Pharmacokinetics and response to pravastatin in paediatric patients with familial hypercholesterolaemia and in paediatric cardiac transplant recipients in relation to polymorphisms of the SLCO1B1 and ABCB1 genes

AIMS: Our aim was to investigate associations between the single nucleotide polymorphisms (SNPs) in the SLCO1B1 (encoding OATP1B1) and ABCB1 (encoding P-glycoprotein) genes with the pharmacokinetics and efficacy of pravastatin in children with heterozygous familial hypercholesterolaemia (HeFH) and in paediatric cardiac transplant recipients. METHODS: Twenty children with HeFH (aged 4.9-15.6 years) and 12 cardiac transplant recipients (aged 4.4-18.7 years and receiving triple immunosuppressive medication) who had participated in previous pharmacokinetic and pharmacodynamic studies with pravastatin were genotyped for the -11187G > A and 521T > C SNPs in the SLCO1B1 gene and for the 2677G > T/A and 3435C > T SNPs in the ABCB1 gene. RESULTS: Two HeFH patients with the -11187GA genotype had a 81% lower peak plasma pravastatin concentration (Cmax) (difference in means -13.9 ng ml(-1), 95% CI -21.1, -6.7; P < 0.001) and a 74% smaller area under the plasma concentration-time curve (AUC0, infinity) (-25.3 ng ml(-1) h, 95% CI -35.6, -15.0; P < 0.0001) and significantly greater increase in high density lipoprotein (HDL) cholesterol after 2 months treatment with pravastatin than patients with the reference genotype. No significant differences were seen in the pharmacokinetics or effects of pravastatin between HeFH patients with the SLCO1B1 521TC and 521TT genotypes. The cardiac transplant recipients with the SLCO1B1 521TC genotype (n = 3) had a 46% lower Cmax (-67.7 ng ml(-1), 95% CI -135.7, 0.3; P = 0.055) and 62% lower AUC(0,24 h) (-228.5 ng ml(-1) h, 95% CI -402.7, -54.3; P = 0.016) and a shorter half-life (t1/2) (0.9 +/- 0.1 vs. 1.3 +/- 0.4 h, P = 0.015) of pravastatin than those with the reference genotype. Decreases in total and low-density lipoprotein cholesterol by pravastatin were significantly smaller, and the increase in HDL-cholesterol was greater in the transplant recipients with the 521TC genotype compared with patients with the 521TT reference genotype. CONCLUSIONS: In children with HeFH and in paediatric cardiac transplant recipients receiving immunosuppressive medication, the -11187G > A and SLCO1B1 521T > C SNPs were associated with decreased plasma concentrations of pravastatin. These differences are opposite to those seen previously in healthy adults. The mechanisms underlying these phenomena are unclear and warrant further study.     

No significant effect of SLCO1B1 polymorphism on the pharmacokinetics of rosiglitazone and pioglitazone

AIMS

To examine possible effects of polymorphism in the SLCO1B1 gene, encoding the hepatic uptake transporter organic anion transporting polypeptide (OATP) 1B1, on the pharmacokinetics of rosiglitazone and pioglitazone in a prospective genotype panel study.

METHODS

Sixteen healthy volunteers with the homozygous SLCO1B1 c.521TT genotype (controls), 12 with the heterozygous c.521TC genotype and four with the homozygous c.521CC genotype ingested a single 4-mg dose of rosiglitazone and a single 15-mg dose of pioglitazone in a cross-over study with a wash-out period of at least 1 week.

RESULTS

SLCO1B1 polymorphism had no statistically significant effect on any of the pharmacokinetic variables of rosiglitazone, pioglitazone or their metabolites. The mean ± SD area under the plasma rosiglitazone concentration–time curve from time 0 to infinity (AUC_0–∞) was 2024 ± 561 ng ml⁻¹ h in the c.521TT subjects, 1763 ± 288 ng ml⁻¹ h in the c.521TC subjects (geometric mean ratio c.521TC/c.521TT 0.89; 95% confidence interval 0.72, 1.11) and 1729 ± 346 ng ml⁻¹ h in the c.521CC subjects (c.521CC/c.521TT 0.87; 0.63, 1.20). The AUC_0–∞ of pioglitazone averaged 6244 ± 1909 ng ml⁻¹ h in the c.521TT subjects, 5123 ± 1165 ng ml⁻¹ h in the c.521TC subjects (c.521TC/c.521TT 0.83; 0.65, 1.06) and 4851 ± 1123 ng ml⁻¹ h in the c.521CC subjects (c.521CC/c.521TT 0.79; 0.55, 1.14). There was a significant correlation between the AUC_0–∞ of rosiglitazone and pioglitazone (r = 0.717, P < 0.001).

