Genetic contribution to variable human CYP3A-mediated metabolism

The prevalence of ADSL (rs3788579) and CYP1A2 (rs17861162) polymorphisms in female breast cancer patients in North-West Iran

INTRODUCTION

Breast cancer is a prevalent and significant contributor to cancer-related mortality among women worldwide. Its increasing incidence, especially in regions like North-West Iran, necessitates a deeper understanding of genetic factors contributing to its development. Genetic alterations, particularly single nucleotide polymorphisms (SNPs), are implicated in breast cancer susceptibility, making investigation in this context crucial. This study explores the role of CYP1A2-rs17861162 and ADSL-rs3788579 SNPs in breast cancer risk among Iranian women.

METHODS

This study involved 200 female breast cancer patients and 200 healthy controls in North-West Iran. DNA was extracted from blood samples, and PCR-RFLP was used for genotyping the CYP1A2 and ADSL genes.

RESULTS

The CYP1A2-rs17861162 SNP exhibited a shift from the C allele to the G allele in breast cancer patients, resulting in a 21.7% decrease in CC genotype frequency and a 21.6% and 77.8% increase in CG and GG genotypes, respectively, compared to controls. In ADSL-rs3788579 SNP, breast cancer patients had a significantly higher prevalence of the T allele, with a 28.5% increase compared to controls. In healthy participants, CC was most common, while in the breast cancer group, TT was most common.

CONCLUSION

This study highlights significant genetic alterations in CYP1A2-rs17861162 and ADSL-rs3788579 SNPs among breast cancer patients in North-West Iran, suggesting their potential as diagnostic and prognostic biomarkers. Further research is warranted to elucidate the precise mechanisms underlying their contributions to breast cancer susceptibility in this population.

Pharmacogenetics-based population pharmacokinetic analysis for dose optimization of ritonavir-boosted atazanavir in Thai adult HIV-infected patients

BACKGROUND

This population pharmacokinetic-pharmacogenetic study aimed to investigate the optimal dose of RTV-boosted ATV (ATV/RTV) for Thai adult HIV-infected patients.

METHODS

A total of 1460 concentrations of ATV and RTV from 544 patients receiving an ATV/RTV-based regimen were analyzed. The CYP3A5 6986 A > G, ABCB1 3435 C > T, ABCB1 2677 G > T, SLCO1B1 521 T > C, and NR1I2 63396 C > T were genotyped. A population pharmacokinetic model was performed using a nonlinear mixed-effect model (NONMEM®). Monte Carlo simulations were conducted to compare the percentages of patients achieving the therapeutic range of ATV through concentrations (C_trough).

RESULTS

The apparent oral clearance of ATV (CL/F_ATV) without RTV was 7.69 L/h with interindividual variability (IIV) of 28.7%. Patients with CYP3A5 6986 GG had a 7.1% lower CL/F_ATV than those with AA or AG genotype. The CL/F_ATV decreased by 10.8% for females compared with males. Simulation results showed higher percentages (~70%) of patient receiving doses of 200/100 or 200/50 mg achieved the target ATV C_trough, while more patients (~40%) receiving a standard dose (300/100 mg) had ATV C_trough above this target.

CONCLUSIONS

Both CYP3A5 6986 A > G and female decreased CL/F_ATV in Thai HIV-infected patients. Simulations supported that the reduced dose of ATV/RTV was sufficient to achieve the target concentration for Thai population.

Can We Predict Individual Concentrations of Tacrolimus After Liver Transplantation? Application and Tweaking of a Published Population Pharmacokinetic Model in Clinical Practice

BACKGROUND

Various population pharmacokinetic models have been developed to describe the pharmacokinetics of tacrolimus in adult liver transplantation. However, their extrapolated predictive performance remains unclear in clinical practice. The purpose of this study was to predict concentrations using a selected literature model and to improve these predictions by tweaking the model with a subset of the target population.

METHODS

A literature review was conducted to select an adequate population pharmacokinetic model (L). Pharmacokinetic data from therapeutic drug monitoring of tacrolimus in liver-transplanted adults were retrospectively collected. A subset of these data (70%) was exploited to tweak the L-model using the $PRIOR subroutine of the NONMEM software, with 2 strategies to weight the prior information: full informative (F) and optimized (O). An external evaluation was performed on the remaining data; bias and imprecision were evaluated for predictions a priori and Bayesian forecasting.

