The prevalence of CYP2D6 and CYP2C19 genotypes in a population of healthy Dutch volunteers

Clinical Guidance for Dosing and Monitoring Oral Antihormonal Drugs in Patients with Breast Cancer After Roux-en-Y Gastric Bypass

ABSTRACT

Obesity is associated with an increased risk of cancers, such as breast cancer. Roux-en-Y gastric bypass (RYGB) is a common surgical intervention used to induce weight loss, reduce comorbidities, and improve overall survival. Due to alterations in the gastrointestinal tract, RYGB is associated with changes in oral drug disposition, which can affect treatment outcomes. Oral antihormonal agents were monitored in 9 patients who previously underwent RYGB. The results of therapeutic drug monitoring and estradiol concentrations were analyzed, and a review of the relevant literature was performed. As only 1 of the 6 patients prescribed tamoxifen achieved a therapeutic endoxifen concentration with the standard dose of 20 mg/d, a higher starting dose of 40 mg/d was recommended to increase the probability of attaining a therapeutic plasma concentration. All patients with decreased CYP2D6 metabolic activity could not achieve therapeutic plasma concentrations; therefore, CYP2D6 genotyping was recommended before the initiation of tamoxifen therapy to identify patients who should be switched to aromatase inhibitors. Anastrozole and letrozole exposure in patients who underwent RYGB patients appeared sufficient, with no dose adjustment required. However, until more data become available, monitoring aromatase inhibitor efficacy is recommended. Monitoring the drug concentrations is a viable option; however, only indicative data on therapeutic drug monitoring are available. Therefore, estradiol concentrations should be measured.

The Frequency of CYP2C19 Loss-of-Function Variants in Patients with Non-Cardioembolic Ischemic Stroke or Transient Ischemic Attack in the Dutch Population

INTRODUCTION

The CYP2C19 enzyme converts clopidogrel into an active metabolite. Carriers of CYP2C19 loss-of-function (LOF) variants with a history of ischemic stroke or transient ischemic attack (TIA) using clopidogrel may have a higher risk of recurrent stroke. To study the implications of genetic CYP2C19 heterogeneity in treatment of cerebral ischemia, knowledge about the prevalence of CYP2C19 LOF variants within the population is important. We investigated the frequency of CYP2C19 LOF variants in patients with non-cardioembolic ischemic stroke or TIA in the Dutch population.

METHODS

We performed a single-center observational study with a cross-sectional design in a Dutch thrombectomy-capable stroke center. We included all patients presenting with non-cardioembolic ischemic stroke or TIA. We determined the frequency of CYP2C19 LOF variants in the full cohort. Additionally, we compared the frequency of CYP2C19 LOF variants in two subgroups: patients with first-ever non-cardioembolic ischemic stroke or TIA versus patients with recurrent ischemic stroke or TIA using clopidogrel because of a history of ischemic stroke or TIA.

RESULTS

We enrolled 410 patients between January 1, 2021, and July 1, 2021. 109 (26.6%) patients were carriers of CYP2C19 LOF variants. We found no difference in the frequency of CYP2C19 LOF variants between patients with first-ever ischemic stroke or TIA versus patients with recurrent ischemic stroke or TIA using clopidogrel (25.9 vs. 31.9%, respectively, p = 0.31).

DISCUSSION AND CONCLUSION

About a quarter of patients with non-cardioembolic ischemic stroke or TIA in the Dutch population carry a CYP2C19 LOF variant. This is lower than estimates found in studies with Asian populations but similar to estimates found among Caucasian patients in other parts of the world.

Physiologically based pharmacokinetic (PBPK) modeling of the role of CYP2D6 polymorphism for metabolic phenotyping with dextromethorphan

The cytochrome P450 2D6 (CYP2D6) is a key xenobiotic-metabolizing enzyme involved in the clearance of many drugs. Genetic polymorphisms in CYP2D6 contribute to the large inter-individual variability in drug metabolism and could affect metabolic phenotyping of CYP2D6 probe substances such as dextromethorphan (DXM). To study this question, we (i) established an extensive pharmacokinetics dataset for DXM; and (ii) developed and validated a physiologically based pharmacokinetic (PBPK) model of DXM and its metabolites dextrorphan (DXO) and dextrorphan O-glucuronide (DXO-Glu) based on the data. Drug-gene interactions (DGI) were introduced by accounting for changes in CYP2D6 enzyme kinetics depending on activity score (AS), which in combination with AS for individual polymorphisms allowed us to model CYP2D6 gene variants. Variability in CYP3A4 and CYP2D6 activity was modeled based on in vitro data from human liver microsomes. Model predictions are in very good agreement with pharmacokinetics data for CYP2D6 polymorphisms, CYP2D6 activity as described by the AS system, and CYP2D6 metabolic phenotypes (UM, EM, IM, PM). The model was applied to investigate the genotype-phenotype association and the role of CYP2D6 polymorphisms for metabolic phenotyping using the urinary cumulative metabolic ratio (UCMR), DXM/(DXO + DXO-Glu). The effect of parameters on UCMR was studied via sensitivity analysis. Model predictions indicate very good robustness against the intervention protocol (i.e. application form, dosing amount, dissolution rate, and sampling time) and good robustness against physiological variation. The model is capable of estimating the UCMR dispersion within and across populations depending on activity scores. Moreover, the distribution of UCMR and the risk of genotype-phenotype mismatch could be estimated for populations with known CYP2D6 genotype frequencies. The model can be applied for individual prediction of UCMR and metabolic phenotype based on CYP2D6 genotype. Both, model and database are freely available for reuse.

Increased frequency of CYP2C19 loss-of-function alleles in clopidogrel-treated patients with recurrent cerebral ischemia

AIM

Clopidogrel is used as secondary prevention after cerebral ischemia. Previous - mainly Asian - studies have shown that genetic variations in CYP2C19 are associated with an increased risk of recurrent stroke in clopidogrel-treated patients. Evidence on the impact of this drug-gene interaction in European neurology patients is currently limited. Aim of this study is to compare the prevalence of CYP2C19 loss-of-function (LoF) alleles in a population with recurrent cerebral ischemia to 2 reference groups from the same region.

METHODS

CYP2C19-genotyping (*2 and *3) was performed in clopidogrel-treated patients who presented with a recurrent ischemic stroke/TIA. Genotype distributions were compared with two reference groups; a cohort of consecutive patients who underwent elective coronary stent implantation and a cohort of healthy Dutch volunteers.

RESULTS

In total, 188 cases with a recurrent ischemic event were identified, of whom 38 (20.2%) with an early recurrent event (24 hours to 90 days after previous event). Among the total case group, 43.6% of the patients carried at least one CYP2C19 LoF allele, compared with 27.6% and 24.7% in respectively the cardiology and the healthy volunteers reference group (p<0.001 for both comparisons). Among the cases with an early recurrent event, 55.2% of patients were carriers of ≥ 1 CYP2C19 LoF allele (p<0.0001).

