Five genetic polymorphisms of cytochrome P450 enzymes in the Czech non-Roma and Czech Roma population samples.

Objectives Cytochromes P450 play a role in human drugs metabolic pathways and their genes are among the most variable in humans. The aim of this study was to analyze genotype frequencies of five common polymorphisms of cytochromes P450 in Roma/Gypsy and Czech (non-Roma) population samples with Czech origin. Methods Roma/Gypsy (n=302) and Czech subjects (n=298) were genotyped for CYP1A2 (rs762551), CYP2A6 (rs4105144), CYP2B6 (rs3745274) and CYP2D6 (rs3892097; rs1065852) polymorphisms using PCR-RFLP or Taqman assay. Results We found significant allelic/genotype differences between ethnics in three genes. For rs3745274 polymorphism, there was increased frequency of T allele carriers in Roma in comparison with Czech population (53.1vs. 43.7%; p=0.02). For rs4105144 (CYP2A6) there was higher frequency of T allele carriers in Roma in comparison with Czech population (68.7 vs. 49.8%; p<0.0001). For rs3892097 (CYP2D6) there was more carriers of the A allele between Roma in comparison with Czech population (39.2 vs. 38.2%; p=0.048). Genotype/allelic frequencies of CYP2D6 (rs1065852) and CYP1A2 (rs762551) variants did not significantly differ between the ethnics. Conclusions There were significant differences in allelic/genotype frequencies of some, but not all cytochromes P450 polymorphisms between the Czech Roma/Gypsies and Czech non-Roma subjects.

Objective To discuss the distribution of single nucleotide polymorphism (SNPs) of the gene of cytochrome P450 (CYP) P1A1 (rs4646903) and CYP1B1 (rs1056836) on breast cancer patients and its relation between clinical pathology. Methods A case-control study were performed to analyze 337 breast cancer patients and 469 healthy individuals taking physical examination in West China Hospital of Sichuan University from September 2012 to February 2016. The direct sequencing method was used to analyze the distribution of SNPs in the gene of CYP1A1 (rs4646903) and CYP1B1 (rs1056836) , and the disparity of clinical pathological characteristics in patients with different genotype among the breast cancer population were detected. Results There was no statistic difference of the distribution of CYP1A1 (rs4646903) in genotype between the two groups (χ2=0.409, P>0.05) . There was a remarkable difference of the distribution of CYP1B1 (rs1056836) in genotype between the two groups (χ2=0.009, P<0.01) . In 337 cases of breast cancer patients, the distribution in the polymorphism of CYP1A1 gene (rs4646903) was not associated with the clinical pathological characteristics of the tumor. The single nucleotide polymorphism of the gene of CYP1B1 (rs1056836) had significant correlation with the metastasis of lymph node and the TNM stage (P< 0.05) . The homozygous mutant genotype was associated with higher negative rate of lymph node transformation and lower TNM stage. Conclusions The single nucleotide polymorphism of the gene of CYP1B1 (rs1056836) is associated with the risk of developing breast cancer. The homozygous mutant genotype in the breast cancer patients, have lower metastatic rate of axillary lymph node and TNM stage. Key words: Breast neoplasms; CYP1A1; CYP1B1; Polymorphism; Onset risk

