Interaction of Oatp1b2 expression and nonalcoholic steatohepatitis on pravastatin plasma clearance.

The downregulation of hepatic uptake transporters, including those of the OATP family, are a well known consequence of nonalcoholic steatohepatitis (NASH). Prior studies have shown that the combination of NASH and Oatp1b2 knockout synergistically reduces the clearance of pravastatin (PRAV) in the methionine and choline deficient (MCD) mouse model of NASH, and the current study therefore aimed to determine the impact of NASH and genetic heterozygosity of Oatp1b2 on PRAV clearance, modeling the overlap between the 24% of the human population who are heterozygous for non-functioning OATP1B1, and the ~15% with NASH, potentially placing these people at higher risk of statin-induced myopathy. Therefore, male C57BL/6 wild-type (WT), Oatp1b2+/- (HET), and Oatp1b2-/- (KO) mice were fed either a control (methionine and choline sufficient) or methionine and choline-deficient (MCD) diet to induce NASH. After six weeks of feeding, pravastatin was administered via the carotid artery. Blood and bile samples were collected throughout 90 min after PRAV administration. The concentration of PRAV in plasma, bile, liver, kidney, and muscle was determined by liquid chromatography-tandem mass spectrometry. MCD diet did not alter the plasma AUC values of PRAV in either WT or HET mice. However, the MCD diet increased plasma AUC by 4.4-fold in KO mice. MCD diet and nonfunctional Oatp1b2 synergistically increased not only plasma AUC but also the extrahepatic tissue concentration of pravastatin, whereas the partially decreased function of Oatp1b2 and NASH together were insufficient in significantly altering PRAV pharmacokinetics. These data suggest that a single copy of fully functional OATP1B1 in NASH patients may be sufficient to avoid the increase of pravastatin toxicity.

UHPLC-MS/MS assay for simultaneous determination of amlodipine, metoprolol, pravastatin, rosuvastatin, atorvastatin with its active metabolites in human plasma, for population-scale drug-drug interactions studies in people living with HIV.

Thanks to highly active antiretroviral treatments, HIV infection is now considered as a chronic condition. Consequently, people living with HIV (PLWH) live longer and encounter more age-related chronic co-morbidities, notably cardiovascular diseases, leading to polypharmacy. As the management of drug-drug interactions (DDIs) constitutes a key aspect of the care of PLWH, the magnitude of pharmacokinetic DDIs between cardiovascular and anti-HIV drugs needs to be more thoroughly characterized. To that endeavour, an UHPLC-MS/MS bioanalytical method has been developed for the simultaneous determination in human plasma of amlodipine, metoprolol, pravastatin, rosuvastatin, atorvastatin and its active metabolites. Plasma samples were subjected to protein precipitation with methanol, followed by evaporation at room temperature under nitrogen of the supernatant, allowing to attain measurable plasma concentrations down to sub-nanogram per milliliter levels. Stable isotope-labelled analytes were used as internal standards. The five drugs and two metabolites were analyzed using a 6-min liquid chromatographic run coupled to electrospray triple quadrupole mass spectrometry detection. The method was validated over the clinically relevant concentrations ranging from 0.3 to 480 ng/mL for amlodipine, atorvastatin and p-OH-atorvastatin, and 0.4 to 480 ng/mL for pravastatin, 0.5 to 480 ng/mL for rosuvastatin and o-OH-atorvastatin, and 3 to 4800 ng/mL for metoprolol. Validation performances such as trueness (95.4-110.8%), repeatability (1.5-13.4%) and intermediate precision (3.6-14.5%) were in agreement with current international recommendations. Accuracy profiles (total error approach) were lying within the limits of ±30% accepted in bioanalysis. This rapid and robust UHPLC-MS/MS assay allows the simultaneous quantification in plasma of the major currently used cardiovascular drugs and offers an efficient analytical tool for clinical pharmacokinetics as well as DDIs studies.

Organic Anion Transporter Polypeptide 1B1 Polymorphism Modulates the Extent of Drug-Drug Interaction and Associated Biomarker Levels in Healthy Volunteers.

