Joint use of population pharmacokinetics and machine learning for prediction of valproic acid plasma concentration in elderly epileptic patients.

BACKGROUND: Valproic acid (VPA) is a commonly used broad-spectrum antiepileptic drug. For elderly epileptic patients, VPA plasma concentrations have a considerable variation. We aim to establish a prediction model via a combination of machine learning and population pharmacokinetics (PPK) for VPA plasma concentration. METHODS: A retrospective study was performed incorporating 43 variables, including PPK parameters. Recursive Feature Elimination with Cross-Validation was used for feature selection. Multiple algorithms were employed for ensemble model, and the model was interpreted by Shapley Additive exPlanations. RESULTS: The inclusion of PPK parameters significantly enhances the performance of individual algorithm model. The composition of categorical boosting, light gradient boosting machine, and random forest (7:2:1) with the highest R2 (0.74) was determined as the ensemble model. The model included 11 variables after feature selection, of which the predictive performance was comparable to the model that incorporated all variables. CONCLUSIONS: Our model was specifically tailored for elderly epileptic patients, providing an efficient and cost-effective approach to predict VPA plasma concentration. The model combined classical PPK with machine learning, and underwent optimization through feature selection and algorithm integration. Our model can serve as a fundamental tool for clinicians in determining VPA plasma concentration and individualized dosing regimens accordingly.

Cyclosporine-A induced cytotoxicity within HepG2 cells by inhibiting PXR mediated CYP3A4/CYP3A5/MRP2 pathway.

Cyclosporine-A (CsA) is currently used to treat immune rejection after organ transplantation as a commonly used immunosuppressant. Liver injury is one of the most common adverse effects of CsA, whose precise mechanism has not been fully elucidated. Pregnane X receptor (PXR) plays a critical role in mediating drug-induced liver injury as a key regulator of drug and xenobiotic clearance. As a nuclear receptor, PXR transcriptionally upregulates the expression of drug-metabolizing enzymes and drug transporters, including cytochrome P4503A (CPY3A) and multidrug resistance-associated protein 2 (MRP2). Our study established CsA-induced cytotoxic hepatocytes in an in vitro model, demonstrating that CsA dose-dependently increased the aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) level secreted in the HepG2 cell supernatant, as well as viability and oxidative stress of HepG2 cells. CsA also dose-dependently decreased the PXR, CYP3A4, CPY3A5, and MRP2 levels of HepG2 cells. Mechanistically, altering the expression of PXR, CYP3A4, CYP3A5, and MRP2 affected the impact of CsA on AST and LDH levels. Moreover, altering the expression of PXR also changed the level of CYP3A4, CPY3A5, and MRP2 of HepG2 cells treated by CsA. Our presented findings provide experimental evidence that CsA-induced liver injury is PXR tightly related. We suggest that PXR represents an attractive target for therapy of liver injury due to its central role in the regulation of the metabolizing enzymes CYP3A and MRP2-mediated bile acid transport and detoxification.

Tacrolimus inhibits insulin release and promotes apoptosis of Min6 cells through the inhibition of the PI3K/Akt/mTOR pathway.

