Effects of genetic polymorphisms of CYP2J2, CYP2C9, CYP2C19, CYP4F2, CYP4F3 and CYP4A11 enzymes in preeclampsia and gestational hypertension.

INTRODUCTION: The aim of this study was to investigate the effects of cytochrome P450 (CYP) 2J2, CYP2C9, CYP2C19 and CYP4F2, CYP4F3 and CYP4A11 genetic polymorphisms in preeclampsia and gestational hypertension (GHT) patients in a sample of Turkish population. MATERIALS-METHODS: Patients (n = 168; 110 GHT and 58 preeclampsia) and healthy pregnant women (n = 155, controls) participated in the study. For genotyping, polymerase chain reaction (PCR) and restriction analysis (RFLP) were used. Substance levels were measured using LC-MS. RESULTS: Plasma DHET levels in GHT and preeclampsia patients were significantly lower than those in the control group (62.7%, 66.3% vs.100.0%, respectively, p < 0.0001). An increase in CYP2J2*7 allele frequency was observed in the preeclampsia group, as compared to GHT group (12.1% vs. 4.5%; odds ratio, O.R. = 2.88, p < 0.01). The frequencies of CYP2C19*2 and*17 alleles were higher in GHT group as compared to the control group (17.7% vs. 11.6%, O.R. = 1.99, p < 0.01; and 28.6% vs.18.4%, O.R. = 2.03, p < 0.01, respectively). An increased frequency of CYP4F3 rs3794987 G allele was found in GHT group as compared to the control group (48.0% vs. 38.0%; O.R. = 1.53, p < 0.01). DISCUSSION: DHET plasma levels were significantly reduced in hypertensive pregnant groups as compared to the control group. The allele frequency distributions for CYP2J2*7, CYP2C19 *2, *17 and CYP4F3 rs3794987 were significantly different in hypertensive pregnant patients as compared to the healthy control subjects. Our results may suggest that investigated genetic polymorphisms may be useful in diagnosis and clinical management of GHT and preeclampsia patients.

Comparative Assessment of Outcomes in Drug Treatment for Smoking Cessation and Role of Genetic Polymorphisms of Human Nicotinic Acetylcholine Receptor Subunits.

Objective: To investigate the effects of genetic polymorphisms of human nicotinic acetylcholine receptor subunits α3, α4 and α5, which are encoded by CHRNA3, CHRNA4 CHRNA5 genes, respectively, on nicotine addiction and outcomes of pharmacological treatments for smoking cessation. Methods: A total of 143 smokers and 130 non-smokers were included. Genotyping for CHRNA3 rs578776, CHRNA4 rs1044396-rs1044397, CNRNA5 rs16969968 polymorphisms was performed by PCR, flowed by RFLP. Clinical outcomes and success rates of pharmacological treatments for smoking cessation with nicotine replacement therapy (NRT), bupropion or varenicline were determined at the 12th week of the treatment. Results: Overall, 52 out of 143 (36.4%) smokers who received pharmacotherapy were able to quit smoking. Success rates for smoking cessation were similar for female (30.3%) and male (41.6%) subjects (p = 0.16). The success rate for smoking cessation treatment with varenicline (58.5%) was significantly higher as compared to other treatments with NRT (20.0%), bupropion (32.3%) or bupropion + NRT (40.0%) (chi-square test, p = 0.001). Smoker vs. non-smoker status and the clinical outcomes of drugs used for smoking cessation were found similar in subjects carrying wild-type and variant alleles of human nicotinic acetylcholine receptor α subunits. Conclusion: In this study, smoking cessation treatment with varenicline was significantly more effective than treatments with nicotine replacement or bupropion in a cohort of Turkish subjects. Smoker/non-smoker status and the clinical outcomes of treatment with pharmacological agents were similar in subjects with wild-type or variant alleles for human nicotinic acetylcholine receptor subunits α3 (CHRNA3), α4 (CHRNA4) and α5 (CHRNA5).