Objective To explore the associations of the genetic polymorphisms of cytochrome P450, family 2, subfamily D, polypeptide 6 (CYP2D6) and cytochrome P450, family 2, subfamily C, polypeptide 9 (CYP2C9) with early-onset severe pre-eclampsia and the efficacy of labetalol therapy. Methods Totally 105 gravidas diagnosed with early-onset severe pre-eclampsia (experimental group) and 103 healthy gravidas (control group) were recruited from Beijing Obstetrics and Gynecology Hospital between August 2013 and July 2016. Labetalol was given to control blood pressures in gravidas with early-onset severe pre-eclampsia. If labetalol administration alone did not exceed the mean dose (100 mg, one dose per eight hours) and effectively controlled the blood pressures, it would be considered to be valid (n=75), otherwise it would be viewed as an invalid treatment. Genotype and allele frequencies of CYP2C9 gene (rs1057910 and rs4918758) and CYP2D6 gene (rs1065852, rs28371725, rs35742686 and rs3892097) in the gravidas were analyzed by TaqMan probe polymerase chain reaction. Differences in the genotype and allele frequencies were compared between the experimental and control groups, and the valid and invalid labetalol treatment groups. Chi-square test, analysis of variance and LSD test were used as statistical methods. Results The gravidas in both experimental and control groups were AA genotype in CYP2C9 gene rs1057910, TT genotype in CYP2D6 gene rs35742686 and CC genotype in CYP2D6 gene rs3892097. Frequencies of CC and CT genotypes in CYP2D6 gene rs28371725 in the experimental group were higher than those in the control group [18.1% (19/105) vs 14.6% (15/103); 56.2% (59/105) vs 42.7% (44/103); χ2=6.707], and higher C allele frequency in CYP2D6 gene rs28371725 was also observed in the experimental group [46.2% (97/210) vs 35.9% (74/206), χ2=4.529] (all P 0.05). Compared with the gravidas with CT or TT genotype of CYP2D6 gene rs28371725, those with CC genotype had longer gestational age [(32.5±2.1) vs (29.5±1.8) and (29.8±2.2) weeks] and higher plasma albumin [(27.2±9.3) vs (20.3±10.4) and (22.5±7.4) g/L], but lower systolic pressure and 24 hours urine protein (LSD test, all P<0.05). The G allele frequency in CYP2D6 gene rs1065852 in invalid labetalol treatment group was higher than that in valid labetalol treatment group [93.3% (56/60) vs 76.0% (114/150), χ2=8.351, P=0.004]. Conclusions The polymorphism of CYP2D6 gene rs28371725 may be associated with early-onset severe pre-eclampsia, and the allele of G in CYP2D6 gene rs1065852 may be associated with the efficacy of labetalol in treatment of early-onset severe pre-eclampsia. Key words: Pre-eclampsia; Labetalol; CYP2D6; CYP2C9; Polymorphism, single nucleotide

The human cytochrome P450 (CYP) enzymes play critical roles in the metabolism of numerous exogenous and endogenous molecules. All genes encoding P450 in families 1-3 are polymorphic,particularly CYP2C9,CYP2C19,CYP2D6 and CYP3A5. Polymorphic P450s are involved in the metabolism of more than 50% of clinical drugs. Genetic variation in the CYP genes is he main cause for individual variation in drug response. Over the past several years,Alleles are responsible for the variable enzymatic activity of P450 and the variable expression of CYP genes,have been identified. The phenotype can be determined by genotyping the functional variants or tag variants of the CYP genes. This helps doctors to choose ppropriate medication for patients to enhance the curative effect and to reduce the side effect,especially when drugs with narrow therapeutic index are involved. Knowledge of genetic variants of the CYP genes is necessary for both drug therapy and drug development. With a high degree of multiplexing,microarrays offer promise for simultaneously enotyping a large number of genetic variants of CYP genes,and thus provide technical basis for realizing personalized medicine. However,DNA preparation is the bottleneck for developing microarrays for genotyping genetic variants of the CYP genes. Extensive application of predictive CYP microarrays in clinical practice will be made in the near uture. Key words: Cytochrome P450 ; Polymorphism ; Drug metabolism; Microarray

