Methadone vs morphine: comparison of their effect on phagocytic functions

Area of Science:

• Immunology
• Pharmacology
• Toxicology

Background:

• Opioid maintenance therapy is crucial for managing opioid addiction.
• Understanding the immunomodulatory effects of opioids is essential for patient safety.
• Morphine is known to affect immune functions, necessitating comparison with methadone.

Purpose of the Study:

• To compare the effects of methadone and morphine on phagocytic physiology in mice.
• To assess the potential risks associated with methadone in opioid maintenance protocols.
• To evaluate the immunotoxicological profile of methadone relative to morphine.

Main Methods:

• In vivo studies in mice to assess reticuloendothelial system (RES) activity.
• Evaluation of polymorphonuclear leukocyte (PMN) superoxide anion production.
• Assessment of hematologic changes, Candida albicans infection exacerbation, and phagocytosis/killing assays.
• Measurement of spleen and liver weights.

Main Results:

• Both methadone and morphine reduced RES activity and PMN superoxide anion production.
• Methadone did not induce hematologic changes or exacerbate C. albicans infections.
• Methadone did not inhibit phagocytosis and killing by various immune cells.
• Methadone did not reduce spleen and liver weights, unlike morphine.

Conclusions:

• Methadone exhibits a more favorable immunotoxicological profile compared to morphine.
• Methadone appears to be a safer option in opioid maintenance therapy due to lower toxicity.
• Findings in mice align with previous observations in human subjects.