CONCLUSIONS

The SLCO1B1 c.521T→C SNP does not affect the pharmacokinetics of rosiglitazone or pioglitazone, indicating that OATP1B1 plays no significant role in the disposition of these drugs.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• A common single nucleotide polymorphism (SNP) (c.521T→C) of the SLCO1B1 gene, encoding the hepatic uptake transporter organic anion transporting polypeptide (OATP) 1B1, has been associated with marked changes in the pharmacokinetics of the antidiabetic drug repaglinide.
• Rosiglitazone and pioglitazone are competitive inhibitors of OATP1B1 and might thus be its substrates.
• Gemfibrozil, an inhibitor of OATP1B1 in vitro, considerably increases the plasma concentrations of rosiglitazone and pioglitazone in vivo in humans.

WHAT THIS STUDY ADDS

• The SLCO1B1 c.521T→C SNP was not associated with changes in rosiglitazone or pioglitazone pharmacokinetics in healthy volunteers.
• OATP1B1 is thus unlikely to play an important role in the disposition of rosiglitazone or pioglitazone.

     

Frequencies of single nucleotide polymorphisms and haplotypes of organic anion transporting polypeptide 1B1 SLCO1B1 gene in a Finnish population

Objective Organic anion transporting polypeptide 1B1 (OATP1B1) is a drug uptake transporter located at the sinusoidal membrane of hepatocytes. Our aim was to establish high-throughput genotyping assays for the major known single nucleotide polymorphisms (SNP) in the SLCO1B1 gene encoding OATP1B1 and to investigate the frequencies of SNPs and haplotypes of SLCO1B1 in a large Caucasian population.Methods Distribution of SLCO1B1 alleles was determined in 468 healthy Finnish Caucasian subjects at 11 variant sites spanning the entire gene by using allelic discrimination with TaqMan 5′ nuclease assays.Results The allelic frequencies of SLCO1B1 SNPs were 9.7% for g.−11187G>A, 0.4% for g.−11110T>G, 8.0% for g.−10499A>C, 46.2% for c.388A>G, 13.1% for c.411G>A, 13.1% for c.463C>A, 20.2% for c.521T>C, 53.2% for c.571T>C, 46.4% for c.597C>T, 4.0% for c.1929A>C and 48.8% for c.*439T>G. Altogether, 26 haplotypes were statistically inferred. The most common haplotype, with a frequency of 35.6%, contained variant allele C at position c.571, but had the reference nucleotide at all other positions investigated. The functionally significant c.521T>C SNP existed in four major haplotypes, which could be differentiated by the g.−11187G>A, g.−10499A>C and c.388A>G SNPs. The frequencies of these haplotypes were 7.9% for g.−11187G/g.−10499C/c.388G/c.521C (*16), 6.9% for AAGC (*17), 2.7% for GAAC (*5) and 2.4% for GAGC (*15).Conclusion Sequence variations of SLCO1B1 occur at high frequencies in the Caucasian population. Further studies are needed to characterise the effects of SLCO1B1 haplotypes, especially *16, *17, *15 and *5, on drug pharmacokinetics and response, and to determine the frequencies of SLCO1B1 SNPs and haplotypes in different populations.     

