DELSYM
Clinical safety rating: caution
Comprehensive clinical and safety monograph for DELSYM (DELSYM).
Dextromethorphan is a non-competitive NMDA receptor antagonist and sigma-1 receptor agonist, which suppresses cough by elevating the threshold for coughing in the medullary cough center.
| Metabolism | Metabolized primarily by CYP2D6 to dextrorphan, an active metabolite; also undergoes O-demethylation and N-demethylation. |
| Excretion | Renal excretion of unchanged drug and metabolites, primarily dextrorphan glucuronide; <5% excreted unchanged in urine. Biliary/fecal elimination is negligible. |
| Half-life | Terminal elimination half-life of dextromethorphan is approximately 11 hours (range 9-14 hours) in extensive metabolizers; in poor metabolizers (CYP2D6 deficiency), half-life can exceed 24 hours, leading to accumulation. |
| Protein binding | ~45-50% bound to plasma albumin; main binding protein is albumin. |
| Volume of Distribution | 5-6 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral: ~10-25% due to extensive first-pass metabolism (CYP2D6 and CYP3A4); bioavailability is higher in poor metabolizers. |
| Onset of Action | Oral: 15-30 minutes for cough suppression. |
| Duration of Action | 12 hours per single dose (extended-release formulation); clinical effect may last up to 12 hours due to sustained release mechanism. |
60 mg orally every 12 hours (extended-release suspension).
| Dosage form | SUSPENSION, EXTENDED RELEASE |
| Renal impairment | No dose adjustment recommended for mild-to-moderate renal impairment; safety in severe renal impairment not established. |
| Liver impairment | No dose adjustment recommended for mild-to-moderate hepatic impairment; safety in severe hepatic impairment not established. |
| Pediatric use | Children 6-11 years: 30 mg orally every 12 hours. Children 12 years and older: 60 mg orally every 12 hours. Do not exceed 60 mg in 24 hours for ages 6-11 or 120 mg for ages 12+. |
| Geriatric use | Start at low end of dosing range; monitor for anticholinergic effects and sedation. No specific dose adjustment in elderly but caution due to increased sensitivity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for DELSYM (DELSYM).
| Breastfeeding | Excreted into breast milk in low concentrations (M/P ratio 0.1–0.4). Considered compatible with breastfeeding by American Academy of Pediatrics; however, monitor infant for drowsiness, respiratory depression, and poor feeding. Avoid if infant is premature or has respiratory compromise. Use shortest duration possible. |
| Teratogenic Risk | Category D (positive evidence of human fetal risk): First trimester exposure associated with rare reports of congenital malformations including cardiac defects and oral clefts based on observational studies. Second and third trimester use may cause fetal respiratory depression, bradycardia, and neonatal adaptation syndrome with prolonged use near term. Risks increase with higher doses and chronic use. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to dextromethorphan or any component","Use with or within 14 days of MAO inhibitors","Use in patients with respiratory depression or severe asthma"]
| Precautions | ["Do not use in children under 4 years of age","Avoid use with MAO inhibitors or for 2 weeks after stopping","Chronic use may lead to dependence and abuse","Caution in patients with respiratory depression, asthma, or chronic obstructive pulmonary disease"] |
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| Fetal Monitoring | Monitor maternal respiratory rate and oxygen saturation, especially with prolonged or high-dose use. For fetal assessment: consider fetal nonstress test and biophysical profile if maternal respiratory depression suspected. Monitor neonatal adaptation for signs of opioid withdrawal (irritability, hypertonia, tremors) after delivery in women with chronic use. |
| Fertility Effects | No human data demonstrate negative effects on fertility. Animal studies show no impairment of fertility at clinically relevant doses. Potential indirect effects if chronic use leads to hypothalamic-pituitary-gonadal axis suppression (e.g., hypogonadism), but not documented with dextromethorphan. |