As every individual is a product of his/her genes and environment, which can be regarded as a paraphrase of an individual’s phenotypic characteristic, it becomes apparent as to why the concept of personalised medicine, i.e. tailoring a treatment regimen to an individual’s needs, remains an ever-prevalent topic in the medical community. Human cytochrome P450 enzymes (CYPs) are accountable for the oxidative metabolism of approximately 50% of commonly used drugs as well as endogenous compounds. However, CYP activity is exceedingly variable amongst individuals. Over the course of my PhD project, I worked on five different projects that implicated the utility of two valuable tools in personalised medicine: namely, phenotyping and therapeutic drug monitoring. The determination of a person’s enzymatic activity through phenotyping can help guide a GP’s effort to personalise drug therapy by administering the applicable dose, thereby improving efficacy and reducing side effects at the start of therapy. Therapeutic drug monitoring (TDM) on the other hand, enables the continued observation of a patient’s drug concentration, predominantly in plasma, thus allowing patients that are at risk of either over-/ or underdosing to be identified. In the past two decades, many different in vivo phenotyping cocktails, enabling the simultaneous assessment of multiple CYP isoforms, e.g. Cooperstown- [1], Inje- [2], Quebec- [3], Karolinska- [4], and the Pittsburgh-cocktail [5], as well as a great number of in vitro cocktails [6-14] were developed. Metabolism studies performed in vitro are useful to the extent of acquiring anticipatory information of in vivo predictions of CYP- inhibition/ -induction in an efficient time and cost saving manner. It is, however, uncommon to use established in vivo cocktails for in vitro studies [7]. Nevertheless, using probe substrates previously unaccustomed to in vitro cocktail studies, e.g. efavirenz (CYP2B6), losartan (CYP2C9), and metoprolol (CYP2D6), we were able to show the potential of the Basel cocktail [15, 16] to characterise a variety of different liver cell models. Of particular interest to our study was the characterisation of 3D primary human hepatocytes (PHH), co-cultured with 3T3-mouse fibroblasts [17]. By using the same batch of PHH in 2D and 3D-culture, we were able to show the functional benefits of a co-culture system, enabling hepatocytes to reside in a 3D environment, and leading to improved CYP activity and mRNA expression. In subsequent studies, we were able to provide explanations for pending in vivo observations [15], through combining knowledge of freshly acquired in vitro and in vivo characterisation data of the Basel cocktail. In the second study, we demonstrated that the α-hydroxymetoprolol formation is not mediated solely by CYP2D6, since under induced conditions and through experiments in isoform specific supersomes, the involvement of CYP3A4 also became apparent. This does not, however, impede the continued applicability of metoprolol as probe substrate of CYP2D6 since the involvement of CYP3A4 only becomes apparent when induction is evaluated, which is commonly not done for CYP2D6. In the third study, we were able to show, through an in vitro interactions study, that flurbiprofen can be used to replace losartan as a phenotyping drug for CYP2C9. Subsequently, a pilot study (n=2) showed the prospect of simplifying the cocktail administration through the use of a combi-capsule containing all six probe drugs of the modified Basel cocktail. After having previously tested the phenotyping capacities of the Basel cocktail in two studies involving young, healthy, male volunteers [15, 16], the fourth study of this thesis demonstrates that we successfully used caffeine (CYP1A2) and midazolam (CYP3A4) to phenotype elderly, patients of both sexes that were being treated for non-small cell lung cancer (NSCLC) with erlotinib (Tarceva®). In so doing, we were able to show that subjects with a slow CYP3A4 metabolism had a higher likelihood of developing cutaneous toxicity than patients with an extensive metabolism. While the fourth study touched upon the possible usefulness of collecting DBS with which to perform TDM, as opposed to conventional plasma samples, the fifth and final study was devoted entirely to this topic. Here, we demonstrated the development, validation, and application of an automated DBS extraction method, while incorporating an evaluation of an antiretroviral adherence/ therapeutic drug monitoring study. Our study was able to show that concentrations of two antiretroviral drugs, nevirapine and efavirenz, could reliably be determined by automated extraction in DBS samples that had been obtained in a challenging setting in rural Tanzania.

Active hexose correlated compound (AHCC), a Basidiomycotina extract, is a well-tolerated nutritional supplement with no reported adverse effects. It has demonstrated potential antitumor activity and immune modulator activity. However, there is no current information regarding its metabolism and the potential for drug-drug interactions for AHCC in combination with chemotherapy. The objective of this study was to characterize AHCC hepatic metabolism, specifically involving the potential for drug interactions with selected chemotherapy agents. High-throughput cytochrome P-450 (CYP450) metabolism inhibition experiments were conducted in vitro evaluating CYP450 3A4, 2C8, 2C9, and 2D6 followed by an evaluation of AHCC as a substrate of these same isoenzymes. An ex vivo model of cryopreserved human hepatocytes was used to evaluate the CYP450 metabolism induction potential of AHCC for CYP450 3A4, 2C8/2C9, and 2D6. No inhibition of CYP450 activity was observed in presence of AHCC; however, AHCC was a substrate of CYP450 2D6. The CYP450 induction metabolism assays indicate that AHCC is an inducer of CYP450 2D6. AHCC does have the potential for drug-drug interactions involving CYP450 2D6, such as doxorubicin or ondansetron; however, the overall data suggest that AHCC would be safe to administer with most other chemotherapy agents that are not metabolized via the CYP450 2D6 pathway.