Understanding transporter-mediated drug-drug interactions is an integral part of risk assessment in drug development. Recent studies support the use of hexadecanedioate (HDA), tetradecanedioate (TDA), coproporphyrin (CP)-I, and CP-III as clinical biomarkers for evaluating organic anion-transporting polypeptide (OATP)1B1 (SLCO1B1) inhibition. The current study investigated the effect of OATP1B1 genotype c.521T>C (OATP1B1-Val174Ala) on the extent of interaction between cyclosporin A (CsA) and pravastatin, and associated endogenous biomarkers of the transporter (HDA, TDA, CP-I, and CP-III), in 20 healthy volunteers. The results show that the levels of each clinical biomarker and pravastatin were significantly increased in plasma samples of the volunteers following administration of pravastatin plus CsA compared with pravastatin plus placebo. The overall fold change in the area under the concentration-time curve (AUC) and maximum plasma concentration (Cmax ) was similar among the four biomarkers (1.8-2.5-fold, paired t-test P value < 0.05) in individuals who were homozygotes or heterozygotes of the major allele, c.521T. However, the fold change in AUC and Cmax for HDA and TDA was significantly abolished in the subjects who were c.521-CC, whereas the respective fold change in AUC and Cmax for pravastatin and CP-I and CP-III were slightly weaker in individuals who were c.521-CC compared with c.521-TT/TC genotypes. In addition, this study provides the first evidence that SLCO1B1 c.521T>C genotype is significantly associated with CP-I but not CP-III levels. Overall, these results suggest that OATP1B1 genotype can modulate the effects of CsA on biomarker levels; the extent of modulation differs among the biomarkers.

Impact of Genetic Variation on Pravastatin Systemic Exposure in Pediatric Hypercholesterolemia.

This study investigated the impact of SLCO1B1 genotype on pravastatin systemic exposure in children and adolescents with hypercholesterolemia. Participants (8-20 years) with at least one allelic variant of SLCO1B1 c.521T>C (521TC, n = 15; 521CC, n = 2) and wild-type controls (521TT, n = 15) completed a single oral dose pharmacokinetic study. Interindividual variability of pravastatin acid (PVA) exposure within SLCO1B1 genotype groups exceeded the approximately twofold difference in mean PVA exposure observed between SLCO1B1 genotype groups (P > 0.05, q > 0.10). The 3'α-iso-pravastatin acid and lactone isomer formation in the acidic environment of the stomach prior to absorption also was variable and affected PVA exposure in all genotype groups. The SLCO1B1 c.521 gene variant contributing to variability in systemic exposure to PVA in our pediatric cohort was comparable to previous studies in adults. However, other demographic and physicochemical factors seem to also contribute to interindividual variability in the dose-exposure relationship.

Prediction of the Pharmacokinetics of Pravastatin as an OATP Substrate Using Plateable Human Hepatocytes With Human Plasma Data and PBPK Modeling.

Plateable human hepatocytes with human plasma were utilized to generate the uptake transporter kinetic data for pravastatin, an organic anion-transporting polypeptide (OATP) transporter substrate. The active hepatic uptake of pravastatin was determined with a Jmax value of 134.4 pmol/min/million cells and Km of 76.77 µM in plateable human hepatocytes with human plasma. The physiologically-based pharmacokinetic (PBPK) model with incorporation of these in vitro kinetic data successfully simulated the i.v. pharmacokinetic profile of pravastatin without applying scaling factor (the mean predicted area under the curve (AUC) is within 1.5-fold of the observed). Furthermore, the PBPK model also adequately described the oral plasma concentration-time profiles of pravastatin at different dose levels. The current investigation demonstrates an approach allowing us to build upon the translation of in vitro OATP uptake transporter data to in vivo, with a hope of utilizing the in vitro data for the prospective human pharmacokinetic (PK) prediction.

Effect of inhalation exposure to toluene on the activity of organic anion transporting polypeptide (Oatp) using pravastatin as a probe drug in rats.

