CYP3A5 Genotype Research Articles

Pharmacogenomic response of low dose haloperidol in critically ill adults with delirium

PurposeTo characterize the pharmacogenomic response of low-dose haloperidol for delirium treatment in critically ill adults. Materials and methodsSingle-center, pilot study of a convenience sample of ICU adults with delirium treated with low-dose IV haloperidol. Patients were evaluated for delirium with the ICDSC every 8 h. Serum haloperidol concentrations were collected on ICU days 2–6, CYP2D6 and CYP3A4 genotypes were characterized and patients were categorized as extensive (EM), intermediate (IM) or poor metabolizers (PM). ResultsThe 22 patients (median age 67 [IQR 48,77] years; median APACHE III 81[IQR 54,181]; CYP2D6 [EM = 12, IM = 7, PM = 3], CYP3A [EM = 18, IM = 4]) received a median [IQR] daily haloperidol dose of 3.0 [2.4, 4.5] mg. After adjusting for age, SOFA, and ICU day, neither an association between CYP2D6 (IM p = .67/PM p = .25) or CYP3A4 (IM p = .44) metabolizer status and serum haloperidol concentrations was found. After adjusting for age, SOFA, and ICU day, neither an association between daily haloperidol dose (p = .77) or ICDSC score (p = .13) and serum haloperidol concentrations was found. No patient experienced QTc interval prolongation (≥500 ms). ConclusionsThis pilot study, the first to evaluate the pharmacogenomic response of low-dose haloperidol when used to treat delirium in the ICU, suggests CYP2D6/CYP3A4 metabolizer status does not affect the serum haloperidol concentrations.

SUN-342 UNUSUAL HIGH DOSE OF TACROLIMUS IN RENAL TRANSPLANT PATIENTS: A CASE SERIES

Tacrolimus, is an immunosuppressant, characterized by highly variable pharmacokinetics (PK) and a small therapeutic window, which make therapeutic drug monitoring (TDM) mandatory for maintaining adequate exposure. TDM allows dose adjustment in order to avoid graft rejection and tac-induced adverse effects, which are the most challenging after transplantation. Tacrolimus is metabolized specifically by the CYP3A isoenzyme: CYP3A4 and CYP3A5. Many single nucleotide polymorphisms (SNPs) such as CYP3A4*1B -392A>G, CYP34*22 15389C>T, and CYP3A5*3 6986A>G related to the expression levels of CYP enzymes may explain a part of the variability in tacrolimus PK. It is admitted that patients harboring the predominant CYP3A5*3, associated with enzymatic function loss, require roughly 50% lower tacrolimus doses than those with CYP3A5*1. CYP3A4*1B. Recently, it has been shown that CYP3A4*22 carriers had a lower clearance of tacrolimus (-16%). We describe herein two cases of renal transplant patients who have great difficulty in reaching the desired trough blood levels despite the use of high dose tacrolimus. It is a retrospective study reporting the case of 2 patients with difficulty in reaching the desired trough blood levels of tacrolimus. Our first patient is a 34-year-old man who received a living donor kidney transplant (his mother) on March 15, 2017. He was prescribed Tacrolimus at an initial dose of 14 mg/day divided every 12 hours (0.12-0.15 mg/kg/day) in association with a corticosteroid and mycophenolate mofetil. The trough blood concentration C0 was 5ng/ml. The dose was progressively increased reaching a daily dose of 22 mg divided every 12 hours with the trough blood concentration C0 = 6.4 ng/ml.CYP3A4 and CYP3A5 genotyping were performed using polymerase chain reaction-restriction fragment length polymorphism (PCR–RFLP). The patient was heterozygous for the CYP3A5*3 allele (*1/*3) and homozygous for the CYP3A4*1B (*1B/*1B) and CYP3A4*22 alleles (*1/*1). So the patient was considered a high metabolizer, the reason behind the need for elevated doses of tacrolimus to achieve a therapeutic trough concentration. Our second patient is a 42-year-old man who received a living donor kidney transplant (his sister) on September 28, 2016. He was initially prescribed Tacrolimus at 12mg/day in two divided doses (0.12-0.15 mg/kg/day) in association with a corticosteroid and mycophenolate mofetil. The trough blood concentration (C0) was 3 ng/ml. The dose was then progressively increased reaching a daily dose of 20 mg/day. C0 was 4.1 ng/ml. The patient was homozygous for the three alleles (CYP3A5*1/*3, CYP3A4*1B/*1B, and CYP3A4*1/*1). Our patient is a CYP3A5 expressor and a CYP3A4*1B and CYP3A4*22 carrier, thereby making him a high metabolizer and requiring high doses of tacrolimus in order to achieve a therapeutic trough concentration. The present case series appears to confirm the main responsibility of the CYA3A4 and CYP3A5 genetic polymorphisms in determining the dose requirements of tacrolimus in renal transplant patients. Although pharmacogenetic analysis cannot substitute TDM, the availability of genotyping renders possible to better define the initial tacrolimus dosage.

