Population pharmacokinetics and dosing optimization of olanzapine in Chinese paediatric patients: Based on the impact of sex and concomitant valproate on clearance.

WHAT IS KNOWN AND OBJECTIVE: Olanzapine is an atypical antipsychotic drug used for mental disorders. There are limited studies providing sufficient pharmacokinetic data, thus the variability of concentrations of olanzapine used in Chinese paediatric patients aged 10 to 17 years remains to be evaluated. METHODS: Therapeutic drug monitoring data were collected from 151 paediatric patients aged 10 to 17 years who received olanzapine. The model was developed with a NONMEM software program. The final model validation and evaluation were assessed by bootstrap, diagnostic scatter plots, and normalized prediction distribution error (NPDE). Regimens of different dosages were simulated to reach the target concentration levels of 20 ng/ml, by using the final model with typical parameters. RESULTS: The one-compartment model was considered the best fit for the data. Typical estimates of the absorption rate constant (Ka), apparent clearance (CL/F), and apparent distribution volume (V/F) in the final model were 0.142 h-1 , 15.4 L/h, and 322 L, respectively. Sex and concomitant valproate (VPA) were included as significant predictors of olanzapine clearance, which was described by the following equation: CL/F = 15.4 × (1 + 0.546 × SEX) × (1 + 0.264 × VPA). Results of Monte-Carlo simulation suggested that male paediatric patients with concomitant VPA were advised to take no less than 15 mg per day of olanzapine orally, and in female paediatric patients with concomitant VPA, a dosing regimen of 10 mg may be sufficient to achieve the therapeutic range of olanzapine. WHAT IS NEW AND CONCLUSION: Our results identified concomitant valproate and sex as significant covariates in olanzapine population pharmacokinetics. Our model may be a useful tool for recommending dosage adjustments for physicians. The pharmacokinetics of olanzapine in patients aged 10 to 17 years was generally similar to that of adults and the elderly.

Combined oncolytic adenovirus carrying MnSOD and mK5 genes both regulated by survivin promoter has a synergistic inhibitory effect on gastric cancer.

Gastric cancer (GC) is one of the major causes of cancer-related mortality. The use of oncolytic virus for cancer gene-virotherapy is a new approach for the treatment of human cancers. In this study, a novel Survivin promoter-driven recombinant oncolytic adenovirus carrying mK5 or MnSOD gene was constructed, which was modified after deletion of the E1B gene. Human plasminogen Kringle 5 mutant (mK5) and manganese superoxide dismutase (MnSOD) are both potential tumor suppressor genes. By constructing Ad-Surp-mK5 and Ad-Surp-MnSOD oncolytic adenoviruses, we hypothesized that the combination of the two viruses would enhance the therapeutic efficacy of GC as compared to the one virus alone. The results of the in vitro experiments revealed that the combination of adenovirus carrying mK5 and MnSOD gene exhibited stronger cytotoxicity to GC cell lines as compared to the virus alone. Additionally, the virus could selectively kill cancer cells and human somatic cells. Cell staining, flow cytometry, and western blot analysis showed that the combination of two adenoviruses containing therapeutic genes could promote the apoptosis of cancer cells. In vivo experiments further verified that Ad-Surp-mK5 in combination with Ad-Surp-MnSOD exhibited a significant inhibitory effect on the growth of GC tumor xenograft as compared to the virus alone, and no significant difference was observed in the bodyweight of treatment and the normal mice. In conclusion, the combination of our two newly constructed recombinant oncolytic adenoviruses containing mK5 or MnSOD therapeutic genes could significantly inhibit gastric cancer growth by inducing apoptosis, suggestive of its potential for GC therapy.

Optimization of the Administration Strategy for the Armed Oncolytic Adenovirus ZD55-IL-24 in Both Immunocompromised and Immunocompetent Mouse Models.