Para-aminosalicylic acid significantly reduced tenofovir exposure in human subjects: Mismatched findings from in vitro to in vivo translational research.

AIMS: Tenofovir and para-aminosalicylic acid (PAS) may be coprescribed to treat patients with concomitant infections of human immunodeficiency virus and Mycobacterium tuberculosis bacteria. Both drugs are known to have remarkable renal uptake transporter-mediated clearance. Owing to the lack of clinical studies on drug-drug interaction between the 2 drugs, we conducted a translational clinical study to investigate the effect of PAS on tenofovir pharmacokinetics (PK). METHODS: Initially, we studied in vitro renal uptake transporter-mediated drug-drug interactions using stably transfected cells with human organic anion transporters (OAT1 and OAT3). Later, we estimated clinical drug interactions using static and physiologically based PK modelling. Finally, we investigated the effects of PAS-calcium formulation (PAS-Ca) on tenofovir disoproxil fumarate PK in healthy male Korean subjects. RESULTS: PAS inhibited OAT1- and OAT3-mediated tenofovir uptake in vitro. The physiologically based PK drug-drug interaction model suggested a 1.26-fold increase in tenofovir peak plasma concentration when coadministered with PAS. By contrast, an open-label, randomized, crossover clinical trial evaluating the effects of PAS-Ca on tenofovir PK showed significantly altered geometric mean ratio (90% confidence intervals) of maximum plasma concentration (Cmax ) and area under the curve (AUC0-inf ) by 0.33 (0.28-0.38) and 0.29 (0.26-0.33), respectively. CONCLUSION: Our study findings suggest that the PAS-Ca formulation significantly reduced systemic exposure to tenofovir through an unexplained mechanism, which was contrary to the initial prediction. Caution should be exercised while predicting in vivo PK profiles from in vitro data, particularly when there are potential confounders such as pharmaceutical interactions.

Effects of Genetic Polymorphisms of Drug Transporter ABCB1 (MDR1) and Cytochrome P450 Enzymes CYP2A6, CYP2B6 on Nicotine Addiction and Smoking Cessation.

OBJECTIVES: To determine the effects of genetic polymorphisms of ABCB1 (MDR1), CYP2A6, CYP2B6 on smoking status, and clinical outcomes of smoking cessation therapies in a Turkish population. METHODS: 130 smokers and 130 non-smokers were recruited. Individuals who never smoked were described as non-smokers. 130 smokers were treated with nicotine replacement therapy (NRT) (n = 40), bupropion (n = 47), bupropion + NRT (n = 15), and varenicline (n = 28). Smokers were checked by phone after 12 weeks of treatment whether they were able to quit smoking or not. Genotyping and phenotyping were performed. RESULTS: Cessation rates were as follows; 20.0% for NRT, 29.8% for bupropion, 40.0% for bupropion + NRT, 57.1% for varenicline (p = 0.013). The frequency of ABCB1 1236TT-2677TT-3435TT haplotype was significantly higher in non-smokers as compared to smokers (21.5% vs. 10.8, respectively; p = 0.018). Neither smoking status nor smoking cessation rates were associated with genetic variants of CYP2A6 (p = 0.652, p = 0.328, respectively), or variants of CYP2B6 (p = 0.514, p = 0.779, respectively). CONCLUSION: Genetic variants of the drug transporter ABCB1 and the 1236TT-2677TT-3435TT haplotype was significantly associated with non-smoking status. Neither ABCB1 nor CYP2A6, CYP2B6 genetic variants were associated with smoking cessation rates at the 12th week of drug treatment.

[Relationship Between Alcohol Dependence and Neuropeptide Y (NPY) Gene Promoter Polymorphisms in A Turkish Sample]. / Türkiye Örnekleminde Nöropeptit Y Geni (NPY) Promotor Polimorfizmleri ve Alkol Bagimliligi Arasindaki Iliski.