RESULTS

Seventy-nine patients (851 concentrations) were enrolled in the study. The predictive performance of L-model was insufficient for a priori predictions, whereas it was acceptable with Bayesian forecasting, from the third prediction (ie, with ≥2 previously observed concentrations), corresponding to 1 week after transplantation. Overall, the tweaked models showed a better predictive ability than the L-model. The bias of a priori predictions was -41% with the literature model versus -28.5% and -8.73% with tweaked F and O models, respectively. The imprecision was 45.4% with the literature model versus 38.0% and 39.2% with tweaked F and O models, respectively. For Bayesian predictions, whatever the forecasting state, the tweaked models tend to obtain better results.

CONCLUSIONS

A pharmacokinetic model can be used, and to improve the predictive performance, tweaking the literature model with the $PRIOR approach allows to obtain better predictions.

Different Inductive Effects of Praziquantel Racemate and its Enantiomers on the Enzyme CYP3A4 Mediated by Pregnane X Receptor and its Variants

BACKGROUND

Praziquantel (PZQ), which possesses an asymmetric center, is classified as a pyrazinoisoquinoline and has been the mainstay in the treatment of schistosomiasis since 1980. PZQ undergoes a pronounced first-pass metabolism in the liver through the CYP450 system which could be mediated by nuclear receptors.

OBJECTIVE

The purpose of this study was to investigate the possible different induction effects of CYP3A4 by PZQ racemate and enantiomers via the pregnane X receptor (PXR) and the effect of PXR polymorphism on the induction potency of PZQs.

METHODS

The dual-luciferase reporter gene systems constructed in HepG2 cells were used to measure the abilities of PZQs to induce CYP3A4 expression mediated by PXR. The mRNA and protein levels of CYP3A4 were evaluated by polymerase chain reaction (PCR) and western blotting, respectively.

RESULTS

In HepG2 cells transfected with PXRwt, PXR158, PXR163, PXR370 or PXR403 expression plasmids, PZQ racemate and its enantiomers up-regulated the luciferase activity in a concentration-dependent manner, while reaching saturation after transfected with PXR379 expression plasmids. The mRNA and protein expression of CYP3A4 was effectively activated in PXR-transfected HepG2 cells. The induction ability of CYP3A4 mediated by PXR activation by PZQ racemate and its enantiomers were statistically different between the same PXR group and different PXR groups.

CONCLUSION

The enantioselective induction effects of PZQs on CYP3A4 were related to the enantioselective activations of PXR by PZQs and were influenced by the PXR gene polymorphism. These findings provide a basis for further understanding the enantiomeric metabolism and the variable efficacy of PZQs.

A safety, tolerability, and pharmacokinetic study of a novel simvastatin silica-lipid hybrid formulation in healthy male participants

Simvastatin (SIM) is a commonly used cholesterol-lowering drug that can reduce the risk of major cardiovascular events. However, due to its poor intrinsic water solubility, the drug is poorly absorbed from the gastrointestinal tract and exhibits a low oral bioavailability of approximately 5%. The aim of this study was to fabricate and optimize SIM encapsulated silica-lipid hybrids (SLH) as a solid-state lipid-based formulation to enhance absorption and bioavailability during a human in vivo pharmacokinetic study. SLH formulations were formulated by spray drying a submicron emulsion with either Aerosil® 300 fumed silica nanoparticles (SLH-A) or Syloid® 244 amorphous micronized silica (SLH-B). A cross-over, double-blinded study design was implemented to evaluate the performance of SLH formulations compared with a commercially available formulation in 12 healthy male participants after oral administration under fasting conditions. SLH formulations enhanced the bioavailability of SIM up to 1.6-fold and more importantly the active simvastatin acid (SIMA), 3.5-fold when compared with an equivalent dose of commercial formulation. The results demonstrate that the porous nanostructure of SLH impact systemic SIM and SIMA concentrations and may serve as a novel approach to enhance the bioavailability of specifically the parent or metabolite. No significant difference was observed in exposure when SLH formulations were administered at 10 mg in comparison with 20 mg of the commercial formulation, suggesting the potential for dose reduction. The study indicated that SLH formulations were safe and well-tolerated when administered to healthy males, confirming the commercial potential of SLH to enhance the bioavailability of poorly water-soluble drugs. Graphical abstract.