ZD55-IL-24 is an armed oncolytic adenovirus similar but superior to ONYX-015. Virotherapeutic strategies using ZD55-IL-24 have been demonstrated to be effective against several cancer types. However, it is unclear whether the traditional administration strategy is able to exert the maximal antitumor efficacy of ZD55-IL-24. In this study, we sought to optimize the administration strategy of ZD55-IL-24 in both A375-bearing immunocompromised mouse model and B16-bearing immunocompetent mouse model. Although the underlying antitumor mechanisms are quite different, the obtained results are similar in these two mouse tumor models. We find that the antitumor efficacy of ZD55-IL-24 increases as injection times increase in both of these two models. However, no obvious increase of efficacy is observed as the dose of each injection increases. Our further investigation reveals that the administration strategy of sustained ZD55-IL-24 therapy can achieve a better therapeutic effect than the traditional administration strategy of short-term ZD55-IL-24 therapy. Furthermore, there is no need to inject every day; every 2 or 3 days of injection achieves an equivalent therapeutic efficacy. Finally, we find that the sustained rather than the traditional short-term ZD55-IL-24 therapy can synergize with anti-PD-1 therapy to reject tumors in B16-bearing immunocompetent mouse model. These findings suggest that the past administration strategy of ZD55-IL-24 is in fact suboptimal and the antitumor efficacy can be further enhanced through administration strategy optimization. This study might shed some light on the development of clinically applicable administration regimens for ZD55-IL-24 therapy.

Enhanced anti-melanoma efficacy through a combination of the armed oncolytic adenovirus ZD55-IL-24 and immune checkpoint blockade in B16-bearing immunocompetent mouse model.

Although the recent treatment in melanoma through the use of anti-PD-1 immunotherapy is successful, the efficacy of this approach remains to be improved. Here, we explore the feasibility of combination strategy with the armed oncolytic adenovirus ZD55-IL-24 and PD-1 blockade. We find that combination therapy with localized ZD55-IL-24 and systemic PD-1 blockade leads to synergistic inhibition of both local and distant established tumors in B16-bearing immunocompetent mouse model. Our further mechanism investigation reveals that synergistic therapeutic effect is associated with marked promotion of tumor immune infiltration and recognition in both local and distant tumors as well as spleens. PD-1 blockade has no obvious effect on promotion of tumor immune infiltration and recognition. Localized therapy with ZD55-IL-24, however, can help PD-1 blockade to overcome the limitation of relatively low tumor immune infiltration and recognition. This study provides a rationale for investigation of such combination therapy in the clinic.

[Effect of acupoint thread-embedding on macrophage polarization of epididymis adipose tissue in obese mice].

OBJECTIVE: To observe the effect of acupoint thread-embedding at "Zusanli" (ST 36) and "Fenglong" (ST 40) on the macrophage polarization of epididymis adipose tissue in obese mice, and to explore the action mechanism of acupoint thread-embedding on weight control. METHODS: Among 30 male C57BL/6 mice, 10 mice were randomly selected and fed with normal diet, and the remaining 20 mice were fed with high-fat diet to establish the obesity model. Sixteen mice with successful obesity model were randomly divided into a model group and an acupoint thread-embedding group, 8 mice in each group. Eight mice were selected from mice which were fed with normal diet as the normal group. On the next day of successful modeling, acupoint thread-embedding was performed at "Zusanli" (ST 36) and "Fenglong" (ST 40) in the acupoint thread-embedding group, once every 10 days for 4 times. The body weight was recorded at 0, 8, 16, 24, 32, 40 days into intervention; the level of glucose metabolism was compared after intervention; the level of lipid metabolism and weight of epididymal adipose tissue were compared at the end of the intervention; the mRNA expression of M1 and M2 macrophage-related cytokines interleukin-10 (IL-6), monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10) were detected by real-time PCR; the mRNA and protein expression of M1 macrophage labeled inducible nitric oxide synthase (iNOS) and M2 macrophage labeled arginase-1 (Arg-1) were detected by real-time PCR and Western blot. RESULTS: Compared with the normal group, the body weight at 0, 8, 16, 24, 32, 40 days into intervention in the model group was increased (P<0.05); the results of glucose tolerance test at 0, 30, 60, 120 min and insulin tolerance test at 0, 30, 60, 90, 120 min in the model group were higher than those in the normal group (P<0.05); the levels of total cholesterol and triacylglycerol in the model group were significantly higher than those in the normal group (P<0.001, P<0.01); the weight of epididymal adipose tissue in the model group was significantly higher than that in the normal group (P<0.001); the mRNA expression of IL-6, MCP-1, TNF-α and iNOS was increased (P<0.05, P<0.01, P<0.001), that of IL-10, Arg-1 was decreased (P<0.01), the protein expression of iNOS was up-regulated (P<0.01), and that of Arg-1 was down-regulated (P<0.001). Compared with the model group, the body weight at 16, 24, 32, 40 days into treatment in the acupoint thread-embedding group was reduced (P<0.05); the results of glucose tolerance test at 30, 60, 120 min and insulin tolerance test at 30, 60 min in the acupoint thread-embedding group were lower than those in the model group (P<0.05); the levels of total cholesterol and triacylglycerol in the acupoint thread-embedding group were significantly lower than those in the model group (P<0.01, P<0.05); the weight of epididymal adipose tissue in the acupoint thread-embedding group was significantly lower than that in the model group (P<0.01); the mRNA expression of IL-6, MCP-1, TNF-α and iNOS was reduced (P<0.05), that of IL-10, Arg-1 was increased (P<0.05), the protein expression of iNOS was down-regulated (P<0.05), and that of Arg-1 was up-regulated (P<0.01). CONCLUSION: Acupoint thread-embedding at "Zusanli" (ST 36) and "Fenglong" (ST 40) may play a role in weight control by regulating the polarization of macrophages.

