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Interindividual dose/concentration relationship for methadone in hair
Sue Paterson1, Rosa Cordero, Mike McPhillips
1Toxicology Unit, Imperial College Faculty of Medicine, St. Dunstan's Road, London, England W6 8RP. s.paterson@ic.ac.uk
Journal of Analytical Toxicology
|February 18, 2003
Summary
Methadone levels in hair were measured in patients on long-term methadone maintenance therapy. No correlation was found between the prescribed methadone dose and the drug concentration detected in hair samples.
Area of Science:
- Pharmacology
- Analytical Chemistry
- Forensic Toxicology
Background:
- Methadone maintenance therapy is a common treatment for opioid use disorder.
- Understanding drug concentration in biological matrices like hair is crucial for treatment monitoring and forensic applications.
Purpose of the Study:
- To quantify methadone concentrations in hair samples from patients undergoing long-term methadone maintenance.
- To investigate the relationship between prescribed methadone dosage and hair methadone levels.
Main Methods:
- Hair samples were collected from 60 patients on methadone maintenance (oral and intravenous routes).
- Methadone was extracted using methanol, derivatized with MTBSTFA, and analyzed by gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring mode.
- The assay demonstrated a limit of quantitation of 0.4 ng/mg hair.
Main Results:
- Methadone concentrations in hair samples were successfully measured.
- No significant interindividual correlation was observed between the prescribed methadone dose and the measured methadone concentration in hair.
Conclusions:
- Hair analysis can quantify methadone in patients on long-term maintenance therapy.
- Prescribed dosage may not directly predict methadone concentration in hair, suggesting complex pharmacokinetic factors or adherence variations.