As a calcineurin inhibitor, tacrolimus is commonly used as a first­line immunosuppressant in organ transplant recipients. Post­transplantation diabetes mellitus (PTDM) is a common complication following kidney transplantation and is associated with immunosuppressant drugs, such as tacrolimus. PTDM caused by tacrolimus may be related to its influence on insulin secretion and insulin resistance. However, the specific mechanism has not been fully elucidated. The aim of the present study was to investigate whether the PI3K/Akt/mTOR signaling pathway served an important role in the pathogenesis of PTDM induced by tacrolimus. In the present study, the Cell Counting Kit­8 assay was used to measure the effect of tacrolimus on the viability of Min6 mouse insulinoma cells. The effects of tacrolimus on the insulin secretion and the activity of caspase­3 of Min6 cells stimulated by glucose exposure were measured by ELISA. Superoxide dismutase (SOD) and malondialdehyde (MDA) levels were measured using WST­8 and thiobarbituric acid assays, respectively. The effects of tacrolimus on the mRNA expression levels of PI3K, Akt and mTOR were detected by reverse transcription­quantitative PCR (RT­qPCR), whereas the protein expression levels of PI3K, Akt, mTOR, phosphorylated (p)­AKT and p­mTOR in Min6 cells were assessed using western blotting. The present data indicated that, compared with the control group, 5, 25 and 50 ng/ml tacrolimus treatment could inhibit the insulin secretion of Min6 cells stimulated by glucose solution, and 50 ng/ml tacrolimus could notably decrease the stimulation index (P<0.05). Moreover, 50 ng/ml tacrolimus markedly increased the activity of caspase­3 by 175.1% (P<0.05), it also decreased the SOD activity (P<0.01) and increased MDA levels (P<0.05). The RT­qPCR results demonstrated that the mRNA expression levels of PI3K, Akt and mTOR were downregulated by 25 and 50 ng/ml tacrolimus (P<0.01). Furthermore, the western blotting results suggested that tacrolimus had no significant effects on the expression levels of total PI3K, Akt and mTOR proteins (P>0.05), but 25 and 50 ng/ml tacrolimus could significantly inhibit the expression levels of p­Akt and p­mTOR (P<0.01). In conclusion, tacrolimus decreased the activity and insulin secretion of pancreatic ß cells and induced the apoptosis of islet ß cells by inhibiting the mRNA expression levels of PI3K, Akt and mTOR and reducing the phosphorylation of Akt and mTOR proteins in the PI3K/Akt/mTOR signaling pathway, which may ultimately lead to the occurrence of diabetes mellitus, and may be considered as one of the specific mechanisms of PTDM caused by tacrolimus.

Long-Term Influence of CYP3A5, CYP3A4, ABCB1, and NR1I2 Polymorphisms on Tacrolimus Concentration in Chinese Renal Transplant Recipients.

BACKGROUND: The highly pharmacokinetic variability of tacrolimus makes it difficult to adjust the dose. In the current study, we investigated the influence of gene polymorphisms and other clinical factors on long-term tacrolimus dosing in Chinese renal transplant recipients. METHODS: A total of 276 renal transplant recipients were enrolled. The tacrolimus trough concentration and other clinical variables were recorded for 5 years following transplantation. Eight single nucleotide polymorphisms in four genes (CYP3A5, CYP3A4, ABCB1, and NR1I2) were genotyped using polymerase chain reaction-restriction fragment length polymorphism analysis and sequencing. The dose-adjusted tacrolimus trough concentrations were calculated and compared among patients according to allelic status. RESULTS: The alleles CYP3A5*3 and CYP3A4*18B were significantly associated with dose-adjusted tacrolimus blood trough concentrations and had a strong time-genotype interaction with tacrolimus pharmacokinetics. NR1I2 g.7635A>G had a significant interaction with time, but the dose-adjusted tacrolimus concentration did not significantly differ over 5 years posttransplantation, except for the GG genotype of NR1I2 g.7635A>G. Sex differences had an important influence on tacrolimus concentration during the later post-transplantation period. CONCLUSIONS: The interindividual variability of tacrolimus concentration appears to be due in part to the effects of these identified genetic variants and clinical characteristics. Thus, genotyping of the CYP3A4 and CYP3A5 genes should be considered with respect to determining tacrolimus dose regimens during the post-transplantation period.

Recruitment and enrollment of African Americans and Caucasians in a health promotion trial for persons with serious mental illness.

African Americans with serious mental illness (SMI) continue to experience inadequate representation in clinical trials. Persons with SMI, regardless of race, have an increased burden of all cardiovascular disease (CVD) risk factors including obesity, hypertension, diabetes mellitus, dyslipidemia, metabolic syndrome and tobacco smoking. Having SMI and being African American, however, is each associated with an increased risk of CVD mortality compared to the general population. There is a critical need, therefore, to adapt health promotion interventions for African Americans with SMI. We sought to examine overall recruitment into a randomized clinical trial of CVD prevention among persons with SMI, and to examine racial differences in interest, enrollment, and potential barriers to participation. Although similar levels of interest in participation were seen between African Americans and Caucasians in signing screening consent, 9.6% fewer African Americans enrolled due to inability to complete initial data collection. Further work is needed to better understand the nature of the barriers encountered by African Americans with SMI who otherwise may be interested in participating within clinical trials.