1. Toluene, used as a pure substance or in solvent mixtures, is the cause of occupational exposures of large numbers of workers in the world. The organic anion transporting polypeptides (OATP: human; Oatp: rodents) are drug carriers which have been frequently associated to drug-drug interactions. The objective of this study was to evaluate the influence of inhalation exposure to toluene in Oatp in vivo activity using pravastatin as a probe drug in rats. 2. Male Wistar rats ((n = 6 per sampling time) were exposed to 85 mg/m3 toluene by inhalation or air in a nose only exposure system for 6 h/d, 5 d/week during 4 weeks, in order to simulate the occupational exposure to toluene at level slightly above the occupational exposure limit proposed by the American Conference of Governmental Industrial Hygienists (ACGIH). After 4 weeks of exposure, animals received a single dose of 20 mg/kg pravastatin orally. 3. Areas under concentration × time curves extrapolated to infinite (AUC0-∞) were calculated by Gauss Laguerre quadrature. Non-exposed animals showed AUC0-∞ of 726.0 (261.8) ng h/mL for pravastatin and rats exposed to toluene 85 mg/m3 showed AUC0-∞ of 681.8 (80.1) ng h/mL [data presented as mean (standard error of the mean)]. No significant difference was observed in pravastatin kinetic disposition between groups in terms of 95% confidence interval for the difference between means. 4. Toluene exposure by inhalation did not change the in vivo activity of Oatp evaluated by pravastatin kinetic disposition in rats.

Feasibility of the functional expression of the human organic anion transporting polypeptide 1B1 (OATP1B1) and its genetic variant 521T/C in the mouse liver.

The objective of this study was to examine the feasibility of functional expression of the human organic anion transporting polypeptide 1B1 (hOATP1B1) forms in the liver of the mouse. After the mouse received the gene of interest (i.e., luciferase as the reporter or hOATP1B1) via hydrodynamic gene delivery (HGD) method, the expression was found to be liver-specific while alterations in the serum biochemistry and hepatocyte histology were apparently transient and reversible. The reporter activity was also detected in the plasma, but not in the blood cell in mice that received HGD, suggesting that the protein is probably released due to transiently increased permeability in hepatocytes by HGD. Using this delivery condition, the expression of hOATP1B1 was readily detected in the liver, but not in other tissues, of the mice receiving HGD for the transporter gene. Compared with the sham control mice, the uptake of pravastatin into the liver increased significantly in mice receiving hOATP1B1 wild type; the uptake parameters decreased consistently in mice expressing the 521T>C variant compared with that of the wild type control. These observations suggest that the functional expression of human transporter gene in mice is feasible, further suggesting that this treatment is practically useful in the pharmacokinetic studies for hOATP1B1 substrates.

Quantitative Analyses of Hepatic OATP-Mediated Interactions Between Statins and Inhibitors Using PBPK Modeling With a Parameter Optimization Method.

This study aimed to construct a widely applicable method for quantitative analyses of drug-drug interactions (DDIs) caused by the inhibition of hepatic organic anion transporting polypeptides (OATPs) using physiologically based pharmacokinetic (PBPK) modeling. Models were constructed for pitavastatin, fluvastatin, and pravastatin as substrates and cyclosporin A (CsA) and rifampicin (RIF) as inhibitors, where enterohepatic circulations (EHC) of statins were incorporated. By fitting to clinical data, parameters that described absorption, hepatic elimination, and EHC processes were optimized, and the extent of these DDIs was explained satisfactorily. Similar in vivo inhibition constant (Ki ) values of each inhibitor against OATPs were obtained, regardless of the substrates. Estimated Ki values of CsA were comparable to reported in vitro values with the preincubation of CsA, while those of RIF were smaller than reported in vitro values (coincubation). In conclusion, this study proposes a method to optimize in vivo PBPK parameters in hepatic uptake transporter-mediated DDIs.

Using improved serial blood sampling method of mice to study pharmacokinetics and drug-drug interaction.