CONCLUSION

In this clopidogrel-treated population with recurrent cerebral ischemia the frequency of CYP2C19 LoF alleles was significantly higher than in reference groups, especially in early recurrent events. This study adds to the growing body of evidence that genotype-guided antiplatelet therapy could improve patient outcomes.

Understanding genetic risk factors for common side effects of antidepressant medications

Background

Major depression is one of the most disabling health conditions internationally. In recent years, new generation antidepressant medicines have become very widely prescribed. While these medicines are efficacious, side effects are common and frequently result in discontinuation of treatment. Compared with specific pharmacological properties of the different medications, the relevance of individual vulnerability is understudied.

Methods

We used data from the Australian Genetics of Depression Study to gain insights into the aetiology and genetic risk factors to antidepressant side effects. To this end, we employed structural equation modelling, polygenic risk scoring and regressions.

Results

Here we show that participants reporting a specific side effect for one antidepressant are more likely to report the same side effect for other antidepressants, suggesting the presence of shared individual or pharmacological factors. Polygenic risk scores (PRS) for depression associated with side effects that overlapped with depressive symptoms, including suicidality and anxiety. Body Mass Index PRS are strongly associated with weight gain from all medications. PRS for headaches are associated with headaches from sertraline. Insomnia PRS show some evidence of predicting insomnia from amitriptyline and escitalopram.

Conclusions

Our results suggest a set of common factors underlying the risk for antidepressant side effects. These factors seem to be partly explained by genetic liability related to depression severity and the nature of the side effect. Future studies on the genetic aetiology of side effects will enable insights into their underlying mechanisms and the possibility of risk stratification and prophylaxis strategies.

Antidepressants are commonly prescribed medications, but adverse side effects are cause for treatment discontinuation. We analysed data from a large group of adults who have taken antidepressants to understand why some people experience specific side effects. Our results suggest that a person’s genetic characteristics play a role. For example, participants genetically predisposed to a higher body mass index were more likely to report weight gain from antidepressants. These results open up the possibility of predicting adverse side effects as we increase our knowledge on the genetics of related complex traits. Future studies can focus on performing large-scale genetic studies of antidepressant side effects to gain further insights into the mechanisms underlying antidepressant side effects and to identify genetic markers of side effects that could be used in the clinic.

Campos et al. study the genetic aetiology of antidepressant side effects. Using data from the Australian Genetics of Depression study, the authors show that polygenic risk scores for traits such as BMI, insomnia and headaches have a shared genetic basis with side effects to commonly used antidepressant drugs.

Pharmacogenetics and Forensic Toxicology: A New Step towards a Multidisciplinary Approach

Pharmacogenetics analyzes the individual behavior of DNA genes after the administration of a drug. Pharmacogenetic research has been implemented in recent years thanks to the improvement in genome sequencing techniques and molecular genetics. In addition to medical purposes, pharmacogenetics can constitute an important tool for clarifying the interpretation of toxicological data in post-mortem examinations, sometimes crucial for determining the cause and modality of death. The purpose of this systematic literature review is not only to raise awareness among the forensic community concerning pharmacogenetics, but also to provide a workflow for forensic toxicologists to follow in cases of unknown causes of death related to drug use/abuse. The scientific community is called on to work hard in order to supply evidence in forensic practice, demonstrating that this investigation could become an essential tool both in civil and forensic contexts. The following keywords were used for the search engine: (pharmacogenetics) AND (forensic toxicology); (pharmacogenetics) AND (post-mortem); (pharmacogenetics) AND (forensic science); and (pharmacogenetics) AND (autopsy). A total of 125 articles were collected. Of these, 29 articles were included in this systematic review. A total of 75% of the included studies were original articles (n = 21) and 25% were case reports (n = 7). A total of 78% (n = 22) of the studies involved deceased people for whom a complete autopsy was performed, while 22% (n = 6) involved people in good health who were given a drug with a subsequent pharmacogenetic study. The most studied drugs were opioids (codeine, morphine, and methadone), followed by antidepressants (tricyclic antidepressants and venlafaxine). Furthermore, all studies highlighted the importance of a pharmacogenetics study in drug-related deaths, especially in cases of non-overdose of drugs of abuse. This study highlights the importance of forensic pharmacogenetics, a field of toxicology still not fully understood, which is of great help in cases of sudden death, deaths from overdose, deaths after the administration of a drug, and also in cases of complaint of medical malpractice.

Role of Drug-Gene Interactions and Pharmacogenetics in Simvastatin-Associated Pulmonary Toxicity

Introduction

Simvastatin has previously been associated with drug-induced interstitial lung disease. In this retrospective observational study, cases with non-specific interstitial pneumonia (NSIP) or idiopathic pulmonary fibrosis (IPF) with simvastatin-associated pulmonary toxicity (n = 34) were evaluated.

Objective

To identify whether variations in genes encoding cytochrome P450 (CYP) enzymes or in the SLCO1B1 gene (Solute Carrier Organic anion transporting polypeptide 1B1 gene, encoding the organic anion transporting polypeptide 1B1 [OATP1B1] drug transporter enzyme), and/or characteristics of concomitantly used drugs, predispose patients to simvastatin-associated pulmonary toxicity.

Methods

Characteristics of concomitantly used drugs and/or variations in the CYP or SLCO1B1 genes and drug–gene interactions were assessed. The outcome after withdrawal of simvastatin and/or switch to another statin was assessed after 6 months.

Results

Multiple drug use involving either substrates and/or inhibitors of CYP3A4 and/or three or more drugs with the potential to cause acidosis explained the simvastatin-associated toxicity in 70.5% (n = 24) of cases. Cases did not differ significantly from controls regarding CYP3A4, CYP2C9, or OATP1B1 phenotypes, and genetic variation explained only 20.6% (n = 7) of cases. Withdrawal of simvastatin without switching to another statin or with a switch to a hydrophilic statin led to improvement or stabilization in all NSIP cases, whereas all cases who were switched to the lipophilic atorvastatin progressed.

Conclusion

Simvastatin-associated pulmonary toxicity is multifactorial. For patients with this drug-induced pulmonary toxicity who need to continue taking a statin, switching to a hydrophilic statin should be considered.

ClinicalTrials.gov identifier

NCT00267800, registered in 2005.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40264-021-01105-8.