Perceptions of health system orientation: quality, patient centeredness, and cultural competency.

As part of a pragmatic trial to reduce hypertension disparities, we conducted a baseline organizational assessment to identify aspects of organizational functioning that could affect the success of our interventions. Through qualitative interviewing and the administration of two surveys, we gathered data about health care personnel's perceptions of their organization's orientations toward quality, patient centeredness, and cultural competency. We found that personnel perceived strong orientations toward quality and patient centeredness. The prevalence of these attitudes was significantly higher for these areas than for cultural competency and varied by occupational role and race. Larger percentages of survey respondents perceived barriers to addressing disparities than barriers to improving safety and quality. Health care managers and policy makers should consider how we have built strong quality orientations and apply those lessons to cultural competency.

Association of CYP3A4*18B and CYP3A5*3 polymorphism with cyclosporine-related liver injury in Chinese renal transplant recipients.

OBJECTIVE: The purpose of this study was to investigate the associations between CYP3A4*18B and CYP3A5*3 polymorphism and cyclosporine-related liver injuries in Chinese renal transplant recipients. METHODS: We genotyped 339 renal transplant recipients treated with a triple immunosuppressive regimen including cyclosporine for CYP3A4*18B and CYP3A5*3 polymorphism using the polymerase chain reaction restriction fragment length polymorphism assay. RESULTS: The incidence of liver injury in the study population was 36.9% (125/339). At 1 month after transplantation, the trough concentration of cyclosporine (C0) in the group with CYP3A4*1/*1(GG alleles) was significantly higher than in the group with CYP3A4*18B/*1 8B(AA alleles) (p < 0.05). At 3 months after transplantation, the C0 in the group with CYP3A4*1/*1 and group with CYP3A4*1/*18B was markedly higher than in the group with CYP3A4*18B/*18B (p < 0.05). The GG genotypes of CYP3A4*18B were more common in the liver injury group compared with the control group (p < 0.05). Univariate logistic regression analysis showed that subjects carrying the GG genotypes had a 5.136- and 2.528-fold higher risk of developing cyclosporine-related liver injury than those with the AA and GA genotypes. When adjusted for sex, the risk of the CYP3A4*18B genotypes was OR = 4.969 for GG compared to AA (p = 0.030), and OR = 2.634 for GG compared to GA (p = 0.025). However, no association was observed between CYP3A5*3 polymorphisms with cyclosporine-related liver injury. CONCLUSIONS: These results suggested that the wild type of CYP3A4*18B is a risk factor for the development of cyclosporine- related liver injuries in Chinese renal transplant recipients.

Influence of bedsharing activity on breastfeeding duration among US mothers.

IMPORTANCE: Some professional associations advocate bedsharing to facilitate breastfeeding, while others recommend against it to reduce the risk of sudden infant death syndrome and suffocation deaths. A better understanding of the quantitative influence of bedsharing on breastfeeding duration is needed to guide policy. OBJECTIVE: To quantify the influence of bedsharing on breastfeeding duration. DESIGN, SETTING, AND PARTICIPANTS: Longitudinal data were from the Infant Feeding Practices Study II, which enrolled mothers while pregnant and followed them through the first year of infant life. Questionnaires were sent at infant ages 1 to 7, 9, 10, and 12 months, and 1846 mothers answered at least 1 question regarding bedsharing and were breastfeeding at infant age 2 weeks. EXPOSURES: Bedsharing, defined as the mother lying down and sleeping with her infant on the same bed or other sleeping surfaces for nighttime sleep or during the major sleep period. MAIN OUTCOMES AND MEASURES: Survival analysis to investigate the effect of bedsharing on duration of any and exclusive breastfeeding. RESULTS: Longer duration of bedsharing, indicated by a larger cumulative bedsharing score, was associated with a longer duration of any breastfeeding but not exclusive breastfeeding, after adjusting for covariates. Breastfeeding duration was longer among women who were better educated, were white, had previously breastfed, had planned to breastfeed, and had not returned to work in the first year postpartum. CONCLUSIONS AND RELEVANCE: Multiple factors were associated with breastfeeding, including bedsharing. Given the risk of sudden infant death syndrome related to bedsharing, multipronged strategies to promote breastfeeding should be developed and tested.