Vernonia cinerea has been widely used in traditional medicines for various diseases and shown to aid in smoking abstinence and has anticancer properties. V.cinerea bioactive compounds, including flavonoids and hirsutinolide-type sesquiterpene lactones, have shown an inhibition effect on the nicotine-metabolizing cytochrome P450 2A6 (CYP2A6) enzyme and hirsutinolides reported suppressing cancer growth. In this study, V.cinerea ethanol extract and its bioactive compounds, including four flavonoids and four hirsutinolides, were investigated for an inhibitory effect on human liver microsomal CYPs 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4 using cocktail inhibition assays combined with LC-MS/MS analysis. Among tested flavonoids, chrysoeriol was more potent in inhibition on CYP2A6 and CYP1A2 than other liver CYPs, with better binding efficiency toward CYP2A6 than CYP1A2 (Ki values in competitive mode of 1.93±0.05 versus 3.39±0.21μM, respectively). Hirsutinolides were prominent inhibitors of CYP2A6 and CYP2D6, with IC50 values of 12-23 and 15-41μM, respectively. These hirsutinolides demonstrated time-dependent inhibition, an indication of mechanism-based inactivation, toward CYP2A6. Quantitative prediction of microsomal metabolism of these flavonoids and hirsutinolides, including half-lives and hepatic clearance rate, was examined. These findings may have implications for further in vivo studies of V.cinerea. Copyright © 2017 John Wiley & Sons, Ltd.

Psychoactive substances such as the ring substituted phenylethylamine 3,4-methylenedioxymethamphetamine (MDMA; “ecstasy”) are widely used in recreational settings. Additionally, recent research highlights substance-assisted psychotherapy as potential new effective treatment for various psychiatric disorders, e.g. post-traumatic stress disorder (PTSD). MDMA releases and inhibits the uptake of serotonin (5-HT), norepinephrine (NE), and dopamine (DA) via an interaction with the respective monoamine transporter. Additionally, MDMA increases blood levels of the hormone oxytocin. Through these mechanisms, MDMA produces autonomic and distinct psychological effects such as increased empathy and sociability - effects that may prove to be helpful in psychotherapy. Despite the widespread recreational use and growing interest in using MDMA for medical purposes, interindividual differences in the response to MDMA are not elucidated. Genetic variants, such as single-nucleotide polymorphisms (SNPs) may influence the individual effects of MDMA. To address this matter, we used a uniquely large population of up to 166 subjects assembled from pooled but highly standardized phase I MDMA studies and conducted in-depth analyses on the clinical safety and on the influence of different genetic variations on the effects of MDMA. The first part of the present thesis was to evaluate the clinical safety pharmacology of single-dose administrations of 75 or 125 mg of MDMA. In up to a third of the subjects, administration of MDMA showed notable increases in maximum systolic blood pressure (>160 mmHg), heart rate (>100 bpm), and body temperature (>38 °C). Those effects on autonomic measures were significantly greater in subjects receiving 125 mg of MDMA. Acute and subacute adverse reactions such as headache, bruxism or lack of appetite were also dose-dependent and more frequent in women than men. However, no extreme outliers were observed, and the use of MDMA was considered as safe in controlled clinical settings. Nevertheless, we suggest a lower therapeutic dose for women. Due to the sympathomimetic stimulation, risks of MDMA might be higher in patients with cardiovascular diseases and should be further investigated in psychiatric patients with comorbidities. In the second part of this thesis focus was laid on the identification of pharmacogenetic roles in the effects of MDMA. Specifically, the influence of genetic variants within genes coding for relevant cytochromes P450 (CYPs), and pharmacodynamic targets such as the 5-HT, NE, and DA system, and oxytocin receptors, on the response to MDMA was tested. We found that CYP2D6 poor metabolizers (PMs) exhibited increased plasma levels of MDMA, leading to accelerated cardiovascular and psychostimulant responses to acute MDMA administration. Polymorphisms in CYP2D6, CYP1A2, CYP2C19, and CYP2B6 altered the metabolism of MDMA to 3,4-methylenedioxyamphetamine (MDA), but showed no clinical relevance. In additional analyses, moderating effects for MDMA-induced feelings of trust and desire for company between variations of an oxytocin receptor single nucleotide polymorphism (SNP OXTR rs1042778) were shown. To our knowledge, investigations assessing the influence of the monoamine system gene variations on the effects of MDMA were mostly the first on this matter. Subsequently, results had to be rigorously corrected for statistical errors and tested for specific hypothesis. Most of the tested genetic polymorphisms in the 5-HT (7 SNPs and 1 repeat polymorphism), NE (5 SNPs), and DA (10 SNPs and 1 repeat polymorphism) systems did not alter the effects of MDMA when adjusting for multiple comparisons. Only SNPs in the NE transporter gene SLC6A2 (rs1861647, rs2242446, and rs36029) significantly altered the acute MDMA-induced cardiovascular response. In summary, apart from variations within CYPs, genetic polymorphisms seem to play a subordinate role in the acute MDMA effects and are unlikely to sum up all interindividual variations. Results from the present thesis showed that MDMA was overall safe and well-tolerated with only moderate adverse effects in a clinical setting. Furthermore, pharmacogenetic analysis highlighted possible relevant genetic variations for the pharmacokinetic and pharmacodynamics effects of MDMA and point out targets of interest, which can define the scope of future studies with MDMA.

