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 at therapeutic doses. It is a standard component in numerous over-the-counter (OTC) and prescription cough and cold formulations in India, widely used for the symptomatic relief of non-productive (dry) cough.
Adult: 5mg to 20mg every 4 to 8 hours. Maximum: 120mg per 24 hours. Typical OTC dose: 5-10mg.
Note: Oral administration. Can be taken with or without food. Tablet/Syrup: Swallow whole with water. Do not crush or chew sustained-release formulations. Use a calibrated measuring device for liquid formulations. Do not use for more than 7 days for self-medication. If cough persists, consult a physician.
Dextromethorphan suppresses cough by elevating the threshold for coughing in the cough center located in the medulla oblongata. It does not inhibit ciliary activity. Its action is not mediated through opioid receptors, hence it lacks respiratory depression and significant constipation at standard antitussive doses.
Pregnancy: Category C (US FDA). Animal studies have shown adverse effects. No adequate and well-controlled studies in pregnant women. Use only if potential benefit justifies potential risk to the fetus. Avoid in first trimester unless absolutely necessary.
Driving: May cause drowsiness, dizziness, or blurred vision. Patients should not drive or operate heavy machinery until they know how the medicine affects them.
| Monoamine Oxidase Inhibitors (MAOIs) e.g., Phenelzine, Selegiline, Moclobemide | Risk of severe, potentially fatal serotonin syndrome. | Contraindicated |
| Selective Serotonin Reuptake Inhibitors (SSRIs) e.g., Fluoxetine, Sertraline | Increased risk of serotonin syndrome. | Major |
| Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs) e.g., Venlafaxine, Duloxetine | Increased risk of serotonin syndrome. | Major |
| Other serotonergic drugs (Tramadol, Tapentadol, Triptans, Linezolid) | Increased risk of serotonin syndrome. | Major |
| CYP2D6 Inhibitors (e.g., Quinidine, Paroxetine, Fluoxetine) | Increased dextromethorphan levels, converting extensive metabolizers to poor metabolizer phenotype, increasing toxicity risk. | Moderate |
| CYP3A4 Inhibitors (e.g., Ketoconazole, Clarithromycin, Grapefruit juice) | Increased dextromethorphan levels. | Moderate |
| Alcohol, Benzodiazepines, Opioids, Sedative Antihistamines | Additive CNS depression (drowsiness, dizziness, impaired coordination). | Moderate |
| Anticholinergic drugs | Additive anticholinergic effects (dry mouth, blurred vision, urinary retention). | Moderate |
Same composition (Dextromethorphan Hydrobromide (5mg)), different brands: