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# Dextromethorphan
## Overview
Dextromethorphan is a cough suppressant (antitussive). It acts centrally on the cough center in the medulla oblongata.
## Primary Indications
Symptomatic relief of cough.
## Adult Dosing
* **Immediate-release:** 10 mg to 20 mg every 4 hours as needed, or 30 mg every 6 to 8 hours as needed.
* **Extended-release:** 60 mg every 12 hours.
* **Maximum dose:** Generally 120 mg per 24 hours.
## Pediatric Dosing
* **Ages 6 to <12 years:** 5 mg to 10 mg every 4 hours as needed, or 15 mg every 6 to 8 hours as needed. Maximum 60 mg per 24 hours.
* **Ages 12 years and older:** Same as adult dosing.
* **Note:** Not recommended for cough in children under 6 years of age unless specifically directed by a healthcare provider. Safety and efficacy in younger pediatric populations are not well established.
## Dose Adjustments
No specific dose adjustments are typically required for hepatic or renal impairment. However, caution and potentially reduced dosing may be considered in severe hepatic impairment.
## Contraindications
* Hypersensitivity to dextromethorphan.
* Concomitant use with monoamine oxidase inhibitors (MAOIs) or within 14 days of discontinuing an MAOI.
* Use in patients receiving certain serotonin reuptake inhibitors (SSRIs) or other serotonergic agents may require caution due to potential for serotonin syndrome.
## Adverse Effects
Common: Dizziness, drowsiness, nausea, vomiting, constipation.
Less common: Confusion, hallucinations, respiratory depression (at high doses).
## Key Drug Interactions
* **MAOIs:** Risk of severe serotonin syndrome (hypertension, hyperthermia, seizures).
* **SSRIs, SNRIs, tricyclic antidepressants, buspirone, tramadol, St. John's Wort:** Increased risk of serotonin syndrome.
* **CYP2D6 inhibitors (e.g., fluoxetine, paroxetine, quinidine):** May increase dextromethorphan plasma concentrations, leading to increased adverse effects.
## Monitoring
Monitor for effectiveness in cough suppression and for signs of adverse effects, particularly central nervous system effects and serotonin syndrome.
## Clinical Pearls
* Dextromethorphan is available in numerous over-the-counter (OTC) products, often in combination with other agents (e.g., decongestants, antihistamines, expectorants). Always review the complete ingredient list of combination products to avoid unintended duplication of therapy or administration of unnecessary medications.
* High doses can cause psychoactive effects and abuse potential.
* Dextromethorphan is a substrate of CYP2D6. Genetic variations in CYP2D6 can affect metabolism and response.
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*Disclaimer: This information is for educational purposes only and does not constitute medical advice. Always verify current prescribing information with an official drug reference or consult with a qualified healthcare professional before making any treatment decisions.*