Differential Effects of Components in Artemisia annua Extract on the Induction of Drug-Metabolizing Enzyme Expression Mediated by Nuclear Receptors

Artemisia annua tea is a popular dosage form used to treat and prevent malaria in some developing countries. However, repeated drinking leads to an obviously decreased efficacy, which may be related to the induction of metabolizing enzymes by artemisinin. In the present study, the ability of different components in A. annua to activate the pregnane X receptor and constitutive androstane receptor was evaluated by the dual luciferase reporter gene system. The changes in mRNA and protein expression of CYP3A4 and CYP2B6 were determined by quantitative real-time PCR and Western blotting. Results showed that in the pregnane X receptor-mediated CYP3A4 reporter gene system, chrysosplenetin and arteannuin B exhibited a weak induction effect on pregnane X receptor wt, while arteannuin A had a strong induction effect on pregnane X receptor wt and pregnane X receptor 370 and a weak induction effect on pregnane X receptor 163. In the pregnane X receptor-mediated CYP2B6 reporter gene system, arteannuin A had a moderate induction effect on pregnane X receptor wt and pregnane X receptor 379, and a weak induction effect on pregnane X receptor 403, while arteannuin B had a weak induction effect on pregnane X receptor wt and pregnane X receptor 379. Arteannuin A had a strong induction effect on constitutive androstane receptor 3 in constitutive androstane receptor-mediated CYP3A4/2B6 reporter gene systems, while arteannuin B showed a weak induction effect on constitutive androstane receptor 3 in the constitutive androstane receptor-mediated CYP2B6 reporter gene system. The mRNA and protein expressions of CYP3A4 and CYP2B6 were increased when the pregnane X receptor or constitutive androstane receptor was activated. Various components present in A. annua differentially affect the activities of pregnane X receptor isoforms and the constitutive androstane receptor, which indicates the possibility of a drug-drug interaction. This partly explains the decline in efficacy after repeated drinking of A. annua tea.

Body weight-based initial dosing of tacrolimus in renal transplantation: Is this an ideal approach?

BACKGROUND

Tacrolimus dosing immediately posttransplant is based on body weight. Recent studies have highlighted that the dosing of tacrolimus purely based on weight may not be appropriate, particularly in individuals who are obese.

OBJECTIVES

This study aimed to estimate the effect of body mass index (BMI) and the weight-based dosing on tacrolimus trough levels in recipients of renal transplants.

DESIGN AND PARTICIPANTS

This study was conducted on 400 of the 863 patients registered in the Salford, UK, renal transplant database between 2012 and 2019 who had complete and analysable datasets. Data were collected at baseline (first tacrolimus trough level after transplantation), after 1 month and 6 months posttransplantation. The cohort was split into three groups based on BMI (kg/m² ; Group 1 ≤ 25, Group 2 > 25-30 and Group 3 > 30) which were compared with respect to tacrolimus dose, plasma levels and concentration/dose (C/D) ratio at the three-time points.

RESULTS

Patients in the higher BMI group (Group 3) had significantly higher baseline tacrolimus trough levels despite receiving a lower initiation dose per kilogram of body weight. After 1 and 6-months posttransplant, the higher BMI group were receiving a significantly lower tacrolimus dose relative to their body weight, with a significant negative correlation between body weight and tacrolimus/kg body weight. There was no adverse relationship evident between tacrolimus dosing or concentration and graft function.

CONCLUSIONS

Our study showed that standard dosing of tacrolimus based on body weight in individuals who were obese did not adversely affect their tacrolimus concentrations or transplant function.

Influence of CYP3A5 and SLCO1B1 polymorphisms on atazanavir/r concentrations in Thai HIV-infected patients

Aim: To evaluate the influence of genetic polymorphisms on plasma trough concentrations of atazanavir (ATV) and ritonavir (RTV). Patients & methods: The concentration-to-dose ratios were compared between different genotype groups of CYP3A5, ABCB1, SLCO1B1 and NR1I2 in 490 patients. Multiple regression analysis was used to examine the association between genetic and clinical factors and log-transformed concentration-to-dose ratio of ATV and RTV. Results: Higher concentrations of ATV and RTV were significantly associated with CYP3A5 6986 GG and SLCO1B1 521 TC or CC. Female patients had significantly higher ATV plasma concentration than male patients. Conclusion: Genetic polymorphisms and gender are factors affecting the variability of ATV and RTV concentrations in the Thai population. Thus, genetic testing is worth considering when atazanavir + low dose ritonavir is prescribed.

