1. Clinical Overview
A fixed-dose combination lozenge used for the symptomatic relief of sore throat and associated dry, non-productive cough. Amylmetacresol is a topical antiseptic and local anesthetic for the throat, while Dextromethorphan is a centrally-acting antitussive. It is a widely used OTC product in India for upper respiratory tract infections.
| Onset | Duration | Bioavailability |
|---|---|---|
| Amylmetacresol: Local effect within 2-5 minutes. Dextromethorphan: Systemic effect within 15-30 minutes. | Amylmetacresol: Local anesthetic/antiseptic effect lasts 1-2 hours per lozenge. Dextromethorphan: Antitussive effect lasts 5-6 hours. | Amylmetacresol: Negligible systemic absorption from oral mucosa. Dextromethorphan: Approximately 11% (extensive first-pass metabolism). |
2. Mechanism of Action
Amylmetacresol acts locally on the oropharyngeal mucosa to denature bacterial proteins and fungal cell membranes, providing antiseptic action. It also has a mild local anesthetic effect, soothing throat pain. Dextromethorphan is a sigma-1 receptor agonist and NMDA receptor antagonist that acts centrally on the cough center in the medulla oblongata, raising the threshold for cough reflex.
3. Indications & Uses
- Symptomatic relief of sore throat
- Symptomatic relief of dry, non-productive (tickly) cough associated with upper respiratory tract infections (e.g., common cold, pharyngitis)
4. Dosage & Administration
Adult Dosage: One lozenge to be dissolved slowly in the mouth every 2-3 hours. Maximum: 8 lozenges in 24 hours.
Administration: Allow lozenge to dissolve slowly in the mouth. Do not chew or swallow whole. Do not consume food or drink immediately after taking the lozenge to prolong local effect. Use at regular intervals for symptomatic relief.
5. Side Effects
Common side effects may include:
- Nausea
- Gastrointestinal discomfort
- Drowsiness
- Dizziness
- Local mouth numbness or irritation
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| MAO Inhibitors (Phenelzine, Selegiline, Moclobemide) | Risk of severe serotonin syndrome, hyperpyrexia, death. | Contraindicated |
| SSRIs, SNRIs, Tricyclic Antidepressants | Increased risk of serotonin syndrome. | Major |
| Other CNS Depressants (Alcohol, Benzodiazepines, Opioids) | Additive sedation and CNS depression. | Major |
| CYP2D6 Inhibitors (Quinidine, Fluoxetine, Paroxetine) | Increased Dextromethorphan plasma levels, increased risk of side effects. | Moderate |
| Linezolid, Methylene Blue | Potential serotonin syndrome. | Major |
7. Patient Counselling
- DO allow the lozenge to dissolve slowly in the mouth.
- DO not exceed the recommended daily dose.
- DO not use for persistent or chronic cough without consulting a doctor.
- DO not give to children under 6 without medical advice.
- DO not use if cough is productive with colored phlegm.
- DO inform your doctor if you are taking antidepressants.
8. Toxicology & Storage
Overdose: Nausea, vomiting, drowsiness, dizziness, blurred vision, nystagmus, ataxia, respiratory depression, seizures, serotonin syndrome (agitation, hyperreflexia, hyperthermia), coma. In children, overdose can occur with as few as 4-5 lozenges.
Storage: Store below 30°C in a cool, dry place. Protect from light and moisture. Keep in original packaging. Keep out of reach and sight of children. Do not use after the expiry date printed on the pack.