In pharmacokinetic evaluation of mice, using serial sampling methods rather than a terminal blood sampling method could reduce the number of animals needed and lead to more reliable data by excluding individual differences. In addition, using serial sampling methods can be valuable for evaluation of the drug-drug interaction (DDI) potential of drug candidates. In this study, we established an improved method for serially sampling the blood from one mouse by only one incision of the lateral tail vein, and investigated whether our method could be adapted to pharmacokinetic and DDI studies. After intravenous and oral administration of ibuprofen and fexofenadine (BCS class II and III), the plasma concentration and pharmacokinetic parameters were evaluated by our method and a terminal blood sampling method, with the result that both methods gave comparable results (ibuprofen: 63.8 ± 4.0% and 64.4%, fexofenadine: 6.5 ± 0.7% and 7.9%, respectively, in bioavailability). In addition, our method could be adapted to DDI study for cytochrome P450 and organic anion transporting polypeptide inhibition. These results demonstrate that our method can be useful for pharmacokinetic evaluation from the perspective of reliable data acquisition as well as easy handling and low stress to mice and improve the quality of pharmacokinetic and DDI studies.

Synergistic interaction between genetics and disease on pravastatin disposition.

BACKGROUND & AIMS: A genome wide association study and multiple pharmacogenetic studies have implicated the hepatic uptake transporter organic anion transporting polypeptide-1B1 (OATP1B1) in the pharmacokinetics and musculoskeletal toxicity of statin drugs. Other OATP uptake transporters can participate in the transport of pravastatin, partially compensating for the loss of OATP1B1 in patients carrying the polymorphism. Non-alcoholic steatohepatitis (NASH) in humans and in a diet-induced rodent model alter the expression of multiple OATP transporters. METHODS: To determine how genetic alteration in one Oatp transporter can interact with NASH-associated changes in Oatp expression we measured the disposition of intravenously administered pravastatin in Slco1b2 knockout (Slco1b2(-/-)) and wild-type (WT) mice fed either a control or a methionine and choline deficient (MCD) diet to induce NASH. RESULTS: Genetic loss of Oatp1b2, the rodent ortholog of human OATP1B transporters, caused a modest increase in pravastatin plasma concentrations in mice with healthy livers. Although a diet-induced model of NASH decreased the expression of multiple hepatic Oatp transporters, it did not alter the disposition of pravastatin compared to WT control mice. In contrast, the combination of NASH-associated decrease in compensatory Oatp transporters and Oatp1b2 genetic loss caused a synergistic increase in plasma area under the curve (AUC) and tissue concentrations in kidney and muscle. CONCLUSIONS: Our data show that NASH alters the expression of multiple hepatic uptake transporters which, due to overlapping substrate specificity among the OATP transporters, may combine with the pharmacogenetic loss of OATP1B1 to increase the risk of statin-induced adverse drug reactions.

The role of hepatic transport and metabolism in the interactions between pravastatin or repaglinide and two rOatp inhibitors in rats.

A change in the function or expression of hepatic drug transporters may have significant effect on the efficacy or safety of orally administered drugs. Although a number of clinical drug-drug interactions associated with hepatic transport proteins have been reported, in practice it is not always straightforward to discriminate other pathways (e.g. drug metabolism) from being involved in these interactions. The present study was designed to assess the interactions between organic anion transporting polypeptide (Oatp) substrates (pravastatin or repaglinide) and inhibitors (spironolactone or diphenhydramine) in vivo in rats. The mechanisms behind the interactions were then investigated using in vitro tools (isolated hepatocytes and rat liver microsomes). The results showed a significant increase in the systemic exposures of pravastatin (2.5-fold increase in AUC) and repaglinide (1.8-fold increase in AUC) after co-administration of spironolactone to rats. Diphenhydramine increased the AUC of repaglinide by 1.4-fold. The in vivo interactions observed in rats between Oatp substrates and inhibitors may a priori be classified as transport-mediated drug-drug interactions. However, mechanistic studies performed in vitro using both isolated rat hepatocytes and rat liver microsomes showed that the interaction between pravastatin and spironolactone may be solely linked to the inhibition of pravastatin uptake in liver. On the contrary, the inhibition of cytochrome P450 seemed to be the reason for the interactions observed between repaglinide and spironolactone. Although the function and structure of transport proteins may vary between rats and humans, the approach used in the present study can be applied to humans and help to understand the role of drug transport and drug metabolism in a given drug-drug interaction. This is important to predict and mitigate the risk of drug-drug interactions for a candidate drug in pre-clinical development, it is also important for the optimal design of drug-drug interactions studies in the clinic.

