Effects of Soy Isoflavones and Green Tea Extract on Simvastatin Pharmacokinetics and Influence of the SLCO1B1 521T > C Polymorphism.

Objectives: Green tea and soy products are extensively consumed by many people and they may influence the activity of drug metabolizing enzymes and drug transporters to result in drug interactions. This study was performed to evaluate the effect of green tea and soy isoflavone extracts on the pharmacokinetics of simvastatin in healthy subjects and to clarify the role of polymorphisms in the SLCO1B1 drug transporter in this effect. Methods: This was an open-label, three-phase randomized crossover pharmacokinetic study. A single dose of simvastatin 20 mg was taken on three occasions (without herbs, with green tea, and with soy isoflavones) by healthy male Chinese subjects. The green tea and soy isoflavone extracts were given at a dose containing EGCG 800 mg once daily or soy isoflavones about 80 mg once daily for 14 days before simvastatin dosing with at least 4-weeks washout period between phases. Results: All the 18 subjects completed the study. Intake of soy isoflavones was associated with reduced systemic exposure to simvastatin acid [geometric mean (% coefficient of variation) AUC0-24h from 16.1 (44.2) h⋅µg/L to 12.1 (54.6) h⋅µg/L, P < 0.05) but not the lactone. Further analysis showed that the interaction between simvastatin and the soy isoflavones only resulted in a significant reduction of AUC in subjects with the SLCO1B1 521TT genotype and not in those with the 521C variant allele. There was no overall effect of the green tea extract on simvastatin pharmacokinetics but the group with the SLCO1B1 521TT genotype showed reduced AUC values for simvastatin acid. Conclusion: This study showed repeated administration of soy isoflavones reduced the systemic bioavailability of simvastatin in healthy volunteers that was dependent on the SLCO1B1 genotype which suggested that soy isoflavones-simvastatin interaction is impacted by genotype-related function of this liver uptake transporter.

Effect of Green Tea Extract and Soy Isoflavones on the Pharmacokinetics of Rosuvastatin in Healthy Volunteers.

Background and Aim: Green tea and soy products are extensively consumed in daily life. Research has shown that green tea catechins and soy isoflavones may influence the activity of drug metabolizing enzymes and drug transporters. We examined whether regular consumption of green tea extract or soy isoflavones affected the pharmacokinetics of a single dose of rosuvastatin in healthy subjects and whether any interactions were influenced by the polymorphism in the drug transporter ABCG2. Study Design: This was an open-label, three-phase randomized crossover study with single doses of rosuvastatin. Methods: Healthy Chinese male subjects were given a single dose of rosuvastatin 10 mg on 3 occasions: 1. without herbs; 2. with green tea extract; 3. with soy isoflavone extract. The green tea and soy isoflavone extract were given at a dose containing EGCG 800 mg once daily or soy isoflavones-80 mg once daily for 14 days before statin dosing and at the same time as the statin dosing with at least 4-weeks washout period between phases. Results: Twenty healthy male subjects completed the study and the intake of green tea extract significantly reduced the systemic exposure to rosuvastatin by about 20% reducing AUC0-24h from [geometric mean (% coefficient of variation)] 108.7 (28.9) h·µg/L to 74.1 (35.3) h·µg/L and Cmax from 13.1 (32.2) µg/L to 7.9 (38.3) µg/L (P < 0.001 for both), without affecting the elimination half-life. The ABCG2 421C>A polymorphism had a significant effect on rosuvastatin exposure but no impact on the interaction with green tea. Soy isoflavones had no significant effect on rosuvastatin pharmacokinetics. Conclusion: This study showed that repeated administration of green tea extract significantly reduced the systemic exposure of rosuvastatin in healthy volunteers. These effects might be predicted to either reduce or increase the lipid-lowering effect of rosuvastatin depending on the mechanism of the effect.

Telmisartan increases systemic exposure to rosuvastatin after single and multiple doses, and in vitro studies show telmisartan inhibits ABCG2-mediated transport of rosuvastatin.