Safety considerations with the use of platelet inhibitors for elderly patients with non-ST- elevation acute coronary syndrome

Introduction: Dual antiplatelet therapy (DAPT) is standard treatment for patients with acute coronary syndrome (ACS). This includes lifelong aspirin combined with a P2Y₁₂ inhibitor for 1 year. The indication for one of the P2Y₁₂ inhibitors (clopidogrel, prasugrel, ticagrelor) is dependent on the treatment strategy; whether patients undergo coronary angiography or are treated medically only. Tailoring antiplatelet therapy to the risk profile of the individual patient is of specific importance to the older patient.Areas covered: In this review, we discuss dual antiplatelet therapy in elderly patients with ACS. We present the options to tailor antiplatelet therapy based on platelet function testing, CYP2C19 genotyping and patients' thrombotic and bleeding risk. Finally, we discuss alternatives for dual antiplatelet therapy.Expert opinion: DAPT in elderly patients with ACS should consist of aspirin with clopidogrel or ticagrelor. Weighing patients' thrombotic and bleeding risk, based on clinical judgment or with use of specific risk scores, is probably the most convenient method to individualize antiplatelet therapy; however, CYP2C19 genotyping can also be used. In elderly patients with an increased bleeding risk, clopidogrel is a safe and effective alternative to ticagrelor. An alternative to 12 months DAPT could be ticagrelor monotherapy after a short period of DAPT.

Effect of CYP2C19 genotypes on tamoxifen metabolism and early-breast cancer relapse

CYP2C19*2 and CYP2C19*17 might influence tamoxifen metabolism and clinical outcome. Our aim was to investigate the effect of CYP2C19 genotypes on tamoxifen concentrations and metabolic ratios (MRs) and breast cancer recurrence in a large cohort of Caucasian women. Genetic variants (CYP2D6 and CYP2C19 genotypes), tamoxifen and metabolites concentrations, baseline characteristics, and breast cancer recurrence from the CYPTAM study (NTR1509) were used. CYP2C19*2 and CYP2C19*17 genotypes were evaluated as alleles and as groups based on CYP2D6 genotypes (high, intermediate and low activity). Log-rank test and Kaplan–Meier analysis were used to evaluate differences in recurrence defined as relapse-free survival (RFS). Classification tree analyses (CTAs) were conducted to assess the levels of interactions per polymorphism (CYP2D6 and CYP2C19 genotypes) on endoxifen concentrations. No differences in mean concentrations and MRs were observed when comparing CYP2C19 genotypes (CYP2C19*1/*1; CYP2C19*1/*2; CYP2C19*2/*2; CYP2C19*1/*17; CYP2C19*17/*17; CYP2C19*2/*17). Only significant differences (p value < 0.05) in mean concentrations and MRs were observed when comparing tamoxifen activity groups (high, intermediate and low activity). A log-rank test did not find an association across CYP2C19 genotypes (p value 0.898). CTAs showed a significant relationship between CYP2D6 and endoxifen (p value < 0.0001), but no association with CYP2C19 genotypes was found. CYP2C19 polymorphisms do not have a significant impact on tamoxifen metabolism or breast cancer relapse.

Impact of CYP2D6, CYP3A5, and ABCB1 Polymorphisms on Plasma Concentrations of Donepezil and Its Metabolite in Patients With Alzheimer Disease

BACKGROUND

Donepezil is one of the most commonly prescribed drugs for the treatment of Alzheimer disease. It is predominantly metabolized through CYP2D6 and to a lesser extent by CYP3A4/5. There are conflicting reports regarding the influence of CYP2D6, CYP3A5, and ABCB1 polymorphisms on the plasma concentration of donepezil. This study investigated the influence of these polymorphisms and sex on the plasma concentrations of donepezil and its active metabolite, 6-O-desmethyl donepezil (6ODD), in 47 patients with Alzheimer disease.

METHODS

Plasma donepezil and 6ODD concentrations were measured using liquid chromatography tandem mass spectrometry. Sex, the concomitant use of psychotropics, and CYP2D6, CYP3A5, and ABCB1 polymorphisms were analyzed as possible influencers.

RESULTS

The mean plasma concentrations of donepezil and 6ODD were well correlated (R2 = 0.418). The mean plasma concentration ratio of donepezil to 6ODD (metabolic ratio) was significantly lower in intermediate metabolizers of CYP2D6 than in extensive metabolizers. The metabolic ratio in patients receiving psychotropics was significantly lower than in those not receiving psychotropics. Among intermediate metabolizers, patients positive for CYP3A5 *3/*3 showed a significant increase in plasma mean 6ODD concentrations when compared with those who did not express this gene (CYP3A5 *1/*1 or *1/*3).

CONCLUSIONS

Results indicate that the mean plasma concentration ratio of donepezil to 6ODD is associated with CYP2D6 polymorphism and the concomitant use of psychotropics in patients with Alzheimer disease. In intermediate metabolizers, CYP3A5 may play a significant role in the metabolism of donepezil.

Common CYP2D6, CYP2C9, and CYP2C19 Gene Variants, Health Anxiety, and Neuroticism Are Not Associated With Self-Reported Antidepressant Side Effects

Many patients prescribed an antidepressant stop taking it because of side effects. Genetic factors and psychological factors including state or trait anxiety, may explain variation in side effect outcomes. Our aim was to examine the relative contribution of genetic and psychological factors in people with self-reported antidepressant side effects. We undertook a case control study (n = 194) of people who took a selective serotonin reuptake inhibitor (SSRI) or serotonin/noradrenaline reuptake inhibitor (SNRI) in the past 2 years, recruited via social media advertising. Cases had previously not tolerated at least one trial of an SSRI or SNRI, evidenced by stopping the drug or reducing the dose by at least 50% because of a side effect. Control participants had taken an SSRI or SNRI but did not meet case criteria. Variation in the genes CYP2D6, CYP2C19, and CYP2C9 was analyzed by Sanger sequencing on DNA extracted from blood or saliva. Participants completed the Short Health Anxiety Inventory-18, K10, and NEO-FFI-3 personality questionnaire. Participants were 87.1% female. 70.8% had a current K10 score of 22 or more. There was no consistent evidence that cases had higher psychological distress, health anxiety, or neuroticism. There was low correspondence between participants' CYP2D6, CYP2C19, and CYP2C9 phenotypes and their history of antidepressant tolerability. For this cohort of patients a history of not tolerating SSRI or SNRI therapy was not associated with variation in the pharmacogenes we tested, nor was it associated with health anxiety or neuroticism.

Inconsistency in race and ethnic classification in pharmacogenetics studies and its potential clinical implications

Introduction

Racial and ethnic categories are frequently used in pharmacogenetics literature to stratify patients; however, these categories can be inconsistent across different studies. To address the ongoing debate on the applicability of traditional concepts of race and ethnicity in the context of precision medicine, we aimed to review the application of current racial and ethnic categories in pharmacogenetics and its potential impact on clinical care.