SLCO1B1 521T-->C functional genetic polymorphism and lipid-lowering efficacy of multiple-dose pravastatin in Chinese coronary heart disease patients

AIMS: Pravastatin is a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, which is widely used both in primary and secondary prevention of coronary heart disease (CHD). Pravastatin is not subject to metabolism by cytochrome P450s, but it is actively transported from blood into target tissues (e.g. hepatocytes in the liver) by the organic anion transporting polypeptide 1B1 (OATP1B1), encoded by SLCO1B1. The aim of the present study was to evaluate the impact of SLCO1B1 521T-->C (Val174Ala) functional genetic polymorphism on the lipid-lowering efficacy of multiple-dose pravastatin in Chinese patients with CHD. METHODS: Forty-five hospitalized patients with CHD prospectively received pravastatin as a single-agent therapy (20 mg day(-1) p.o.) for 30 days. Serum triglycerides, total cholesterol, low-density lipoprotein-cholesterol and high-density lipoprotein-cholesterol concentrations were determined before and after pravastatin treatment. RESULTS: Pravastatin treatment significantly decreased plasma lipids in all patients (P < 0.001). Importantly, we showed an attenuated pravastatin pharmacodynamic effect on total cholesterol in patients with 521TC heterozygote genotype (from 5.52 +/- 0.51 mmol l(-1) to 4.70 +/- 0.35 mmol l(-1), % change -14.5 +/- 6.6%, N = 9) compared with 521TT homozygote genotype (from 5.47 +/- 1.15 mmol l(-1) to 4.21 +/- 0.89 mmol l(-1), % change -22.4 +/- 10.3%, N = 36) (mean +/- SD, P = 0.03, two-tailed test with alpha set at 5%). SLCO1B1 521T-->C functional polymorphism did not significantly influence pravastatin pharmacodynamics on other plasma lipids (P > 0.05). CONCLUSIONS: The 521T-->C polymorphism of SLCO1B1 appears to modulate significantly the total cholesterol-lowering efficacy of pravastatin in Chinese patients with CHD. Further studies are warranted to determine the extent to which SLCO1B1 genetic variation may contribute to resistance to pravastatin in Asian patients treated with standard doses of pravastatin.     

The effect of SLCO1B1 polymorphism on repaglinide pharmacokinetics persists over a wide dose range

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Organic anion transporting polypeptide 1B1 is an influx transporter expressed on the basolateral membrane of hepatocytes.
• A common single nucleotide polymorphism, c.521T→C (p.Val174Ala), of the SLCO1B1 gene has been associated with increased plasma repaglinide concentrations in healthy volunteers.
• Previous studies at low repaglinide doses have suggested that the effect of SLCO1B1 c.521T→C polymorphism on the pharmacokinetics of repaglinide could be dose-dependent.

WHAT THIS STUDY ADDS

• Repaglinide peak plasma concentration and area under the plasma concentration–time curve increased linearly along with repaglinide dose ranging from 0.25 to 2 mg in both the predominant c.521TT and rare c.521CC genotype group.
• The effect of SLCO1B1 c.521T→C polymorphism on repaglinide pharmacokinetics persists over a wide dose range.

AIMS

To establish whether the effect of SLCO1B1[encoding organic anion transporting polypeptide 1B1 (OATP1B1)] c.521T→C (p.Val174Ala) polymorphism on the pharmacokinetics of repaglinide is dose-dependent.

METHODS

Twelve healthy volunteers with the SLCO1B1 c.521TT genotype (controls) and eight with the c.521CC genotype ingested a single 0.25-, 0.5-, 1- or 2-mg dose of repaglinide in a dose-escalation study with a wash-out period of ≥1 week.

RESULTS

The mean area under the plasma concentration–time curve from time 0 to infinity (AUC_0–∞) of 0.25, 0.5, 1 or 2 mg repaglinide was 82% (95% confidence interval 47, 125), 72% (24, 138), 56% (24, 95) or 108% (59, 171) (P ≤ 0.001) larger in participants with the SLCO1B1 c.521CC genotype than in those with the c.521TT genotype, respectively. Repaglinide peak plasma concentration and AUC_0–∞ increased linearly along with repaglinide dose in both genotype groups (r > 0.88, P < 0.001). There was a tendency towards lower blood glucose concentrations after repaglinide administration in the participants with the c.521CC genotype than in those with the c.521TT genotype.

CONCLUSIONS

The effect of SLCO1B1 c.521T→C polymorphism on the pharmacokinetics of repaglinide persists throughout the clinically relevant dose range.     