PURPOSE: The ATP-binding cassette transporter G2 (ABCG2) plays an important role in the disposition of rosuvastatin. Telmisartan, a selective angiotension-II type 1 (AT1) receptor blocker, inhibits the transport capacity of ABCG2, which may result in drug interactions. This study investigated the pharmacokinetic interaction between rosuvastatin and telmisartan and the potential mechanism. METHODS: In this two-phase fixed-order design study, healthy subjects received single doses of 10 mg rosuvastatin at baseline and after telmisartan 40 mg daily for 14 days. Patients with hyperlipidaemia who had been taking rosuvastatin 10 mg daily for at least 4 weeks were given telmisartan 40 mg daily for 14 days together with rosuvastatin. Plasma concentrations of rosuvastatin were measured over 24 h before and after telmisartan administration. In vitro experiments using a bidirectional transport assay were performed to investigate the involvement of ABCG2 in the interaction. RESULTS: Co-administration of telmisartan significantly increased the maximum plasma concentration (C max) and the area under the plasma concentration-time curve (AUC) of rosuvastatin by 71 and 26 %, respectively. The T max values were reduced after administration of telmisartan. There was no significant difference in the interaction of rosuvastatin with telmisartan between healthy volunteers and patients receiving long-term rosuvastatin therapy or among subjects with the different ABCG2 421 C>A genotypes. The in vitro experiment demonstrated that telmisartan inhibited ABCG2-mediated efflux of rosuvastatin. CONCLUSION: This study demonstrated that telmisartan significantly increased the systemic exposure to rosuvastatin after single and multiple doses.

Effects of polymorphisms in ABCG2, SLCO1B1, SLC10A1 and CYP2C9/19 on plasma concentrations of rosuvastatin and lipid response in Chinese patients.

AIM: This study examined whether the ABCG2 421C>A polymorphism and variants in other genes potentially related to the pharmacokinetics of rosuvastatin influenced the plasma concentration of rosuvastatin in Chinese patients with hypercholesterolemia. PATIENTS & METHODS: Overnight fasting blood samples were collected from 291 patients who had received a rosuvastatin 10 mg night-time dose for at least 4 weeks. Plasma concentrations of rosuvastatin and N-desmethyl rosuvastatin were quantified using liquid chromatography tandem mass spectrometry. RESULTS: In subjects with the ABCG2 421AA genotype (n = 39), the mean plasma concentrations of rosuvastatin and its metabolite were 63 and 41% greater than the values in those with the 421CA genotype (n = 108) and 120 and 99% greater than in those with the 421CC genotype (n = 129). The plasma concentrations of rosuvastatin were associated (r = -0.194; p = 0.001) with the percentage reduction in low-density lipoprotein cholesterol with rosuvastatin, but the association was not significant after adjusting for the ABCG2 421C>A polymorphism. The SLCO1B1 521T>C polymorphism was associated with increased plasma concentrations of rosuvastatin and impaired N-demethylation of rosuvastatin, but had no impact on its lipid-lowering effect. Polymorphisms in CYP2C9, CYP2C19 and SLC10A1 had minimal effects. CONCLUSION: These findings suggest that the increased plasma concentrations of rosuvastatin in Chinese patients are associated with increased lipid-lowering effects and lower doses of rosuvastatin should be effective in subjects with the ABCG2 421C>A variant.

Electronic chemical pathology consultation service and dried blood spot metabolic screening in hospital patients.

AIM: Inborn errors of metabolism (IEM) are an unpopular and difficult subject and most clinicians are unfamiliar with them. Although chemical pathologists have a long-standing practice in advising test strategy and result interpretation especially from primary care, such consultations are usually informal, unstructured and those related to IEM are infrequently requested. This study aims to provide a formal electronic consultation service and to apply tandem mass spectrometry-based dried blood spot metabolic screening (DBSM) as a rapid first-line test for patients suspected of IEM. METHODS: DBSM and a chemical pathology consultation were ordered through the hospital computer terminals. DBSM detected 29 metabolic disorders. The clinical data and metabolic results for the 12-month period were reviewed. RESULTS: There were 279 consultations of which 209 were initiated by paediatricians and 70 by adult physicians. The main reasons for consultation were developmental delay, neurological abnormalities, unexplained biochemical abnormalities and monitoring of patients with IEM. There were 158 DBSM requests. One positive case of isovaleric acidaemia was detected. CONCLUSIONS: All high-risk paediatric patients should have a DBSM and a timely electronic chemical pathology consultation as a rapid and cost-effective first-line screening. Provision of a visible, accessible and helpful consultation service enables professional reimbursement.