SAT-325 ASSOCIATION OF CYP3A5 POLYMORPHISM WITH TACROLIMUS LEVELS AND GRAFT OUTCOMES IN INDIAN KIDNEY TRANSPLANT RECIPIENTS

Tacrolimus which is the sheet anchor of post-transplant immunosuppression has a narrow therapeutic index. It is imperative to achieve therapeutic tacrolimus levels for optimum graft survival as sub-optimal levels can predispose to graft rejections and toxic levels pose a risk of nephrotoxicity. The inter-individual variations in the pharmacokinetics of tacrolimus can be in part attributed to polymorphism in Cytochrome P450 (CYP) enzymes. The expressor [CYP3A5*1/*1] status leads to faster metabolism of tacrolimus than that in non- expressors [CYP3A5*3/*3]. Although it is well known that these differences in genotype affect tacrolimus levels, but their effect on long term graft outcome is equivocal. It is not proven that knowing the genotype pre-transplant and adjusting the induction dose accordingly improves graft outcomes. We aim to evaluate the association of CYP3A5 genotypes on tacrolimus trough levels and graft outcomes in adult and pediatric kidney transplant recipients. In this single-center study, consecutive kidney transplant recipients, both pediatric and adults, on tacrolimus therapy for atleast 3 months were enrolled. Genotyping was done using PCR-RFLP for CYP3A5 *1/*1, [expressors] *1/*3,[intermediate expressors] *3/*3 [non -expressors] polymorphisms., and patients were divided into these 3 groups. These groups were analyzed with retrospectively available data for differences in dose-adjusted tacrolimus levels at 1,3,12 months and graft outcomes - acute biopsy-proven rejection, chronic rejection, chronic allograft dysfunction, new-onset proteinuria, eGFR at 1,3,12 months and at last followup available, and graft loss. All groups received 0.1mg/kg/day dose of tacrolimus on day 0 of transplant and then the levels were modified according to subsequent trough tacrolimus levels. Out of 142 patients, 26% were females. Median age 48yrs, 11/142 had age <18 yrs. 16% were expressors[CYP3A5 *1/*1], 40.6% were intermediate[CYP3A5*1/*3], 43.4% were non-expressors[CYP3A5*3/*3]. Dose adjusted tacrolimus trough levels were significantly higher in non-expressors at 1 month [p=0.001], 3 months [p=0.015], 12 months [p=0.018]. Acute biopsy proven rejections were more in expressors [31.4%vs 22.6% p =0.042]. Also, chronic rejections were more in expressors [21%vs 6.53% p = 0.044] Non-expressors had higher incidence of chronic allograft dysfunction [48.4% vs 25.2% p=0.0004]. After being started with 0.1mg/kg/day of tacrolimus, expressors requied more dose escalations to reach therapeutic targets - median 3[0-6] vs 0[0-3] p =0.04. Non-expressors required more dose reductions to achieve targets - median 7[4-13] vs 2.5[0-16] p=0.02. The prevalence of non-expressors [CYP3A5 *3/*3] was 43.4% in Indian transplant recipients. When started at 0.1mg/kg/day dose, expressors had higher rates of subtherapeutic levels requiring more dose-escalation, while non-expressors required dose reductions due to supratherapeutic levels. Graft rejections both acute and chronic were more common in the expressors while non-expressors were at a higher risk of chronic allograft dysfunction. Our data support the use of pretransplant CYP3A5 genotyping to facilitate the individualization of tacrolimus dosing. Genotype guided dosing from the day of transplantation can improve graft outcomes by reducing nephrotoxicity [due to high doses] and rejections [due to suboptimal doses].

Tacrolimus treatment in childhood refractory nephrotic syndrome: A retrospective study on efficacy, therapeutic drug monitoring, and contributing factors to variable blood tacrolimus levels

Tacrolimus, an immunosuppressive drug, was recommended by the 2012 KDIGO guidelines to treat nephrotic syndrome (NS) in children and adults. However, it has high interpatient pharmacokinetic variability and exposure levels should be monitored, although there are no specified target concentrations. This retrospective study aimed to review efficacy and safety after concomitant treatment with tacrolimus and prednisone, and to identify factors that contribute to the variable blood-trough-concentration-to-dose (C0/Dose) ratio in children with refractory NS (RNS). A 6-month therapy induced complete or partial remission in 95% of patients. One-year follow-up indicated a high remission rate and low nephrotoxicity. Under maintenance dosages, approximately 95% of the C0 values were 2–7 ng/mL. Body weight (BW), age, CYP3A5 polymorphisms were the factors affecting the C0/Dose ratio. The C0/Dose ratio in patients with a BW of <20 kg was 1.5-fold than that in patients with BW of ≥40 kg. Moreover, the C0/Dose ratio in patients aged 1–≤6 and 6–≤12 years was significantly lower than that in patients aged 12–≤18 years, by 25% and 48%, respectively. There were no significant association between CYP3A5 genotyping and C0/Dose ratio in younger children (1–≤6 years), rather than older children (6–≤18 years). In conclusion, routine CYP3A5 genotyping should be considered in children aged over 6 years and exposure levels (C0) of 2–7 ng/mL may be feasible when tacrolimus is combined with low-dose prednisone to treat childhood RNS.

Impact of Population and Pharmacogenetics Variations on Efavirenz Pharmacokinetics and Immunologic Outcomes During Anti-Tuberculosis Co-Therapy: A Parallel Prospective Cohort Study in Two Sub-Sahara African Populations.

