A one-year follow-up study of treatment-compliant suicide attempt survivors: relationship of CYP2D6-CYP2C19 and polypharmacy with suicide reattempts.

This study of a cohort of 1-year treatment-compliant survivors of a suicide attempt examined for the first time whether a high CYP2D6-CYP2C19 metabolic capacity (pharmacogenes related to psychopathology, suicide, and attempt severity) and/or polypharmacy treatments predicted repeat suicide attempts, adjusting for sociodemographic and clinical factors as confounders. Of the 461 (63% women) consecutively hospitalized patients who attempted suicide and were evaluated and treated after an index attempt, 191 (67.5% women) attended their 6- and 12-month follow-up sessions. Clinicians were blinded to the activity scores (AS) of their genotypes, which were calculated as the sum of the values assigned to each allele (CYP2C19 *2, *17; CYP2D6 *3, *4, *4xN, *5, *6, *10, wtxN). No differences were found in polypharmacy prescription patterns and the variability of CYP2D6 and CYP2C19 genotypes between adherents and dropouts, but the formers were older, with a higher frequency of anxiety and bipolar disorders and fewer alcohol and substance use disorders. The risk of reattempts was higher for CYP2D6 ultrarapid (AS > 2) metabolizers (ß = 0.561, p = 0.005) and violent suicide survivors (ß = -0.219, p = 0.042) if the attempt occurred during the first 6-month period, individuals with an increased number of MINI DSM-IV Axis I mental disorders (ß = 0.092, p = 0.032) during the second 6-month period and individuals with a combined high CYP2D6-CYP2C19 metabolic capacity (AS > 4) (ß = 0.345, p = 0.024) and an increased use of drugs other than antidepressants, anxiolytics-depressants and antipsychotics-lithium (ß = 0.088, p = 0.005) in multiple repeaters during both periods. CYP2D6 and CYP2C19 rapid metabolism and polypharmacy treatment for somatic comorbidities must be considered to prevent the severe side effects of short-term multiple suicide reattempts after a previous attempt.

Relationships between CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 metabolic phenotypes and genotypes in a Nicaraguan Mestizo population.

Interethnic variability in the drug-metabolizing capacity of CYP450 enzymes may lead to discrepancies in the relationship between genotypes and phenotypes worldwide. The present study was aimed to analyze for the first time whether there is a relationship between clinically relevant CYP450 genetic polymorphisms and their drug oxidation capacity (metabolic phenotype) in a population of healthy Nicaraguan volunteers. Two hundred and twelve participants were genotyped for CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4, and their actual metabolic phenotype (evaluated by the Metabolic Ratio, MR) was analyzed by using the CEIBA cocktail approach. The results showed the wide interindividual variability in all the studied enzymes and a significant difference (p < 0.004) in the activity of CYP1A2 between male and female subjects. The number of CYP2C19 (p < 0.0001) and CYP2D6 (p < 0.0001) active alleles were shown inversely correlated with their corresponding MR, although there were marked genotype-phenotype discrepancies. There was an actual enzyme capacity overlapping (MR) between genotypically Poor (gPMs) and Extensive Metabolizers (gEMs) of 3.14% subjects for CYP2D6 and 0.94% for CYP2C9. Similarly, there was an overlapping for metabolic phenotypes of 11.48% of genotypically ultrarapid metabolizers (gUMs) for CYP2C19 and 2.09% for CYP2D6 and gEMs. Therefore, the current approach for metabolic phenotype prediction based just on genotype does not predict properly for all individuals within this Nicaraguan Mestizo population, thus representing a potential barrier for the clinical implementation of personalized medicine in this region. However, it is necessary to improve the prediction of phenotype from genotype in order to improve the pharmacogenetic implementation in populations with specific ethnic backgrounds.

Genomic Ancestry, CYP2D6, CYP2C9, and CYP2C19 Among Latin Americans.