Defining screening panel of functional variants of CYP1A1, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 genes in Serbian population

Plethora of drugs and toxic substances is metabolized by cytochrome P450 enzymes (CYP450). These enzymes are coded by highly variable genes abundant with single nucleotide variants (SNVs) and small insertions/deletions (indels) that affect the functionality of the enzymes, increasing or decreasing their activity. CYP genes genotyping, followed by haplotype inference, provides substrate specific metabolic phenotype prediction. This is crucial in pharmacogenetics and applicable in molecular autopsy. However, high number of alleles in CYP450 superfamily and interethnic variability in frequency distribution require precise gene panel customization. To estimate informativeness of SNVs and alleles in CYP gene families 1, 2, and 3, associated with metabolic alterations, 500 unrelated individuals from 5 regions of Serbia were genotyped using TaqMan assays to determine frequencies of CYP2C9 *2 and *3, CYP2C19 *2 and *17 alleles, four variants in CYP2D6 (rs3892097, rs1065852, rs28371725, rs28371706) gene, and CYP3A4*1B allele. In addition, CYP1A1 rs4646903 and rs1048943 (m1 and m2) variants were genotyped by RFLP. Our results showed that frequencies of tested variants in Serbian population corresponded to general European population and somewhat differed from neighboring populations. SNV rs1065852, the main contributor to non-functional CYP2D6 *4, significantly departed from Hardy-Weinberg equilibrium. With the exception of rs28371706 in CYP2D6 and rs2740574 in CYP3A4, which were very rare in our sample, all other tested variants in CYP2 family are informative and appropriate for pharmacogenetic testing, molecular autopsy, and medico-legal genetic analyses.

In vitro inhibition of human CYP2D6 by the chiral pesticide fipronil and its metabolite fipronil sulfone: Prediction of pesticide-drug interactions

Fipronil is a chiral insecticide employed worldwide in crops, control of public hygiene and control of veterinary pests. Humans can be exposed to fipronil through occupational, food, and environmental contamination. Therefore, the risk assessment of fipronil in humans is important to protect human health. Fipronil sulfone is the major metabolite formed during fipronil metabolism by humans. Since the CYP450 enzymes are the main ones involved in drug metabolism, the evaluation of their inhibition by fipronil and its main metabolite is important to predict drug-pesticide interactions. The aim of this work was to investigate the inhibition effects of rac-fipronil, S-fipronil, R-fipronil and fipronil sulfone on the main human CYP450 isoforms. The results showed that CYP2D6 is the only CYP450 isoform inhibited by these xenobiotics. In addition, no enantioselective differences were observed in the inhibition of CYP450 isoforms by fipronil and its individuals' enantiomers. Rac-fipronil, S-fipronil and R-fipronil are moderate CYP2D6 inhibitors showing a competitive inhibition profile. On the other hand, the metabolite fipronil sulfone showed to be a strong inhibitor of CYP2D6 also by competitive inhibition. These results highlight the importance of metabolite evaluation on pesticide safety since the metabolism of fipronil into fipronil sulfone increases the risk of pesticide-drug interactions for drugs metabolized by CYP2D6.

Resveratrol and Its Human Metabolites-Effects on Metabolic Health and Obesity

Resveratrol is one of the most widely studied polyphenols and it has been assigned a plethora of metabolic effects with potential health benefits. Given its low bioavailability and extensive metabolism, clinical studies using resveratrol have not always replicated in vitro observations. In this review, we discuss human metabolism and biotransformation of resveratrol, and reported molecular mechanisms of action, within the context of metabolic health and obesity. Resveratrol has been described as mimicking caloric restriction, leading to improved exercise performance and insulin sensitivity (increasing energy expenditure), as well as having a body fat-lowering effect by inhibiting adipogenesis, and increasing lipid mobilization in adipose tissue. These multi-organ effects place resveratrol as an anti-obesity bioactive of potential therapeutic use.