Using expression data for quantification of active processes in physiologically based pharmacokinetic modeling.

Active processes involved in drug metabolization and distribution mediated by enzymes, transporters, or binding partners mostly occur simultaneously in various organs. However, a quantitative description of active processes is difficult because of limited experimental accessibility of tissue-specific protein activity in vivo. In this work, we present a novel approach to estimate in vivo activity of such enzymes or transporters that have an influence on drug pharmacokinetics. Tissue-specific mRNA expression is used as a surrogate for protein abundance and activity and is integrated into physiologically based pharmacokinetic (PBPK) models that already represent detailed anatomical and physiological information. The new approach was evaluated using three publicly available databases: whole-genome expression microarrays from ArrayExpress, reverse transcription-polymerase chain reaction-derived gene expression estimates collected from the literature, and expressed sequence tags from UniGene. Expression data were preprocessed and stored in a customized database that was then used to build PBPK models for pravastatin in humans. These models represented drug uptake by organic anion-transporting polypeptide 1B1 and organic anion transporter 3, active efflux by multidrug resistance protein 2, and metabolization by sulfotransferases in liver, kidney, and/or intestine. Benchmarking of PBPK models based on gene expression data against alternative models with either a less complex model structure or randomly assigned gene expression values clearly demonstrated the superior model performance of the former. Besides accurate prediction of drug pharmacokinetics, integration of relative gene expression data in PBPK models offers the unique possibility to simultaneously investigate drug-drug interactions in all relevant organs because of the physiological representation of protein-mediated processes.

Influence of SLCO1B1 polymorphisms on the drug-drug interaction between darunavir/ritonavir and pravastatin.

The authors investigated whether SLCO1B1 polymorphisms contribute to variability in pravastatin pharmacokinetics when pravastatin is administered alone versus with darunavir/ritonavir. HIV-negative healthy participants were prospectively enrolled on the basis of SLCO1B1 diplotype: group 1 (*1A/*1A, n = 9); group 2 (*1A/*1B, n = 10; or *1B/*1B, n = 2); and group 3 (*1A/*15, n = 1; *1B/*15, n = 5; or *1B/*17, n = 1). Participants received pravastatin (40 mg) daily on days 1 through 4, washout on days 5 through 11, darunavir/ritonavir (600/100 mg) twice daily on days 12 through 18, with pravastatin 40 mg added back on days 15 through 18. Pharmacokinetic studies were conducted on day 4 (pravastatin alone) and day 18 (pravastatin + darunavir/ritonavir). Pravastatin area under the plasma concentration-time curve (AUC(tau)) was 21% higher during administration with darunavir/ritonavir compared with pravastatin alone; however, this difference was not statistically significant (P = .11). Group 3 variants had 96% higher pravastatin AUC(tau) on day 4 and 113% higher pravastatin AUC(tau) on day 18 compared with group 1. The relative change in pravastatin pharmacokinetics was largest in group 3 but did not differ significantly between diplotype groups. In sum, the influence of SLCO1B1*15 and *17 haplotypes on pravastatin pharmacokinetics was maintained in the presence of darunavir/ritonavir. Because OATP1B1 inhibition would be expected to be greater in carriers of normal or high-functioning SLCO1B1 haplotypes, these findings suggest that darunavir/ritonavir is not a potent inhibitor of OATP1B1-mediated pravastatin transport in vivo.

Identification of the rate-determining process in the hepatic clearance of atorvastatin in a clinical cassette microdosing study.

Clearance of atorvastatin occurs through hepatic uptake by organic anion transporting polypeptides (OATPs) and subsequent metabolism by cytochrome P450 (CYP) 3A4. To demonstrate the relative importance of OATPs and CYP3A4 in the hepatic elimination of atorvastatin in vivo, a clinical cassette microdose study was performed. A cocktail consisting of a microdose of atorvastatin along with probe substrates for OATPs (pravastatin) and CYP3A4 (midazolam) was orally administered to eight healthy volunteers. The pharmacokinetics of this cocktail was observed at baseline, after an oral dose of 600 mg rifampicin (an inhibitor of OATPs), and after an intravenous dose of 200 mg itraconazole (a CYP3A4 inhibitor). Rifampicin increased the pravastatin dose-normalized area under the plasma concentration-time curve (AUC) (4.6-fold), and itraconazole significantly increased the midazolam dose-normalized AUC (1.7-fold). The atorvastatin dose-normalized AUC increased 12-fold when coadministered with rifampicin but did not change when coadministered with itraconazole. These results indicate that hepatic uptake via OATPs makes the dominant contribution to the hepatic elimination of atorvastatin at a subtherapeutic microdose.