The armed oncolytic adenovirus ZD55-IL-24 eradicates melanoma by turning the tumor cells from the self-state into the nonself-state besides direct killing.

ZD55-IL-24 is similar but superior to the oncolytic adenovirus ONYX-015, yet the exact mechanism underlying the observed therapeutic effect is still not well understood. Here we sought to elucidate the underlying antitumor mechanism of ZD55-IL-24 in both immunocompetent and immunocompromised mouse model. We find that ZD55-IL-24 eradicates established melanoma in B16-bearing immunocompetent mouse model not through the classic direct killing pathway, but mainly through the indirect pathway of inducing systemic antitumor immunity. Inconsistent with the current prevailing view, our further results suggest that ZD55-IL-24 can induce antitumor immunity in B16-bearing immunocompetent mouse model in fact not due to its ability to lyse tumor cells and release the essential elements, such as tumor-associated antigens (TAAs), but due to its ability to put a "nonself" label in tumor cells and then turn the tumor cells from the "self" state into the "nonself" state without tumor cell death. The observed anti-melanoma efficacy of ZD55-IL-24 in B16-bearing immunocompetent mouse model was practically caused only by the viral vector. In addition, we also notice that ZD55-IL-24 can inhibit tumor growth in B16-bearing immunocompetent mouse model through inhibiting angiogenesis, despite it plays only a minor role. In contrast to B16-bearing immunocompetent mouse model, ZD55-IL-24 eliminates established melanoma in A375-bearing immunocompromised mouse model mainly through the classic direct killing pathway, but not through the antitumor immunity pathway and anti-angiogenesis pathway. These findings let us know ZD55-IL-24 more comprehensive and profound, and provide a sounder theoretical foundation for its future modification and drug development.

Effect of venlafaxine dosage, valproic acid concentration, sex, and age on steady state dose-corrected concentrations of venlafaxine and O-desmethylvenlafaxine: A retrospective analysis of therapeutic drug monitoring data in a Chinese population.

PURPOSE: This study aimed to investigate the influence of diagnosis, body weight, sex, age, smoking, formulations, and concomitant drugs on steady-state dose-corrected serum concentrations (C/D) of venlafaxine (VEN) and O-desmethylvenlafaxine (ODV). METHODS: A retrospective analysis of therapeutic drug monitoring (TDM) was carried out. Patients' demographic data, therapeutic regimens, and concentrations were collected. RESULTS: We included 91 verified samples from 80 patients. Females had by average 13% smaller body weight, 50% higher C/D of VEN, and VEN + ODV and 25% smaller ODV/VEN than males. Patients >60 years had by average 33-59% higher C/D levels of ODV and VEN + ODV than younger patients. The concomitant use of valproic acid caused an average 51% higher C/D of ODV and a 2.2-fold larger ODV/VEN, while clozapine was related with 40% smaller ratio of ODV/VEN and 38% lower C/D levels of ODV. Positive correlations were detected between valproic acid concentrations and the C/D of VEN and VEN + ODV. In a multiple linear regression analysis, variance in the C/D of VEN + ODV was partly attributed to the daily dose of VEN, sex, age and valproic acid concentration. CONCLUSION: Our results suggested daily dose of VEN, sex, age, and valproic acid as indicators for the C/D of VEN + ODV in Chinese patients. TDM as a valuable tool was suggested in elderly female patients and patients receiving polypharmacy.

