Dextromethorphan Hydrobromide is a centrally-acting, non-opioid antitussive agent. It is the d-isomer of the codeine analog, levorphanol, but lacks significant analgesic, sedative, or addictive properties. It is a standard-of-care for the symptomatic relief of non-productive cough associated with upper respiratory tract infections and allergies. In the Indian context, it is widely available as an over-the-counter (OTC) syrup, often in combination with other agents like antihistamines, expectorants, or decongestants.
Adult: 10 ml (15 mg) every 4 to 6 hours, or 20 ml (30 mg) every 6 to 8 hours. Maximum: 120 mg in 24 hours.
Note: Shake the bottle well before use. Use the measuring cup or spoon provided. Can be taken with or without food. Do not use for more than 7 days for self-medication. If cough persists or is accompanied by fever, rash, or persistent headache, consult a doctor.
Dextromethorphan and its active metabolite, dextrorphan, act centrally on the cough center in the medulla oblongata to elevate the threshold for coughing. It does not inhibit ciliary activity. Its action is not mediated through opioid receptors.
Pregnancy: Category C (US FDA). Animal studies have shown adverse effects. There are no adequate and well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus. Avoid in first trimester unless absolutely necessary.
Driving: May cause drowsiness or dizziness. Patients should not drive or operate heavy machinery until they know how the medicine affects them.
| Monoamine Oxidase Inhibitors (MAOIs) e.g., Phenelzine, Selegiline, Linezolid | Risk of severe, potentially fatal serotonin syndrome. | Contraindicated |
| Selective Serotonin Reuptake Inhibitors (SSRIs) e.g., Fluoxetine, Paroxetine, Sertraline | Increased risk of serotonin syndrome. | Major |
| Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs) e.g., Venlafaxine, Duloxetine | Increased risk of serotonin syndrome. | Major |
| Other CNS Depressants (Alcohol, Benzodiazepines, Opioids, Sedating Antihistamines) | Additive CNS depression, sedation, and impaired psychomotor performance. | Major |
| CYP2D6 Inhibitors (e.g., Quinidine, Fluoxetine, Paroxetine, Bupropion) | Increased dextromethorphan plasma levels, converting extensive metabolizers to poor metabolizer phenotype, increasing toxicity risk. | Moderate |
| CYP3A4 Inhibitors (e.g., Ketoconazole, Clarithromycin, Grapefruit juice) | Increased dextromethorphan plasma levels. | Moderate |
Same composition (Dextromethorphan Hydrobromide (7.5mg/5ml)), different brands: