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# Dextromethorphan (Dextromethorphan HBr)
## Overview
Dextromethorphan is a synthetic analog of codeine that acts as a centrally-acting antitussive. It exerts its effect by elevating the cough threshold in the medulla oblongata. Unlike codeine, it lacks significant analgesic or addictive properties at therapeutic doses.
## Primary Indications
Symptomatic relief of non-productive cough associated with common cold, bronchitis, or inhaled irritants.
## Adult Dosing
* **Immediate-release:** 10–20 mg every 4 hours OR 30 mg every 6–8 hours.
* **Extended-release:** 60 mg twice daily.
* **Maximum Daily Dose:** 120 mg/day.
## Pediatric Dosing
* **Children 6–12 years:** 5–10 mg every 4 hours OR 15 mg every 6–8 hours. Maximum: 60 mg/day.
* **Children 4–6 years:** 2.5–5 mg every 4 hours. Maximum: 30 mg/day.
* **Under 4 years:** Generally not recommended due to lack of efficacy and risk of serious adverse events. Consult institutional/local guidelines.
## Dose Adjustments
* **Renal/Hepatic Impairment:** No specific guidelines; use with caution. Consider reduced frequency or dose in severe hepatic impairment due to reduced metabolism.
## Contraindications
* Hypersensitivity to dextromethorphan.
* Concurrent use or use within 14 days of Monoamine Oxidase Inhibitors (MAOIs).
* Presence of chronic or asthmatic cough (generally contraindicated for suppression).
## Adverse Effects
* **Common:** Dizziness, drowsiness, nausea, vomiting, stomach pain.
* **Serious:** Serotonin syndrome (if combined with serotonergic agents), hallucinations, confusion, and potential for abuse (dissociative effects at high doses).
## Key Drug Interactions
* **MAOIs:** Risk of severe hyperpyrexia, excitation, and death.
* **SSRIs/SNRIs:** Increased risk of serotonin syndrome.
* **CNS Depressants (Alcohol, Opioids, Sedatives):** Enhanced sedation.
* **CYP2D6 Inhibitors (e.g., Fluoxetine, Quinidine):** May increase plasma concentrations of dextromethorphan.
## Monitoring
* Monitor frequency and severity of cough.
* Observe for signs of toxicity (confusion, altered mental state, respiratory depression).
* Assess for misuse or intentional overdose if used in adolescent populations.
## Clinical Pearls
* Dextromethorphan is ineffective for productive, "wet" coughs where clearing mucus is necessary.
* Often marketed in multi-ingredient products (e.g., with acetaminophen, phenylephrine); ensure total daily intake of all ingredients is considered to avoid toxicity.
* Evidence for efficacy in pediatric populations is limited; guidelines do not recommend it for children under age 4–6.
* Patients should seek medical evaluation if cough persists for more than 7 days or is accompanied by high fever, rash, or persistent headache.
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**Educational Disclaimer:** This information is for educational purposes only. Clinical practice protocols vary. Always verify specific dosing, local formulary policies, and package inserts before prescribing or administering medication.