OBJECTIVE: Neuropeptide Y (NPY) is a protein widely expressed in the central nervous system and involved in diverse physiological processes, such as emotional regulation, nutritional behavior, and stress. In some populations, studies on alcohol dependence (AD) and the NPY gene have found that NPY variations increase alcohol consumption and thus may potentially be associated with AD. In this study, we investigated the relationship between NPY gene promoter polymorphisms and phenotypes related to alcohol use. METHOD: A total of 417 male participants comprising 252 individuals with AD and 165 healthy individuals were included in this study and phenotypic data were collected. Polymerase chain reaction-restriction fragment length polymorphism (PCR/RFLP) and DNA sequencing METHODS were used for genotyping the rs16147 and rs17149106 polymorphisms in the promoter region of the NPY gene. The data of 384 participants were analysed to evaluate the possible relationship between genotypes and the diagnosis of AD, family history of AD, the severity of AD using the Michigan Alcoholism Screening Test (MAST), the age of onset of problematic alcohol use, the average amount of alcohol consumed per day for the last six months and the lifetime maximum alcohol consumption in one day. RESULTS: A significant difference was found between the AD and control groups concerning rs16147 polymorphism genotype distribution (p=0.025). No association with polymorphisms and alcohol-related phenotypes were demonstrated in the AD group. CONCLUSION: To our knowledge, this study shows for the first time in the literature that alcohol dependence is associated with NPY rs16147 polymorphism in the Turkish population.

[Effects of Nitric Oxide Synthase-1 Exon 1f-VNTR Gene Polymorphism on the Clinical Symptoms of Alcohol Dependence,Impulsivity and Comorbid Attention Deficit Hyperactivity Disorder]. / Alkol Bagimlilarinda Nitrik Oksit Sentaz-1 Ekzon 1f-VNTR Gen Polimorfizmi’nin Bagimlilik ile Iliskili Klinik Özellikler, Dürtüsellik ve Eslik Eden Dikkat Eksikligi Hiperaktivite Belirtileri Üzerine Etkisi.

OBJECTIVE: We planned to compare individuals with alcohol dependence (AD) and healthy controls on the frequency of NOS1 exon 1f-VNTR gene polymorphism and to investigate the effects of this polymorphism on the clinical symptoms of alcohol dependence, impulsiveness and comorbid attention deficit hyperactivity disorder (ADHD) symptoms. METHOD: A total of 282 participants consisting of 153 patients and 129 age and gender matched healthy individuals were inluded in the study. All participants were evaluated with Structured Clinical Interview for DSM-IV Axis 1 disorders (SCID-I) and Michigan Alcohol Screening Test (MAST), Barratt Impulsiveness Scale (BIS-11), UPPS Impulsive Behavior Scale, Adult Attention Deficit and Hyperactivity Diagnosis Scale (ADHDS), Family History Research Diagnostic Criteria (FHDRC). The QF-PCR fragment protocols were used for genetic analyses. Allele fragments of ≤176 bp and >176 bp sizes were separated and 3 different genotypes were determined as the SS, SL and LL. Associations of these genotypes with symptoms of AD severity, impulsiveness and comorbid ADHD were investigated. RESULTS: The AD and control groups did not differ significantly on the basis of NOS1 exon 1f-VNTR gene polymorphism. Also, significant correlations between this polymorphism and symptoms of AD severity, impulsiveness and ADHD were not determined. CONCLUSION: Results of our study do not indicatea significant association between the NOS1 exon 1f-VNTR genotypes and AD, subgroups of AD, impulsiveness or comorbid ADHD semptoms.

Decreased Activity and Genetic Polymorphisms of CYP2C19 in Behçet's Disease.