A Retrospective Analysis of Steady-State Olanzapine Concentrations in Chinese Patients Using Therapeutic Drug Monitoring: Effects of Valproate and Other Factors.

BACKGROUND: The objective of this study was to investigate the serum concentrations of olanzapine in relation to age, sex, and other factors in Chinese patients aged between 10 and 90 years. METHODS: Data for 884 olanzapine patients, deposited between 2016 and 2017, were retrieved from the therapeutic drug monitoring database of the Affiliated Brain Hospital of Guangzhou Medical University. The effects of covariates on serum olanzapine concentration, dose-normalized concentration (C/D ratio), and normalized concentration (C/D/weight) were investigated. RESULTS: Generally, male patients had lower olanzapine concentration, C/D ratio, and C/D/weight than female patients (P < 0.001). Smoking and drinking reduced olanzapine concentration, C/D ratio, and C/D/weight (P < 0.001). Coadministration with valproate decreased olanzapine concentration, C/D ratio, and C/D/weight by about 16%, 30%, and 40%, respectively (P < 0.001). Patients younger than 60 years had higher olanzapine concentrations (P < 0.05) but lower C/D ratios and C/D/weight (P < 0.001) than patients older than 60 years. Age was correlated with olanzapine concentration (r = -0.082, P < 0.05), C/D ratio (r = 0.196, P < 0.001), and C/D/weight (r = 0.169, P < 0.001). Sample timing after dose and diagnostic factors also contributed to the olanzapine concentrations. Multiple linear regression analysis revealed significant influences of dosage, age, sex, valproate comedication, smoking, postdose interval, and schizophrenia (vs bipolar affective disorders) on serum olanzapine concentrations. CONCLUSIONS: The metabolism of olanzapine may be altered by several factors. Patients characterized with a combination of factors may benefit from therapeutic drug monitoring for the adjustment of olanzapine dose to minimize adverse reactions.

Effects of Comedication and Genetic Factors on the Population Pharmacokinetics of Lamotrigine: A Prospective Analysis in Chinese Patients With Epilepsy.

Lamotrigine (LTG) is a second-generation anti-epileptic drug widely used for focal and generalized seizures in adults and children, and as a first-line medication in pregnant women and women of childbearing age. However, LTG pharmacokinetics shows high inter-individual variability, thus potentially leading to therapeutic failure or side effects in patients. This prospective study aimed to establish a population pharmacokinetics model for LTG in Chinese patients with epilepsy and to investigate the effects of genetic variants in uridine diphosphate glucuronosyltransferase (UGT) 1A4, UGT2B7, MDR1, ABCG2, ABCC2, and SLC22A1, as well as non-genetic factors, on LTG pharmacokinetics. The study population consisted of 89 patients with epilepsy, with 419 concentrations of LTG. A nonlinear mixed effects model was implemented in NONMEM software. A one-compartment model with first-order input and first-order elimination was found to adequately characterize LTG concentration. The population estimates of the apparent volume of distribution (V/F) and apparent clearance (CL/F) were 12.7 L and 1.12 L/h, respectively. The use of valproic acid decreased CL/F by 38.5%, whereas the co-administration of rifampicin caused an increase in CL/F of 64.7%. The CL/F decreased by 52.5% in SLC22A1-1222AA carriers. Patients with the ABCG2-34AA genotype had a 42.0% decrease in V/F, whereas patients with the MDR1-2677TT and C3435TT genotypes had a 136% increase in V/F. No obvious genetic effect of UGT enzymes was found relative to the concentrations of LTG in Chinese patients. Recommended dose regimens for patients with different gene polymorphisms and comedications were estimated on the basis of Monte Carlo simulations and the established model. These findings should be valuable for developing individualized dosage regimens in adult and adolescent Chinese patients 13-65 years of age.

Meta-analysis of the Efficacy and Safety of Adjunctive Rosuvastatin for Dyslipidemia in Patients with Schizophrenia.