Identification of a less toxic vinca alkaloid derivative for use as a chemotherapeutic agent, based on in silico structural insights and metabolic interactions with CYP3A4 and CYP3A5

Vinca alkaloids are chemotherapeutic agents used in the treatment of both pediatric and adult cancer patients. Cytochrome P450 3A5 (CYP3A5) is 9- to 14-fold more efficient at clearing vincristine than cytochrome P450 3A4 (CYP3A4) is. However, patients who express an inactive form of the polymorphic CYP3A5 enzyme suffer from severe neurotoxicity during vincristine treatment, resulting in chemotherapy failure. Previous studies have found that the addition of new features to the parent drug can enhance its binding affinity to tubulin manyfold and could therefore yield novel anticancer drugs. However, there is no report of any study of the metabolic activities of CYP3A4 and CYP3A5 with respect to vincristine and vinblastine, so we studied the interactions of these two drugs and 15 vinca derivatives with CYP3A4 and CYP3A5 by performing docking studies using GOLD. Six of the vinca derivatives in complexes with CYP3A4 and CYP3A5 were further investigated in 100-ns molecular dynamic simulations. Interaction energies, hydrogen bonds, and linear interaction energies were calculated and principal component analysis was carried out to visualize the binding interface in each complex. The results indicate that the addition of dimethylurea at the C20' position in vincristine may increase its binding affinity and lead to enhanced interactions with the less polymorphic CYP3A4 rather than CYP3A5. Thus, dimethylurea vincristine may be a useful drug in cancer chemotherapy treatment as it should be significantly less likely than vincristine to induce severe neurotoxicity in patients. Graphical Abstract Proposed modification of Vinca alkaloid derivatives to decrease the neurotoxicity level in cancer patients exhibiting CYP3A4 gene rather than polymorphic CYP3A5 gene.

Pharmacogenomic Testing in Child and Adolescent Psychiatry: An Evidence-Based Review

Significant advances have been made in the application of pharmacogenomic testing for the treatment of patients with psychiatric disorders. Over the past decade, a number of studies have evaluated the utility of pharmacogenomic testing in pediatric patients with psychiatric disorders. The evidence base for pharmacogenomic testing in youth with depressive and anxiety disorders as well as attention/deficit hyperactivity disorder (ADHD) is reviewed in this article. General pharmacogenomic principles are summarized and functional polymorphisms in P450 enzymes (and associated metabolizer phenotypes), the serotonin transporter promoter polymorphisms, serotonin 2A receptor genes (e.g., HT2AR) and catecholamine pathway genes (e.g., COMT) are reviewed. These commonly tested pharmacogenomic markers are discussed with regard to studies of drug levels, efficacy and side effects. The translation of pharmacogenomics to individualized/precision medicine in pediatric patients with ADHD, anxiety and depressive disorders has accelerated; however, its application remains challenging given that there are numerous divergent pathways between medication/medication dose and clinical response and side effects. Nonetheless, by leveraging variations in individual genes that may be relevant to medication metabolism or medication target engagement, pharmacogenomic testing may have a role in predicting treatment response, side effects and medication selection in youth with ADHD, depressive and anxiety disorders.

Interpreting quantitative urine buprenorphine and norbuprenorphine levels in office-based clinical practice

BACKGROUND

Quantitative urine buprenorphine testing is used to monitor patients receiving buprenorphine for the treatment of opioid use disorder (OUD), however the interpretation of urine buprenorphine testing is complex. Currently, interpretation of quantitative buprenorphine testing is guided by data from drug assay development studies and forensic labs rather than clinical treatment cohorts.

METHODS

In this retrospective study, we describe the patterns of urine buprenorphine and norbuprenorphine levels in patients prescribed sublingual buprenorphine for OUD in an office-based addiction treatment clinic. Urine buprenorphine and norbuprenorphine levels were analyzed in patients who reported having adulterated their urine, patients clinically suspected of adulterating their urine, and patients without concern for urine adulteration. Finally, we tested the accuracy of urine buprenorphine, norbuprenorphine, and norbuprenorphine: buprenorphine ratio (Norbup:Bup) to identify adulterated urine samples.

RESULTS

Patients without suspicion for urine adulteration rarely provided specimens with buprenorphine >=1000ng/ml (4.4%), while the proportion provided by those who endorsed or were suspected of urine adulteration was higher (42.9%, 40.6%, respectively). Compared to patients without reported urine adulteration, specimens from patients who reported or were suspected of urine adulteration had significantly higher buprenorphine (p=0.0001) and lower norbuprenorphine (<0.0001) levels, and significantly lower Norbup:Bup ratios (p=0.04). Buprenorphine >=700ng/ml offered the best accuracy for discriminating between adulterated and non-adulterated specimens.

CONCLUSION

This study describes the patterns of urine buprenorphine and norbuprenorphine levels from patients with OUD receiving buprenorphine treatment in an office-based addiction treatment clinic. Parameters for identifying urine adulterated by submerging buprenorphine medication in the urine specimen are discussed.