We present the distribution of CYP2D6, CYP2C9, and CYP2C19 variants and predicted phenotypes in 33 native and admixed populations from Ibero-America (n > 6,000) in the context of genetic ancestry (n = 3,387). Continental ancestries are the major determinants of frequencies of the increased-activity allele CYP2C19*17 and CYP2C19 gUMs (negatively associated with Native American ancestry), decreased-activity alleles CYP2D6*41 and CYP2C9*2 (positively associated with European ancestry), and decreased-activity alleles CYP2D6*17 and CYP2D6*29 (positively associated with African ancestry). For the rare alleles, CYP2C9*2 and CYPC19*17, European admixture accounts for their presence in Native American populations, but rare alleles CYP2D6*5 (null-activity), CYP2D6-multiplication alleles (increased activity), and CYP2C9*3 (decreased-activity) were present in the pre-Columbian Americas. The study of a broad spectrum of Native American populations from different ethno-linguistic groups show how autochthonous diversity shaped the distribution of pharmaco-alleles and give insights on the prevalence of clinically relevant phenotypes associated with drugs, such as paroxetine, tamoxifen, warfarin, and clopidogrel.

Interethnic Variability in CYP2D6, CYP2C9, and CYP2C19 Genes and Predicted Drug Metabolism Phenotypes Among 6060 Ibero- and Native Americans: RIBEF-CEIBA Consortium Report on Population Pharmacogenomics.

Pharmacogenetic variation in Latin Americans is understudied, which sets a barrier for the goal of global precision medicine. The RIBEF-CEIBA Network Consortium was established to characterize interindividual and between population variations in CYP2D6, CYP2C9, and CYP2C19 drug metabolizing enzyme genotypes, which were subsequently utilized to catalog their "predicted drug metabolism phenotypes" across Native American and Ibero American populations. Importantly, we report in this study, a total of 6060 healthy individuals from Ibero-America who were classified according to their self-reported ancestry: 1395 Native Americans, 2571 Admixed Latin Americans, 96 Afro-Latin Americans, 287 white Latin Americans (from Cuba), 1537 Iberians, and 174 Argentinean Ashkenazi Jews. Moreover, Native Americans were grouped into North-, Central-, and South Amerindians (from Mexico, Costa Rica, and Peru, respectively). All subjects were studied for the most common and functional CYP2D6, CYP2C9, and CYP2C19 allelic variants, and grouped as genotype-predicted poor or ultrarapid metabolizer phenotypes (gPMs and gUMs, respectively). Native Americans showed differences from each ethnic group in at least two alleles of CYP2D6, CYP2C9, and CYP2C19. Native Americans had higher frequencies of wild-type alleles for all genes, and lower frequency of CYP2D6*41, CYP2C9*2, and CYP2C19*17 (p < 0.05). Native Americans also showed less CYP2C19 gUMs than the rest of the population sample. In addition, differences within Native Americans (mostly North vs. South) were also found. The interethnic differences described supports the need for population-specific personalized and precision medicine programs for Native Americans. To the best of our knowledge, this is the largest study carried out in Native Americans and other Ibero-American populations analyzing CYP2D6, CYP2C9, and CYP2C19 genetic polymorphisms. Population pharmacogenomics is a nascent field of global health and warrants further research and education.

Pharmacogenetic research activity in Central America and the Caribbean: a systematic review.

AIM: The present review was aimed at analyzing the pharmacogenetic scientific activity in Central America and the Caribbean. MATERIALS & METHODS: A literature search for pharmacogenetic studies in each country of the region was conducted on three databases using a list of the most relevant pharmacogenetic biomarkers including 'phenotyping probe drugs' for major drug metabolizing enzymes. The review included 132 papers involving 47 biomarkers and 35,079 subjects (11,129 healthy volunteers and 23,950 patients). RESULTS: The country with the most intensive pharmacogenetic research was Costa Rica. The most studied medical therapeutic area was oncology, and the most investigated biomarkers were CYP2D6 and HLA-A/B. Conclusion: Research activity on pharmacogenetics in Central American and the Caribbean populations is limited or absent. Therefore, strategies to promote effective collaborations, and foster interregional initiatives and research efforts among countries from the region could help for the rational clinical implementation of pharmacogenetics and personalized medicine.

Worldwide interethnic variability and geographical distribution of CYP2C9 genotypes and phenotypes.

