Abexol

Guaifenesin + Dextromethorphan + Menthol is a combination medication used for symptomatic relief of cough and chest congestion associated with upper respiratory tract infections and related conditions.

Approved Indications:

• Relief of productive cough associated with colds, bronchitis, or other upper respiratory tract infections (guaifenesin).
• Relief of dry, irritating cough (dextromethorphan).
• Temporary soothing of throat irritation and mild nasal congestion (menthol).

Clinically Accepted Off-Label Uses:

• Symptomatic relief of cough and chest congestion in influenza.
• Adjunct therapy in mild acute bronchitis to improve comfort and expectoration.

Adults & Adolescents (>12 years):

• 10 mL of syrup every 4–6 hours as needed.
• Maximum daily dose: 60 mL per day.

Children (6–12 years):

• 5 mL every 4–6 hours as needed.
• Maximum daily dose: 30 mL per day.

Children (2–6 years):

• 2.5 mL every 4–6 hours as needed.
• Maximum daily dose: 15 mL per day.

Children <2 years:

• Use only under medical supervision.

Special Populations:

• Renal or Hepatic Impairment: Caution advised; monitor for accumulation or adverse effects.
• Elderly: Use standard dosing; monitor for CNS effects (drowsiness, dizziness).

Administration Notes:

• Shake well before use.
• Take with a full glass of water to enhance expectorant effect.
• Avoid combining with other products containing dextromethorphan or guaifenesin.

This combination works through three complementary mechanisms:

• Guaifenesin: Expectorant that increases the volume and reduces viscosity of respiratory secretions, facilitating mucus clearance.
• Dextromethorphan: Centrally acting antitussive that suppresses cough reflex by acting on the medullary cough center without depressing respiration.
• Menthol: Local anesthetic and mild decongestant that provides a cooling sensation, reduces throat irritation, and may stimulate cold-sensitive receptors to improve airflow perception.
  Together, the combination provides relief from both productive and non-productive cough while soothing throat irritation and easing mucus clearance.

Guaifenesin:

• Rapidly absorbed orally; bioavailability ~60–70%.
• Widely distributed; minimal protein binding.
• Metabolized in liver to inactive metabolites; excreted mainly via urine.
• Half-life: ~1 hour.

Dextromethorphan:

• Well absorbed orally; peak plasma concentration 2–2.5 hours.
• Extensive hepatic metabolism via CYP2D6; low bioavailability due to first-pass effect.
• Half-life: 3–6 hours (varies with CYP2D6 genotype).
• Excreted primarily in urine as metabolites.

Menthol:

• Rapidly absorbed via oral mucosa and gastrointestinal tract.
• Metabolized in liver; excreted in urine as glucuronide conjugates.
• Provides local symptomatic relief rather than systemic pharmacologic effect.

Onset of Action: Symptomatic relief usually within 15–30 minutes; expectorant effect may take longer.

• Pregnancy: Category C — use only if clearly needed; animal studies show no major teratogenic effects, but human data are limited.
• Lactation: Dextromethorphan and guaifenesin are excreted in small amounts in breast milk; caution is advised. Menthol is generally considered safe in small topical or oral doses.
• Note: Avoid high doses and prolonged use during pregnancy and breastfeeding.

• Primary Class: Cough and cold combination
• Subclasses:
• Guaifenesin: Expectorant
• Dextromethorphan: Centrally acting antitussive
• Menthol: Topical analgesic and mild decongestant

• Known hypersensitivity to guaifenesin, dextromethorphan, menthol, or formulation excipients.
• Patients on MAO inhibitors within the last 14 days (risk of serotonin syndrome due to dextromethorphan).
• Severe respiratory depression or chronic bronchitis with mucus retention (risk with dextromethorphan).

• High-risk patients:
• Asthma or COPD — dextromethorphan may mask symptoms.
• Hepatic or renal impairment — monitor for accumulation.
• Children under 2 years — avoid unless under supervision.
• Serious risks:
• Serotonin syndrome with concomitant serotonergic drugs (rare).
• CNS depression or drowsiness, particularly in elderly or when combined with alcohol.
• Monitoring:
• Discontinue if persistent cough, fever, or purulent sputum develops.
• Other precautions:
• Avoid alcohol while using this medication.

Common:

• Dizziness, drowsiness
• Nausea, vomiting
• Gastrointestinal discomfort
• Mild throat irritation

Serious/Rare:

• Allergic reactions (rash, urticaria, anaphylaxis)
• CNS effects: confusion, hallucinations at high doses (dextromethorphan abuse potential)
• Rare serotonergic effects if combined with other serotonergic agents

Onset & Dose Dependence: Usually mild and transient; CNS effects are dose-dependent.

• Drug-Drug:
• MAO inhibitors — risk of serotonin syndrome.
• CNS depressants (alcohol, sedatives) — increased drowsiness.
• Other serotonergic drugs (SSRIs, SNRIs, triptans) — risk of serotonin syndrome.
• Drug-Food: No significant interactions; taking with food may reduce mild GI upset.
• Drug-Alcohol: Avoid alcohol — may potentiate CNS depression.
• Enzyme Systems: Dextromethorphan metabolized by CYP2D6; inhibitors or inducers may alter levels.

• Combination therapy remains a first-line symptomatic treatment for mixed cough (productive and non-productive) in adults and children above 6 years.
• Safety guidance emphasizes avoidance in children under 2 years and caution with serotonergic drugs.
• Recommendations include short-term use (usually ≤7 days) to prevent masking serious respiratory infections.

• Store at 20°C–25°C (room temperature).
• Protect from moisture and direct sunlight.
• Keep container tightly closed.
• Do not freeze.
• Shake well before use; keep out of reach of children.