Cigarette Smoking and Health Characteristics in Individuals With Serious Mental Illness Enrolled in a Behavioral Weight Loss Trial.

Objective: Cigarette smoking is the most preventable cause of disease and death in the US. We examined the prevalence of smoking and the association between smoking status and health characteristics in persons with serious mental illness. Methods: A total of 291 overweight or obese adults with serious mental illness were enrolled in a behavioral weight loss trial. Cigarette smoking, co-occurring medical diagnoses, dietary intake, blood pressure, cardiovascular fitness, body mass index, quality of life, and psychiatric symptoms were assessed at baseline in 2008-2011. Fasting glucose and lipid markers were measured from blood samples. Cardiovascular risk profile was calculated based on the global Framingham Health Study Risk Equation. Results: A total of 128 (44%) of participants were current smokers or had smoked in the previous one year. The smokers had significantly higher diastolic blood pressure and blood triglyceride levels, and lower HDL cholesterol than the nonsmokers, adjusted for age, sex, education, and diagnosis. They were more likely to have a history of emphysema, and had a 10-year cardiovascular disease risk of 13.2%, significantly higher than the 7.4% in the nonsmokers. The smokers also had elevated ratings of psychopathology on the BASIS-24 scale. Smokers did not differ from nonsmokers in cardiovascular fitness, body mass index, depression, quality of life, or other comorbid medical diagnoses. There was no characteristic in which smokers appeared healthier than nonsmokers. Conclusions: The prevalence of smoking in this contemporary cohort of individuals with serious mental illness who were motivated to lose weight was more than twice that in the overall population. Smokers had more indicators of cardiovascular disease and poorer mental health than did nonsmokers. The high burden of comorbidity in smokers with serious mental illness indicates a need for broad health interventions.

Racial patterns of cardiovascular disease risk factors in serious mental illness and the overall U.S. population.

BACKGROUND: Serious mental illness (SMI) and minority race are each associated with elevated cardiovascular disease (CVD) mortality. However, little is known about racial variation in CVD risk factors in individuals with SMI. This study aimed to determine racial patterns of CVD risk factors in individuals with SMI and to compare these patterns to those of the general population. METHODS: Overweight/obese adults with SMI (163 whites; 111 African Americans) examined from 2008 to 2011 during a weight loss trial were compared at study baseline to overweight/obese adults (1103 whites; 550 African Americans) of similar age, sex, and race in the 2007 to 2010 National Health and Nutrition Examination Survey. RESULTS: All CVD risk factors except cholesterol were higher in SMI than the overall U.S. population. After adjusting for age and sex, both racial groups with SMI had similarly high risks of smoking, obesity, diabetes, and hypertension, while African Americans with SMI had lower risks of high cholesterol (RR 0.73; 95% CI 0.57-0.94) and metabolic syndrome (RR 0.75; 95% CI 0.63-0.91) than whites with SMI. In the U.S. population sample, African Americans compared to whites had higher risks of obesity (RR 1.23; 95% CI 1.14-1.34), diabetes (RR 1.68; 95% CI 1.21-2.34), and hypertension (RR 1.44; 95% CI 1.31-1.60) but no significant difference in smoking, high cholesterol, and metabolic syndrome. CONCLUSIONS: Compared to the general population, the greater burden and dissimilar racial pattern of CVD risk factors in SMI underscore the need for CVD prevention programs targeting the SMI population.