INTRODUCTION: Notably differences in CYP2C9 allele frequencies among worldwide populations have been reported, with an interesting low frequency of the CYP2C9*2 allele in Amerindians compared with Admixed and European populations. AREAS COVERED: Literature was searched using the PubMed database and was focused on worldwide original research papers on CYP2C9 alleles and CYP2C9 phenotypes ("predicted" from CYP2C9 genotypes and "measured" metabolic phenotype with a probe drug) among healthy volunteers according to their ethnicity and geographical distribution. Seventy-eight original research articles including a total of 31,978 subjects were identified. EXPERT OPINION: CYP2C9*2 allele is the most frequent in Caucasian populations (average 14%), with the lowest frequencies for Africans (0.46%), East Asians (0.56%) and Native Americans (1.25%), which is in agreement with the hypothesis about the low prevalence in Amerindians. CYP2C9*3 shows the highest frequency among South Asians (11.7%), while CYP2C9*5 (1.56%) and *8 (4.70%) in African Americans. The predicted poor metabolizers (gPMs) were found overall in a low frequency, with the highest frequency detected for South Asians, in accordance with the CYP2C9*3 frequency in these populations. This study shows the worldwide variability in the CYP2C9 allele frequencies across different ethnic and geographic groups. Data about CYP2C9 "measured" metabolic phenotypes is still limited.

Population pharmacogenetics of Ibero-Latinoamerican populations (MESTIFAR 2014).

MESTIFAR 2014 28-30 November 2014, Panama City, Panama The CEIBA consortium was created within the Ibero-American network of Pharmacogenetics (RIBEF) to study population pharmacogenetics. The current status of these initiatives and results of the MESTIFAR project were analyzed in Panama, 28-30 November 2014. The MESTIFAR project focused on studying CYPs genetic polymorphisms in populations of different ethnic origin. So far, more than 6000 healthy volunteers have been evaluated, making this one of the largest population pharmacogenomic studies worldwide. Three symposia were organized, 'Pharmacogenetics of indigenous and mestizos populations and its clinical implications', 'Methodological innovation in pharmacogenetics and its application in health', and 'General discussion and concluding remarks', about mechanisms and proposals for training, diffusion of pharmacogenetics for Spanish- and Portuguese-speaking health professionals, and 'bench to bedside' pilot projects.

Interethnic variability of CYP2D6 alleles and of predicted and measured metabolic phenotypes across world populations.

INTRODUCTION: The frequency of CYP2D6 alleles, related to either a lack of or increased enzymatic activity, which may lead to poor metabolism (PM) or ultrarapid metabolism (UM), can vary across ethnic groups and hence across geographic regions. AREAS COVERED: Worldwide original research papers on CYP2D6 allelic frequencies, metabolic phenotype frequencies measured with a probe drug, and/or genotype frequencies that studied > 50 healthy volunteers, were included in analyses to describe the distributions of alleles, phenotypes predicted from genotypes (predicted poor metabolizers [gPMs], predicted ultrarapid metabolizers [gUMs]) and metabolic phenotypes (mPMs, mUMs) across ethnic groups and geographic regions. The analysis included 44,572 individuals studied in 172 original research papers. EXPERT OPINION: As of today, Africa and Asia are under-represented in this area relative to the total number of their inhabitants, so that further studies in these regions are warranted. The CYP2D6*4 allele frequency was higher in Caucasians, CYP2D6*10 in East Asians, CYP2D6*41 and duplication/multiplication of active alleles in Middle Easterns, CYP2D6*17 in Black Africans and CYP2D6*29 in African Americans, than in other ethnic groups. Overall, gPMs and mPMs are more frequent among Caucasians, and gUMs among Middle Easterns and Ethiopians. However, mUMs could not be evaluated because only two studies were found presenting this information. Further studies including mUMs are thus warranted. There is a correspondence between gPMs and mPMs, but the few studies of mUMs meant that their relationship with gUMs could not be demonstrated. Finally, evolutionary aspects of the CYP2D6 allele distribution appear to support the Great Human Expansion model.

Liver enzyme abnormalities during antipsychotic treatment: a case report of risperidone-associated hepatotoxicity.

