What is the recommended inpatient dosing for Robitussin (dextromethorphan)?

Inpatient Dosing of Robitussin (Dextromethorphan)

For inpatient management of cough, dextromethorphan (Robitussin) should be dosed at 10-15 mg orally three to four times daily, with a maximum daily dose not exceeding 120 mg. 1

Dosing Guidelines

Standard Adult Dosing

• Initial dose: 10-15 mg orally
• Frequency: Every 4-6 hours as needed
• Maximum daily dose: 120 mg 1

Special Populations

• Elderly patients: Use lower doses (start with 10 mg) due to increased sensitivity to side effects 1
• Patients with renal impairment: Consider dose reduction
• Patients with hepatic impairment: Consider dose reduction, especially with CYP2D6 metabolism concerns

Clinical Considerations

Indications for Use

Dextromethorphan is appropriate for:

• Persistent dry cough not responding to first-line treatments
• Cough due to chronic bronchitis
• Nocturnal cough disrupting sleep 1
• Minor throat and bronchial irritation

Duration of Treatment

• Limit treatment to short-term use (3-7 days) to avoid potential dependence 1
• Assess response after 2-4 days of therapy
• Discontinue if no improvement is seen 1

Monitoring

• Monitor for adequate expectoration despite cough suppression 1
• Watch for signs of serotonin syndrome in patients taking other serotonergic medications
• Assess for improvement in cough frequency and severity

Precautions and Contraindications

Drug Interactions

• Use with caution in patients taking:
  • Monoamine oxidase inhibitors (MAOIs)
  • Selective serotonin reuptake inhibitors (SSRIs)
  • Other medications that may interact with dextromethorphan and cause serotonin syndrome 1, 2

Contraindications

• Avoid in pregnancy, especially in the third trimester 1
• Not recommended for children due to safety concerns and limited evidence of efficacy 1
• Use caution in patients with history of substance abuse

Efficacy Considerations

• Dextromethorphan has shown mixed results in clinical trials 3
• Some studies have shown efficacy in reducing subjective cough scores 3
• In chronic cough, dextromethorphan (20 mg) has been shown to reduce cough frequency similar to codeine, with potentially greater reduction in cough intensity 4
• For acute cough associated with upper respiratory infections, evidence of efficacy is limited 5

Alternative Treatments

If dextromethorphan is ineffective or contraindicated, consider:

• Benzonatate: 100-200 mg four times daily 1
• Ipratropium bromide inhaler for cough due to URI or bronchitis 1
• Simple home remedies like honey and lemon for acute viral cough 1

Remember that antitussive agents should only be used for short-term symptomatic relief of coughing, and the underlying cause of the cough should be addressed whenever possible.