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# Dextromethorphan (DM) Cough Suppressant
## Overview
Dextromethorphan is an over-the-counter (OTC) cough suppressant that acts centrally on the cough center in the medulla oblongata. It is available in various formulations, including liquids, lozenges, and extended-release capsules.
## Primary Indications
* Symptomatic relief of cough.
## Adult Dosing
* **Immediate-release:** 10-20 mg every 4 hours, or 30 mg every 6-8 hours.
* **Extended-release:** 60 mg every 12 hours.
* **Maximum dose:** Generally not to exceed 120 mg in 24 hours for immediate-release, and 120 mg in 24 hours for extended-release, though specific product labeling should be consulted.
## Pediatric Dosing
* **Ages 6 to under 12 years:** 5-10 mg every 4 hours, or 15 mg every 6-8 hours. Do not exceed 60 mg in 24 hours.
* **Ages 12 years and older:** Same as adult dosing.
* **Ages under 6 years:** Safety and efficacy are not established. Avoid use.
## Dose Adjustments
* No specific dose adjustments are generally required for renal or hepatic impairment, but caution and lower doses may be considered in severe impairment. Consult product labeling or specialist.
## Contraindications
* Hypersensitivity to dextromethorphan.
* Use within 14 days of MAO inhibitor therapy.
* Patients with respiratory depression.
* Not recommended for chronic cough due to conditions like asthma or emphysema unless directed by a physician due to potential for bronchospasm or mucus retention.
## Adverse Effects
* Dizziness, drowsiness, confusion, nausea, vomiting, constipation, and rash are common.
* At higher doses or in overdose, can cause euphoria, hallucinations, respiratory depression, stupor, coma, and serotonin syndrome.
## Key Drug Interactions
* **MAO Inhibitors:** Concomitant use can lead to serotonin syndrome.
* **SSRIs, SNRIs, Triptans, Other Serotonergic Agents:** Increased risk of serotonin syndrome.
* **CYP2D6 Inhibitors (e.g., quinidine, fluoxetine, paroxetine):** Can increase dextromethorphan plasma concentrations, leading to increased risk of toxicity.
## Monitoring
* Monitor for effectiveness in suppressing cough.
* Assess for adverse effects, particularly CNS effects and signs of serotonin syndrome.
## Clinical Pearls
* Dextromethorphan is often found in combination products with other medications (e.g., decongestants, antihistamines, expectorants, analgesics). Counsel patients to avoid duplication of ingredients if taking multiple products.
* Extended-release formulations should not be crushed or chewed.
* Be aware of the potential for abuse at supra-therapeutic doses.
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*This information is for educational purposes only and does not substitute for professional medical advice. Always consult with a qualified healthcare provider to determine the best course of treatment for your specific condition and to ensure all current prescribing information has been reviewed.*