Efavirenz-based combination antiretroviral-therapy (cART) is the recommended regimen during tuberculosis (TB) therapy. In a multi-national parallel prospective-cohort study, we investigated the impact of population and pharmacogenetic variations for efavirenz pharmacokinetics, auto-induction, and immunologic outcome during antituberculosis treatment. A total of 921 treatment-naïve HIV patients with (196 Ethiopians and 231 Tanzanians) or without TB co-infection (285 Ethiopians and 209 Tanzanians) were enrolled and treated with efavirenz-based cART. TB-HIV patients started rifampicin-based anti-TB therapy 4 weeks before cART. Efavirenz plasma concentrations were measured on the 4th and 16th weeks of cART. Genotyping for CYP2B6, CYP3A5, ABCB1, UGT2B7, and SLCO1B1 was done. CD4 cells-count was measured at baseline, 12th, 24th, and 48th weeks of cART. Among HIV-only cohort, plasma efavirenz concentration and median CD4 cell count were significantly higher in Tanzanians than Ethiopians, and both CYP2B6 genotype and population-variation were significant predictors of efavirenz plasma concentration. Within-population analyses indicated a pronounced efavirenz autoinduction in Tanzanians as reflected by a significant decrease of plasma efavirenz concentration over time (p = 0.0001), but not in Ethiopians. Among TB-HIV cohort, there were no significant between-population differences in plasma efavirenz concentrations or CD4 cell-recovery, and CYP2B6 genotype but not population-variation was a significant predictor of efavirenz plasma exposure. In Tanzanian patients, short-term anti-TB co-treatment significantly reduced the mean plasma efavirenz concentration in CYP2B6*1/*1 genotype at week-4 (p = 0.005), but not at week-16 of cART. In Ethiopian patients, anti-TB cotreatment increased the mean plasma efavirenz concentration among CYP2B6*6 carriers at week-4 (p = 0.003) and week-16 (p = 0.035) of cART. In general, long-term anti-TB co-treatment increased plasma efavirenz concentration at week 16 of cART in both Ethiopians and Tanzanians being higher in CYP2B6*6/*6 > *1/*6 > *1/*1 genotypes. In TB-HIV patients, baseline body mass index (BMI), viral load, and WHO clinical-stage but not genotype, population-variation, or efavirenz concentration were significant predictors of immunologic outcome at week-48. In summary efavirenz auto-induction, pharmacokinetics, and the immunologic outcome are influenced by population-variation, anti-TB co-medication, and CYP2B6 genotype. CYP2B6 genotype is a significant predictor of efavirenz plasma exposure regardless of population-variation or antituberculosis co-treatment, but population-variation is insignificant during antituberculosis treatment. CYP2B6 genotype, population, and geographic differences need to be considered for efavirenz dosage-optimization.

CYP3A Polymorphism and Chronic Mercury Intoxication.

We analyzed the relationship between polymorphic loci of CYP3A genes (CYP3A4 (rs2740574), CYP3A5 (rs776746) and CYP3A7 (rs2257401)) with the development of chronic mercury intoxication. Of 170 men examined, 120 were workers chronically exposed to mercury vapors and 50 were carriers of GG-HSPA1B (+1267A/G) genotype associated with chronic mercury intoxication. Urinary content of 4-hydroxyantipyrine (4-HAP) generated in the reaction predominantly catalyzed by CYP3A4/CYP3A5 was studied in workers without chronic mercury intoxication (group 1, N=46) and patients in the delayed period of chronic mercury intoxication (group 2, N=74) depending on the genotypes of CYP3A4 and CYP3A5. For polymorphic loci CYP3A5 and CYP3A7, a tendency to an increase in the frequency of genotypes with rare alleles was found (p=0.071 and p=0.078) in the combined group (group 2 together with GGHSPA1B genotype carriers) relative to group 1. The high level of linkage disequilibrium was noted, especially for the pair rs776746 and rs2257401 (LD (r)=0.89). In group 2, a trend to 4-HAP decrease compared to group 1 (p=0.056 and p=0.065) was revealed for carriers of AA-CYP3A4 and GG-CYP3A5 genotypes. The involvement of CYP3A in the development of mercury neurotoxic effect remains unclear.

CYP3A5 polymorphisms and their effects on tacrolimus exposure in an ethnically diverse South African renal transplant population.

