Dextromethorphan

# Dextromethorphan ## Overview - **Classification**: Antitussive (cough suppressant) - **Mechanism**: Acts centrally on the cough center in the medulla to elevate the cough threshold. It is an N-methyl-D-aspartate (NMDA) receptor antagonist and a serotonin reuptake inhibitor. ## Primary Indications 1. **Cough Suppression**: Relief of non-productive cough associated with minor throat and bronchial irritation (e.g., common cold, flu). ## Adult Dosing ### Standard Dosing **Cough Suppression** - **Dose**: **10-20 mg** - **Frequency**: Every 4 hours as needed - **Route**: Oral (syrup, lozenge, tablet) - **Maximum Dose**: **120 mg** in 24 hours **Extended-Release Formulation** - **Dose**: **60 mg** - **Frequency**: Every 12 hours as needed - **Route**: Oral (extended-release liquid/capsule) - **Maximum Dose**: **120 mg** in 24 hours ### Dose Adjustments - **Renal Impairment**: No specific adjustments defined; use with caution. - **Hepatic Impairment**: No specific adjustments defined; use with caution due to hepatic metabolism. - **Elderly Patients**: No specific adjustments needed, but start with lower doses and monitor for adverse effects. ## Pediatric Dosing ### Neonates (0-28 days) - **Dose**: Not recommended. - **Special Notes**: Avoid use in this age group due to lack of efficacy/safety data and potential for serious adverse effects. ### Infants (1-12 months) - **Dose**: Not recommended. - **Special Notes**: Avoid use in this age group due to lack of efficacy/safety data and potential for serious adverse effects. ### Children (1-12 years) **Cough Suppression** - **Ages 1-3 years**: Not recommended. - **Aages 4-6 years**: - **Dose**: **2.5-5 mg** - **Frequency**: Every 4 hours as needed - **Maximum**: **30 mg** in 24 hours - **Special Notes**: Many professional organizations advise against routine use of cough/cold medicines in children < 6 years. Use with extreme caution. - **Ages 6-12 years**: - **Dose**: **5-10 mg** - **Frequency**: Every 4 hours as needed - **Maximum**: **60 mg** in 24 hours - **Special Notes**: Closely monitor for sedation or other adverse effects. ### Adolescents (13-18 years) **Cough Suppression** - **Dose**: **10-20 mg** - **Frequency**: Every 4 hours as needed - **Maximum**: **120 mg** in 24 hours - **Special Notes**: Follow adult dosing guidelines. ## Safety Information ### Contraindications - **Absolute**: Concomitant use with MAO inhibitors (MAOIs) or within 14 days of discontinuing an MAOI. - **Absolute**: Hypersensitivity to dextromethorphan or excipients. - **Absolute**: Concurrent use with linezolid (an MAOI-like drug). - **Relative**: Productive cough (coughing helps clear secretions). - **Relative**: Chronic cough (e.g., from smoking, asthma, emphysema) where suppression may be harmful. ### Common Adverse Effects - **Common (1-10%)**: Drowsiness, dizziness, nausea, vomiting, stomach discomfort. - **Serious but Rare**: Serotonin syndrome (especially with other serotonergic agents), hallucinations (with abuse/overdose), respiratory depression. ### Key Drug Interactions - **MAO Inhibitors (MAOIs)**: Risk of **serotonin syndrome** (agitation, confusion, fever, sweating, tremor, hyperreflexia). AVOID concurrent use and for 14 days after MAOI discontinuation. - **SSRIs, TCAs, SNRIs**: Increased risk of **serotonin syndrome**. Monitor closely for symptoms; consider alternative antitussives. - **CYP2D6 Inhibitors (e.g., quinidine, fluoxetine, paroxetine)**: Can significantly increase dextromethorphan levels, enhancing effects and adverse reactions. Reduce dextromethorphan dose or consider alternative. ## Monitoring & Follow-up - **Before Treatment**: Assess cough type (productive vs. non-productive). Review patient's medication list for interacting drugs (especially MAOIs, SSRIs). - **During Treatment**: Monitor for effective cough suppression and absence of severe adverse effects (e.g., excessive sedation, signs of serotonin syndrome). - **Clinical Signs**: Watch for drowsiness, dizziness, nausea. Seek medical attention if experiencing confusion, agitation, high fever, or muscle rigidity. ## Clinical Pearls - 💡 **Over-the-Counter (OTC)**: Dextromethorphan is widely available OTC, but patients should be counseled on proper dosing. - 💡 **Abuse Potential**: Dextromethorphan has abuse potential, especially at high doses, leading to dissociative effects and hallucinations. Counsel patients on appropriate use. - 💡 **Serotonin Syndrome**: Emphasize the critical interaction with MAOIs and other serotonergic drugs to prevent this life-threatening condition. - 💡 **Not for Children <4 years**: Strongly advise against use in very young children due to lack of proven efficacy and potential for harm. - 💡 **Hydration**: Encourage adequate hydration to help thin mucus and ease expectoration, even with cough suppression. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.