From the Guidelines
The recommended dose of dextromethorphan for cough suppression in patients with normal renal function is 10-15 mg tid or qid, with a maximum dose of 120 mg/d. This dosage is based on the evidence provided by the Chest guideline and expert panel report 1. The report suggests that dextromethorphan can be used as an initial treatment for cough suppression, especially in patients with severe cough.
Key Considerations
- Dextromethorphan works by acting on the cough center in the medulla oblongata of the brain to suppress the cough reflex.
- The medication is available in various over-the-counter formulations, including syrups, lozenges, and extended-release preparations.
- Patients should be advised that dextromethorphan may cause drowsiness and should not be combined with alcohol or other CNS depressants.
- If cough persists beyond 7 days, worsens, or is accompanied by fever, rash, or persistent headache, medical attention should be sought as these symptoms may indicate a more serious condition.
Important Dosage Information
- The dosage of dextromethorphan may vary depending on the specific formulation and the patient's response to treatment.
- The maximum dose of 120 mg/d should not be exceeded to minimize the risk of adverse effects.
- Patients with renal impairment may require dose adjustments, but this is not applicable to patients with normal renal function.
Comparison with Other Treatments
- The Chest guideline and expert panel report also suggests the use of other medications, such as codeine, pholcodine, and morphine, for cough suppression in patients with lung cancer 1.
- However, these medications may have a higher risk of adverse effects and should be used with caution.
- Dextromethorphan is a relatively safe and effective option for cough suppression, making it a suitable choice for initial treatment.
From the FDA Drug Label
Directions • shake bottle well before use • measure only with dosing cup provided • do not use dosing cup with other products • dose as follows or as directed by doctor adults and children 12 years of age and over 10 mL every 12 hours, not to exceed 20 mL in 24 hours The recommended dose of dextromethorphan for cough suppression in patients with normal renal function is:
- Adults and children 12 years of age and over: 10 mL every 12 hours, not to exceed 20 mL in 24 hours 2
From the Research
Dextromethorphan Dosing for Cough Suppression
- The recommended dose of dextromethorphan for cough suppression in patients with normal renal function is not explicitly stated in the provided studies.
- However, a study from 1987 3 administered a single dose of 60 mg of dextromethorphan to 10 healthy human volunteers, which may serve as a reference point.
- Another study from 1996 4 used a single 40 mg oral dose of dextromethorphan in patients with chronic renal failure and healthy subjects, but this study focused on the assessment of CYP2D6 activity rather than determining the optimal dose for cough suppression.
- It is essential to note that the optimal dose and safety of chronic dosing of dextromethorphan are not fully known, as mentioned in a 2016 review 5.
- A 2020 review 6 discussed the pharmacokinetics and pharmacodynamics of dextromethorphan, highlighting the importance of considering individual variability in metabolism and potential drug interactions when determining the appropriate dose.
Considerations for Dosing
- Dextromethorphan is metabolized to its active metabolite, dextrorphan, which is responsible for its therapeutic effects 6.
- The metabolism of dextromethorphan can be influenced by genetic variations in enzymes and interactions with other drugs, leading to large inter-individual variability in pharmacological and toxicological effects 6.
- A 2022 article 7 discussed the re-purposing of dextromethorphan for various indications, including its use as a compounded formulation with bupropion for treatment of major depressive disorder, but did not provide information on dosing for cough suppression.