Tacrolimus forms the cornerstone for immunosuppression in solid-organ transplantation. It has a narrow therapeutic window with wide inter- and intra-patient variability (IPV). Cytochrome P-450 3A5 (CYP3A5) is the main enzyme involved in tacrolimus metabolism, and rs776746A&gt;G is the most frequently studied polymorphism in the CYP3A5 gene. The rs776746A&gt;G (i.e. CYP3A5*3) single-nucleotide polymorphism in CYP3A5 alters tacrolimus predose trough concentration (C0) and may also affect IPV, which may lead to immune- and/or drug-mediated allograft injury. CYP3A5*3 may result in absent (*3/*3), partial (*1/*3) or normal (*1/*1) CYP3A5 expression. The effect of CYP3A5*3 on tacrolimus exposure and variability has not been examined in South African (SA) transplant recipients. To determine the frequencies and effect of CYP3A5 and adenosine triphosphate-binding cassette subfamily B member 1 (ABCB1) polymorphisms on tacrolimus C0/dose ratios in different ethnic groups attending a tertiary renal transplant clinic in SA, and other factors that may explain inter- and IPV in tacrolimus C0. All consenting stable renal transplant recipients on tacrolimus at the Livingstone Hospital Renal Unit in Port Elizabeth, SA, were included. Tacrolimus concentrations were obtained using a microparticle enzyme immunoassay method (ARCHITECT analyser, Abbott Laboratories). Polymerase chain reaction/restriction fragment length polymorphism was used to genotype for CYP3A5*3 and *6 allelic variants. There were 43 participants (35% black African, 44% mixed ancestry and 21% white), with a mean age of 44.5 years, median duration post-transplant of 47 months and median (interquartile range) creatinine and estimated glomerular filtration rate levels of 118(92- 140) µmol/L and 62 (49 - 76) mL/min at study inclusion. The mean tacrolimus C0 in the study was 6.7 ng/mL, with no difference across the different ethnic groups. However, the mean total daily dose of tacrolimus required was 9.1 mg (0.12 mg/kg), 7.2 mg (0.09 mg/kg) and 4.3 mg (0.06 mg/kg) in black, mixed-ancestry and white patients, respectively (p=0.017). The frequencies for CYP3A5 expressors (i.e. CYP3A5*1/*1 + CYP3A5*1/*3 genotypes) were 72%, 100%, 76% and 12% for all patients combined and black, mixed-ancestry and white patients, respectively. The frequencies for CYP3A5 non-expressors (i.e. CYP3A5*3/*3 genotypes) were 0%, 24% and 88% among the black, mixed-ancestry and white patients, respectively. None of the patients carried the CYP3A5*6 allele. CYP3A5*1/*1 and CYP3A5*1/*3 genotype carriers required a two-fold increase in dose compared with the non-expressor genotype carriers, CYP3A5*3/*3 (p&lt;0.05). CYP3A5*3/*3 carriers also demonstrated higher IPV than CYP3A5*1/*1 and *1/*3 carriers (18.1% v. 14.2%; p=0.125). Compared with global transplant populations, SA renal transplant recipients demonstrated a very high rate of CYP3A5 expression, with a significant impact on tacrolimus pharmacokinetics. Genetic variation in CYP3A5 expression affects tacrolimus dosing requirements, and knowing the CYP3A5 genotype of transplant patients may allow better dose prediction compared with current standard dosing recommendations in a multi-ethnic population. Overall, black African patients required higher doses of tacrolimus than their white counterparts. While further prospective studies are needed to better evaluate dosing algorithms, it would appear that the starting dose of tacrolimus should be higher in black and mixed-race patients.

Effects of donor–recipient combinational CYP3A5 genotypes on tacrolimus dosing in Chinese DDLT adult recipients

BackgroundFor liver transplant (LT) recipients, the liver CYP3A5 metabolic enzymes are determined by the donor’s genes, whereas the intestinal enzymes are encoded by the recipient’s genes. This combinational form confuses the metabolism of tacrolimus (Tac) in vivo. This retrospective study was conducted to investigate the combined effects of donor–recipient CYP3A5 genotype on tacrolimus pharmacokinetics in Chinese LT adult patients. MethodsThree hundred seventy-three LT patients from two Chinese organ transplant centers were enrolled, and both recipients and donors were genotyped for CYP3A5. Patients were divided into four groups (RNDN, REDN, RNDE, REDE) according to CYP3A5*3 allele expressers (E) and non-expressers (N) in recipients (R) and donors (D). The dose-adjusted trough levels (C/D ratio) of tacrolimus were assessed for six months among the four groups. Multiple linear regression analysis was performed to assess the effects of the CYP3A5 genotype and several clinical variables on the C/D ratio. ResultsThe RNDN group consistently had the largest C/D ratio throughout the entire study period, whereas the REDE group had the smallest C/D ratio, and the REDN/RNDE group had an intermediate (RNDN > REDN/RNDE > REDE) ratio. The C/D ratio in the RNDN and RNDE groups was higher than that in the REDN and REDE groups within three months, respectively; the ratio in the RNDN group was higher than that in the RNDE group, and the ratio in the REDN group was higher than that in the REDE group at six months. The effect of the donor CYP3A5 genotype on C/D values was observed throughout the timeline, and the recipient’s genetics correlated only in the first three months. Among non-genetic factors, hemoglobin (HGB) and albumin (ALB) were correlated with Tac C/D values at a few time points. ConclusionsTo predict the initial dose of tacrolimus in LT patients, both donor and recipient CYP3A5 genotypes must be taken into account; during the maintenance phase of targeted blood concentration, the donor’s CYP3A5 genotype may be of prime importance, especially at three months after transplantation.

Effect of Smoking Cessation on the Pharmacokinetics and Pharmacodynamics of Clopidogrel after PCI: The Smoking Cessation Paradox Study.

