Dextromethorphan (Tussin) Dosing for Geriatric Patients
The recommended dose of Tussin (dextromethorphan) syrup for geriatric patients is 10-15 mg every 6-8 hours, with a maximum daily dose of 60 mg, following the "start low, go slow" principle to minimize adverse effects. 1
Dosing Recommendations
- Standard adult dosing of dextromethorphan is often too high for geriatric patients and should be reduced to prevent adverse effects 1
- For Tussin syrup containing 200 mg/10 mL concentration, the appropriate geriatric dose would be 0.5-0.75 mL every 6-8 hours 1
- Maximum daily dose should not exceed 60 mg (3 mL of 200 mg/10 mL concentration) in 24 hours 1
- Titration should be slower in elderly patients compared to younger adults to minimize side effects 1, 2
Rationale for Reduced Dosing
- Elderly patients experience significant alterations in pharmacokinetics including decreased renal function, changes in drug distribution, and reduced metabolic clearance 3, 2
- The water content of the aging body decreases while fat content increases, affecting drug distribution volumes 2
- Elderly patients have diminished homeostatic mechanisms, leading to stronger drug responses and higher rates of adverse effects 2
- CNS-active medications like dextromethorphan can cause dose-dependent effects that may be more pronounced in elderly patients 1
Monitoring and Side Effects
- Monitor for sedation, dizziness, and cognitive effects during treatment with dextromethorphan in geriatric patients 1
- Risk of falls is increased with CNS-active medications in elderly patients due to sedation and dizziness 1
- Common adverse effects include neurological, cardiovascular, and gastrointestinal disturbances, which are usually dose-related 4
- Dextromethorphan should be used for the shortest duration necessary to achieve symptom relief 1
Drug Interactions and Precautions
- Avoid combining dextromethorphan with other CNS depressants or serotonergic medications in elderly patients 1
- Dextromethorphan in combination with quinidine should be used with extreme caution due to increased risk of drug interactions 1
- Dextromethorphan should not be co-administered with monoamine oxidase inhibitors (MAOIs) as this combination can lead to serious adverse reactions 4
- Reassess efficacy regularly to determine if continued treatment is necessary 1
Common Pitfalls to Avoid
- Prescribing standard adult doses of dextromethorphan to elderly patients increases the risk of adverse effects 1
- Extended-release formulations may not be appropriate for elderly patients who need more careful dose titration 1
- Combining with other medications that have CNS effects should be avoided or done with extreme caution 1
- Prolonged use without regular reassessment of benefits versus risks should be avoided 1