Dextromethorphan Hydrobromide + Guaifenesin

• Approved Indications:
• Symptomatic relief of cough caused by minor throat and bronchial irritation due to the common cold, bronchitis, or other respiratory tract infections.
• Dextromethorphan: Suppression of nonproductive (dry) cough.
• Guaifenesin: Expectorant to loosen and thin mucus, facilitating productive cough.
• Off-label / Clinically Accepted Uses:
• Adjunct therapy for symptomatic relief in acute bronchitis.
• Supportive treatment in mild chronic bronchitis to aid mucus clearance.
• Temporary relief of cough associated with upper respiratory allergic conditions.

• Route: Oral.
• Adults and Children 12 years and older:
• Dextromethorphan: 10–20 mg every 4 hours as needed.
• Guaifenesin: 200–400 mg every 4 hours as needed.
• Maximum daily dose: Dextromethorphan 120 mg; Guaifenesin 2400 mg.
• Children 6 to under 12 years:
• Dextromethorphan: 5–10 mg every 4 hours as needed.
• Guaifenesin: 100–200 mg every 4 hours as needed.
• Maximum daily dose should not exceed half of adult dose.
• Children under 6 years:
• Use not generally recommended unless directed by a healthcare professional.
• Elderly:
• Initiate at lower doses; monitor closely for side effects.
• Special Populations (Renal/Hepatic Impairment):
• Use with caution; dosage adjustments may be necessary in severe impairment.
• Administration Notes:
• Take with a full glass of water to enhance expectorant effect.
• Avoid concomitant use with other cough and cold products without medical advice.
• Avoid alcohol during treatment.

Dextromethorphan hydrobromide acts centrally on the cough center in the medulla by non-competitive antagonism of N-methyl-D-aspartate (NMDA) receptors and sigma-1 receptor agonism, increasing the threshold for cough reflex and suppressing nonproductive cough. Guaifenesin acts peripherally by irritating the gastric mucosa, which reflexively increases respiratory tract fluid secretion, thereby thinning bronchial mucus and facilitating its clearance by productive coughing. This combination provides both suppression of unwanted dry cough and promotion of mucus expectoration.

• Absorption: Both drugs are well absorbed orally.
• Distribution:
• Dextromethorphan crosses the blood-brain barrier to exert central antitussive effects.
• Guaifenesin has limited CNS penetration.
• Metabolism:
• Dextromethorphan is extensively metabolized by hepatic CYP2D6 to dextrorphan, an active metabolite.
• Guaifenesin undergoes minimal metabolism; mostly excreted unchanged.
• Half-life:
• Dextromethorphan: Approximately 3–4 hours.
• Guaifenesin: Approximately 1 hour.
• Elimination: Primarily renal excretion of metabolites and unchanged drug.

• Pregnancy: Category C (both components). Animal studies have not demonstrated direct fetal harm but human data are limited; use only if clearly needed.
• Lactation: Both drugs are excreted in small amounts in breast milk. Use with caution; potential effects on the nursing infant are unknown.

• Primary Class: Respiratory symptom relief agent.
• Subclass:
• Dextromethorphan: Non-opioid antitussive.
• Guaifenesin: Expectorant.

• Known hypersensitivity to dextromethorphan, guaifenesin, or formulation excipients.
• Concurrent or recent (within 14 days) use of monoamine oxidase inhibitors (MAOIs).
• Children under 6 years of age (unless prescribed).
• Severe respiratory depression or impaired respiratory function.

• Use with caution in patients with chronic cough associated with asthma, smoking, or emphysema.
• Risk of serotonin syndrome if used with serotonergic agents.
• Potential CNS effects: drowsiness, dizziness; avoid activities requiring alertness.
• Avoid alcohol and CNS depressants during therapy.
• Use cautiously in renal or hepatic impairment.
• Monitor for allergic reactions including rash or angioedema.

• Common:
• Dizziness
• Drowsiness
• Nausea
• Vomiting
• Gastrointestinal discomfort
• Serious/Rare:
• Allergic reactions (rash, swelling)
• Hallucinations or confusion (with overdose or misuse of dextromethorphan)
• Serotonin syndrome (especially with drug interactions)
• Respiratory depression (rare)

• MAO inhibitors: Contraindicated due to risk of hypertensive crisis and serotonin syndrome.
• Serotonergic drugs: Increased risk of serotonin syndrome.
• CYP2D6 inhibitors: May increase plasma levels of dextromethorphan, increasing toxicity risk.
• CNS depressants: Additive sedative effects with alcohol, benzodiazepines, opioids.
• Other cough and cold medications: Use cautiously to avoid additive effects.

• FDA warnings emphasize the risk of misuse and serotonin syndrome.
• Recommendations to avoid use in children under 2 years, and caution in children under 6 years.
• Guidance to limit treatment duration to the shortest time necessary for symptomatic relief.

• Store at 20°C to 25°C (68°F to 77°F).
• Protect from moisture and light.
• Keep container tightly closed.
• Keep out of reach of children.
• Do not freeze.