Exploring the relationship between lifestyles, diets and genetic adaptations in humans

Background

One of the most important dietary shifts underwent by human populations began to occur in the Neolithic, during which new modes of subsistence emerged and new nutrients were introduced in diets. This change might have worked as a selective pressure over the metabolic pathways involved in the breakdown of substances extracted from food. Here we applied a candidate gene approach to investigate whether in populations with different modes of subsistence, diet-related genetic adaptations could be identified in the genes AGXT, PLRP2, MTRR, NAT2 and CYP3A5.

Results

At CYP3A5, strong signatures of positive selection were detected, though not connected to any dietary variable, but instead to an environmental factor associated with the Tropic of Cancer. Suggestive signals of adaptions that could indeed be connected with differences in dietary habits of populations were only found for PLRP2 and NAT2. Contrarily, the demographic history of human populations seemed enough to explain patterns of diversity at AGXT and MTRR, once both conformed the evolutionary expectations under selective neutrality.

Conclusions

Accumulated evidence indicates that CYP3A5 has been under adaptive evolution during the history of human populations. PLRP2 and NAT2 also appear to have been modelled by some selective constrains, although clear support for that did not resist to a genome wide perspective. It is still necessary to clarify which were the biological mechanisms and the environmental factors involved as well as their interactions, to understand the nature and strength of the selective pressures that contributed to shape current patterns of genetic diversity at those loci.

Electronic supplementary material

The online version of this article (doi:10.1186/s12863-015-0212-1) contains supplementary material, which is available to authorized users.

The effect of the Pheroid delivery system on the in vitro metabolism and in vivo pharmacokinetics of artemisone

OBJECTIVES

The objectives were to determine the pharmacokinetics (PK) of artemisone and artemisone formulated in the Pheroid® drug delivery system in primates and to establish whether the formulation affects the in vitro metabolism of artemisone in human and monkey liver and intestinal microsomes.

METHODS

For the PK study, a single oral dose of artemisone was administered to vervet monkeys using a crossover design. Plasma samples were analyzed by means of liquid chromatography-tandem mass spectrometry. For the in vitro metabolism study, clearance was determined using microsomes and recombinant CYP3A4 enzymes, and samples were analyzed by means of ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry.

RESULTS

Artemisone and M1 plasma levels were unexpectedly low compared to those previously recorded in rodents and humans. The in vitro intrinsic clearance (CLint) of the reference formulation with monkey liver microsomes was much higher (1359.33 ± 103.24 vs 178.86 ± 23.42) than that of human liver microsomes. The in vitro data suggest that microsomal metabolism of artemisone is inhibited by the Pheroid delivery system.

CONCLUSIONS

The in vivo results obtained in this study indicate that the Pheroid delivery system improves the PK profile of artemisone. The in vitro results indicate that microsomal metabolism of artemisone is inhibited by the Pheroid delivery system.

Screening of Genetic Polymorphisms of CYP3A4 and CYP3A5 Genes

Given the CYP3A4 and CYP3A5's impact on the efficacy of drugs, the genetic backgrounds of individuals and populations are regarded as an important factor to be considered in the prescription of personalized medicine. However, genetic studies with Korean population are relatively scarce compared to those with other populations. In this study, we aimed to identify CYP3A4/5 polymorphisms and compare the genotype distributions among five ethnicities. To identify CYP3A4/5 SNPs, we first performed direct sequencing with 288 DNA samples which consisted of 96 Koreans, 48 European-Americans, 48 African-Americans, 48 Han Chinese, and 48 Japanese. The direct sequencing identified 15 novel SNPs, as well as 42 known polymorphisms. We defined the genotype distributions, and compared the allele frequencies among five ethnicities. The results showed that minor allele frequencies of Korean population were similar with those of the Japanese and Han Chinese populations, whereas there were distinct differences from European-Americans or African-Americans. Among the pharmacogenetic markers, frequencies of CYP3A4*1B (rs2740574) and CYP3A5*3C (rs776742) in Asian groups were different from those in other populations. In addition, minor allele frequency of CYP3A4*18 (rs28371759) was the highest in Korean population. Additional in silico analysis predicted that two novel non-synonymous SNPs in CYP3A5 (+27256C>T, P389S and +31546T>G, I488S) could alter protein structure. The frequency distributions of the identified polymorphisms in the present study may contribute to the expansion of pharmacogenetic knowledge.