Generic Name

Chlorpheniramine Maleate

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Classification

FDA Approved Indications

• Allergic rhinitis
• Urticaria (hives)
• Hay fever
• Other allergic symptoms

Mechanism of Action

Chlorpheniramine Maleate blocks peripheral H1 receptors, preventing histamine from exerting its effects, thereby reducing allergy symptoms.

Dosage and Administration

Adult: 4 mg every 4-6 hours as needed, not to exceed 24 mg per 24 hours

Pediatric: 2-4 mg every 4-6 hours as needed, dosage depends on age and weight; consult prescribing information

Geriatric: Use with caution; start at lower doses due to increased sensitivity and potential for sedation and side effects

Renal Impairment: Adjust dose based on severity of impairment, consult specific guidelines

Hepatic Impairment: Use with caution; monitor for increased effects due to decreased metabolism

Pharmacokinetics

Absorption: Well absorbed from gastrointestinal tract

Distribution: Widely distributed; crosses blood-brain barrier

Metabolism: Partially metabolized in the liver

Excretion: Excreted primarily in urine

Half Life: about 12-15 hours but may vary based on patient factors

Contraindications

• Known hypersensitivity to chlorpheniramine or other antihistamines
• Use with caution in patients with urinary retention, glaucoma, asthma, or gastrointestinal obstruction

Precautions

• Caution in elderly patients, may cause sedation, impairment of mental and motor ability, anticholinergic effects

Adverse Reactions - Common

• Sedation and drowsiness (Common)
• Anticholinergic effects such as dry mouth, urinary retention, blurred vision, dizziness (Common)

Adverse Reactions - Serious

• Seizures, hypersensitivity reactions (rash, anaphylaxis) (Rare)

Drug-Drug Interactions

• CNS depressants (enhances sedation)
• Monoamine oxidase inhibitors (increased anticholinergic effects)

Drug-Food Interactions

• Alcohol (enhances sedative effects)

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Take medication exactly as prescribed
• Do not drive or operate machinery until you know how this medication affects you
• Caution about alcohol use and other CNS depressants
• Report excessive drowsiness, dry mouth, or other side effects

Special Considerations

Black Box Warnings:

• None currently

Genetic Factors: None established

Lab Test Interference: None known

Overdose Management

Signs/Symptoms: Severe anticholinergic effects, drowsiness, convulsions, hallucinations

Treatment: Supportive care, activated charcoal if ingested recently, symptomatic treatment, and airway management as needed.

Storage and Handling

Storage: Store at room temperature away from light and moisture

Stability: Stable for shelf life as per manufacturer instructions