The disposition of pravastatin in a rat model of streptozotocin-induced diabetes and organic anion transporting polypeptide 2 and multidrug resistance-associated protein 2 expression in the liver.

The combination of diabetes and hyperlipidemia promotes the development of atherosclerosis. Therefore, it is important for diabetic patients to control blood fat. 3-Hydroxy-3-methylglutaryl enzyme A (HMG-CoA) reductase inhibitors (statins), like pravastatin, are frequently administered to diabetic patients for this purpose. Although the alterations of metabolic enzymes and transporters in the diabetic liver maybe change the disposition of pravastatin, the effect has not been fully investigated. In the present study, we investigated the disposition of pravastatin and the mRNA expression of transporters in the liver. Pravastatin (5 mg.kg(-1) body weight) was administered intravenously to diabetic rats, and the pravastatin concentrations in the plasma, urine, and bile were measured by high-performance liquid chromatography. Changes in the mRNA expressions of multidrug resistance-associated protein 2 (MRP2) and organic anion transporting polypeptide 2 (OATP2) in the liver were also estimated using reverse transcriptase-polymerase chain reaction (RT-PCR). We found that the plasma pravastatin concentration was lower in the diabetic rat because the transportation of pravastatin into hepatocytes was promoted along with increased expression of OATP2. The biliary excretion ratio of pravastatin was significantly lower in the diabetic rat because the pravastatin transportation into bile was reduced along with the decreased expression of MRP2. To clarify these phenomena, the analysis of mRNA expression using real-time PCR and the measurement of the amount and the activity of proteins are necessary in future study.

Different effects of the ABCG2 c.421C>A SNP on the pharmacokinetics of fluvastatin, pravastatin and simvastatin.

AIMS: This study aimed to investigate possible effects of the ABCG2 c.421C>A (p.Gln141Lys; rs2231142) genotype on fluvastatin, pravastatin and simvastatin pharmacokinetics. MATERIALS & METHODS: In a crossover study, five healthy volunteers with the ABCG2 c.421A/A genotype, four with the c.421C/A genotype and 23 with the c.421C/C genotype ingested a single 40-mg dose of fluvastatin, pravastatin and simvastatin, with a washout period of 1 week. Plasma statin concentrations were measured up to 12 h. RESULTS: The estimated marginal mean area under the plasma concentration-time curve from 0 h to infinity (AUC(0-infinity)) of fluvastatin was 97% (p = 0.015) or 72% (p = 0.009) larger in participants with the A/A genotype than in those with the C/A or C/C genotype. The AUC(0-infinity) of simvastatin lactone was 111% (p = 0.005) larger in participants with the A/A genotype than in participants with the C/C genotype. The simvastatin acid:lactone AUC(0-infinity) ratio was 46% (p = 0.017) smaller in individuals with the A/A genotype than in those with the C/C genotype. The ABCG2 genotype had no significant effect on simvastatin acid or pravastatin pharmacokinetics. CONCLUSIONS: Genetic variability in ABCG2 markedly affects the pharmacokinetics of fluvastatin and simvastatin lactone, but has no significant effect on pravastatin or active simvastatin acid. Genotyping for ABCG2 in addition to SLCO1B1 and ABCB1 polymorphisms could help in predicting statin pharmacokinetics when selecting a statin and its dose for an individual patient.

Effect of drug transporter genotypes on pravastatin disposition in European- and African-American participants.