In vivo effect of Schisandrin B on cytochrome P450 enzyme activity.

To investigate the possible drug interaction, this study is designed to evaluate the ability of Schisandrin B (Sch B) to modulate cytochrome P450 3A activity (CYP3A) in vivo and to alter the pharmacokinetic profiles of CYP3A substrate (midazolam) in treated rats. Rats were repeated administered with physiological saline (negative control group), ketoconazole (75 mg/kg, positive control group) or varied doses of Sch B (experimental groups) for three consecutive days. Subsequently, changes in hepatic microsomal CYP3A activity and the pharmacokinetic profiles of midazolam and 1'-hydroxy midazolam in plasma were studied to evaluate CYP3A activity. The results indicated that Sch B significantly dose-dependently inhibited rat hepatic microsomal CYP3A activity with Ki value of 16.64 mg/kg and showed the characteristic of a noncompetitive inhibitor. Oral administration of Sch B for 3 days in rats produced significant effect on the pharmacokinetics of oral midazolam. Sch B resulted in a significant, dose-dependent increase in midazolam AUC0-∞ except at the dose of 2 mg/kg, while AUC0-∞ increased by 26.1% (8 mg/kg) and 60.6% (16 mg/kg), respectively. In the pharmacokinetic profiles of 1'-hydroxy midazolam, the significant, dose-dependent decrease in AUC0-∞ was observed except at the dose of 2 mg/kg, while AUC0-∞ reduced by 44.5% (8 mg/kg) and 49.2% (16 mg/kg), respectively. These results suggested that 3-day treatment of Sch B could increase concentration and oral bioavailability of drug metabolized by CYP3A. When the drug, consisting of Sch B, is used in the clinic for more than 3 days, the possible drug-drug interactions should be taken into consideration.

A behavioral weight-loss intervention in persons with serious mental illness.

BACKGROUND: Overweight and obesity are epidemic among persons with serious mental illness, yet weight-loss trials systematically exclude this vulnerable population. Lifestyle interventions require adaptation in this group because psychiatric symptoms and cognitive impairment are highly prevalent. Our objective was to determine the effectiveness of an 18-month tailored behavioral weight-loss intervention in adults with serious mental illness. METHODS: We recruited overweight or obese adults from 10 community psychiatric rehabilitation outpatient programs and randomly assigned them to an intervention or a control group. Participants in the intervention group received tailored group and individual weight-management sessions and group exercise sessions. Weight change was assessed at 6, 12, and 18 months. RESULTS: Of 291 participants who underwent randomization, 58.1% had schizophrenia or a schizoaffective disorder, 22.0% had bipolar disorder, and 12.0% had major depression. At baseline, the mean body-mass index (the weight in kilograms divided by the square of the height in meters) was 36.3, and the mean weight was 102.7 kg (225.9 lb). Data on weight at 18 months were obtained from 279 participants. Weight loss in the intervention group increased progressively over the 18-month study period and differed significantly from the control group at each follow-up visit. At 18 months, the mean between-group difference in weight (change in intervention group minus change in control group) was -3.2 kg (-7.0 lb, P=0.002); 37.8% of the participants in the intervention group lost 5% or more of their initial weight, as compared with 22.7% of those in the control group (P=0.009). There were no significant between-group differences in adverse events. CONCLUSIONS: A behavioral weight-loss intervention significantly reduced weight over a period of 18 months in overweight and obese adults with serious mental illness. Given the epidemic of obesity and weight-related disease among persons with serious mental illness, our findings support implementation of targeted behavioral weight-loss interventions in this high-risk population. (Funded by the National Institute of Mental Health; ACHIEVE ClinicalTrials.gov number, NCT00902694.).

Image-guided stereotactic radiosurgery for locally advanced pancreatic adenocarcinoma results of first 85 patients.