Methods

One hundred and three total pharmacogenetics papers involving the CYP2C9, CYP2C19, and CYP2D6 genes were analyzed for their country of origin, racial, and ethnic categories used, and allele frequency data. Correspondence between the major continental racial categories promulgated by National Institutes of Health (NIH) and those reported by the pharmacogenetics papers was evaluated.

Results

The racial and ethnic categories used in the papers we analyzed were highly heterogeneous. In total, we found 66 different racial and ethnic categories used which fall under the NIH race category “White”, 47 different racial and ethnic categories for “Asian”, and 62 different categories for “Black”. The number of categories used varied widely based on country of origin: Japan used the highest number of different categories for “White” with 17, Malaysia used the highest number for “Asian” with 24, and the US used the highest number for “Black” with 28. Significant variation in allele frequency between different ethnic subgroups was identified within 3 major continental racial categories.

Conclusion

Our analysis showed that racial and ethnic classification is highly inconsistent across different papers as well as between different countries. Evidence-based consensus is necessary for optimal use of self-identified race as well as geographical ancestry in pharmacogenetics. Common taxonomy of geographical ancestry which reflects specifics of particular countries and is accepted by the entire scientific community can facilitate reproducible pharmacogenetic research and clinical implementation of its results.

Analysis of the CYP2C19 genotype associated with bleeding in Serbian STEMI patients who have undergone primary PCI and treatment with clopidogrel

PURPOSE

Bleeding is one of the possible adverse events during clopidogrel therapy. The CYP2C19 gene is the most significant genetic factor which influences response to clopidogrel treatment. We aimed to examine the contribution of the CYP2C19 gene to bleeding occurrence during clopidogrel therapy in Serbian patients with ST segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI).

METHODS

This case-control study included 53 patients who experienced bleeding and 55 patients without bleeding. Bleeding events were defined and classified using the Bleeding Academic Research Consortium (BARC) criteria. All patients were prescribed daily doses of clopidogrel during the 1-year follow-up after PCI. The CYP2C19*17 (c.-806C>T, rs12248560), rs11568732 (c.-889T>G, CYP2C19*20), CYP2C19*2 (c.681G>A; rs4244285) and CYP2C19*3 (c.636G>A; rs4986893) variants were analysed in all 108 patients. Additionally, sequencing of all nine exons, 5'UTR and 3'UTR in the rs11568732 carriers was performed.

RESULTS

Association between bleeding (BARC type ≥ 2) and the CYP2C19*17 variant was not observed [odds ratio (OR), 0.53; 95% confidence interval (CI), 0.2-1.1; p = 0.107). The rs11568732 variant showed significant association with bleeding (OR, 3.7; 95% CI, 1.12-12.44; p = 0.025). Also, we found that the rs11568732 variant appears independently of haplotype CYP2C19*3B, which is contrary to the previous findings.

CONCLUSIONS

Our results indicate the absence of CYP2C19*17 influence and turn the attention to the potential significance of the rs11568732 variant in terms of adverse effects of clopidogrel. However, it is necessary to conduct an independent conformation study in order to verify this finding. Also, an analysis of the functional implication of the rs11568732 variant is necessary in order to confirm the significance of this variant, both in relation to its influence on gene expression and in relation to its medical significance.

On-the-road driving performance after use of the antihistamines mequitazine and l-mequitazine, alone and with alcohol

OBJECTIVE

Previous studies demonstrated that mequitazine produces mild sedation after single doses. Its enantiomer, l-mequitazine, has a stronger potency for the H1 receptor. The aim of the current study was to assess the effects of l-mequitazine and mequitazine, alone and with alcohol, on driving.

METHODS

Twenty-five healthy volunteers were treated with l-mequitazine 2.5, 5.0 and 10 mg, mequitazine 10 mg and placebo, alone and in combination with alcohol in a double-blind crossover design. Driving performance was assessed using the standardized highway driving test in normal traffic. Its primary measure is the Standard Deviation of the Lateral Position (SDLP). Secondary measures consisted of an auditory word learning test during driving, and subjective measures of driving performance.

RESULTS

L-mequitazine 2.5 and 5.0 mg showed no effect on SDLP in the highway driving test, while SDLP significantly increased after l-mequitazine 10 mg (alone +1.59 cm; with alcohol +1.41 cm) and mequitazine 10 mg (with alcohol +1.17 cm). Alcohol significantly impaired all performance measures (SDLP +2.63 cm) but did not interact with the effects of treatment. Subjective measures indicated that participants were aware of the impairing effects of alcohol, but not of l-mequitazine and mequitazine.

CONCLUSION

L-mequitazine can be considered safe to drive in dosages of 2.5 and 5.0 mg. L-mequitazine 10 mg led to mild driving impairment. Alcohol impaired all performance measures and added to the effects of l-mequitazine and mequitazine.

Gender difference in prescription opioid abuse: A focus on oxycodone and hydrocodone

Several data gathered in the last decade indicate an increase of abuse of prescription opioid drugs oxycodone (OXY) and hydrocodone (HYDRO) in women. However, to date there are no conclusive evidences investigating the gender-dependent abuse liability of prescription opioids. This study aims to supply a specific focus on women's data through a selective summary of the literature analyzing gender differences in the pharmacokinetic and pharmacodynamic dimension of OXY and HYDRO. Findings from this study suggest that the majority of OXY and HYDRO pharmacokinetic and pharmacodynamic effects do not differ according to gender, though confirming a significant difference in the incidence of adverse effects as demonstrated by the increased gastrointestinal adverse reactions in female subjects. Although the majority of recent clinical studies include an equal number of female and male subjects, the main outcome parameters do not relate specifically to gender differences. Due to the gender influence in activity of CYP3A4 and its crucial role in metabolism of both OXY than HYDRO, we suggest that assessing pharmacokinetic and pharmacodynamic interactions in clinical studies may be useful to clarify the effect of the higher CYP3A4 activity in female in relation to CYP2D6 genotype. Overall, considering the paucity of data regarding gender differences in European Union, this work highlights that impact of new abuse deterrent formulations should be assessed with a special focus on data concerning female subjects.

Evaluation of the relationship between polymorphisms in CYP2C19 and the pharmacokinetics of omeprazole, pantoprazole and rabeprazole

AIM

To evaluate the possible association between polymorphisms in CYP2C19 and the pharmacokinetics of omeprazole, rabeprazole and pantoprazole.

MATERIALS & METHODS

151 healthy volunteers were evaluated for polymorphisms in the CYP2C19 gene using real-time polymerase chain reaction. Plasma concentrations were measured using high-performance liquid chromatography coupled to mass spectrometry.

RESULTS

Carriers of the *2 allele displayed poor metabolism for all the PPIs studied (around 50% decrease in clearance). Subjects with the *17 allele showed a light increase in clearance compared with *1/*1 (not significant).