Effect of SLCO1B1 genetic polymorphism on the pharmacokinetics of nateglinide

AIMS: Nateglinide is a meglitinide analogue with antidiabetic action. A recent study showed that SLCO1B1 (which codes the OATP1B1 gene, also known as OATP-C, OATP2) is a major determinant which markedly affects the pharmacokinetics of repaglinide. Our objective was to assess the association between single nucleotide polymorphisms (SNPs) of SLCO1B1 and the pharmacokinetics of nateglinide. METHODS: Seventeen healthy volunteers with different SLCO1B1 genotypes (11 with 521TT, four with 521TC and two with 521CC) were enrolled in this study. Each was given a single oral dose of 90 mg nateglinide. Plasma concentrations of nateglinide were measured up to 8 h by HPLC. RESULTS: The C(max) and AUC(0,infinity) of nateglinide were 83% (P = 0.002) and 82% (P = 0.001) higher in the SLCO1B1521TC subjects (n = 4), and 76% (P = 0.016) and 108% (P = 0.001) higher in the SLCO1B1521CC subjects (n = 2) than in the SLCO1B1521TT subjects (n = 11), respectively. The t(1/2) of nateglinide in SLCO1B1521CC subjects was 78% longer than that in 521TT subjects (P = 0.036). The difference in t(max) values among the three genotypic groups was not statistically significant. CONCLUSIONS: Our results suggest that OATP1B1-mediated hepatic uptake of nateglinide may be the prior step for its metabolism and elimination. SLCO1B1521T > C SNP might play an important role in the pharmacokinetics of nateglinide.     

Mixed effects of OATP1B1, BCRP and NTCP polymorphisms on the population pharmacokinetics of pravastatin in healthy volunteers

1.?Pravastatin is a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor used for the treatment of hyperlipidaemia. This study aims to investigate the effects of genetic polymorphisms in OATP1B1, BCRP and NTCP on pravastatin population pharmacokinetics in healthy Chinese volunteers using a non-linear mixed-effect modelling (NONMEM) approach. A two-compartment model with a first-order absorption and elimination described plasma pravastatin concentrations well.

2.?Genetic polymorphisms of rs4149056 (OATP1B1) and rs2306283 (OATP1B1) were found to be associated with a significant (p?<?0.01) decrease in the apparent clearance from the central compartment (CL/F), while rs2296651 (NTCP) increased CL/F to a significant degree (p?<?0.01). The combination of these three polymorphisms reduced the inter-individual variability of CL/F by 78.8%.

3.?There was minimal effect of rs2231137 (BCRP) and rs2231142 (BCRP) on pravastatin pharmacokinetics (0.01?<?p?<?0.05), whereas rs11045819 (OATP1B1), rs1061018 (BCRP) and rs61745930 (NTCP) genotypes do not appear to be associated with pravastatin pharmacokinetics based on the population model (p?>?0.05).

4.?The current data suggest that the combination of rs4149056, rs2306283 and rs2296651 polymorphisms is an important determinant of pravastatin pharmacokinetics.     

