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Dextromethorphan and codeine: comparison of plasma kinetics and antitussive effects
European Journal of Respiratory Diseases
|May 1, 1984
Summary
Codeine and dextromethorphan show similar plasma levels and antitussive effects in patients with pathological cough. Peak cough suppression correlated with drug dosage, not immediate plasma concentration.
Area of Science:
- Pharmacology
- Clinical Therapeutics
Background:
- Pathological cough requires effective antitussive agents.
- Understanding the pharmacokinetics and pharmacodynamics of dextromethorphan and codeine is crucial for optimizing cough suppression.
Purpose of the Study:
- To investigate the plasma kinetics of dextromethorphan and codeine.
- To evaluate the dose-response relationship of their antitussive effects in patients with pathological cough.
Main Methods:
- Acute oral doses of dextromethorphan and codeine were administered to 8 patients with pathological cough.
- Plasma concentrations and antitussive effects were measured.
- A dose-response study was conducted for both drugs.
Main Results:
- Peak plasma concentrations of codeine and dextromethorphan were comparable.
- No correlation was found between instantaneous plasma concentrations and antitussive response.
- Peak antitussive effect was significantly related to the logarithm of the dose for both drugs.
- 30 mg codeine phosphate and 60 mg dextromethorphan hydrobromide showed similar efficacy, superior to 30 mg dextromethorphan and placebo.
Conclusions:
- Dextromethorphan and codeine exhibit similar pharmacokinetic profiles and dose-dependent antitussive effects.
- Therapeutic efficacy is linked to dosage rather than transient plasma levels.