Prediction of transport, pharmacokinetics, and effect of drugs

Echinacea preparations are one of the best selling herbal medicinal products with a well established therapeutic use in the prophylaxis of upper respiratory tract infections. Their consumption is increasing, but information about their ability to inhibit cytochrome P450 enzymes (CYP) is fragmentary. The picture is further complicated by a lack of phytochemical characterization of previously tested preparations. Due to its well characterized immunomodulatory activity, the standardized Swiss registered Echinacea purpurea (L.) Moench Echinaforce extract was selected for detailed study. With the single baculovirus-expressed CYP isoforms 1A2, 2C19, 2D9 and 3A4, inhibitory actions were measured by monitoring fluorescent metabolites derived from enzyme substrates (supersome assay). The Echinaforce extract induced mild inhibition of all these isoforms, with CYP 3A4 being the most, and CYP 2D6 the least sensitive enzyme. To assess whether CYP inhibition might be a general feature of Echinacea preparations, an additional nine commercially available preparations were screened using CYP 3A4. All tested preparations were able to inhibit CYP 3A4, but inhibitory potencies (expressed as median inhibitory concentration, IC50) varied by a factor of 150. The alkylamides are thought to be responsible for the immunomodulatory activity of Echinacea, and so the concentration of 2E,4E,8Z,10E/Z-tetranoic acid isobutylamide (1) and total alkylamide content were determined in all preparations, and the latter was found to be associated with their CYP 3A4 inhibitory potency. The chemically pure alkylamides dodeca-2E,4E,8Z,10E/Z-tetranoic acid isobutylamide (1) and dodeca-2E,4E-dieonoic acid isobutylamide (2) showed inhibitory activity on CYP 2C19, 2D6 and 3A4. However, unlike the Echinaforce extract, the alkylamides did not induce CYP 1A2 inhibition. Thus, other, as yet unidentified constituents also contribute to the overall weak inhibitory effects seen with Echinacea preparations in-vitro.