BACKGROUND: Drug-induced liver enzyme abnormalities may indicate hepatic injury. Antipsychotic drugs also may cause increase in the liver enzymes and serum bilirubin levels. The present report evaluates the case of a patient with risperidone-associated hepatocellular damage. CASE SUMMARY: A 19-year-old Caucasian man was admitted to the Department of Psychiatry with paranoid schizophrenia and risperidone was administered in a gradually increasing dose up to 8 mg/day. After 3 weeks of treatment, he experienced asthenia and weight loss. The level of aspartate aminotransferase was 283 IU/L (normal: <30 IU/L), and the alanine aminotransferase level was 778 IU/L (normal: <36 IU/L). Treatment with risperidone was immediately discontinued. Six days after drug withdrawal, the alanine aminotransferase level fell more than 50%, and a complete return to normalcy was seen within 2 months. RESULTS: In the present case, a possible causal association between risperidone and hepatocellular damage has been observed due to the temporal relationship between the administration of the drug and the onset of hepatic abnormalities, and a following rapid recovery after stopping the drug. As the hepatic damage could be related to the plasma concentration of risperidone which is highly influenced by the hepatic enzyme CYP2D6, the patient was genotyped for CYP2D6. He was classified as homozygous wild type for CYP2D6. CONCLUSIONS: The risk for developing hepatotoxicity during risperidone therapy cannot be supported by the patient CYP2D6 genotype. In clinical practice, it may be recommended to obtain baseline liver function tests before starting risperidone and regular screening for liver enzyme changes during therapy.

CYP2D6 variation, behaviour and psychopathology: implications for pharmacogenomics-guided clinical trials.

Individual and population differences in polymorphic cytochrome P450 enzyme function have been known for decades. The biological significance of these differences has now been deciphered with regard to drug metabolism, action and toxicity as well as disposition of endogenous substrates, including neuroactive compounds. While the cytochrome P450 enzymes occur abundantly in the liver, they are expressed in most tissues of the body, albeit in varying amounts, including the brain. The latter location of cytochrome P450s is highly pertinent for susceptibility to neuropsychiatric diseases, not to mention local drug metabolism at the site of psychotropic drug action in the brain. In the current era of personality medicine with companion theranostics (i.e. the fusion of therapeutics with diagnostics), this article underscores that such versatile biological roles of cytochrome P450s offer multiple points of entry for personalized medicine and rational therapeutics. We focus our discussion on CYP2D6, one of the most intensively researched drug and endogenous compound metabolism pathways, with a view to relevance for, and optimization of, pharmacogenomic-guided clinical trials. Working on the premise that CYP2D6 is related to human behaviour and certain personality traits such as serotonin and dopamine system function, we further suggest that the motivation of healthy volunteers to participate in clinical trials may in part be influenced by an under- or over-representation of certain CYP2D6 metabolic groups.

MDR-1 genotypes and quetiapine pharmacokinetics in healthy volunteers.

BACKGROUND: P-glycoprotein is an efflux transporter encoded by the multidrug-resistance MDR-1 gene, which influences the absorption and excretion of a variety of drugs. The relation between quetiapine pharmacokinetics and MDR-1 genetic polymorphisms remains controversial. Therefore, the aim of the present study was to analyze the association between quetiapine plasma concentrations and MDR-1 genetic polymorphisms in a bioequivalence trial. METHODS: Quetiapine bioequivalence was studied in 24 unrelated healthy Caucasian adults with an open-label, randomized, cross-over, two-sequence and two-period design. Subjects were genotyped for 3435C>T and 1236C>T single-nucleotide polymorphisms. A linear mixed model was performed to compare pharmacokinetic parameters. RESULTS: Subjects with 3435T/T genotype vs. C carriers showed a higher area under the concentration-time curve from 0 to 36 h (p=0.01). Subjects classified according to 1236C>T SNP and haplotypes showed no statistically significant differences. CONCLUSIONS: These results suggest that the polymorphic MDR-1, in particular the 3435C>T allelic variant, might influence plasma levels of quetiapine.

Losartan hydroxylation phenotype in an Ecuadorian population: influence of CYP2C9 genetic polymorphism, habits and gender.

AIM: To describe for the first time CYP2C9 hydroxylation phenotype with CYP2C9 genotypes in a Hispanic (Ecuadorian) population using losartan; and the relevance of gender, tobacco, ethanol and caffeine consumption on the enzyme hydroxylation capacity. METHODS: Ecuadorian healthy volunteers (n = 194) received a single oral dose of 25 mg losartan. Losartan metabolic ratio was defined as losartan:E3174 concentration. CYP2C9 alleles *2, *3, *4, *5 and *6 were analyzed. RESULTS: No phenotypically poor metabolizers were found. The metabolic ratio (mean ± standard deviation) was higher (p < 0.05) in CYP2C9*1/*3 carriers (12.4 ± 13.8; n = 6) versus CYP2C9*1/*1 (4.9 ± 7.0; n = 167), as well as in females versus males (6.72 ± 9.72 and 3.76 ± 4.48, respectively; p < 0.05). Only the following genotypes, CYP2C9*1/*1, CYP2C9*1/*2 and CYP2C9*1/*3, were found with a frequency of 86.1%, 10.8% and 3.1%, respectively. CONCLUSION: Despite the mean metabolic ratio being higher in this population than in others previously studied across genotypes, no poor metabolizers, either phenotypically or genotypically, were found.