BACKGROUND: Locally advanced unresectable pancreatic adenocarcinoma is characterized by poor survival despite chemotherapy and conventional radiation therapy (RT). Recent advances in real-time image-guided stereotactic radiosurgery (SRS) have made it possible to treat these cancers in two to four fractions followed by systemic chemotherapy. AIMS: The aims of this study includes the following: (1) obtain local control of the disease; (2) improve the survival of these unresectable patients; (3) evaluate the toxicity of SRS; and (4) report results of the largest series from a single center. METHODS: Pancreatic SRS involves delivery of high doses of accurately targeted radiation given non-invasively in two to four fractions. We treated 85 consecutive patients with locally advanced and recurrent pancreatic adenocarcinoma from February 2004 to November 2009. Age range: 36-88 years, median 66 years; sex: 50 males, 35 females; race: 79 Caucasian, five African American, one Asian; histology: 80 adenocarcinoma, three islet cell, two other. Pre-SRS staging: T(3-4) 85; N(+) 16, N(x) 57, N(0) 12; M(0) 64, M(1) 21. All patients were unresectable at the time of SRS. Seventy-one had no prior surgical resection, and 14 had local recurrence after prior surgical resection. Twenty-nine patients had progression of disease after prior conventional RT. Location of the tumor: head, 57; body and tail, 28. Pre-SRS chemotherapy was given in 48 patients. All patients received gemcitabine-based chemotherapy regimen after SRS. Median tumor volume was 60 cm(3). PET/CT scans done in 55 patients were positive in 52 and negative in three patients. Average maximum standard uptake value was 6.9. Pain score on a scale of 1-10 was: 0-3 in 54, 4-7 in 18, and 8-10 in 13 patients. SRS doses ranged from 15 to 30 Gy with a mean dose of 25.5 Gy delivered in 3 days divided in equal fractions. Mean conformality index was 1.6, and mean isodose line was 80%. RESULTS: Tumor control: complete, partial, and stable disease were observed in 78 patients for the duration of 3-36 months with median of 8 months. Pain relief was noted in majority of patients lasting for 18-24 weeks. Most of the patients died of distant disease progression while their primary tumor was controlled. Overall median survival from diagnosis was 18.6 months and from SRS it was 8.65 months. For the group of 35 patients with adenocarcinoma without prior surgical resection or RT and no distant metastases, the average and 1-year survival from diagnosis was 15 months and 50%, respectively, and from SRS it was 11.15 months and 30.5%, respectively. TOXICITY: A total of 19 (22.37%) patients developed grades III/IV GI toxicity including duodenitis, 12 (14.1%); gastritis, 11 (12.9%); diarrhea, three (3.5%); and renal failure was noted in one (1.2%). Three patient had both gastritis and duodenitis. Toxicity was significantly more prevalent in the first 40 patients compared with the last 45 patients (32.5 vs 13.9%). CONCLUSIONS: SRS for unresectable pancreatic carcinoma can be delivered in three fractions with minimal morbidity and a local tumor control rate of 91.7%. The survival is comparable or better than the reported results for advanced pancreatic cancer, specifically for the group of previously untreated patients with unresectable tumors. Development of distant metastases remains a significant factor.

Association between inosine triphosphate pyrophosphohydrolase deficiency and azathioprine-related adverse drug reactions in the Chinese kidney transplant recipients.

