Pregabalin and Methadone Plasma Levels in Patients Receiving Methadone Maintenance Treatment: An Observational Study

Area of Science:

• Pharmacology
• Addiction Medicine
• Clinical Toxicology

Background:

• The combination of pregabalin and opioids poses a significant risk of fatalities.
• High rates of pregabalin misuse are reported among patients undergoing methadone maintenance treatment (MMT).
• The specific risks associated with pregabalin misuse in MMT patients, particularly concerning methadone dosage and plasma concentrations, remain unclear.

Purpose of the Study:

• To investigate the relationship between pregabalin misuse and methadone dose and plasma levels in MMT patients.
• To assess the impact of pregabalin misuse on retention and survival rates within MMT programs.

Main Methods:

• An observational study involving 273 MMT patients in Tel Aviv, Israel.
• Inclusion criteria required urine drug screening for pregabalin concurrent with methadone plasma level evaluation.
• Data on methadone dose, plasma levels, urine drug screens, and patient demographics were collected from medical records.

Main Results:

• Patients misusing pregabalin (positive urine screen) showed significantly higher methadone plasma levels compared to non-misusers (693.8 vs. 572.3 ng/ml).
• Pregabalin misuse was associated with increased likelihood of testing positive for other substances, including benzodiazepines, methylphenidate, and fentanyl.
• Patients with positive pregabalin screens had significantly shorter retention and survival rates in MMT.

Conclusions:

• MMT patients misusing pregabalin exhibit elevated methadone plasma levels despite receiving normal or low methadone doses.
• These findings underscore the critical need for routine monitoring of methadone plasma levels in MMT patients to mitigate risks associated with pregabalin misuse.