Behçet's disease (BD) is a systemic autoimmune disorder. Cytochrome P450 enzymes (CYPs) are responsible for various drug metabolism reactions as well as those of endogenous substances which may be associated with autoimmune disease susceptibility. Recently, we reported that in patients with BD, CYP2C9 seems to be down-regulated due to inflammation. In the same Turkish patients with BD, we investigated whether also CYP2C19 activity is decreased. Lansoprazole (30 mg) was given as a probe drug to evaluate CYP2C19 activity in 59 patients with BD and 27 healthy control volunteers. An HPLC method was used to determine plasma lansoprazole and its metabolite, 5-hydroxy lansoprazole, concentrations. The genotyping for CYP2C19 *2, *3 and *17 polymorphisms was made using PCR-RFLP. The median lansoprazole/5-hydroxy lansoprazole metabolic ratio (MR) in patients with BD was 2.6-fold higher as compared to the healthy control group (p = 0.001, 22.6 (1.3-26) and 8.8 (0.5-140) as median and range, respectively). The CYP2C19*17*17 genotype frequency was found to be significantly less in the BD group as compared to the healthy controls (1.7% versus 14.8% in controls, p = 0.01). Additionally, colchicine treatment did not affect the CYP2C19 enzyme activity in six patients (p = 0.43). In conclusion, the patients with BD had lower CYP2C19 enzyme activity and lower frequency of the CYP2C19*17 allele as compared to those of the healthy controls. Further studies are warranted on the mechanisms underlying this relation. This study should also be applied to other autoimmune diseases similarly characterized by local or systemic inflammation.

Effects of Genetic Polymorphisms of Cytochrome P450 Enzymes and MDR1 Transporter on Pantoprazole Metabolism and Helicobacter pylori Eradication.

Pantoprazole is a proton pump inhibitor that is commonly used in the treatment of peptic ulcer disease (PUD) and metabolized by cytochrome P450 (CYP) enzymes CYP2C19 and CYP3A4. Pantoprazole is a substrate for multi-drug resistance protein 1 (MDR1). Single nucleotide polymorphisms (SNPs) in CYP2C19, CYP3A4 and MDR1 affect enzyme activity or gene expression of proteins and may alter plasma pantoprazole concentrations and treatment success in PUD. In this study, we aimed to investigate the association between genetic polymorphisms in CYP2C19, CYP3A4 and MDR1 and pharmacokinetics of pantoprazole and therapeutic outcome in patients with either Helicobacter pylori-associated [H.P.(+)]-PUD or [H.P.(+)]-gastritis. The plasma pantoprazole concentrations were determined by using an HPLC method at the third hour after a 40-mg tablet of pantoprazole administration in 194 newly diagnosed patients with either [H.P.(+)]-PUD or [H.P.(+)]-gastritis. Genotyping was performed by using PCR-RFLP and DNA sequencing. Among patients appearing for follow-up examination (n = 105), the eradication rate for H. pylori was 82.8% (n = 87). The median pantoprazole plasma concentrations in poor metabolizers (PM), rapid metabolizers (RM) and ultrarapid metabolizers (URM) were 2.07, 1.69 and 1.28 µg/ml, respectively (p = 0.04). CYP3A4*1G and *22 polymorphisms did not affect plasma pantoprazole concentrations and H. pylori eradication rate. The MDR1 genetic polymorphisms did not affect plasma pantoprazole concentrations. MDR1 3435CC-2677GG-1236CC haplotype carriers had lower H. pylori eradication rate (60%) than the remaining subjects (84.9%) while the difference was not statistically significant (p = 0.07). In conclusion, while CYP2C19 genetic polymorphisms significantly affected plasma pantoprazole concentrations, polymorphisms of CYP2C19, CYP3A4 and MDR1 did not affect H. pylori eradication rates.

[µ-Opioid Receptor Gene (OPRM1) Polymorphisms A118G and C17T in Alcohol Dependence: A Turkish Sample]. / Türkiye'de Alkol Bagimliliginda µ-Opioid Reseptör Geni (OPRM1) A118G ve C17T Polimorfizmleri.