Azathioprine (AZA) is a thiopurine prodrug commonly used in patients with kidney transplantation. The aim of this study is to explore in patients with kidney transplantation whether AZA-related side effects can be explained by the inosine triphophate pyrophosphatase (ITPA) or thiopurine S-methyltransferase (TPMT) polymorphisms using both pheno-and genotyping. Erythrocyte ITPA and TPMT activity of 155 patients with kidney transplantation and AZA therapy was determined by HPLC. The frequencies of ITPA and TPMT polymorphisms were detected. Among 155 patients, three cases with zero activity were homozygote for 94C>A. The allele frequency of the 94C>A polymorphism was 0.12. Allele for the IVS2+21A>C mutation in the patients of this study was not found. Thirty-five cases had stopped azathioprine medication or were on reduced dose due to AZA-related side effects, including hematotoxicity (n = 12), hepatotoxicity (n = 18), gastrointestinal toxicity (n = 5, one patient developed hepatotoxicity simultaneously) and flu-like symptoms (n = 1). No statistical significant associations between ITPA 94C>A phenotype or genotype and AZA-related hematotoxicity or hepatotoxicity could be detected. However, five patients who developed gastrointestinal disturbance, two patients were homozygote for 94C>A and other three patients had 94C>A heterozygous allele. The patient who experienced flu-like symptoms were the remaining homozygote for 94C>A. This study demonstrates that ITPA activity reduced in patients with 94C>A mutation (P < 0.01). Patients with ITPA 94C>A homozygous allele are at high risk to develop AZA-related gastrointestinal toxicity and flu-like symptoms (P < 0.01). TPMT wild-type/ITPA variant (homozygote) is closely related to the AZA-induced side effects (P < 0.01).

Effects of Schisandra sphenanthera extract on the pharmacokinetics of midazolam in healthy volunteers.

AIMS: To assess the effect of Schisandra sphenanthera extract (SchE) on the pharmacokinetics of midazolam, a probe drug of CYP3A, and its metabolite 1'-hydroxy midazolam in healthy volunteers. METHODS: Twelve healthy male volunteers were orally treated with SchE, three capsules twice daily for 7 days. Pharmacokinetic investigations of oral midazolam administration at 15 mg were performed both before and at the end of the SchE treatment period. The plasma midazolam and 1'-hydroxy midazolam concentrations were determined by high-performance liquid chromatography-tandem mass spectrometry. Estimated pharmacokinetic parameters before and with SchE were calculated with noncompartmental techniques. RESULTS: Following administration of SchE, the average increases (%) of individual increases in AUC, AUMC and C(max) of midazolam were 119.4% [95% confidence interval (CI) 83.9, 155.0], 183.4% (95% CI 120.5, 246.2) and 85.6% (95% CI 14.4, 156.9), respectively (P < 0.01 or 0.05). On average, there was a 133.3% (95% CI 8.9, 257.7) increase in midazolam t(max) (P < 0.01). The average decrease (%) in CL/F was 52.1% (95% CI 44.9, 59.4) (P < 0.01). No significant changes were seen in midazolam half-life. After co-administration of SchE, the average increase (%) in t(max) of 1'-hydroxy midazolam was 150.0% (95% CI 22.2, 277.8) (P < 0.05). No significant differences were observed in the other pharmacokinetic parameters of 1'-hydroxy midazolam. CONCLUSIONS: SchE can markedly increase the oral bioavailability of midazolam in healthy volunteers. SchE is an inhibitor of CYP3A and has a high susceptibility to alter the disposition of drugs metabolized by CYP3A.

Relationships between thiopurine S-methyltransferase polymorphism and azathioprine-related adverse drug reactions in Chinese renal transplant recipients.

OBJECTIVE: To systematically investigate the relationships between thiopurine S-methyltransferase (TPMT) polymorphisms and azathioprine-related adverse drug reactions in patients with kidney transplantation. METHODS: Erythrocyte TPMT activity of 150 patients with kidney transplantation and AZA therapy was determined by HPLC. The frequency of four common TPMT mutant alleles, TPMT*2, *3A, *3B, and *3C was determined by allele-specific PCR and PCR-restriction fragment length polymorphism (PCR-RFLP) analysis. RESULTS: Thirty cases (20%) had stopped azathioprine medication or were on reduced dose due to azathioprine-related side effects. The TPMT activity range of cases who never experienced side effects was 16.63-68.25 U, the mean of the controls was 38.43 +/- 11.59 U. The mean value of 12 cases with hematotoxicity was 23.50 +/- 10.33 U, much lower than the control mean (P < 0.05). No significant difference between the mean value of 18 cases with hepatotoxicity and the control mean (P > 0.05) was seen. No case with TPMT deficiency was found in all patients studied, and TPMT*2, *3A, and *3B were not detected in any of them. TPMT*3C heterozygous alleles were found in 4.7% (seven cases) of these patients, all seven cases had intermediate TPMT activity, and the mean was 16.75 +/- 2.09 U, much lower than other TPMT wild-type patients (P < 0.05). In the seven TPMT*3C patients, four cases experienced side effects (hematotoxicity, n = 2; hepatotoxicity, n = 2). CONCLUSIONS: This study demonstrates that TPMT activity is reduced in patients with TPMT*3C mutation. AZA-induced hematotoxicity is related to the reduced TPMT activity.