安徽地区汉族心血管疾病患者SLCO1B1与ApoE基因多态性分布及其在他汀类药物临床个体化应用中的意义

目的:探讨脂质及药物代谢相关基因SLCO1B1和ApoE的基因多态性在安徽地区汉族心血管疾病患者中的分布,以评估他汀类药物个体化用药的效益/风险比。方法:利用PCR-荧光探针法技术检测2019年1月至2020年8月合肥市第二人民医院736例心血管疾病患者外周血基因组中SLCO1B1基因的rs2306283(388A>G)和rs4149056(521T>C)位点和ApoE基因的rs429358(388T>C)和rs7412(526C>T)位点的基因多态性分布特点,并与已报道的中国其他地区汉族心血管疾病患者的数据进行比较,分析不同地区间的基因型分布差异。结果:检测到安徽地区汉族心血管疾病患者中SLCO1B1基因型有6种,分别为*1a/*1a型(6.11%)、*1a/*1b型(29.08%)、*1b/*1b型(44.57%)、*1a/*15型(4.08%)、*1b/*15型(15.49%)、*15/*15型(0.68%),未检测到*1a/*5型、*5/*5型和*5/*15型;ApoE基因有6种表型,分别为E2/E2型(0.41%)、E2/E3型(11.96%)、E2/E4型(1.09%)、E3/E3型(67.66%)、E3/E4型(17.93%)、E4/E4型(0.95%)。两种基因的基因多态性频率分布满足Hardy-Weinberg遗传平衡,具有群体代表性。本研究人群中携带SLCO1B1正常肌病风险型的比例最高,约占79.76%;SLCO1B1中度肌病风险型和高度肌病风险型的人群比例较低,分别为19.57%和0.68%。ApoE大众类基因型比例最高,约占68.75%;ApoE保护类基因型及风险类基因型的人群比例分别为12.37%和18.88%。不同性别间SLCO1B1和ApoE基因表型患者差异无统计学意义。与华南地区心血管疾病患者相比,安徽地区ApoE基因多态性分布差异有统计学意义(P<0.05)。结论:安徽地区736例心血管疾病患者SLCO1B1和ApoE基因型分别以他汀药物剂量耐受性较高的正常肌病风险型和对他汀药物敏感的大众类基因型为主,服用他汀类药物诱发肌病的风险较低,降脂疗效较好;且两种基因的多态性分布均不受性别的影响,但ApoE基因多态性分布特征可能在地域上存在差异。因此,检测SLCO1B1和APOE基因多态性对于临床评估效益/风险比有重要的指导意义。     

有机阴离子转运多肽1B1（OATP1B1）基因多态性对他汀类药物影响的研究进展

有机阴离子转运多肽1B1(OATP1B1)是一种负责转运多种内外源性物质进入肝细胞发挥作用的摄入型转运蛋白。他汀类药物又称3-羟基-3-甲基戊二酸单酰辅酶A(HMG-CoA)还原酶抑制剂,临床上广泛应用于调脂及心脑血管疾病的预防,其疗效及不良反应有显著的个体化差异。研究表明OATP1B1基因多态性是导致他汀类药物个体化差异的重要因素。对OATP1B1基因多态性对他汀类药物影响的研究进展进行综述,为他汀类药物的个体化、安全化应用提供可能的理论指导。     

SLCO1B1突变致1例甲氨蝶呤清除延迟患儿的药学监护

目的:分析甲氨蝶呤清除延迟的影响因素,使临床更加合理地使用甲氨蝶呤( MTX)、减少不良反应的发生。方法:对1例发生MTX 排泄延迟、出现胃肠道黏膜损伤症状并继发鼠伤寒沙门菌感染的急性淋巴细胞性白血病(ALL)高危患儿的生理病理因素、合并用药情况进行分析,并通过测序法分析SLCO1B1多态性,探讨影响MTX清除延迟的相关因素。结果:根据MTX血药浓度,临床药师判断该患儿Block-1时发生了MTX早期清除延迟,Block-2时发生早期和晚期清除延迟。另结合相关文献,临床药师选择SLCO1B1的3个SNP位点进行测序分析,发现患儿为SLCO1B1c.521、c.1865+4846和c.1865+248 3个位点的突变纯合子。SLCO1B1突变和合并使用奥美拉唑可能是导致患儿发生MTX早期清除延迟的原因;腹水可能是导致其发生晚期清除延迟的原因。结论:临床医师在使用MTX治疗ALL患儿时,应综合考虑患儿的生理病理因素和遗传因素等,如有条件,可同时检测相关基因型,根据基因型和肾脏清除率等制定合适的治疗方案或采取一定的预防措施,同时尽量避免选择会导致患儿甲氨蝶呤排泄延迟的相关药物,以减少MTX不良反应的发生。     

The impact of SLCO1B1 polymorphisms on the plasma concentration of lopinavir and ritonavir in HIV-infected men

AIMS

To investigate possible associations between three SLCO1B1 single nucleotide polymorphisms (388A→G, 463C→A, 521T→C) and lopinavir/ritonavir plasma concentrations.

METHODS

The study included 99 human immunodeficiency virus-infected men on stable highly active antiretroviral therapy containing lopinavir/ritonavir. Trough concentrations of lopinavir and ritonavir in plasma were quantified using liquid chromatography–tandem mass spectrometry. Genotyping of SLCO1B1388A→G, 463C→A and 521T→C polymorphisms was performed by allelic discrimination using real-time polymerase chain reaction.