OBJECTIVES: Previous investigations on opioid system genetics have identified polymorphisms of the OPRM1 gene expressing µ-opioid receptors to be significantly associated with some features of alcohol dependence (AD). In the present study, we evaluated the relationship between single nucleotide polymorphisms (SNP) in the OPRM1 gene, A118G (rs1799971, Asn40Asp) and C17T (rs1799972, Arg6Val), and AD diagnosis, level of alcohol consumption, and AD severity in a Turkish sample. METHODS: 121 AD patients and 117 healthy male subjects were included in the study. OPRM1 A118G (N40D) and C17T (A6V) polymorphisms were evaluated using PCR - RFLP (polymerase chain reaction - restriction fragment length polymorphism) method. We evaluated the association between the presence of SNPs and AD diagnosis, family history of AD, AD severity evaluated via the Michigan Alcoholism Screening Test (MAST), the daily average and maximum quantity of alcohol consumed. RESULTS: There was no significant difference in OPRM1 A118G genotype frequencies between the AD and control groups. T allele frequency for the OPRM1 C17T SNP was very low (0.006) in the sample population. OPRM1 A118G SNP G118 allele carriers showed significantly higher levels of AD severity as indicated by the MAST. CONCLUSION: The OPRM1 G118 allele was significantly associated with more severe AD in the Turkish population. Similar to other European populations, the frequency of the OPRM1 T17 allele was very low.

Relation of the Allelic Variants of Multidrug Resistance Gene to Agranulocytosis Associated With Clozapine.

Clozapine use is associated with leukopenia and more rarely agranulocytosis, which may be lethal. The drug and its metabolites are proposed to interact with the multidrug resistance transporter (ABCB1/MDR1) gene product, P-glycoprotein (P-gp). Among various P-glycoprotein genetic polymorphisms, nucleotide changes in exons 26 (C3435T), 21 (G2677T), and 12 (C1236T) have been implicated for changes in pharmacokinetics and pharmacodynamics of many substrate drugs. In this study, we aimed to investigate the association between these specific ABCB1 polymorphisms and clozapine-associated agranulocytosis (CAA). Ten patients with a history of CAA and 91 control patients without a history of CAA, despite 10 years of continuous clozapine use, were included. Patient recruitment and blood sample collection were conducted at the Hacettepe University Faculty of Medicine, Department of Psychiatry, in collaboration with the members of the Schizophrenia and Other Psychotic Disorders Section of the Psychiatric Association of Turkey, working in various psychiatry clinics. After DNA extraction from peripheral blood lymphocytes, genotyping was performed using polymerase chain reaction and endonuclease digestion. Patients with CAA had shorter duration of clozapine use but did not show any significant difference in other clinical, sociodemographic characteristics and in genotypic or allelic distributions of ABCB1 variants and haplotypes compared with control patients. Among the 10 patients with CAA, none carried the ABCB1 all-variant haplotype (TT-TT-TT), whereas the frequency of this haplotype was approximately 12% among the controls. Larger sample size studies and thorough genetic analyses may reveal both genetic risk and protective factors for this serious adverse event.

Lower CYP2C9 activity in Turkish patients with Behçet's disease compared to healthy subjects: a down-regulation due to inflammation?

BACKGROUND: We previously reported on a Swedish patient with Behçet's disease (BD) who was an ultra-rapid metaboliser of drugs catalysed by CYP2C9. Was this extreme metabolism caused by the disease? AIM: This study aims to compare the genotype/phenotype of CYP2C9 in patients with BD and healthy subjects. As the occurrence of BD is high in Turkey, all subjects were recruited from this country. METHODS: Genotyping of CYP2C9 was performed using standard PCR-RFLP and allele-specific PCR methods. Phenotyping of CYP2C9 was performed by administration of a 50-mg single oral dose of losartan and by calculating the urinary metabolic ratio (MR) of probe drug to its metabolite E-3174. Quantitation was performed by HPLC. RESULTS: The frequency of CYP2C9*2 and *3 was not significantly different between the Behçet's disease patients (12.5 and 8.7%) and the healthy subjects (8.9 and 8.2%). The geometric mean losartan MR was higher in the 52 patients (1.75) than in the 96 healthy subjects (1.02) (p = 0.002; t-test). Within the genotypes *1/*1, there was a significant difference of MR between patients and healthy subjects (P = 0.006). All but three of the Behçet's disease patients were treated with colchicine. In nine subsequent patients, we found no significant effect of 2 weeks of treatment with colchicine on the CYP2C9 MR. CONCLUSION: Contrary to expectation, the CYP2C9 activity was lower in Turkish BD patients compared to healthy subjects. As this seems not to be due to colchicine treatment, our hypothesis is that inflammation related to BD might have caused the down-regulation of the CYP2C9 activity due to immune cytokine reactions. The ultra-rapid metabolism of CYP2C9 substrate drugs in the Swedish patient was not due to her BD.