Effects of Schisandra sphenanthera extract on the pharmacokinetics of tacrolimus in healthy volunteers.

AIM: To assess the effect of Schisandra sphenanthera extract (SchE) on the pharmacokinetics of tacrolimus in healthy volunteers. METHODS: Twelve healthy male volunteers were orally treated with SchE, three capsules twice daily for 13 days. Pharmacokinetic investigations of oral tacrolimus administration at 2 mg were performed both before and at the end of the SchE treatment period. Whole blood tacrolimus concentrations were determined by enzyme-linked immunosorbent assay. Estimated pharmacokinetic parameters before and with SchE were calculated with noncompartmental techniques. RESULTS: Following administration of SchE, the average percentage increases of individual increases in AUC, AUMC and C(max) of tacrolimus were 164.2% [95% confidence interval (CI) 70.1, 258.4], 133.1% (95% CI 49.5, 261.3) and 227.1% (95% CI 155.8, 298.4), respectively (P < 0.01 or 0.05). On average, there was a 36.8% (95% CI 13.4, 60.2) increase in tacrolimus t(max) (P < 0.01). The average percentage decreases in CL/F and V/F were 49.0% (95% CI 31.1, 66.9) and 53.7% (95% CI 40.1, 67.4), respectively (P < 0.01). CONCLUSIONS: SchE can increase the oral bioavailability of tacrolimus. The results of this study will add important information to the interaction area between drugs and herbal products.

Quantify single nucleotide polymorphism (SNP) ratio in pooled DNA based on normalized fluorescence real-time PCR.

BACKGROUND: Conventional real-time PCR to quantify the allele ratio in pooled DNA mainly depends on PCR amplification efficiency determination and Ct value, which is defined as the PCR cycle number at which the fluorescence emission exceeds the fixed threshold. Because of the nature of exponential calculation, slight errors are multiplied and the variations of the results seem too large. We have developed a new PCR data point analysis strategy for allele ratio quantification based on normalized fluorescence ratio. RESULTS: In our method, initial reaction background fluorescence was determined based upon fitting of raw fluorescence data to four-parametric sigmoid function. After that, each fluorescence data point was first subtracted by respective background fluorescence and then each subtracted fluorescence data point was divided by the specific background fluorescence to get normalized fluorescence. By relating the normalized fluorescence ratio to the premixed known allele ratio of two alleles in standard samples, standard linear regression equation was generated, from which unknown specimens allele ratios were extrapolated using the measured normalized fluorescence ratio. In this article, we have compared the results of the proposed method with those of baseline subtracted fluorescence ratio method and conventional Ct method. CONCLUSION: Results demonstrated that the proposed method could improve the reliability, precision, and repeatability for quantifying allele ratios. At the same time, it has the potential of fully automatic allelic ratio quantification.

Dual-probe assay for detection of lamivudine-resistance hepatitis B virus by real-time PCR.

A rapid and accurate minor groove binder (MGB) real-time PCR is described for detection lamivudine resistance mutations in hepatitis B virus. The real-time PCR was compared with direct Sanger sequencing in 53 clinical patients samples, the results of the real-time PCR correlate with the nucleotide sequence and the assay has the advantage of detecting a mixture of quasi-species with higher sensitivity than sequencing. As a simple, easy, rapid, accurate and high throughout method, MGB real-time PCR assay should be useful for detecting lamivudine resistance variants during lamivudine therapy in clinical settings.