Cigarette smoking is associated with enhanced clopidogrel effect and platelet inhibition. However, the effect of smoking cessation on clopidogrel pharmacokinetics (PK) and pharmacodynamics (PD) is unknown. We aimed to determine the effect of smoking cessation, confirmed by cotinine measurement, on clopidogrel PK and PD after percutaneous coronary intervention (PCI). Following successful PCI, patients treated with 75 mg/day clopidogrel who reported smoking ≥10 cigarettes/day with NicAlert urine cotinine level 6 were enrolled. Clopidogrel and its metabolite concentrations, VerifyNow P2Y12 reaction units (PRUs), and NicAlert levels were measured in the study group before and at 30 days after smoking cessation and in a control group. CYP1A2 and CYP2C19 genotypes were determined. At 30-day visit (n = 87), 45 patients continued smoking, whereas 42 patients stopped smoking. Baseline PRUs were similar between groups. At 30 days, the smoking cessation group had higher PRUs (150.5 ± 68.6 vs. 118.4 ± 65.9, p = 0.03), greater absolute PRU change (27.7 ± 39.8 vs. -12.9 ± 55.4, p = 0.0002), greater change of PRUs adjusted for baseline platelet reactivity (38.6 ± 10.0, p < 0.01), greater risk of high platelet reactivity (HPR) (odds ratio: 10.14 [1.52-67.5], p = 0.017), and a trend towards decreased H3 clopidogrel metabolite levels (-3.41 ng/mL [-11.00 to 0.54 ng/mL], p = 0.072). CYP2C19 LoF carriers who stopped smoking had the highest PRUs, whereas those with the wild type who continued smoking had the lowest PRUs (p < 0.008). Smoking cessation in clopidogrel-treated patients after PCI is associated with increased platelet reactivity and greater risk of HPR. Alternative P2Y12 inhibitors may be considered in selected patients who stop smoking after PCI.

Off-label use of tacrolimus in children with glomerular disease: Effectiveness, safety and pharmacokinetics.

Glomerular diseases are leading causes of end-stage renal disease in children. Tacrolimus is frequently used off-label in the treatment of glomerular diseases. The effectiveness, safety and pharmacokinetic data of tacrolimus in the treatment of glomerular diseases in children are reviewed in this paper to provide evidence to support its rational use in clinical practice. The remission rates in previously published studies were different. In 19 clinical trials on children with nephrotic syndrome, the overall remission rate was 52.6-97.6%. In four clinical trials on children with lupus nephritis, the overall remission rate was 81.8-89.5%. In a pilot study with paediatric Henoch-Schönlein purpura nephritis patients, the overall remission rate was 100.0%. Infection, nephrotoxicity, gastrointestinal symptoms and hypertension are the most common adverse events. Body weight, age, CYP3A5 genotype, cystatin-C and daily dose of tacrolimus may have significant effects on the pharmacokinetics of tacrolimus in children with glomerular disease. More prospective controlled trials with long follow-up are needed to demonstrate definitely the effectiveness, safety and pharmacokinetics of tacrolimus in children with glomerular diseases.

Kidney podocyte-associated gene polymorphisms affect tacrolimus concentration in pediatric patients with refractory nephrotic syndrome.

Few studies have investigated the correlation between pharmacogenomics and tacrolimus pharmacokinetics in patients with nephrotic syndrome (NS). This study evaluated the influences of genetic polymorphisms of metabolic enzymes, transporters, and podocyte-associated proteins on tacrolimus concentration in Chinese pediatric patients with refractory NS. A total of 167 pediatric patients with refractory NS were included from July 2013 to December 2017. Age of onset was restricted to <14 years of age. Dose-adjusted tacrolimus trough concentration (C0/D) on the third month was calculated, and 20 single-nucleotide polymorphisms in sixteen genes were genotyped. Age was correlated with tacrolimus C0/D (p = 0.006, r = 0.213). Tacrolimus C0/D was higher in CYP3A5 nonexpressers than in CYP3A5 expressers (p = 0.003). ACTN4 rs62121818, MYH9 rs2239781, CYP3A5*3, and age explained 20.5% interindividual variability of tacrolimus concentration in the total cohort. In CYP3A5 nonexpressers, ACTN4 rs62121818 and MYH9 rs2239781 together explained 14.6% variation of tacrolimus C0/D. MYH9 rs2239781, LAMB2 rs62119873 and age together explained 22.3% variability of tacrolimus level in CYP3A5 expressers. CYP3A5*3 was still an important factor affecting tacrolimus concentration in patients with NS. Podocyte-associated gene polymorphisms, especially ACTN4 rs62121818 and MYH9 rs2239781, were the other most important biomarkers for tacrolimus whole blood levels. Genotyping of CYP3A5, ACTN4, and MYH9 polymorphisms may be helpful for better guiding tacrolimus dosing in pediatric patients with refractory NS.

CYP1A2 genotype and acute effects of caffeine on resistance exercise, jumping, and sprinting performance

BackgroundIt has been suggested that polymorphisms within CYP1A2 impact inter-individual variation in the response to caffeine. The purpose of this study was to explore the acute effects of caffeine on resistance exercise, jumping, and sprinting performance in a sample of resistance-trained men, and to examine the influence of genetic variation of CYP1A2 (rs762551) on the individual variation in responses to caffeine ingestion.MethodsTwenty-two men were included as participants (AA homozygotes n = 13; C-allele carriers n = 9) and were tested after the ingestion of caffeine (3 mg/kg of body mass) and a placebo. Exercise performance was assessed with the following outcomes: (a) movement velocity and power output in the bench press exercise with loads of 25, 50, 75, and 90% of one-repetition maximum (1RM); (b) quality and quantity of performed repetitions in the bench press exercise performed to muscular failure with 85% 1RM; (c) vertical jump height in a countermovement jump test; and (d) power output in a Wingate test.ResultsCompared to placebo, caffeine ingestion enhanced: (a) movement velocity and power output across all loads (effect size [ES]: 0.20–0.61; p < 0.05 for all); (b) the quality and quantity of performed repetitions with 85% of 1RM (ES: 0.27–0.85; p < 0.001 for all); (c) vertical jump height (ES: 0.15; p = 0.017); and (d) power output in the Wingate test (ES: 0.33–0.44; p < 0.05 for all). We did not find a significant genotype × caffeine interaction effect (p-values ranged from 0.094 to 0.994) in any of the analyzed performance outcomes.ConclusionsResistance-trained men may experience acute improvements in resistance exercise, jumping, and sprinting performance following the ingestion of caffeine. The comparisons of the effects of caffeine on exercise performance between individuals with the AA genotype and AC/CC genotypes found no significant differences.Trial registrationAustralian New Zealand Clinical Trials Registry. ID: ACTRN12619000885190.