Improved anti-emetic efficacy of 5-HT3 receptor antagonists in cancer patients with genetic polymorphisms of ABCB1 (MDR1) drug transporter.

Chemotherapy-induced nausea and vomiting (CINV) remains a major adverse effect decreasing quality of life in patients with cancer. Genetic variations among patients may be responsible for part of the lack of efficacy of anti-emetic drugs. The aim of this study was to investigate how the genetic variants of the drug transporter ABCB1 (MDR1) gene affect anti-emetic treatment with 5-HT3 receptor antagonists. Patients (n = 239) receiving moderately or highly emetogenic chemotherapy and ondansetron or granisetron were included in the study. Anti-emetic responses were recorded daily. The primary end-point of the assessment was the total control rates of CINV in the acute and delayed phases after chemotherapy. Genotyping was performed by PCR-RFLP. In the acute phase, patients with ABCB13435TT, 1236TT or 2677TT genotypes had a higher control rate of CINV than other genotype groups: (64.7% in 3435TT versus 45.7% in 3435CC+CT, p = 0.016; 65.1% in 1236TT versus 46.4% in 1236CC+CT, p = 0.027; 66.7% in 2677TT versus 46.5% in other genotypes, p = 0.021). Subjects carrying homozygous variant alleles together (TT-TT-TT) showed a significantly higher protection from nausea and vomiting (67.7% in TT-TT-TT versus 47.1% in other genotypes, p = 0.032). After the logistic regression analysis with adjustment for other known covariates, the total control rate was significantly higher in the 3435TT genotype group during the acute phase (p = 0.021). No significant change was found between the total control rates among genotypes in the delayed phase. Each of three 3435TT, C1236TT, 2677TT genotypes of ABCB1 and their combination was associated with about 50% higher anti-emetic response to 5-HT3 receptor antagonists in the acute phase of chemotherapy in patients with cancer receiving moderately or highly emetogenic chemotherapy. ABCB1 (MDR1) genotypes may contribute to predict the anti-emetic efficacy of 5-HT3 antagonists.

Association between ADH1C and ALDH2 polymorphisms and alcoholism in a Turkish sample.

BACKGROUND: Polymorphisms in the genes encoding alcohol metabolizing enzymes are associated with alcohol dependence. AIM: To evaluate the association between the alcohol dehydrogenase 1C (ADH1C) Ile350Val and aldehyde dehydrogenase 2 (ALDH2) Glu504Lys polymorphisms and alcohol dependence in a Turkish sample. METHODS: 235 individuals (115 alcohol-dependent patients and 120 controls) were genotyped for ADH1C and ALDH2 with PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism). Association between the polymorphisms and family history, daily and maximum amount of alcohol consumed was investigated. The associations between alcohol dependence, severity of consumption and family history and the polymorphisms were analyzed by chi-square or Fisher's exact test where necessary. Relationship between genotypes and dependence related features was evaluated using analysis of variance (ANOVA). RESULTS: The -350Val allele for ADH1C (ADH1C*2) was increased in alcohol-dependent patients (P = 0.05). In individuals with a positive family history, the genotype distribution differed significantly (P = 0.031) and more patients carried the Val allele compared with controls (P = 0.025). Genotyping of 162 participants did not reveal the -504Lys allele in ALDH2. CONCLUSIONS: These findings suggest that ADH1C*2 is associated with alcohol dependence in the Turkish population displaying a dominant inheritance model. ADH1C*2 allele may contribute to the variance in heritability of alcohol dependence. The ALDH2 -504Lys/Lys or Glu/Lys genotypes were not present in alcohol-dependent patients, similar to that seen in European populations and in contrast to the findings in the Asian populations.

