Generic Name

Dextromethorphan Polistirex

---

Classification

FDA Approved Indications

• Relief of cough caused by minor throat and bronchial irritation

Mechanism of Action

Dextromethorphan acts centrally on the medullary cough center to elevate the threshold for coughing. It also acts as an NMDA receptor antagonist and sigma-1 receptor agonist, reducing cough reflex sensitivity.

Dosage and Administration

Adult: 20 mg every 4 hours, not to exceed 120 mg in 24 hours

Pediatric: 6-12 years: 10 mg every 12 hours or 20 mg every 4 hours (not to exceed 120 mg/day); under 6 years: consult pediatrician

Geriatric: Same as adult, cautious use due to potential CNS effects

Renal Impairment: Use with caution; dosage adjustments may be necessary

Hepatic Impairment: Use with caution; dosage adjustments may be necessary

Pharmacokinetics

Absorption: Well absorbed orally and sustained over time with polistirex formulation

Distribution: Widely distributed; crosses blood-brain barrier

Metabolism: Primarily hepatic via CYP2D6 and other enzymes

Excretion: Renal (metabolites) and fecal

Half Life: Approximately 3-6 hours

Contraindications

• Use in children under 4 years due to risk of accidental overdose and severe adverse effects

Precautions

• Use with caution in patients with a history of psychiatric disorders, chronic cough, or those taking serotonergic drugs due to risk of serotonin syndrome

Adverse Reactions - Common

• Dizziness (Common)
• Nausea or vomiting (Common)
• Drowsiness (Common)

Adverse Reactions - Serious

• Serotonin syndrome (when combined with serotonergic drugs) (Rare)
• Allergic reactions including rash, pruritus (Rare)

Drug-Drug Interactions

• Serotonergic agents (SSRIs, SNRIs, MAOIs) — risk of serotonin syndrome
• Central nervous system depressants — increased sedation

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Do not exceed recommended dose.
• Avoid alcohol and CNS depressants.
• Report signs of allergic reactions or serotonin syndrome.
• Seek medical advice before use with other serotonergic drugs.

Special Considerations

Black Box Warnings:

• Risks of abuse and misuse due to psychoactive properties, especially in adolescents and young adults.

Genetic Factors: CYP2D6 metabolizer status may affect drug levels and response.

Lab Test Interference: No known significant interference.

Overdose Management

Signs/Symptoms: Dizziness, nausea, vomiting, hallucinations, serotonin syndrome symptoms (agitation, hyperthermia, muscle rigidity)

Treatment: Supportive care, activated charcoal if recent ingestion, benzodiazepines for agitation or seizures, evaluate for serotonin syndrome, and maintain airway.

Storage and Handling

Storage: Store at room temperature, 20-25°C (68-77°F). Keep container tightly closed.

Stability: Stable for 2-3 years, check expiration date.