CONCLUSION

CYP2C19*2 is associated with decreased clearance of all the PPIs, that could be associated with higher drug efficacy. CYP2C19*17 could increase clearance of these drugs, although the effect seems small.

Aberrant CYP2D6 metabolizer phenotypes do not show increased frequency in patients undergoing ECT after antidepressant therapy

We investigated the accumulation of aberrant CYP2D6 genotypes and predicted metabolizer phenotypes (ultrarapid metabolizer, intermediate metabolizer and poor metabolizer) potentially affecting the antidepressant treatment response in depressive patients indicated for electroconvulsive therapy (ECT) compared with patients with a single episode of depression. Seventy-six Dutch White patients with unipolar or bipolar treatment-resistant depression who underwent ECT were genotyped using the Amplichip CYP450 Test for CYP2D6. Two hundred and eight patients with a single episode of unipolar or bipolar depression were used as controls. No difference was observed in the prevalence of CYP2D6 phenotypes (poor metabolizer, intermediate metabolizer, extensive metabolizer and ultrarapid metabolizer) between the ECT and the control patients (5.3, 38.7, 56.0 and 0.0% vs. 6.4, 51.0, 42.6 and 0.0%, respectively). The types of depression (odds ratio = 0.33, P = 0.018) and age (odds ratio = 1.55 for a 10-year increase, P < 0.001), but not CYP2D6 phenotype or activity score were associated with the response to antidepressant treatment. In conclusion, preemptive genotyping for CYP2D6 currently appears to have no clinical implications in treatment-resistant depressive patients indicated for ECT.

Frequency of CYP450 enzyme gene polymorphisms in the Greek population: review of the literature, original findings and clinical significance

The cytochrome P450 (CYP450) enzyme family is involved in the oxidative metabolism of many therapeutic drugs and various endogenous substrates. These enzymes are highly polymorphic. Prevalence of CYP450 enzyme gene polymorphisms vary among different populations and substantial inter- and intra-ethnic variability in frequency of CYP450 enzyme gene polymorphisms has been reported. This paper provides an overview and investigation of CYP450 genotypic and phenotypic reports published in the Greek population.

Gender differences in pharmacokinetics and pharmacodynamics of methadone substitution therapy

Gender-related differences in the pharmacological effects of drug are an emerging topic. This review examines gender differences in both pharmacokinetic and pharmacodynamic aspects of methadone, a long-acting opioid agonist that is prescribed as a treatment for opioid dependence and the management of chronic pain.

Method: We performed a search in the Medline database from 1990 to 2014 in order to find published literature related to gender differences in pharmacokinetics (PK) and pharmacodynamics (PD) of methadone.

Results: None of the studies were carried out with the primary or secondary aim to identify any gender differences in the pharmacokinetic profile of methadone. Importantly; high inter-subjects variability in PK parameters was found also intra female population. The reported differences in volume of distribution could be ascribed to the physiological differences between men and women in body weight and composition, taking into account that the dose of methadone was established irrespective of body weight of patients (Peles and Adelson, 2006). On the other hand, the few studies present in literature found no gender difference in some direct pharmacodynamic parameters. Some reports have suggested that female gender is associated with an increased risk for long-QT-related cardiac arrhythmias in methadone maintenance subjects.

Conclusion: Even though it may be too simplistic to expect variability only in one parameter to explain inter-individual variation in methadone response, we believe that a better knowledge of gender-related differences might have significant implications for better outcomes in opioid dependence substitution therapy in women.

The frequency of CYP2C19 genetic polymorphisms in Russian patients with peptic ulcers treated with proton pump inhibitors

Introduction

Proton pump inhibitors, which are widely used as acid-inhibitory agents for the treatment of peptic ulcers, are mainly metabolized by 2C19 isoenzyme of cytochrome P450 (CYP2C19). CYP2C19 has genetic polymorphisms, associated with extensive, poor, intermediate or ultra-rapid metabolism of proton pump inhibitors. Genetic polymorphisms of CYP2C19 could be of clinical concern in the treatment of peptic ulcers with proton pump inhibitors.

Aim

To investigate the frequencies of CYP2C19*2, CYP2C19*3, and CYP2C19*17 alleles and genotypes in Russian patients with peptic ulcers.

Methods

We retrospectively reviewed the cases of 971 patients of Caucasian origin with Russian nationality from Moscow region with endoscopically and histologically proven ulcers, 428 males (44%) and 543 females (56%). The mean age was 44.6±11.9 years (range: 15–88 years). DNA was extracted from ethylenediaminetetraacetic acid whole blood samples (10 mL). The polymorphisms CYP2C19 681G.A (CYP2C19*2, rs4244285), CYP2C19 636 G.A (CYP2C19*3, rs4986893) and CYP2C19 -806 C.T (CYP2C19*17, rs12248560) were evaluated using real-time polymerase chain reaction.

Results

Regarding CYP2C19 genotype, 317 patients (32.65%) out of 971 were CYP2C19*1/*1 carriers classified as extensive metabolizers. Three hundred and eighty-six (39.75%) with CYP2C19*1/*17 or CYP2C19*17/*17 genotype were ultra-rapid metabolizers. Two hundred and fifty-one people (25.85%) were intermediate metabolizers with CYP2C19*1/*2, CYP2C19*2/*17, CYP2C19*1/*3, CYP2C19*3/*17 genotypes. Seventeen patients (1.75%) with CYP2C19*2/*2, CYP2C19*3/*3, CYP2C19*2/*3 genotypes were poor metabolizers. The allele frequencies were the following: CYP2C19*2 – 0.140, CYP2C19*3 – 0.006, CYP2C19*17 – 0.274.

Conclusion

There is a high frequency of CYP2C19 genotypes associated with modified response to proton pump inhibitors in Russian patients with peptic ulcers. Genotyping for CYP2C19 polymorphisms is suggested to be a useful tool for personalized dosing of proton pump inhibitors.

