Home Drug Guide Dextromethorphan Hydrobromide; Guaifenesin

Drug Guide

Generic Name

Dextromethorphan Hydrobromide; Guaifenesin

Brand Names Mucinex DM, Guaifenesin And Dextromethorphan Hydrobromide

Classification

Therapeutic: Cough Suppressant and Expectorant

Pharmacological: Antitussive and Expectorant

FDA Approved Indications

Cough due to minor throat and bronchial irritation

Mechanism of Action

Dextromethorphan acts on the cough center in the medulla to suppress the cough reflex. Guaifenesin increases cough productivity by thinning mucus in the airways, facilitating its removal.

Dosage and Administration

Adult: Typically, 10-20 mg of dextromethorphan every 4 hours as needed; Guaifenesin 200-400 mg every 4 hours as needed, not exceeding 2.4 g per day.

Pediatric: Usually 5-10 mg dextromethorphan every 4 hours; Guaifenesin 100-200 mg every 4 hours, dosage depending on age and weight; consult specific pediatric dosing guidelines.

Geriatric: Start at lower end of dosing range; monitor for CNS effects.

Renal Impairment: Adjust dose accordingly; consult specific guidelines.

Hepatic Impairment: Use with caution; dosage adjustment may be necessary.

Pharmacokinetics

Absorption: Well absorbed from gastrointestinal tract.

Distribution: Distributed extensively in body; crosses the blood-brain barrier.

Metabolism: Metabolized in the liver, primarily via CYP2D6 enzyme.

Excretion: Excreted mainly in urine.

Half Life: Dextromethorphan approximately 2-4 hours; Guaifenesin about 1 hour.

Contraindications

Use in patients taking MAO inhibitors within the past 14 days.
History of hypersensitivity to these drugs.

Precautions

Use cautiously in patients with cough associated with thick mucus or chronic cough as in smokers or asthma.

Adverse Reactions - Common

Drowsiness, dizziness (Common)
Nausea, vomiting (Less common)

Adverse Reactions - Serious

Serotonin syndrome (when combined with other serotonergic agents) (Rare)
Allergic reactions: rash, difficulty breathing (Rare)

Drug-Drug Interactions

MAO inhibitors (risk of serotonin syndrome)
Serotonergic drugs (SSRIs, SNRIs)

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor cough characteristics, mucus production, and patient response.

Diagnoses:

Risk for ineffective airway clearance

Implementation: Administer as directed, monitor for adverse effects, counsel on proper dosing.

Evaluation: Assess cough frequency and symptom relief.

Patient/Family Teaching

Take as directed; do not exceed recommended dose.
Report persistent cough or if cough is accompanied by fever, rash, or persistent headache.
Avoid alcohol and other CNS depressants.

Special Considerations

Black Box Warnings:

Serotonin syndrome risk when combined with serotonergic drugs.

Genetic Factors: Metabolism via CYP2D6 may vary among individuals, affecting drug levels.

Lab Test Interference: None reported.

Overdose Management

Signs/Symptoms: Dizziness, nausea, vomiting, confusion, hallucinations, seizures.

Treatment: Supportive care, activated charcoal if ingestion recent, and possibly administration of naloxone in cases of severe CNS depression.

Storage and Handling

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

Stability: Stable when stored properly.