Raloxifene for prevention of glucocorticoid-induced bone loss: a 12-month randomised double-blinded placebo-controlled trial.

OBJECTIVES: To study the efficacy of raloxifene in preventing bone mineral density (BMD) loss in women receiving long-term glucocorticoids (GC). The study took the form of a parallel-group randomised double-blinded placebo-controlled trial. METHODS: Postmenopausal women without hypercoagulability risk factors who were prevalent GC users were randomised to receive either raloxifene (60 mg/day) or placebo (1 tablet/day) on top of calcium (1000 mg/day) and calcitriol (0.25 µg/day). BMD of the hip and spine (primary outcome), bone turnover markers and new vertebral fractures (secondary outcomes) at month 12 were assessed. RESULTS: Between December 2006 and December 2008, 114 patients were recruited (age 55.3±7.7 years). The duration and dose of prednisolone received was 62.2±64 months and 6.7±5.9 mg/day, respectively. Baseline vertebral fracture was present in six (5%) patients. In all, 57 patients were allocated to each of the treatment arms. Demographic data, osteoporotic risk factors and BMD at various sites were similar between the two groups of patients. At month 12, a significant gain in the lumbar spine (+1.3±0.4%; p=0.004) and total hip BMD (+1.0±0.4%; p=0.01) was observed in patients treated with raloxifene but a significant decrease in BMD of the lumbar spine (-0.9±0.4%; p=0.045) and hip (-0.8±0.3%; p=0.01) occurred in the placebo group. The femoral neck BMD did not change significantly in favour of raloxifene. Three new fractures developed exclusively in the patients treated with placebo. Bone formation (serum osteocalcin and procollagen type I N-terminal) and resorption (urine deoxypyridinoline and type I collagen) markers decreased significantly in the raloxifene group but not in patients treated with placebo. Leg cramps were numerically more frequent in the raloxifene group (7% vs 0%) but thromboembolism was not reported in any patients. CONCLUSIONS: In postmenopausal women receiving long-term GCs, raloxifene is well tolerated and significantly increases spinal and hip BMD after 12 months of treatment.

Development of a broad toxicological screening technique for urine using ultra-performance liquid chromatography and time-of-flight mass spectrometry.

Withdrawal of the support for the REMEDi HS drug profiling system has necessitated its replacement within our laboratories with an alternative broad toxicological screening technique. To this end, a novel method, based on ultra-performance liquid chromatography (UPLC) and time-of-flight (TOF) mass spectrometry, was developed for the routine analysis of urine samples. Identification was achieved by comparison of acquired data to libraries containing more than 300 common drugs and metabolites, and was based on a combination of retention time, exact mass and fragmentation patterns. Validation data for the method is presented and comprised an evaluation of the following parameters: precision; transferability of the methodology between the six collaborating laboratories; specificity; extraction recovery and stability of processed samples; matrix effects and sensitivity. This paper presents the benefits of supplementary fragmentation data with particular regard to increasing specificity and confidence of identification and its usefulness with overdosed samples. The utility of the method was assessed by the parallel analysis of 30 authentic urine samples using the REMEDi HS and UPLC-TOF. The latter provided enhanced detection, leading to the identification of twice as many drugs. Furthermore it did not miss any compounds that were identified by REMEDi HS. The UPLC-TOF findings were further verified by a combination of data from three other conventional screening techniques, i.e., GC-MS, HPLC-DAD and UPLC-MS/MS.