Impact of genetic variants of selected cytochrome P450 isoenzymes on pharmacokinetics and pharmacodynamics of clopidogrel in patients co-treated with atorvastatin or rosuvastatin.

Impaired antiplatelet effect of clopidogrel (CLP) can result from drug-drug interactions and genetic polymorphisms of drug-metabolizing enzymes. The aim of the study was to evaluate the effect of genetic polymorphisms of ABCB1 and the selected cytochrome P450 isoenzymes on the pharmacodynamics and pharmacokinetics of CLP and its metabolites in patients co-treated with atorvastatin or rosuvastatin. The study involved 50 patients after coronary angiography/angioplasty treated with CLP and atorvastatin (n= 25) or rosuvastatin (n= 25) for at least 6months. Plasma concentrations of CLP, diastereoisomers of thiol metabolite (inactive H3 and active H4), and inactive CLP carboxylic acid metabolite were measured by UPLC-MS/MS method. Identification of the CYP2C19*2, CYP2C19*17, CYP3A4*1G, CYP1A2*1F, and ABCB1 C3435T genetic polymorphisms was performed by PCR-RFLP, while platelet reactivity units (PRU) were tested using the VerifyNow P2Y12 assay. There were significant differences in the pharmacokinetic parameters of the H4 active metabolite of CLP in the atorvastatin and rosuvastatin group divided according to their CYP2C19 genotype. There were no significant associations between CYP3A4, CYP1A2, and ABCB1 genotypes and pharmacokinetic parameters in either statin groups. In the multivariate analysis, CYP2C19*2 genotype and non-genetic factors including BMI, age, and diabetes significantly affected platelet reactivity in the studied groups of patients (P< 0.01). In the atorvastatin group, CYP2C19*2, CYP3A4*1G, and ABCB1 C3435T TT genotypes were independent determinants of PRU values (P< 0.01). The CYP2C19*2 allele is the primary determinant of the exposition to the H4 active metabolite of clopidogrel and platelet reactivity in patients co-treated with atorvastatin or rosuvastatin.

Effect of CYP3A5 genotypes on serum carbamazepine concentrations at steady-state in Vietnamese epileptic patients

Effect of CYP3A5 genotypes on serum carbamazepine concentrations at steady-state in Vietnamese epileptic patients

From Genotype to Phenotype: Content and Activities of Cytochromes P450 2A6 in Human Liver In Vitro and Predicted In Vivo.

Unraveling the molecular mechanisms by which genetic variants of cytochrome P450 2A6 lead to different metabolic phenotypes remains a long-standing but important challenge. CYP2A6 is an enzyme involved in the metabolism of several clinical drugs as well as the metabolic activation of carcinogenic nitrosamines. Herein, CYP2A6 genotypes and phenotypes, as indicated by protein content [by liquid chromatography-mass spectrometry (MS)/MS] and metabolic activities [Vmax, clearance (CL)], were determined for 90 human liver samples. We determined the median, range, and interindividual and intraindividual variation of CYP2A6 content and activity at the microsomal, liver tissue, and whole liver level and predicted hepatic in vivo clearance by in vitro-in vivo extrapolation based on CYP2A6-mediated coumarin metabolism by each CYP2A6 genotype. These results reveal how different CYP2A6 genotypes yield different phenotypic traits in protein content and enzyme activity. For relative Vmax, CL, and protein content, the intraindividual percentage coefficients of variation (ICVs) were 41.0% (18.8%-125.1%), 28.5% (2.39%-133.5%), and 27.8% (2.68%-88.0%), respectively. The high ICVs implied large intraindividual variation at different levels, sometimes in a genotype-dependent manner. Intergenotype analysis revealed that the CYP2A6*4 allele demonstrated the most obvious effect on phenotypic outcomes, both in protein content and in metabolic activity. Indeed, decreased CYP2A6 protein content with the CYP2A6*4 genotype might explain the decreased metabolic activity from the molecular to the organismal level. These findings may allow useful predictions for CYP2A6-mediated drug metabolism on an individual patient basis in accord with the goal of achieving personalized medicine. SIGNIFICANCE STATEMENT: We provide the median, range, and interindividual and intraindividual variation in CYP2A6 content at the microsomal, liver tissue, and whole liver level by liquid chromatography-mass spectrometry (MS)/MS as well as activities at the protein, microsomal, liver tissue, and whole liver level both in vitro and at the organismal level based on CYP2A6-mediated coumarin metabolism with each CYP2A6 genotype, thereby allowing us to elucidate how different CYP2A6 genotypes yield differing phenotypic traits (protein content and enzyme activity), facilitating the development of personalized medicine.

