Tramadol Therapy and CYP2D6 Genotype

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Dean L

Tramadol Therapy and CYP2D6 Genotype

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PubMed ID
28520365 [ View in PubMed
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Abstract

Tramadol is an analgesic used to treat moderate to moderately severe pain. It is a synthetic opioid, related to codeine, and is used to treat both acute and chronic pain. Tramadol is often prescribed for post-operative pain, and pain caused by cancer, osteoarthritis, and other musculoskeletal diseases (1). The CYP2D6 enzyme metabolizes a quarter of all prescribed drugs, including tramadol. Individuals who carry two inactive copies of CYP2D6 are known as poor metabolizers and have higher plasma concentrations of tramadol compared with individuals who have two copies of normal activity alleles (1). Individuals who carry one or more reduced or inactive copies of CYP2D6 are known as intermediate metabolizers, and individuals who carry more than two active copies of CYP2D6 are known as ultrarapid metabolizers. The FDA states that the levels of tramadol are approximately 20% higher in poor metabolizers compared to extensive ("normal") metabolizers, while concentrations of the tramadol metabolite, M1, are 40% lower. Inhibitors of CYP2D6, such as fluoxetine and amitriptyline, also inhibit the metabolism of tramadol, and the full pharmacological impact of these alterations of tramadol dose in terms of either efficacy or safety is unknown (1). A guideline from the Dutch Pharmacogenetics Working Group includes dose recommendations for poor metabolizers (either select an alternative drug-not oxycodone or codeine-or be alert to the symptoms of insufficient pain relief). It also contains dose recommendations for intermediate metabolizers (be alert to decreased efficacy of tramadol, consider increasing the dose and if the response is still inadequate, either select an alternative drug-not oxycodone or codeine, or be alert to the symptoms of insufficient pain relief) and ultrarapid metabolizers (either reduce the dose of tramadol by 30% and be alert to adverse drug events, or select an alternative drug e.g., acetaminophen, NSAID, morphine-not oxycodone or codeine) (see Table 1) (2).

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