RESULTS

The trough concentration of lopinavir in plasma is significantly associated with SLCO1B1521T→C genotypes (P= 0.03). There is a significant trend for increasing concentrations of lopinavir from TT to TC to CC genotypes (P= 0.02). Carriers of the 521C allele display significantly higher lopinavir plasma concentrations relative to the wild-type TT genotype (P= 0.03).

CONCLUSIONS

Reduced uptake of lopinavir by hepatocytes in carriers of the 521C allele may account for these results, but further studies to confirm the clinical importance of SLCO1B1 polymorphisms in lopinavir pharmacokinetics are warranted.     

Role of the SLCO1B1 haplotypes on the rifampicin-induced CYP3A activity

Rifampin, a member of the rifamycin class of antibiotics, is well known for its ability to activate the pregnant X receptor and induce drug-metabolizing enzymes and transporters. Available data suggest rifampin entry into hepatocytes is mediated by OATP1B1. Accordingly, it is therefore plausible that modulation of the intracellular concentration of rifampin by OATP1B1 genetic polymorphisms would influence the degree of CYP3A induction. AIM： To study the association between haplotypes of the SLCO1B1 and the rifampicin-mediated inducible CYP3A4 activity. A single-point determination of midazolam plasma concentration method was developed to assess the constitutive and inducible CYP3A4 activity. A pharmacokinetic study of a single dose of 450 mg rifampicin was conducted to evaluate the mechanism of rifampicin-midazolam interaction in different SLCO1B1 genotypic subjects.METHODS： Twenty-three healthy volunteers with different SLCO1B1 haplotypes （7 for SLCO1B1 ＊ 1a/＊ 1a, 7 for SLCO1B1 ＊ 1b/＊ 1b, 7 for SLCO1B1 ＊ 1b / ＊ 15 and 2 for SLCO1B1 ＊ 15/＊ 15） were enrolled in this study. Each was given a single oral dose of 7.5 nag naidazolam on day 0 and day 6. Rifampicin of 450 nag was given from day 1 to day 5. Plasma concentrations of midazolam were measured for up to 8 hours by LC-MS, and its pharmacokinetic parameters were analyzed. Plasma concentrations of a single oral dose of 450 nag rifampicin were measured for up to 12 hours.[第一段]     

Extreme differences in SLCO1B3 functional polymorphisms in Roma and Hungarian populations

Variants in SLCO1B3 transporter are linked to disposition and uptake of drugs and show high degree of heterogeneity between populations. A total of 467 Roma and 448 Hungarian subjects were genotyped for SLCO1B3 c.334T>G and c.1683-5676A>G variant alleles by PCR-RFLP assay and direct sequencing. We found significant differences in the frequencies of homozygous variant genotypes of SLCO1B3 334GG (41.54% vs. 8.04%, p < 0.001) and 1683-5676GG (0.43% vs. 2.01%, p = 0.028) between Romas and Hungarians. A significantly increased prevalence was found in SLCO1B3 1683-5676G allele frequency in Hungarians compared to the Roma population (15.07% vs. 3.43%, p ≤ 0.001). The frequency of SLCO1B3 334G allele was significantly increased in Roma population compared to Hungarians (70.56% vs. 52.23%, p = 0.001). The LD values between the examined SNPs were 80 and 90 in Roma and in Hungarian samples, respectively. Our results highlight notable pharmacogenetic differences between Roma and Hungarian populations, which may have therapeutic implications.     

Pharmacogenetics of <Emphasis Type="Italic">SLCO1B1</Emphasis>: haplotypes,htSNPs and hepatic expression in three distinct Asian populations

