Home Drug Guide Chlorthalidone and Clonidine Hydrochloride

Drug Guide

Generic Name

Chlorthalidone and Clonidine Hydrochloride

Brand Names Combipres, Clorpres

Classification

Therapeutic: Antihypertensive, Diuretic

Pharmacological: Chlorthalidone - Thiazide-like diuretic; Clonidine - Alpha-2 adrenergic agonist

FDA Approved Indications

Hypertension

Mechanism of Action

Chlorthalidone inhibits sodium reabsorption in the distal tubules of the kidney, promoting diuresis. Clonidine stimulates alpha-2 adrenergic receptors in the brainstem, reducing sympathetic outflow, decreasing blood pressure.

Dosage and Administration

Adult: Dosage varies based on clinical response; typically, 12.5-25 mg daily for chlorthalidone and 0.1-0.3 mg twice daily for clonidine.

Pediatric: Use is not common; dosage should be individualized based on age and response.

Geriatric: Start at lower doses due to increased sensitivity and risk of side effects.

Renal Impairment: Adjust dose based on renal function; chlorthalidone can cause electrolyte imbalances.

Hepatic Impairment: Use with caution; monitor closely.

Pharmacokinetics

Absorption: Well absorbed orally.

Distribution: Widely distributed in body tissues.

Metabolism: Clonidine undergoes hepatic metabolism; chlorthalidone undergoes minimal metabolism.

Excretion: Renal excretion of unchanged drugs and metabolites.

Half Life: Chlorthalidone: ~40-50 hours; Clonidine: ~12-16 hours.

Contraindications

Hypersensitivity to either drug
Severe coronary artery disease (clonidine caution)

Precautions

Orthostatic hypotension, renal impairment, hepatic impairment, pregnancy (clonidine caution), history of depression

Adverse Reactions - Common

Dry mouth (common)
Dizziness (common)
Fatigue (common)

Adverse Reactions - Serious

Bradycardia (rare)
Electrolyte disturbances (hypokalemia, hyponatremia) (common)
Rebound hypertension upon withdrawal (rare)

Drug-Drug Interactions

Other antihypertensives, CNS depressants, MAO inhibitors

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor blood pressure, heart rate, electrolyte levels, renal function.

Diagnoses:

Risk of hypotension
Electrolyte imbalance

Implementation: Administer as prescribed, monitor patient response, educate patient about orthostatic hypotension and adherence.

Evaluation: Assess blood pressure and side effects regularly.

Patient/Family Teaching

Take medication exactly as prescribed.
Change positions slowly to minimize dizziness.
Do not discontinue abruptly to avoid rebound hypertension.
Report signs of electrolyte imbalance or severe side effects.

Special Considerations

Black Box Warnings:

Rebound hypertension if discontinued abruptly.
Clonidine withdrawal symptoms: hypertension, tremors, headaches, nervousness.

Genetic Factors: N/A

Lab Test Interference: N/A

Overdose Management

Signs/Symptoms: Severe hypotension, bradycardia, sedation, respiratory depression.

Treatment: Supportive care, airway management, fluid replacement, atropine for bradycardia, and specific antidotes if available.

Storage and Handling

Storage: Store at room temperature, away from moisture and light.

Stability: Stable under typical storage conditions.