessary.
Hepatic Impairment: Use with caution; dosage adjustments may be needed.
Pharmacokinetics
Absorption: Well-absorbed orally.
Distribution: Atenolol is approximately 50% protein-bound; Chlorthalidone is minimally protein-bound.
Metabolism: Atenolol undergoes minimal metabolism; Chlorthalidone undergoes hepatic metabolism.
Excretion: Primarily renal excretion.
Half Life: Atenolol approximately 6-7 hours; Chlorthalidone approximately 40-50 hours.
Contraindications
- Second- or third-degree AV block
- Sinus bradycardia
- Heart failure (unstable)
- Hypersensitivity to ingredients
Precautions
- Asthma or bronchospastic conditions
- Diabetes mellitus (may mask hypoglycemia)
- Electrolyte imbalances
Adverse Reactions - Common
- Dizziness (Common)
- Fatigue (Common)
- Hypotension (Common)
- Electrolyte disturbances (e.g., hypokalemia) (Common)
Adverse Reactions - Serious
- Bradycardia (Serious)
- Heart failure (worsening) (Serious)
- Electrolyte imbalances leading to arrhythmias (Serious)
- Severe hypotension or shock (Serious)
Drug-Drug Interactions
- Other antihypertensives
- Calcium channel blockers
- NSAIDs increasing blood pressure effects
Drug-Food Interactions
- Alcohol may enhance hypotensive effects
Drug-Herb Interactions
N/ANursing Implications
Assessment: Monitor blood pressure, heart rate, respiratory status, electrolyte levels.
Diagnoses:
- Risk for falls related to hypotension
- Impaired cardiac output
Implementation: Administer with food to decrease GI upset, monitor vital signs closely, especially after initiation or dosage changes.
Evaluation: Assess blood pressure and heart rate regularly to determine efficacy and safety.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Notify provider if experiencing dizziness, fainting, or irregular heartbeat.
- Avoid sudden discontinuation to prevent rebound hypertension.
- Limit alcohol intake and monitor salt intake.
Special Considerations
Black Box Warnings:
- Use with caution in certain patients due to risk of worsening heart failure or bradycardia.
Genetic Factors: Pharmacogenomic variations may affect beta-blocker response.
Lab Test Interference: May alter glucose and lipid levels.
Overdose Management
Signs/Symptoms: Severe bradycardia, hypotension, bronchospasm, hypoglycemia, seizures.
Treatment: Supportive care, activated charcoal if recent ingestion, atropine for bradycardia, vasopressors for hypotension, dialysis in severe cases.
Storage and Handling
Storage: Store at room temperature away from moisture and heat.
Stability: Stable under recommended conditions for specified shelf life.