Objective The aim of this study was to characterize the population frequency of SLCO1B1 polymorphic variants in three distinct healthy Asian populations, namely Chinese (n = 100), Malay (n = 100) and Indian (n = 100), and to explore the association between haplotype-tagged single nucleotide polymorphisms (htSNPs) on hepatic SLCO1B1 mRNA expression. Methods The distribution of polymorphic variants in the SLCO1B1 gene at eight loci that spanned approximately 48 kb was investigated in the three different Asian ethnic groups and in 32 non-cancerous liver tissues from Chinese patients. Results Of the 26 polymorphisms screened, we found eight polymorphic variants that differed in genotypic and allelic frequencies between the Chinese, Malay and Indian populations. Significant interethnic differences were observed in the genotype frequency distributions across the promoter SNP [g.-11187G>A (P = 0.030)] as well as three coding region SNPs [c.388G>A (P < 0.001); c.571T>C (P < 0.001); c.597C>T (P < 0.001)] in the healthy subjects. Haplotype analysis revealed 12 different haplotypes in both the Chinese and Malay populations and 18 haplotypes in the Indian population. In both the Malay and Indian populations, the htSNPs were c.388A>G, c.571T>C and c.597C>T, whereas in the Chinese population they were g.-11187G>A, c.388A>G and c.597C>T. The c.388A>G and c.597C>T htSNPs accounted for more than 70% of the variations between the three major haplotypes in each Asian ethnic group. In terms of the c.388A>G htSNPs, genotypic-phenotypic association analyses revealed that there was no effect on SLCO1B1 expression in hepatic tissues; in addition, no genotypic-phenotypic associations were evident with regards to the c.597C>T htSNP. Conclusion Future studies should investigate the phenotypic effects of the c.388A>G htSNP on the disposition of OATP1B1 substrates in Asian populations. An erratum to this article can be found at     

Inhibition of the organic anion-transporting polypeptide 1B1 by quercetin: an in vitro and in vivo assessment

AIM

To investigate the effect of quercetin on organic anion transporting polypeptide 1B1 (OATP1B1) activities in vitro and on the pharmacokinetics of pravastatin, a typical substrate for OATP1B1 in healthy Chinese-Han male subjects.

METHODS

Using human embryonic kidney 293 (HEK293) cells stably expressing OATP1B1, we observed the effect of quercetin on OATP1B1-mediated uptake of estrone-3-sulphate (E3S) and pravastatin. The influence of quercetin on the pharmacokinetics of pravastatin was measured in 16 healthy Chinese-Han male volunteers receiving a single dose of pravastatin (40 mg orally) after co-administration of placebo or 500 mg quercetin capsules (once daily orally for 14 days).

RESULTS

Quercetin competitively inhibited OATP1B1-mediated E3S uptake with a K_i value of 17.9 ± 4.6 µm and also inhibited OATP1B1-mediated pravastatin uptake in a concentration dependent manner (IC₅₀, 15.9 ± 1.4 µm). In healthy Chinese-Han male subjects, quercetin increased the pravastatin area under the plasma concentration – time curve (AUC(0,10 h) and the peak plasma drug concentration (C_max) to 24% (95% CI 15, 32%, P < 0.001) and 31% (95% CI 20, 42%, P < 0.001), respectively. After administration of quercetin, the elimination half-life (t_1/2) of pravastatin was prolonged by 14% (95% CI 4, 24%, P = 0.027), with no change in the time to reach C_max (t_max). Moreover, quercetin decreased the apparent clearance (CL/F) of pravastatin by 18% (95% CI 75, 89%, P < 0.001).

CONCLUSIONS

These findings suggest that quercetin inhibits the OATP1B1-mediated transport of E3S and pravastatin in vitro and also has a modest inhibitory influence on the pharmacokinetics of pravastatin in healthy Chinese-Han male volunteers. The effects of quercetin on other OATP1B1 substrate drugs deserve further investigation.     

有机阴离子转运多肽1B1的遗传药理学进展

人体存在多种类型的药物转运体,对于药物的吸收、分布和排泄起重要作用。参与药物跨膜转运的转运体功能受影响,将可能导致诸多临床药物的疗效、毒副作用甚至药物相互作用的发生。在各种影响因素中,遗传多态性所起的作用最为重要,可导致基因表达和蛋白功能发生改变。目前,阐明转运体基因的多态性以及基因型与表型之间的相互关系已成为应用遗传信息指导临床个体化用药的必要步骤。本文就肝脏有机阴离子转运多肽1B1（OATP1B1[OATP-C],编码基因SLCO1B1）基因多态性对药代动力学和药效动力学的影响及其临床意义等方面的进展作一综述。     

Lack of effect of genetic polymorphisms of SLCO1B1 on the lipid-lowering response to pitavastatin in Chinese patients

Aim:

To investigate the SLCO1B1 388A>G and 521T>C polymorphisms in hyperlipidemia patients and evaluate the effect of the two polymorphisms on the lipid-lowering efficacy of pitavastatin.

