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Desvenlafaxine Case Study

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Answer: Desvenlafaxine is recommended for this patient among SSRI and SNRI. Because desvenlafaxine is least affected by this patient's CYP2D6 poor metabolizer and CYP2C19 poor metabolizer status among SSRI and SNRI, has no drug-drug interaction with the current medications and has better safety profile compared with other SSRI and SNRI. Rationale: Based on the PharmGKB website and relative articles, the patient has CYP2D6 *4/*4 genotype means she is a poor metabolizer of the CYP2D6 enzyme, CYP2D6 *4 allele has inactive CYP2D6 enzyme activity, she has two inactive alleles resulting being a poor metabolizer of CYP2D6. Also, the patient has CYP3A4 *1/*1 genotype, CYP3A4 * 1 allele has active CYP3A4 activity, however, there is no uniform phenotype …show more content…

Among SSRIs, paroxetine, fluvoxamine, and fluoxetine are mainly metabolized by CYP2D6. Sertraline, citalopram, and escitalopram are mainly metabolized by CYP2C19. There are CPIC guidelines for fluvoxamine and paroxetine regarding CYP2D6, also for citalopram, escitalopram, sertraline regarding CYP2C19. These guidelines suggest the reduction of the dose or alteration of medication if the patient has a poor metabolizer phenotype. Since this patient is a poor metabolizer for both CYP2D6 and CYP2C19, patients may experience side effects from relevant SSRIs due to higher plasma concentration, we may need to avoid using the above SSRIs. Additionally, she tried paroxetine, fluoxetine, and sertraline in the past which were all not successful, we would like to avoid those as well. SNRI that approved to treat depression includes desvenlafaxine, duloxetine, and venlafaxine. Among these SNRIs, venlafaxine is mainly metabolized by CYP2D6, desvenlafaxine is mainly metabolized by conjugation and minor metabolized by CYP3A4, it is also an inhibitor of CYP2D6. Duloxetine is mainly metabolized by CYP1A2 and CYP2D6. Based on the information above and patient's genotyping result, desvenlafaxine will be the best choice for her. Although it is a dose-dependent inhibitor of CYP2D6, this patient has no CYP2D6 enzyme activity, desvenlafaxine won't cause the clinical impact on CYP2D6 in this

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