Serum concentrations of tamoxifen and its metabolites increase with age during steady-state treatment

It has been suggested that the concentrations of tamoxifen and its demethylated metabolites increase with age. We measured the serum concentrations of the active tamoxifen metabolites, 4OHtamoxifen (4OHtam), 4-hydroxy-N-desmethyltamoxifen (4OHNDtam, Endoxifen), tamoxifen and its demethylated metabolites. Their relations to age were examined. One hundred fifty-one estrogen receptor and/or progesterone receptor positive breast cancer patients were included. Their median (range) age was 57 (32-85) years. Due to the long half-life of tamoxifen, only patients treated with tamoxifen for at least 80 days were included in the study in order to insure that the patients had reached steady-state drug levels. Tamoxifen and its metabolites were measured by liquid chromatography-tandem mass spectrometry. Their serum concentrations were related to the age of the patients. To circumvent effects of cytochrome (CYP) 2D6 polymorphisms we also examined these correlations exclusively in homozygous extensive metabolizers. The concentrations of 4OHNDtam, tamoxifen, NDtam (N-desmethyltamoxifen), and NDDtam (N-desdimethyltamoxifen) were positively correlated to age (n = 151, p = 0.017, 0.045, 0.011, and 0.001 respectively). When exclusively studying the CYP2D6 homozygous extensive metabolizers (n = 86) the correlation between 4OHNDtam and age increased (p = 0.008). Up to tenfold inter-patient variation in the serum concentrations was observed. The median (inter-patient range) concentration of 4OHNDtam in the age groups 30-49, 50-69, and >69 years were 65 (24-89), 116 (25-141), and 159 (26-185) ng/ml, respectively. We conclude that the serum concentrations of 4OHNDtam (endoxifen), tamoxifen, and its demethylated metabolites increase with age during steady-state tamoxifen treatment. This may represent an additional explanation why studies on the effects of CYP2D6 polymorphisms on outcome in tamoxifen-treated breast cancer patients have been inconsistent. The observed high inter-patient range in serum concentrations of tamoxifen and its metabolites, especially in the highest age group, suggest that use of therapeutic monitoring of tamoxifen and its metabolites is warranted.

CYP2C19 2 predicts substantial tamoxifen benefit in postmenopausal breast cancer patients randomized between adjuvant tamoxifen and no systemic treatment

Estrogen catabolism is a major function of CYP2C19. The effect of CYP2C19 polymorphisms on tamoxifen sensitivity may therefore not only be mediated by a variation in tamoxifen metabolite levels but also by an effect on breast cancer risk and molecular subtype due to variation in lifelong exposure to estrogens. We determined the association between these polymorphisms and tamoxifen sensitivity in the context of a randomized trial, which allows for the discernment of prognosis from prediction. We isolated primary tumor DNA from 535 estrogen receptor-positive, stages I–III, postmenopausal breast cancer patients who had been randomized to tamoxifen (1–3 years) or no adjuvant therapy. Recurrence-free interval improvement with tamoxifen versus control was assessed according to the presence or absence of CYP2C19*2 and CYP2C19*17. Hazard ratios and interaction terms were calculated using multivariate Cox proportional hazard models, stratified for nodal status. Tamoxifen benefit was not significantly affected by CYP2C19*17. Patients with at least one CYP2C19*2 allele derived significantly more benefit from tamoxifen (HR 0.26; p = 0.001) than patients without a CYP2C19*2 allele (HR 0.68; p = 0.18) (p for interaction 0.04). In control patients, CYP2C19*2 was an adverse prognostic factor. In conclusion, breast cancer patients carrying at least one CYP2C19*2 allele have an adverse prognosis in the absence of adjuvant systemic treatment, which can be substantially improved by adjuvant tamoxifen treatment.

High prevalence of CYP2C19*2 allele in Roma samples: study on Roma and Hungarian population samples with review of the literature

The purpose of our study was to characterise the CYP2C19*2 and CYP2C19*3 alleles in healthy Roma and Hungarian populations. DNA of 500 Roma and 370 Hungarian subjects were genotyped for CYP2C19*2 (G681A, rs4244285) and CYP2C19*3 (G636A, rs4986893) by PCR-RFLP assay and direct sequencing. Significant differences were found comparing the Roma and Hungarian populations in CYP2C19 681 GG (63.6 vs. 75.9%), GA (31.8 vs. 23.0%), AA (4.6 vs. 1.1%), GA+AA (36.4 vs. 24.1%) and A allele frequencies (0.205 vs. 0.125) (p<0.004). Striking differences were found between Roma and Hungarian samples in CYP2C19*1 (79.5 vs. 87.4%) and CYP2C19*2 (20.5 vs. 12.6%) alleles, respectively (p<0.001). None of the subjects was found to carry the CYP2C19*3 allele. Frequencies of the intermedier metabolizer phenotype defined by the *1/*2 genotype (0.318 vs. 0.230, p<0.005) and poor metabolizer predicted by the *2/*2 genotype (0.046 vs. 0.011, p<0.005) was significantly higher in Roma than in Hungarians, respectively. Genotype distribution of the Roma population was similar to those of the population of North India, however, a major difference was found in the frequency of the CYP2C19*2 allele, which is likely a result of admixture with European lineages. In conclusion, the frequencies of the CYP2C19 alleles, genotypes and corresponding extensive, intermediate and poor metabolizer phenotypes studied here in the Hungarian population are similar to those of other European Caucasian populations, but display clear differences when compared to the Roma population.

Impact of genetic polymorphisms in CYP2C9 and CYP2C19 on the pharmacokinetics of clinically used drugs

Human cytochrome P450 (CYP) is a superfamily of hemoproteins which oxidize a number of endogenous compounds and xenobiotics. The human CYP2C subfamily consists of four members: CYP2C8, CYP2C9, CYP2C18 and CYP2C19. CYP2C9 and CYP2C19 are important drug-metabolizing enzymes and together metabolize approximately 20% of therapeutically used drugs. Forty-two allelic variants for CYP2C9 and 34 for CYP2C19 have been reported. The frequencies of these variants show marked inter-ethnic variation. The functional consequences of genetic polymorphisms have been examined, and many studies have shown the clinical importance of these polymorphisms. Current evidence suggests that taking the genetically determined metabolic capacity of CYP2C9 and CYP2C19 into account has the potential to improve individual risk/benefit relationships. However, more prospective studies with clinical endpoints are needed before the paradigm of "personalized medicine" based on the variants can be established. This review summarizes the currently available important information on this topic.

CYP2C19 genetic polymorphism in Saudi Arabians

The main objective of this study was to evaluate CYP2C19 genetic polymorphism in a Saudi Arabian population by determining the frequencies of CYP2C19*2, *3, *4, *6, *7 and *17 alleles and their relevant genotypes. Genomic DNA was isolated from 192 healthy Saudi Arabians, representing different geographical regions, and genotyping of the selected CYP2C19 variants was carried out by direct sequencing after PCR amplification. The allelic frequency of heterozygous CYP2C19*2 was 8.2% with only one individual found to carry the homozygous genotype of this defective allele. None of the other investigated poor metabolizer alleles (i.e. CYP2C19*3, *4, *6 and *7) was detected in the study population. About 46% of the examined volunteers were found to carry CYP2C19*17 genotype (37.5% heterozygous and 8.1% homozygous of the defective allele) with an overall CYP2C19*17 allelic frequency of 26.9%. In addition, a novel CYP2C19 SNP (G356A) and another very rare SNP (C336T) have been identified in this study with a frequency of about 50% for each. Further studies are required to evaluate the metabolic and clinical relevance of CYP2C19*17, G356A and C336T in the Saudi Arabian population.