BACKGROUND: Metabolic syndrome in patients with schizophrenia is a major health concern. The efficacy and safety of adjunctive rosuvastatin in treating dyslipidemia were controversial. AIMS: To assess the efficacy and safety of adjunctive rosuvastatin for dyslipidemia in patients with schizophrenia. METHODS: We systematically searched for relevant controlled clinical trials from the following databases: PubMed, PsycINFO, Cochrane Library, China Knowledge Network, WanFang Database and Chinese Biomedical Database up to September 28, 2017. Standardized mean difference (SMD) and risk ratio (RR) along with their 95% confidence intervals (CIs) were calculated. The quality of the included studies was assessed using the Cochrane risk of bias assessment tool. The GRADE (Grades of Recommendation, Assessment, Development, and Evaluation) system recommendation grading method was used as the reference standard. RESULTS: Four studies (n=274) comparing rosuvastatin (n=138) and control (n=136) groups were identified and analyzed. Adjunctive rosuvastatin showed greater efficacy than control group in low density lipoprotein cholesterol (LDL-C) [4 trials, n=272, SMD: -1.31 (95%CI: -1.93, -0.70), I2=81%], total cholesterol (2 trials, n=164, SMD: -2.00 (95%CI: -2.79, -1.21); I2=76%) and triglycerides (2 trials, n=164, SMD: -1.05 (95%CI: -1.38, -0.72); I2=0%), but not in high density lipoprotein cholesterol (2 trials, n=164, SMD: 0.14 (95%CI: -0.16, 0.45); I2=0%). After removing one study without randomization for LDL-C, significance remained [3 trials, n=172, SMD:-1.07 (95%CI: -1.60, -0.53); I2=63%]. No significant group differences regarding body weight (3 trials, n=208, SMD: -0.40 (95%CI:-1.29, 0.49); I2=89%), body mass index (2 trials, n=164, SMD: -0.34 (95%CI: -1.23, 0.56); I2=87%), waist circumference (3 trials, n=208, SMD): -0.43 (95%CI: -1.31, 0.46); I2=89%), and fasting glucose (4 trials, n=272, SMD: -0.25 (95%CI: -0.65, 0.15); I2=62%) were observed. The adverse reactions and any cause discontinuation rate were similar between the groups. According to the GRADE approach, the evidence levels of main outcomes were rated as "very low" (35.3%) to "low" (64.7%). Of them, the primary outcome (LDL-C) was rated as "very low ". CONCLUSIONS: The data available on the effectiveness and safety of adjunctive rosuvastatin in treating dyslipidemia for patients with schizophrenia is insufficient to come to a definitive interpretation about its efficacy and safety. Further high quality RCTs with extended treatment duration are warranted to confirm the findings. REVIEW REGISTRATION: PROSPERO: CRD42017078230.

Effects of Risperidone and Aripiprazole on Serum Levels of Prolactin, Testosterone and Estradiol in Female Patients with Schizophrenia.

OBJECTIVE: To evaluate the effects of treatment with risperidone and aripiprazole on serum prolactin, testosterone and estradiol levels in female patients with schizophrenia in China. METHODS: In the retrospective study, Data were collected and included prolactin, testosterone and estradiol levels of 30 female patients with risperidone monotherapy. In the prospective study, Another 30 female schizophrenic patients were randomized to receive risperidone or adjunctive aripiprazole for six weeks. Serum prolactin, testosterone and estradiol levels were measured. RESULTS: Serum prolactin, testosterone and estradiol levels in both studies were significantly decreased after risperidone treatment compared with baseline (P<0.05), and prolactin levels remained at a high level. Serum prolactin levels in the adjunctive aripiprazole group were significantly decreased after treatment compared with baseline in the prospective study (P<0.05). Doses of 5 mg and 10 mg of adjunctive aripiprazole achieved the same efficacy at the end of treatment. CONCLUSIONS: Risperidone treatment decreased serum testosterone and estradiol levels. Adjunctive aripiprazole relieved hyperprolactinemia, but had no effect on testosterone or estradiol levels. Adjunctive aripiprazole at a dose of 5 mg is recommended for clinical use.

Effects of food and grapefruit juice on single-dose pharmacokinetics of blonanserin in healthy Chinese subjects.