CARCINOGEN-RELATED CYP1A1 AND GSTM1 GENETIC POLYMORPHISMS IN ORAL CANCER AND ORAL POTENTIALLY MALIGNANT DISORDERS

Objective To assess carcinogen related CYP1A1 and GSTM1 genetic polymorphisms in oral cancer (OC) and oral potentially malignant disorders (OPMD). Study Design One hundred smokers were studied: OC = 30, OPMD = 45 (leukoplakia and oral lichen planus) and 25 controls (Con) by means of biopsy and exfoliative cytology (EC) of the lesion and clinically normal mucosa of a contralateral site. After extracting DNA from EC, polymorphisms study of CYP1A1 using polymerase chain reaction (PCR)-retriction fragment length polymorphism (RFLP) and GSTM1 using conventional PCR were done. Results The CYP1A1 polymorphisms found were (m1/m1), (m1/m2) and (m2/m2). All control showed m1/m1 (wild-type), whereas 80% of OC had (m1/m2) and (m2/m2) genotype. 68% of the OPMD displayed m1/m1. Regarding GSTM1, (no null) wild-type and (null) genotypes were studied; 75% of control had no null, 73% of OC showed null and in OPMD there were no significant differences in the null and no null appearance. Conclusions The modified genotypes of CYP1A1 and GSTM1 could indicate a predisposition for oral cancer development. To assess carcinogen related CYP1A1 and GSTM1 genetic polymorphisms in oral cancer (OC) and oral potentially malignant disorders (OPMD). One hundred smokers were studied: OC = 30, OPMD = 45 (leukoplakia and oral lichen planus) and 25 controls (Con) by means of biopsy and exfoliative cytology (EC) of the lesion and clinically normal mucosa of a contralateral site. After extracting DNA from EC, polymorphisms study of CYP1A1 using polymerase chain reaction (PCR)-retriction fragment length polymorphism (RFLP) and GSTM1 using conventional PCR were done. The CYP1A1 polymorphisms found were (m1/m1), (m1/m2) and (m2/m2). All control showed m1/m1 (wild-type), whereas 80% of OC had (m1/m2) and (m2/m2) genotype. 68% of the OPMD displayed m1/m1. Regarding GSTM1, (no null) wild-type and (null) genotypes were studied; 75% of control had no null, 73% of OC showed null and in OPMD there were no significant differences in the null and no null appearance. The modified genotypes of CYP1A1 and GSTM1 could indicate a predisposition for oral cancer development.

The analysis of pharmacokinetic and pharmacogenomic impact on gefitinib efficacy in advanced non-small cell lung cancer patients: results from a prospective cohort study.

The current study is aimed to examine the impact of pharmacokinetics and gene polymorphisms of enzymes involving in absorption, distribution, metabolism and excretion (ADME) on the efficacy of gefitinib in non-small cell lung cancer (NSCLC) patients. Eligible patients with indication of gefitinib treatment were prospectively enrolled in this study. Two peripheral blood samples at baseline and before cycle 2 day 1 were collected for the detection of single nucleotide polymorphisms (SNPs) of drug ADME enzymes and trough drug concentration (Ctrough) at steady state. Thirteen SNPs were genotyped using the Sequenom Massarray system. Ctrough was determined by validated high-performance liquid chromatographic method with tandem mass spectrometric (LC-MS/MS). Fifty-eight NSCLC patients were enrolled in this study. The median of Ctrough was 175ng/mL (range from 47.8 to 470 ng/mL). The trough concentration was not associated with either objective response or progression free survival (PFS). Ctrough was significantly lower in CYP3A4 rs2242480 CC + CT genotype than in TT genotype (P=0.019) and in ABCG2 rs2231142 AA genotype than in AC + CC genotype (P=0.031). ABCB1 rs2032582 dominant model was significantly correlated with overall response rate (ORR) and patients with GG phenotype respond better than patients with GT + TT phenotypes (84.6% vs. 51.2%, P=0.032). ABCB1 rs10256836 recessive model was significantly correlated with PFS and patients with GG phenotype achieved longer PFS than patients with GC + CC phenotypes (17.40 vs. 10.33 months, P=0.040). The Ctrough of gefitinib was significantly different between CYP3A4 and ABCG2 genotypes, but not with the efficacy of gefitinib treatment. ABCB1 rs2032582 and rs10256836 polymorphisms were correlated treatment outcome. Polymorphisms analysis of ABCB1 could be a predictive biomarker for gefitinib treatment.

Initial dose optimization of tacrolimus for children with systemic lupus erythematosus based on the CYP3A5 polymorphism and coadministration with Wuzhi capsule.

