Morphine/Codeine Ratio, a Key in Investigating a Case of Doping

 Tohid Seif-Barghi 1, 2 ; Navid Moghadam 2, 3, * ; and Farzad Kobarfard 4
۱ Sports Medicine Research Center, Tehran University of Medical Sciences, Tehran, IR Iran
۲ Iran Football Medical Assessment and Rehabilitation Center (IFMARC), Tehran, IR Iran
۳ Sports Medicine Department, Rasool Akram Hospital, Iran University of Medical Sciences, Tehran, IR Iran
۴ Department of Medicinal Chemistry, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran

Asian Journal of Sport Medicine

Introduction: Consumption of codeine can lead to positive urine test for morphine in athletes. Morphine is classified as a prohibited doping drug while Codeine is not. Morphine/codeine ratio is used in forensic medicine to distinguish the consumption of codeine from abuse of morphine and other narcotics.

Case Presentation: We present an athlete with positive urine test for morphine with a history of consumption of codeine. The disciplinary committee came to conclusion that the athlete had not consumed morphine and did not violate doping code based on morphine/codeine ratio.

Conclusions: Analysis of codeine to morphine metabolism rate is needed when we are using morphine/codeine ratio to rule out abuse of narcotics. WADA should consider analysis for the CYP2D6 alleles (main metabolizer of codeine) in case of including morphine/codeine ratio in future prohibited list. The possibility of ultra-rapid CYP2D6 cannot be ruled out in certain results of morphine/codeine near the cut point.

Keywords: Doping in Sports; CYP2D6; Morphine; Codeine

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