Development of a HPLC method for the determination of losartan urinary metabolic ratio to be used for the determination of CYP2C9 hydroxylation phenotypes.

BACKGROUND: Losartan is metabolized to losartan carboxylic acid (E-3174) by the polymorphic cytochrome CYP2C9. The aim of the study was to develop a high-performance liquid chromatographic (HPLC) method with fluorescence detection for simultaneously measuring losartan and its metabolite E-3174 in urine to evaluate the losartan urinary metabolic ratio (MR: losartan/E-3174) for CYP2C9 phenotyping in humans. METHODS: The compounds were separated in a reversed-phase chromatographic column and detected by fluorescence at a wavelength of 250 nm for excitation and of 370 nm for emission. RESULTS: No analytical interferences with endogenous compounds were found, and the extraction recoveries were over 88%. Limits of quantification of 2 ng mL-1 for losartan and 5 ng mL-1 for E-3174 were achieved, as well as good reproducibility with coefficients of variation of <9% in all cases. Analyses with the present HPLC method show significant differences (p<0.05) in losartan MRs between the four CYP2C9 genotype groups in 13 Spanish healthy volunteers. CONCLUSIONS: The method developed is simple and affordable, as well as sensitive and reliable to calculate the MR. Therefore, it appears to be useful for CYP2C9 phenotyping using losartan as a drug test in populations, such as Hispanics with different allele combinations.

High-performance liquid chromatography method using ultraviolet detection for the quantification of aripiprazole and dehydroaripiprazole in psychiatric patients.

BACKGROUND: Aripiprazole (ARI) is an antipsychotic drug that is metabolized to dehydroaripiprazole (DARI) by CYP2D6. Because of the large interindividual variability in ARI and DARI plasma concentrations, therapeutic drug monitoring may be of use in psychiatric patients during treatment with ARI. The aim of the present study was to develop a simple and reliable method for the quantitative determination of ARI and DARI in plasma using liquid-liquid extraction and reverse-phase high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. The method was tested in psychiatric patients during regular treatment with ARI. METHODS: Separation was by the liquid-liquid method, and UV detection at 254 nm. Linear responses for ARI and DARI were obtained between 2 and 1000 ng/mL, and precision assays were lower than 10.4 for both analytes. RESULTS: Lower limit of quantification and detection were 1 and 0.38 ng/mL for ARI and 0.78 and 0.44 ng/mL for DARI, respectively. The method was successfully applied to plasma samples drawn from 22 patients with concentrations ranging between 2 and 189 ng/mL for ARI and between 11 and 359 ng/mL for DARI. CONCLUSIONS: The chromatographic method developed has been demonstrated to be sensitive and reliable for the measurement of ARI and DARI simultaneously in human plasma, and the present method represents an alternative procedure to evaluate plasma concentration in patients during treatment with ARI.

CYP2D6 and the severity of suicide attempts.

AIM: Among people who die by suicide, an increased frequency of CYP2D6 active gene multiplication has been described. Therefore, the present study analyzed the relationship between the severity of the suicidal intent and CYP2D6 number of active genes among survivors. MATERIALS & METHODS: A group of 342 individuals were evaluated with Beck Suicide Intent Scale within 24 h of the failed attempt. 'Severe' suicide attempters were classified as those scoring above percentile 75 in the objective circumstances section of the Suicide Intent Scale Scale. A group of 377 healthy controls were also genotyped. results: A higher number of 'severe' suicide attempters carrying ≥2 active CYP2D6 genes as compared with the rest of the patients population (p < 0.01) or the healthy control group (p < 0.01) was found. CONCLUSION: Considering that 'severe' suicide attempters are more likely eventually to die by suicide, CYP2D6 genetic polymorphism might be of use as a biomarker of death by suicide, which is in agreement with previous findings.