OBJECTIVE: Our aims were to evaluate the effects of polymorphisms in the hepatic drug uptake transporter organic anion transporting polypeptide 1B1 (OATP1B1, SLCO1B1) and efflux transporters multidrug resistance-associated protein 2 (MRP2, ABCC2), bile salt export pump (BSEP, ABCB11), and breast cancer-related protein (BCRP, ABCG2) on single-dose pravastatin pharmacokinetics in healthy European- and African-American participants. METHODS: The pharmacokinetics of a single oral 40 mg dose of pravastatin was determined in 107 participants (69 European-Americans and 38 African-Americans). Participants were genotyped for known OATP1B1, MRP2, BSEP, and BCRP polymorphisms. Baseline serum total and unconjugated plasma bilirubin concentrations were also determined. RESULTS: OATP1B1 genotypes were ethnicity-dependent with a 521C allele frequency of approximately 15% in European-Americans and approximately 1% in African-Americans. SLCO1B1 521TC genotype was associated with significantly higher pravastatin area under the curve [AUC(0-5)] (P=0.01) and Cmax values (P<0.05). When analyzed by diplotype, SLCO1B1*1a/*15 (N=8) participants exhibited 45 and 80% higher AUC values than SLCO1B1*1a/*1a (N=29) (P=0.013) and SLCO1B1*1b/*1b (N=34) (P=0.001) carriers, respectively. SLCO1B1*15/*15 (N=2) participants exhibited 92 and 149% higher AUC values than SLCO1B1*1a/*1a (P=0.017) and SLCO1B1*1b/*1b (P=0.011) carriers, respectively. European-Americans had significantly higher plasma pravastatin AUC(0-5) (P=0.01) and Cmax values (P=0.009) than African-Americans. Neither ABCC2, ABCB11, nor ABCG2 genotypes were associated with differences in pravastatin pharmacokinetics. We did not observe an effect of SLCO1B1 genotype on baseline total or unconjugated bilirubin levels. CONCLUSION: SLCO1B1 genotype, in particular the 521C allele, had a significant effect on the pharmacokinetics of pravastatin. Even when adjusted for the presence of the SLCO1B1 521C or 388G variant allele, European-Americans demonstrated significantly higher pravastatin AUC and Cmax values than African-Americans.

Blockade of adaptive defensive changes in cholesterol uptake and synthesis in AML by the addition of pravastatin to idarubicin + high-dose Ara-C: a phase 1 study.

Following exposure to cytotoxic agents, acute myeloid leukemia (AML) blasts elevate cellular cholesterol in a defensive adaptation that increases chemoresistance, but blockade of HMG-CoA reductase with statins restores chemosensitivity in vitro. This phase 1 study evaluated adding pravastatin (PV) (40-1680 mg/day, days 1-8) to idarubicin (Ida) ([12 mg/ (M2 x day), days 4-6]) + high-dose cytarabine (Ara-C; HDAC) [1.5 g/(M2 x day) by CI, days 4-7] in 15 newly diagnosed and 22 salvage patients with unfavorable (n = 26) or intermediate (n = 10) prognosis cytogenetics. Compared with historical experience with Ida-HDAC, the duration of neutropenia and throbmbocytopenia and the toxicity profile were unaffected by the addition of PV. During PV loading (day 0-4) serum triglyceride and total and LDL cholesterol levels decreased in nearly all patients. Pharmacokinetic studies demonstrated higher and more sustained serum PV levels with PV doses above 1280 mg/day. CR/CRp was obtained in 11 of 15 new patients, including 8 of 10 with unfavorable cytogenetics, and 9 of 22 salvage patients. An MTD for PV + Ida-HDAC was not reached. Addition of PV to Ida-HDAC was safe, and the encouraging response rates support conducting further trials evaluating the effect of cholesterol modulation on response in AML.

SLCO1B1 polymorphism and sex affect the pharmacokinetics of pravastatin but not fluvastatin.