Cytochrome P450 Nomenclature, 2004 David R. Nelson Spectral Analyses of Cytochromes P450 John B. Schenkman and Ingela Jansson Establishment of Functional Human Cytochrome P450 Monooxygenase Systems in Escherichia coli Michael P. Pritchard, Lesley McLaughlin, and Thomas Friedberg Purification of Cytochromes P450: Products of Bacterial Recombinant Expression Systems F. Peter Guengerich and Martha V. Martin Expression of Recombinant Flavin-Containing Monooxygenases in a Baculovirus/Insect Cell System Azara Janmohamed, Prapimpuk Thaunsukon, Elizabeth A. Shephard, and Ian R. Phillips Cytochrome P450 Reconstitution Systems Hiroshi Yamazaki and Tsutomu Shimada Catalytic Assays for Human Cytochrome P450: An Introduction Thomas K. H. Chang and David J. Waxman Enzymatic Analysis of cDNA-Expressed Human CYP1A1, CYP1A2, and CYP1B1 With 7-Ethoxyresorufin as Substrate Thomas K. H. Chang and David J. Waxman Spectrofluorometric Analysis of CYP2A6-Catalyzed Coumarin 7-Hydroxylation David J. Waxman and Thomas K. H. Chang Determination of CYP2B6 Component of 7-Ethoxy-4-Trifluoromethylcoumarin O-Deethylation Activity in Human Liver Microsomes Thomas K. H. Chang, Charles L. Crespi, and David J. Waxman High-Performance Liquid Chromatography Analysis of CYP2C8-Catalyzed Paclitaxel 6a-Hydroxylation Charles L. Crespi, Thomas K. H. Chang, and David J. Waxman Determination of CYP2C9-Catalyzed Diclofenac 4'-Hydroxylation by High-Performance Liquid Chromatography Charles L. Crespi, Thomas K. H. Chang, and David J. Waxman CYP2C19-Mediated (S)-Mephenytoin 4'-Hydroxylation Assayed by High-Performance Liquid Chromatography With Radiometric Detection Charles L. Crespi, Thomas K. H. Chang, and David J. Waxman CYP2D6-Dependent Bufuralol 1'-Hydroxylation Assayed by Reverse-Phase Ion-Pair High-Performance Liquid Chromatography With Fluorescence Detection Charles L. Crespi, Thomas K. H. Chang, and David J. Waxman Spectrophotometric Analysis of Human CYP2E1-Catalyzed p-Nitrophenol Hydroxylation Thomas K. H. Chang, Charles L. Crespi, and David J. Waxman Thin-Layer Chromatography Analysis of Human CYP3A-Catalyzed Testosterone 6b-Hydroxylation David J. Waxman and Thomas K. H. Chang Determination of CYP4A11-Catalyzed Lauric Acid 12-Hydroxylation by High-Performance Liquid Chromatography With Radiometric Detection Charles L. Crespi, Thomas K. H. Chang, and David J. Waxman An Isocratic High-Performance Liquid Chromatography Assay for CYP7A1-Catalyzed Cholesterol 7a-Hydroxylation David J. Waxman and Thomas K. H. Chang Use of 7-Ethoxycoumarin to Monitor Multiple Enzymes in the Human CYP1, CYP2, and CYP3 Families David J. Waxman and Thomas K. H. Chang Benzydamine N-Oxygenation as a Measure of Flavin-Containing Monooxygenase Activity Catherine K. Yeung and Allan E. Rettie Prochiral Sulfoxidation as a Probe for Flavin-Containing Monooxygenases Catherine K. Yeung and Allan E. Rettie Targeting Antipeptide Antibodies Toward Cytochrome P450 Enzymes Robert J. Edwards The Human Cytochrome P450 Allele Nomenclature Committee Web Site: Submission Criteria, Procedures, and Objectives Sarah C. Sim and Magnus Ingelman-Sundberg Genotyping for Cytochrome P450 Polymorphisms Ann K. Daly, Barry P. King, and Julian B. S. Leathart Hepatocyte Cultures in Drug Metabolism and Toxicological Research and Testing Tamara Vanhaecke and Vera Rogiers Isolation of Rat Hepatocytes Peggy Papeleu, Tamara Vanhaecke, Tom Henkens, Greetje Elaut, Mathieu Vinken, Sarah Snykers, and Vera Rogiers Rat Hepatocyte Cultures: Conventional Monolayer and Cocultures With Rat Liver Epithelial Cells Tom Henkens,

Recommendations for Clinical CYP2D6 Genotyping Allele Selection: A Joint Consensus Recommendation of the Association for Molecular Pathology, College of American Pathologists, Dutch Pharmacogenetics Working Group of the Royal Dutch Pharmacists Association, and the European Society for Pharmacogenomics and Personalized Therapy

