Nurses Compass
Drug Guide
Chlorthalidone
Classification
Therapeutic: Antihypertensive; Diuretic
Pharmacological: Thiazide-like diuretic
FDA Approved Indications
- Hypertension
- Edema associated with congestive heart failure, renal impairment, or hepatic cirrhosis
Mechanism of Action
Chlorthalidone inhibits sodium reabsorption in the distal tubules of the nephron, increasing the excretion of sodium, chloride, potassium, and water, leading to decreased blood volume and blood pressure.
Dosage and Administration
Adult: Initially, 12.5 to 25 mg once daily. Dosage may be adjusted based on response, up to 50 mg daily.
Pediatric: Not commonly used in pediatric practice; consult specific guidelines.
Geriatric: Start with lower doses due to increased sensitivity; monitor closely.
Renal Impairment: Adjust dose based on renal function; use cautiously.
Hepatic Impairment: Use with caution; dose adjustments may be necessary.
Pharmacokinetics
Absorption: Well absorbed from gastrointestinal tract
Distribution: Widely distributed in body tissues and fluids
Metabolism: Minimal hepatic metabolism
Excretion: Primarily renal excretion of unchanged drug and metabolites
Half Life: about 40-60 hours, allowing once-daily dosing
Contraindications
- Hypersensitivity to chlorthalidone or sulfonamides
- Anuria
- Electrolyte imbalance
Precautions
- Electrolyte disturbances (hypokalemia, hyponatremia), gout, diabetes mellitus, systemic lupus erythematosus, monitor blood pressure and laboratory parameters regularly. Pregnancy category D; use only if benefits outweigh risks.
Adverse Reactions - Common
- Electrolyte disturbances (hypokalemia, hyponatremia) (Common)
- Hypotension (Common)
- Dizziness (Common)
Adverse Reactions - Serious
- Electrolyte imbalance leading to arrhythmias (Serious)
- Hypersensitivity reactions (Serious)
- Pancreatitis, blood dyscrasias (Rare/Serious)
Drug-Drug Interactions
- NSAIDs may reduce diuretic and antihypertensive effects, Lithium levels increase, Other antihypertensives may have additive effects
Drug-Food Interactions
- Alcohol may enhance hypotensive effects
Drug-Herb Interactions
N/ANursing Implications
Assessment: Monitor blood pressure, serum electrolytes, kidney function, fluid status.
Diagnoses:
- Risk for electrolyte imbalance
- Risk for hypotension
Implementation: Administer in the morning to minimize nocturia. Educate patients on dietary potassium intake.
Evaluation: Assess blood pressure, serum electrolytes, and signs of fluid depletion. Adjust dose as needed.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Monitor for signs of electrolyte imbalance (muscle weakness, cramps), dehydration, dizziness.
- Report rapid heartbeat, confusion, or severe weakness.
- Maintain adequate potassium intake unless contraindicated.
Special Considerations
Black Box Warnings:
- None specific to chlorthalidone
Genetic Factors: Some populations (e.g., African Americans) may respond differently—monitor efficacy and side effects.
Lab Test Interference: May cause alterations in serum electrolyte and glucose levels.
Overdose Management
Signs/Symptoms: Severe hypotension, electrolyte disturbances, dehydration
Treatment: Discontinue drug, provide supportive care, correct electrolyte imbalances, and monitor vital signs.
Storage and Handling
Storage: Store at room temperature, away from moisture and light.
Stability: Stable under normal conditions for shelf life specified by manufacturer.