dextromethorphan hydrobromide: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
dextromethorphan hydrobromide: clinical details
Prescribing considerations
- Confirm that the cough is dry and unproductive; investigate persistent cough, excessive secretions or features suggesting asthma, chronic lung disease or infection.
- Assess serotonergic medicines, CYP2D6 inhibitors, CNS depressants and other cough or cold products.
- Consider hepatic impairment, CYP2D6 poor-metaboliser status and any history of substance misuse, dependence or significant mental-health disorder.
- The selected product contains glucose, sucrose, sorbitol and ethanol, which may affect suitability.
Contraindications and cautions
- Hypersensitivity to dextromethorphan or an excipient.
- Current MAOI treatment or use within the preceding 14 days.
- Concurrent SSRI treatment for the selected product.
- Existing or threatened respiratory failure.
- Children under 12 years.
- Hereditary fructose intolerance, glucose-galactose malabsorption or sucrase-isomaltase insufficiency because of formulation excipients.
Monitoring
- Review for sedation, confusion, agitation, respiratory depression and gastrointestinal effects.
- Monitor for serotonin toxicity when relevant serotonergic or CYP2D6-inhibiting medicines are used.
- Assess for escalating use, dependence or withdrawal symptoms.
- Reassess if the cough persists, worsens or becomes productive.
Clinical pharmacology
Dextromethorphan is rapidly absorbed and undergoes extensive hepatic first-pass metabolism, principally through CYP2D6, to active dextrorphan. Genetic variation and CYP2D6 inhibition can cause substantial variability and prolonged exposure. The parent substance and metabolites are mainly eliminated renally.
Formulation and product differences
- The selected preparation is a pale-brown, peach-flavoured oral syrup.
- It contains sucrose, liquid glucose, sorbitol, ethanol, sodium benzoate, propylene glycol and levomenthol.
- Excipients differ between brands and combination products; check product-specific information rather than assuming interchangeability.
dextromethorphan hydrobromide preparations and strengths
Syrup
Route: Oral
Strengths: 7.5 mg/5 mL
dextromethorphan hydrobromide interactions
Check all prescription, pharmacy and recreational substances before use because some combinations can cause serious toxicity.
Monoamine oxidase inhibitors (MAOIs)
Contraindicated during treatment and for 14 days after stopping because of serotonin syndrome, hypertension and potentially severe neurological reactions.
Selective serotonin reuptake inhibitors (SSRIs)
Contraindicated with the selected product because serotonin syndrome may occur. Fluoxetine and paroxetine can also markedly increase dextromethorphan exposure.
Potent CYP2D6 inhibitors
Quinidine, terbinafine, bupropion, cinacalcet and some antiarrhythmics or antipsychotics can increase and prolong its effects and toxicity.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.