1. The potential of propofol to inhibit the activity of major human cytochrome P450 enzymes has been examined in vitro using human liver microsomes. Propofol produced inhibition of CYP1A2 (phenacetin O -deethylation), CYP2C9 (tolbutamide 4-hydroxylation), CYP2D6 (dextromethorphan O -demethylation) and CYP3A4 (testosterone 6 beta hydroxylation) activities with IC = 40, 49, 213 and 32 mu M respectively. K for propofol against all of these enzymes with the exception of CYP2D6, where propofolishowed little inhibitory activity, was 30, 30 and 19 mu M respectively for CYPs 1A2, 2C9 and 3A4. 2. Furafylline, sulphaphenazole, quinidine and ketoconazole, known selective inhibitors of CYPs 1A2, 2C9, 2D6 and 3A4 respectively, were much more potent than propofol having IC = 0.8, 0.5, 0.2 and 0.1 mu M; furafylline and sulphaphenazole yielded K = 0.6 and 0.7 mu M respectively. i 3. The therapeutic blood concentration of propofol (20 mu M; 3-4 mu g ml) together with the in vitro K estimates for each of the major human P450 enzymes have been used to i estimate the extent of cytochrome P450 inhibition, which may be produced in vivo by propofol. This in vitro - in vivo extrapolation indicates that the degree of inhibition of CYP1A2, 2C9 and 3A4 activity which could theoretically be produced in vivo by propofol is relatively low (40-51%); this is considered unlikely to have any pronounced clinical significance. 4. Although propofol has now been used in 190 million people since its launch in 1986,thereare onlysinglereportsofpossible druginteractions between propofoland either alfentanil or warfarin. Consequently, it is difficult to conclude from either the published literature or the ZENECA safety database whether there is any evidence to indicate that propofol produces clinically significant drug interactions through inhibition of cytochrome P450-related drug metabolism.

Human cytochrome P450 (CYP) enzymes play a key role in the metabolism of drugs and environmental chemicals. Several CYP enzymes metabolically activate procarcinogens to genotoxic intermediates. Phenotyping analyses revealed an association between CYP enzyme activity and the risk to develop several forms of cancer. Research carried out in the last decade demonstrated that several CYP enzymes are polymorphic due to single nucleotide polymorphisms, gene duplications and deletions. As genotyping procedures became available for most human CYP, an impressive number of association studies on CYP polymorphisms and cancer risk were conducted. Here we review the findings obtained in these studies regarding CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C18, CYP2C19, CYP2D6, CYP2E1, CYP3A4, CYP3A5, CYP3A7, CYP8A1 and CYP21 gene polymorphisms. Consistent evidences for association between CYP polymorphisms and lung, head and neck, and liver cancer were reported. Controversial findings suggest that colorectal and prostate cancers may be associated to CYP polymorphisms, whereas no evidences for a relevant association with breast or bladder cancers were reported. We summarize the available information related to the association of CYP polymorphisms with leukaemia, lymphomas and diverse types of cancer that were investigated only for some CYP genes, including brain, esophagus, stomach, pancreas, pituitary, cervical epithelium, melanoma, ovarian, kidney, anal and vulvar cancers. This review discusses on causes of heterogeneity in the proposed associations, controversial findings on cancer risk, and identifies topics that require further investigation. In addition, some recommendations on study design, in order to obtain more conclusive findings in further studies, are provided.

BackgroundAripiprazole (ARI) is the first-line treatment for tic disorders (TD). Cytochrome P450(CYP)2D6 (CYP2D6) and ATP-binding cassette, sub-family B, member 1 (ABCB1) transporter are involved in the metabolism of ARI. However, whether CYP2D6 and ABCB1 genetic polymorphisms influence clinical efficacy and pharmacokinetics of ARI remains unclear.MethodsCYP2D6 and ABCB1 genotyping were performed. Pharmacokinetic parameters of ARI and its metabolite dehydroaripiprazole (DARI) were derived using a previously established population pharmacokinetic model. Drug response after ARI administration was evaluated based on reduction rate of Yale Global Tic Severity Scale score (YGTSS).ResultsSteady-state DARI/ARI metabolic ratios (MRs) of AUC0 − t, Cmin and Cmax were significantly associated with CYP2D6 rs1135840, CYP2D6 rs5030865, CYP2D6 rs1058164, CYP2D6 rs28371702, CYP2D6 rs1065852 and CYP2D6 rs1080989. The clearance (CL) of ARI was influenced by CYP2D6 rs1135840, CYP2D6 rs5030865, and CYP2D6 rs1080989. CYP2D6 rs16947, CYP2D6 rs29001518 and CYP2D6 rs1080985 were correlated with the CL of DARI. The CYP2D6 rs5030865 polymorphism was associated with volume of distribution (V) of DARI. The ABCB1 C3435T (rs1045642) polymorphism influenced the V of ARI. CYP2D6 rs1065852 and CYP2D6 rs1080989 were significantly associated with drug response of ARI.ConclusionPharmacokinetic parameters of ARI were correlated with CYP2D6 polymorphisms. CYP2D6 genotyping was recommended in ARI therapy. Further researches are required to elucidate the role of ABCB1 polymorphisms in ARI metabolism.