A comparison of the acid-inhibitory effects of esomeprazole and rabeprazole in relation to pharmacokinetics and CYP2C19 polymorphism

BACKGROUND

Esomeprazole and rabeprazole are metabolised in the liver by means of the CYP2C19 enzyme, which has several functional genetic polymorphisms. Among Caucasians, 70% of the population has a fast metaboliser phenotype, 25-30% an intermediate and 2-5% a slow metaboliser phenotype. It is unknown whether different PPIs are affected to the same extent by these phenotypic differences.

AIM

To compare the acid-inhibitory effects of esomeprazole 40 mg and rabeprazole 20 mg in relation to CYP2C19 genotype and pharmacokinetics.

METHODS

Eighteen healthy Helicobacter pylori-negative Caucasian subjects with CYP2C19*2-*6 and *17 genotype were included in a randomised investigator-blinded crossover study with esomeprazole 40 mg and rabeprazole 20 mg. Intragastric 24-h pH-monitoring was performed on days 0, 1 and 5 of oral dosing.

RESULTS

Onset of acid inhibition during the first 4 h after administration did not differ significantly between PPIs. During the upright period, the proportion of time with pH >4 was significantly higher with esomeprazole compared to rabeprazole (52.2 vs. 40.3%, P = 0.003). At day 1 and 5, acid inhibition was significantly greater with esomeprazole than with rabeprazole (median intragastric pH: day 1: 3.7 vs. 3.0, P = 0.008; day 5: 4.7 vs. 3.8, P < 0.001; percentage of time pH >4: day 1: 45 vs. 39%, P = 0.054; day 5: 65 vs. 48%, P < 0.001). Differences in acid inhibition between wt/wt and wt/*2 genotype were significant for both PPIs.

CONCLUSIONS

Once-daily dosing with esomeprazole 40 mg provides a more effective and faster acid-inhibitory effect than rabeprazole 20 mg. The acid-inhibitory effect of esomeprazole and rabeprazole are both influenced by CYP2C19 polymorphism.

Population differences in major functional polymorphisms of pharmacokinetics/pharmacodynamics-related genes in Eastern Asians and Europeans: implications in the clinical trials for novel drug development

Drug lag, recently discussed extensively in Japan, can be divided into two phases: clinical development time and application review time. The former factor is still an important problem that might be improved by promoting multi-regional clinical trials and considering the results from other similar populations with Japanese, such as Koreans and Chinese. In this review, we compare the allelic or genotype frequencies of 30 relatively common functional alleles mainly between Eastern Asians and Europeans as well as among 3 major populations in Eastern Asian countries, Japan, Korea, and China, in 12 pharmacokinetics (PK)/pharmacodynamics (PD)-related genes; CYP2C9 (*2 and *3), CYP2C19 (*2, *3 and *17), 13 CYP2D6 haplotypes including *4, *5 and *10, CYP3A5 (*3), UGT1A1 (*28 and *6), NAT2 (*5, *6 and *7), GSTM1 and GSTT1 null genotypes, SLCO1B1 521T>C, ABCG2 421C>A, and HLA-A*31:01 and HLA-B*58:01. In this review, differences in allele frequencies (AFs) or genotype frequencies (GFs) less than 0.1 (in the cases of highest AF (GF) ≥0.1) or less than 0.05 (in the cases of lowest AF (GF) <0.1) were regarded as similar. Between Eastern Asians and Europeans, AFs (or GFs) are regarded as being different for many alleles such as CYP2C9 (*2), CYP2C19 (*2, *3 and *17), CYP2D6 (*4 and *10), CYP3A5 (*3), UGT1A1 (*28 and *6), NAT2 (*5*7), GSTT1 null and ABCG2 421C>A. Among the 3 Eastern Asian populations, however, only AFs of CYP2C19*3, CYP2D6*10, HLA-A*31:01 and HLA-B*58:01 are regarded as dissimilar. For CYP2C19*3, the total functional impact on CYP2C19 could be small if the frequencies of the two null alleles CYP2C19*2 and *3 are combined. Regarding CYP2D6*10, frequency difference over 0.1 is observed only between Japanese and Chinese (0.147). Although environmental factors should be considered for PK/PD differences, we could propose that among Japan, Korea, and China, genetic differences are very small for the analyzed common PK-related gene polymorphisms. On the other hand, AFs of the two HLA alleles important for cutaneous adverse drug reactions are diverse even among Eastern Asians and thus should be taken into account.

Feasibility of pharmacy-initiated pharmacogenetic screening for CYP2D6 and CYP2C19

PURPOSE

Our purpose was to investigate the feasibility of pharmacy-initiated pharmacogenetic (PGt) screening in primary care with respect to patient willingness to participate, quality of DNA collection with saliva kits, genotyping, and dispensing data retrieved from the pharmacy.

METHODS

Polypharmacy patients aged >60 years who used at least one drug with Anatomical Therapeutic Chemical (ATC) code N06AA01-N06AX19 (antidepressants), A02BC01-A02BC05 (proton-pump inhibitors), N05AA01-N05AH04 (antipsychotics), or C07AB02 (metoprolol) in the preceding 2 years were randomly selected. DNA was collected with saliva kits and genotyped for CYP2D6 and CYP2C19 with the AmpliChip. Pharmacy dispensing records were retrieved and screened for drugs interacting with the patient's CYP2D6 and CYP2C19 genotype by using the evidence-based PGt guidelines from the Dutch Pharmacogenetics Working Group.

RESULTS

Out of the 93 invited patients, 54 (58.1%) provided informed consent. Nine saliva samples (16.7%) contained too little DNA. Call rates for CYP2D6 and CYP2C19 were 93.3% and 100%, respectively. Frequencies of genotype-predicted phenotype were 2.4%, 38.1%, 54.8%, and 4.8% for CYP2D6 poor metabolizers (PM), intermediate metabolizers (IM), extensive metabolizers (EM), and ultrarapid metabolizers (UM) respectively. For CYP2C19 genotype-predicted phenotype, frequencies were 2.2%, 15.6%, and 82.2% for PM, IM, and EM, respectively.

CONCLUSIONS

This study shows that pharmacy-initiated PGt screening is feasible for a primary care setting.