Propranolol-induced relaxation in the rat basilar artery.

Propranolol is a non-selective beta-adrenergic receptor blocker used in the treatment of cardiovascular diseases and migraine prophylaxis. Although it has been shown that propranolol dilates the peripheral arteries of rat, its action in the central nervous system vasculature has not been investigated. In this study, the effects of propranolol in rat basilar artery were investigated. Basilar arteries from male Wistar rats were examined in a myograph system. The relaxant effects of propranolol, pindolol, atenolol, pizotifen and methysergide were examined in basilar arteries precontracted by serotonin or PGF2α. Only propranolol and pizotifen induced vasorelaxations; the pD2 values were 5.23±0.13 and 5.94±0.03; respectively. The vasorelaxation induced by propranolol and pizotifen was not affected by endothelium or the presence of l-NOARG and/or indomethacin. The calcium channel blocking activity of propranolol and pizotifen was compared with that of nifedipine in a calcium free solution with high K(+) (60mM) concentration. These drugs shifted the concentration-response curves of calcium induced contractions with pA2 values of 5.45±0.04; 7.14±0.09; and 9.22±0.06 respectively. The P2Y receptor agonist UTP was used to induce sustained and stable contractions in basilar artery segments. Nifedipine caused a marked, but an incomplete relaxation. Cyclopiazonic acid, an inhibitor of sarcoplasmic reticulum calcium channels, but not propranolol or pizotifen abolished the remaining tonus after partial relaxations obtained with nifedipine. These results suggest that propranolol causes vasorelaxation by blocking the L-type voltage-gated calcium channels in the rat basilar artery.

Evaluation of lansoprazole as a probe for assessing cytochrome P450 2C19 activity and genotype-phenotype correlation in childhood.

PURPOSE: Lansoprazole, a cytochrome P450 2C19 (CYP2C19) substrate, has been widely used in children to manage acid-related diseases. CYP2C19 exhibits marked genetic polymorphisms, and distribution of these polymorphisms varies among different ethnic groups. There is limited data regarding the use of probe drugs for determining CYP2C19 activity in children. The aim of this study was to evaluate lansoprazole as an in vivo phenotyping probe for assessing CYP2C19 activity in children. METHODS: The CYP2C19*2, *3, and *17 variants were determined in 244 children. Three hours after a single oral dose of lansoprazole (n = 94) or omeprazole (n = 19), plasma lansoprazole and 5-hydroxy lansoprazole or omeprazole and 5-hydroxy omeprazole concentrations were analyzed by high-performance liquid chromatography. RESULTS: The CYP2C19*17 was the most frequent variant allele (24.4%). The group of patients with CYP2C19*17*17 genotype had a 70% lower (p < 0.05) mean lansoprazole plasma concentration compared with the CYP2C19*1*1 genotype group, whereas the CYP2C19*2*2 group had 6.9-fold higher (p < 0.01) mean lansoprazole plasma concentration. Lansoprazole metabolic ratios (lansoprazole/5-hydroxy-lansoprazole) were found to be significantly lower in the *17*17 [mean ± standard deviation (SD); 2.8 ± 2.1] group and higher in the *2*2 group (63.5 ± 12.2) compared with that of the *1*1 genotype group (6.1 ± 4.5). CONCLUSION: According to our results from a Turkish pediatric population, lansoprazole is a suitable probe drug for phenotyping CYP2C19. The CYP2C19*2 and *17 variants should be taken into consideration in predicting the clinical outcome of therapy with lansoprazole in the pediatric population.