Tacrolimus, an immunosuppressant, has been used to treat paediatric systemic lupus erythematosus, but the optimal initial regimen is not clear. The purpose of this study was to explore the optimal initial dose of tacrolimus for children with systemic lupus erythematosus using population pharmacokinetics and pharmacogenomics. Clinical information, tacrolimus concentrations and related genetic polymorphisms were incorporated into a model using non-linear mixed-effects modelling (NONMEM) analysis. The results showed that weight, the CYP3A5 genotype and combined treatment with Wuzhi capsule can affect tacrolimus clearance in children with systemic lupus erythematosus. Furthermore, at the same weight, the ratios of tacrolimus clearance were 1:2.49:0.57:1.4193 from people who were CYP3A5*3/*3 and did not take Wuzhi capsule, people who had the CYP3A5*1 allele and did not take Wuzhi capsule, people who were CYP3A5*3/*3 and took Wuzhi capsule, and people who had the CYP3A5*1 allele and took Wuzhi capsule, respectively. In addition, we found that 0.10mg/kg split into two doses was suitable for people with weights from 10 to 60kg who were CYP3A5*3/*3 and did not take Wuzhi capsule, who were CYP3A5*3/*3 and took Wuzhi capsule, and who had the CYP3A5*1 allele and took Wuzhi capsule. In people who had the CYP3A5*1 allele and did not take Wuzhi capsule, 0.15mg/kg split into two doses was appropriate for those with weights from 10 to 40kg and 0.10mg/kg split into two doses was appropriate for those with weights from 40 to 60kg. This study is the first study to recommend an optimal initial regimen of tacrolimus for children with systemic lupus erythematosus based on the CYP3A5 polymorphism and coadministration of Wuzhi capsule.

Pregnancy and CYP3A5 Genotype Affect Day 7 Plasma Lumefantrine Concentrations.

Pregnancy and pharmacogenetics variation alter drug disposition and treatment outcome. The objective of this study was to investigate the effect of pregnancy and pharmacogenetics variation on day 7 lumefantrine (LF) plasma concentration and therapeutic responses in malaria-infected women treated with artemether-lumefantrine (ALu) in Tanzania. A total of 277 (205 pregnant and 72 nonpregnant) women with uncomplicated Plasmodium falciparum malaria were enrolled. Patients were treated with ALu and followed up for 28 days. CYP3A4, CYP3A5, and ABCB1 genotyping were done. Day 7 plasma LF concentration and the polymerase chain reaction (PCR) - corrected adequate clinical and parasitological response (ACPR) at day 28 were determined. The mean day 7 plasma LF concentrations were significantly lower in pregnant women than nonpregnant women [geometric mean ratio = 1.40; 95% confidence interval (CI) of geometric mean ratio (1.119-1.1745), P < 0.003]. Pregnancy, low body weight, and CYP3A5*1/*1 genotype were significantly associated with low day 7 LF plasma concentration (P < 0.01). PCR-corrected ACPR was 93% (95% CI = 89.4-96.6) in pregnant women and 95.7% (95% CI = 90.7-100) in nonpregnant women. Patients with lower day 7 LF concentration had a high risk of treatment failure (mean 652 vs. 232 ng/ml, P < 0.001). In conclusion, pregnancy, low body weight, and CYP3A5*1 allele are significant predictors of low day 7 LF plasma exposure. In turn, lower day 7 LF concentration is associated with a higher risk of recrudescence. SIGNIFICANCE STATEMENT: This study reports a number of factors contributing to the lower day 7 lumefantrine (LF) concentration in women, which includes pregnancy, body weight, and CYP3A5*1/*1 genotype. It also shows that day 7 LF concentration is a main predictor of malaria treatment. These findings highlight the need to look into artemether-LF dosage adjustment in pregnant women so as to be able to maintain adequate drug concentration, which is required to reduce treatment failure rates in pregnant women.

Impact of CYP3A5 genotype on tolvaptan pharmacokinetics and their relationships with endogenous markers of CYP3A activity and serum sodium level in heart failure patients.

Tolvaptan efficacy for heart failure has a large interindividual variation. This study aimed to evaluate the influence of CYP3A5 and ABCB1 genotypes on tolvaptan pharmacokinetics and their relationships with plasma markers of CYP3A activity and laboratory test values in heart failure patients. Fifty-eight heart failure patients receiving oral tolvaptan for volume overload were enrolled. Blood samples for determination of pre-dose plasma concentrations of tolvaptan and its metabolites were collected. CYP3A5 and ABCB1 genotypes, plasma 4β-hydroxycholesterol/total cholesterol ratio (4β-OHC/TC) and 25-hydroxyvitamin D (25-OHD), and serum laboratory test values were evaluated. The CYP3A5*3/*3 genotype was associated with a higher plasma concentration of tolvaptan but not with its metabolic ratios. The ABCB1 3435C>T, 2677G>T/A and 1236C>T polymorphisms affected neither tolvaptan pharmacokinetics nor its metabolism. Plasma 4β-OHC/TC and 25-OHD concentration were not correlated with plasma tolvaptan concentration. In a stratified analysis based on CYP3A5 genotype, plasma 4β-OHC/TC had a negative correlation with plasma tolvaptan concentration in the patients with the CYP3A5*1 allele, while the plasma concentration of 25-OHD did not. The CYP3A5*3/*3 genotype was associated with a higher serum sodium level in the patients with volume overload. The plasma concentration of 25-OHD had a positive correlation with the serum total bilirubin level. In conclusion, CYP3A5*3 but not ABCB1 genotypes elevated tolvaptan plasma exposure in heart failure patients. CYP3A5-deficient patients treated with tolvaptan had a higher serum sodium level. The CYP3A5 genotype altered the relationship between plasma tolvaptan and 4β-OHC.