Implementing genotype-guided antithrombotic therapy

Genotyping has the potential to improve the efficacy and safety of major antithrombotic drugs. For warfarin, the stable maintenance dose varies from 1-10 mg/day. The VKORC1 -1639G>A allele and the CYP2C9*2 and *3 alleles (cumulative frequency: 90% in Asians, 65% in Europeans and 20% in Africans), explain 45% of response variability in European and 30% in African populations. The large clinical trials COAG and EU-PACT will define the extent to which pharmacogenetic dosing affects the safety and efficacy of warfarin and coumarin derivatives. The platelet inhibitor clopidogrel requires activation by the CYP2C19 enzyme. CYP2C19*2 and *3 alleles (cumulative frequency: 20-50%) produce null enzyme activity, and their presence attenuates platelet inhibition and increases cardiovascular events. The US FDA-mandated drug labeling recognizes the relevance of genotyping in the selection and dosing of both warfarin and clopidogrel.

Genetic polymorphism of metabolic enzymes P450 (CYP) as a susceptibility factor for drug response, toxicity, and cancer risk

The polymorphic P450 (CYP) enzyme superfamily is the most important system involved in the biotransformation of many endogenous and exogenous substances including drugs, toxins, and carcinogens. Genotyping for CYP polymorphisms provides important genetic information that help to understand the effects of xenobiotics on human body. For drug metabolism, the most important polymorphisms are those of the genes coding for CYP2C9, CYP2C19, CYP2D6, and CYP3A4/5, which can result in therapeutic failure or severe adverse reactions. Genes coding for CYP1A1, CYP1A2, CYP1B1, and CYP2E1 are among the most responsible for the biotransformation of chemicals, especially for the metabolic activation of pre-carcinogens. There is evidence of association between gene polymorphism and cancer susceptibility. Pathways of carcinogen metabolism are complex, and are mediated by activities of multiple genes, while single genes have a limited impact on cancer risk. Multigenic approach in addition to environmental determinants in large sample studies is crucial for a reliable evaluation of any moderate gene effect. This article brings a review of current knowledge on the relations between the polymorphisms of some CYPs and drug activity/toxicity and cancer risk.

Role of cytochrome P450 polymorphisms in the development of pulmonary drug toxicity: a case-control study in the Netherlands

BACKGROUND

Drug-induced pulmonary toxicity is a serious and expanding problem with often unknown aetiology. Many drugs are metabolized by cytochrome P450 (CYP) enzymes.

OBJECTIVE

To establish whether allelic variation in CYP polymorphic genes contributes to variability in drug response and unexpected toxicity.

METHODS

A case-control study was conducted. The cases consisted of patients with drug-induced interstitial lung disease (DI-ILD; n = 59). Two control groups were used: one group of healthy volunteers (n = 173) and one group of patients with idiopathic pulmonary fibrosis (IPF; n = 110).

RESULTS

Of the patients with DI-ILD 91.5% (54/59) had at least one of the studied variant genes compared with 70.5% (122/173, p < 0.001) of the healthy volunteers and 69.1% (76/110, p < 0.001) of the IPF patients. The percentage of individuals with one or more variant CYP genes was higher in the DI-ILD group. Odds ratios were significantly increased and ranged from 3.25 to 40.8, indicating a significant association between the development of DI-ILD and the presence of one or more variant CYP genes.

CONCLUSION

DI-ILD appeared to be associated with the presence of at least one variant CYP allele. This study supports the potential usefulness of personalized medicine by genotyping aiming to improve efficacy, tolerability and drug safety.

Fluoxetina: indícios de uso inadequado

OBJETIVO: Investigar o uso da fluoxetina na cidade de Santo André, SP, por meio de coleta e análise das receitas especiais (RE) prescritas por médicos e arquivadas nas farmácias e drogarias daquela cidade. MÉTODOS: Foram coletadas as receitas especiais retidas durante os meses de agosto do ano de 2005 a julho de 2006, em 13 farmácias de manipulação e em 27 drogarias em diferentes regiões de Santo André. Cada receita especial foi analisada em relação à presença de fluoxetina, em associação ou não a outros princípios ativos, e o sexo do(a) paciente foi anotado. RESULTADOS: Foram analisadas 39.782 RE - 16.124 coletadas das farmácias magistrais e 23.658 das drogarias. Desses totais, 10.919 prescrições continham fluoxetina - 9.259 provenientes das farmácias magistrais (84,8%) e apenas 1.660 (15,2%) das drogarias. As prescrições de fluoxetina eram predominantemente destinadas a mulheres (79,8%). Na imensa maioria das RE, a fluoxetina foi prescrita em associação com um grande número de outras substâncias ativas, inclusive anfetaminas anoréticas, chegando a mais de dez outras em quase a metade das prescrições. Esse tipo de prescrição múltipla, principalmente para mulheres, é comparado com as prescrições de fórmulas magistrais para emagrecer, muito utilizadas no Brasil. CONCLUSÃO: Os dados obtidos sugerem que a utilização de fluoxetina teria um fim estético (perda de peso), e não um fim terapêutico (tratamento de depressão). Discute-se a relação risco-benefício desse possível uso, que poderia ser classificado de inadequado dado as conhecidas reações adversas da fluoxetina e a sua interferência no sistema citocromo P450.

Association of graded allele-specific changes in CYP2D6 function with imipramine dose requirement in a large group of depressed patients

The inactivation and clearance of the tricyclic antidepressant imipramine is dependent on CYP2D6 activity. First, CYP2C19 converts imipramine into the active metabolite desipramine, which is then inactivated by CYP2D6. This retrospective single center study aimed to prove whether CYP2C19 and ample CYP2D6 genotyping (taking into consideration four null alleles and three decreased-activity alleles) could be used to predict imipramine and desipramine plasma concentrations in depressed patients, and whether genotype-based drug dose recommendations might assist in the early management of imipramine pharmacotherapy. In 181 subjects with major depressive disorder, drug doses were recorded, imipramine and desipramine plasma concentrations were monitored and CYP2C19 (*2) and CYP2D6 genotype (*3, *4, *5, *6, *9, *10, *41 and gene duplication) were obtained, yielding graded allele-specific CYP2D6 patient groups. Desipramine and imipramine+desipramine plasma concentration per drug dose unit, imipramine dose at steady state, and imipramine dose requirement significantly depended on CYP2D6 genotype (Kruskal-Wallis test, P<0.0001). Mean (+/-s.d.) drug dose requirements were 131 (+/-109), 155 (+/-70), 217 (+/-95), 245 (+/-125), 326 (+/-213), and 509 (+/-292) mg imipramine/day in carriers of 0, 0.5, 1, 1.5, 2, and >2 active CYP2D6 genes, respectively. Our protocol for CYP2D6 genotyping will thus importantly aid in the prediction of imipramine metabolism, allowing for the use of an adjusted starting dose and faster achievement of predefined imipramine+desipramine plasma levels in all genetic patient subgroups. Therefore, therapeutic efficacy and efficiency may be improved, the number of adverse drug reactions decreased, and hospital stay reduced.