Methods:

The functional polymorphisms of SLCO1B1 (388A>G and 521T>C) were genotyped in 140 Chinese patients with essential hyperlipidemia using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and one-step tetra-primers ARMS-PCR. Eighty-five patients were enrolled in the clinical trial and given 2 mg of pitavastatin daily for 8 weeks. Total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) serum levels were measured at baseline, after 4 weeks and after 8 weeks of treatment.

Results:

The allele frequencies of SLCO1B1 388A>G and 521T>C in essential hyperlipidemia patients were 71.1% and 11.1%, respectively. The 4- and 8-week treatment with pitavastatin significantly reduced TC, TG, and LDL levels, but there was no statistical difference among patients with wild type, SLCO1B1 388A>G or SLCO1B1 521T>C in the lipid-lowering efficacy of pitavastatin.

Conclusion:

The present study found that the allele frequencies of SLCO1B1 388A>G and 521T>C in Chinese patients with essential hyperlipidemia are comparable to those in healthy Chinese population. SLCO1B1 388A>G and 521T>C do not affect the lipid-lowering efficacy of pitavastatin.     

Different effects of SLCO1B1 polymorphism on the pharmacokinetics and pharmacodynamics of repaglinide and nateglinide

Thirty-two healthy volunteers with different SLCO1B1 genotypes ingested a 0.5-mg dose of repaglinide and 60-mg dose of nateglinide with a washout period of 1 week. Participants with SLCO1B1 c.521CC genotype (n = 4) had a 59% (P = 0.001) or 72% (P < 0.001) greater mean area under the plasma repaglinide concentration-time curve (AUC(0-infinity)) than participants with c.521TC (n = 12) or c.521TT (n = 16) genotypes. The AUC(0-infinity) of repaglinide metabolites M2 and M4 were 112% (P = 0.004) and 81% (P = 0.002) larger in participants with c.521CC genotype than in those with c.521TT genotype, but no differences existed in the pharmacokinetics of M1. Maximum decrease in blood glucose concentration correlated with repaglinide AUC(0-infinity) (r = 0.412, P = 0.019). SLCO1B1 polymorphism had no significant effect on the pharmacokinetics or pharmacodynamics of nateglinide or its M7 metabolite. Thus, in contrast to repaglinide, the disposition of nateglinide is unaffected by the SLCO1B1 c.521T>C polymorphism.     

Gemfibrozil and its glucuronide inhibit the hepatic uptake of pravastatin mediated by OATP1B1

When pravastatin (40?mg/day) was co-administered with gemfibrozil (600?mg, b.i.d., 3 days) to man, the AUC of pravastatin increased approximately 2-fold. We have clarified that OATP1B1 is a key determinant of the hepatic uptake of pravastatin in humans. Thus, we hypothesized that gemfibrozil and the main plasma metabolites, a glucuronide (gem-glu) and a carboxylic acid metabolite (gem-M3), might inhibit the hepatic uptake of pravastatin and lead to the elevation of the plasma concentration of pravastatin. Gemfibrozil and gem-glu inhibited the uptake of ¹⁴C-pravastatin by human hepatocytes with K_i values of 31.7?µM and 15.7?µM, respectively and also inhibited pravastatin uptake by OATP1B1-expressing Xenopus laevis oocytes with K_i values of 15.1?µM and 7.6?µM. Additionally, we examined the biliary transport of pravastatin and demonstrated that pravastatin was transported by MRP2 using both human canalicular membrane vesicles (hCMVs) and human MRP2-expressing vesicles. However, gemfibrozil, gem-glu and gem-M3 did not affect the biliary transport of pravastatin by MRP2. Considering the plasma concentrations of gemfibrozil and gem-glu in humans, the inhibition of OATP1B1-mediated hepatic uptake of pravastatin by gem-glu would contribute, at least in part, to the elevation of plasma concentration of pravastatin by the concomitant use of gemfibrozil.