OBJECTIVE: Pravastatin is a hydrophilic substrate and fluvastatin a lipophilic substrate of the hepatic uptake transporter organic anion transporting polypeptide 1B1 encoded by SLCO1B1. Our aim was to compare the effects of SLCO1B1 polymorphism on the pharmacokinetics of pravastatin and fluvastatin. METHODS: We recruited 4 healthy volunteers (3 men and 1 woman) with the homozygous SLCO1B1 c.521CC genotype, 12 (7 men and 5 women) with the heterozygous c.521TC genotype, and 16 (8 men and 8 women) with the homozygous c.521TT genotype (control subjects). In a crossover study each subject ingested a single 40-mg dose of fluvastatin and pravastatin with a washout period of at least 1 week. Plasma fluvastatin and pravastatin concentrations were measured for 12 hours. RESULTS: In men with the c.521CC genotype, the mean peak concentration in plasma and area under the plasma concentration-time curve from time 0 to infinity of pravastatin were 274% (95% confidence interval [CI], 92%-456%; P = .001) and 232% (95% CI, 74%-391%; P = .002) greater than those in men with the c.521TT genotype and 120% (95% CI, 11%-230%; P = .026) and 102% (95% CI, 3%-200%; P = .040) greater than those in men with the c.521TC genotype. In addition, women with the c.521TT genotype had a 147% (95% CI, 12%-281%; P = .028) greater peak concentration in plasma and a 142% (95% CI, 7%-242%; P = .034) greater area under the plasma concentration-time curve from time 0 to infinity than men with the c.521TT genotype. The pharmacokinetic variables of pravastatin were approximately similar among women with different SLCO1B1 genotypes. No significant differences were seen in the pharmacokinetics of fluvastatin between subjects with different SLCO1B1 genotypes or between the sexes. CONCLUSIONS: SLCO1B1 polymorphism has a large effect on the pharmacokinetics of pravastatin but not fluvastatin. This suggests that the lipophilic fluvastatin can penetrate the hepatocyte plasma membrane via passive diffusion or that uptake transporters other than organic anion transporting polypeptide 1B1 mainly mediate its hepatic uptake. Moreover, the results suggest that sex may affect the pharmacokinetics of pravastatin and possibly the functional consequences of SLCO1B1 polymorphism.

Pravastatin prolongs graft survival in an allogeneic rat model of orthotopic single lung transplantation.

OBJECTIVE: MHC class II molecules play central roles in immune recognition and rejection. As statins have been shown to inhibit the production of these molecules, we analyzed the possible immunosuppressive effect of pravastatin, using our rat model of orthotopic lung transplantation. METHODS: Single orthotopic lung transplantation was performed in a Fischer 344-to-Wistar Kyoto strain combination. One group received pravastatin i.p. after transplantation, controls NaCl. Statin serum levels were analyzed by high performance liquid chromatography (HPLC). Animals were sacrificed on postoperative day (POD) 14 and 21. At sacrifice, samples were obtained for histology, immunhistochemistry, flow cytometry and real-time RT-PCR analysis of CD25, TNF-alpha, and MHC class II expression. Rejection was graded via histochemistry, using a system based on the working formulation of The International Society of Heart and Lung Transplantation. Immunohistochemistry was performed for expression of MHC class II, T-cell receptor, CD25, CD4/8 cell, NK cells, granulocytes and monocytes in naïve lungs and grafts from donor and recipient animals. Flow cytometric analysis of recipient peripheral blood mononuclear cells (PBMC) was used to analyze expression of CD3, CD4, CD8, and RT1B in both groups. In vitro analyses of MHC class II expression were performed in parallel. RESULTS: HPLC confirmed effective delivery of pravastatin. Recipients treated with pravastatin showed significantly less rejection on POD 14 and on POD 21, when compared to controls. Immunohistochemistry showed specific differences, suggesting a delay in rejection in the pravastatin group. Flow cytometric analyses showed a higher expression of CD4 in the control group on POD 21. Results of real-time RT-PCR analyses for MHC class II expression showed a significant decrease in expression in the statin-treated group. Flow cytometric analysis of gamma-IFN stimulated rat PBMC showed an inhibition of upregulation of MHC class II expression by pravastatin in vitro. CONCLUSIONS: Pravastatin prolongs graft survival in our allogeneic rat model of orthotopic lung transplantation. We assume that the underlying mechanism for this effect is the inhibition of upregulation of MHC class II molecule synthesis, thus blocking downstream effector mechanisms of the immune system.