PURPOSE: The purpose of this study was to investigate the potential effects of a meal and grapefruit juice on the pharmacokinetics of blonanserin and its metabolite N-desethyl blonanserin in healthy Chinese volunteers. METHODS: This was a single-centre, open-label, fixed-sequence study, where 12 healthy Chinese volunteers received a single dose of 8 mg blonanserin after an overnight fast in period 1 (reference), a high-fat meal during period 2 and with co-administration of 250 mL of grapefruit juice in period 3. The washout period was 7 days. Series of plasma samples were collected after each dose to determine concentrations of blonanserin and its metabolite N-desethyl blonanserin using liquid chromatography-tandem mass spectrometry. Pharmacokinetic parameters were estimated by non-compartmental analysis and compared between periods by standard average bioequivalence ANOVA. Adverse events were monitored throughout the study. RESULTS: All subjects completed the study. High-fat meals significantly increased blonanserin exposure (AUCt) 2.58-fold (90% CI 2.21, 3.02), relative to the reference period. Co-administration of blonanserin with grapefruit juice remarkably prolonged elimination half-life of blonanserin (from 9.7 to 21.4 h) and significantly increased exposures to blonanserin and N-desethyl blonanserin by 5.82-fold (90% CI 4.57, 7.42) and 1.81-fold (90% CI 1.65, 1.98), respectively. CONCLUSIONS: These results suggested that blonanserin was largely metabolised in the intestinal tract before becoming systemically available, and both food and grapefruit juice enhanced exposure to blonanserin and N-desethyl blonanserin. Grapefruit juice increased bioavailability and may have reduced systemic clearance of blonanserin. Further intestinal CYP3A4 and hepatic CYP3A4 might be postulated to explain the delayed elimination of blonanserin. Dose adjustment of blonanserin is needed on the basis of co-intake of known strong CYP3A4 inhibitor. Patients taking high-dose blonanserin also need to be cautious about the ingestion of grapefruit juice.

A Simple HPLC-MS/MS Method for Determination of Tryptophan, Kynurenine and Kynurenic Acid in Human Serum and its Potential for Monitoring Antidepressant Therapy.

The kynurenine pathway, in which tryptophan is metabolized to kynurenine and kynurenic acid, has been linked to depression. A rapid and highly reproducible liquid-chromatography-tandem mass spectrometry (LC-MS/MS) method were established for determining tryptophan, kynurenine and kynurenic acid in human serum. Biological samples were precipitated with methanol before separation on an Agilent Eclipse XDB-C18. The stable-isotope-labeled internal standards (kynurenine-13C415N and kynurenic acid-d5) were used for quantification. Detection was performed using multiple reaction monitoring in electrospray ionization mode at m/z 205.1→188.1 for tryptophan, m/z 209.1→146.1 for kynurenine, m/z 190.1→144.1 for kynurenic acid. Good linearity of analyte to internal standard peak area ratios was seen in the concentration range 1,000-50,000 ng/mL for tryptophan, 100-5,000 ng/mL for kynurenine and 1-60 ng/mL for kynurenic acid. Pooled drug-free human serum was purified using activated charcoal and the method was shown to be linear, with validation parameters within acceptable limits. The newly developed method was successfully used to determine concentrations of tryptophan, kynurenine and kynurenic acid in serum from 26 healthy volunteers and 54 patients with depression. Concentrations of tryptophan and kynurenine were lower in serum from depressed individuals than from healthy individuals.

Development and validation of a sensitive LC-MS/MS assay for the quantification of nizatidine in human plasma and urine and its application to pharmacokinetic study.

We developed and validated a high performance liquid chromatographic method coupled with triple quadrupole mass spectrometry for analysis of nizatidine in human plasma and urine. The biological samples were precipitated with methanol before separation on an Agilent Eclipse Plus C18 column (100mm×46mm, 5µm) with a mixture of methanol and water (95:5, plus 5mM ammonium formate) as the mobile phase at 0.5mL/min. Detection was performed using multiple reaction monitoring modes via electrospray ionization (ESI) at m/z 332.1→155.1 (for nizatidine) and m/z 335.1→155.1 (for [(2)H3]-nizatidine, the internal standard). The linear response range was 5-2000ng/mL and 0.5-80µg/mL for human plasma and urine, with the lower limits of quantification of 5ng/mL and 0.5µg/mL, respectively. The method was validated according to the biological method validation guidelines of the Food and Drug Administration and proved acceptable. This newly developed analytical method was successfully applied in a pharmacokinetic study following single oral administration of a 150mg nizatidine capsule in to 16 healthy Chinese subjects. Maximum and endpoint concentrations in plasma and urine were quantifiable, suggesting our method is appropriate for routine pharmacokinetic analysis.

A rapid LC-MS/MS quantification of peramivir using a simple and inexpensive sample precipitation: application to PK.

AIM: Peramivir is a newly approved selective neuraminidase inhibitor designed to inhibit influenza virus infection. METHODOLOGY/RESULTS: We report a robust and sensitive method utilizing simple precipitation extraction with LC-MS/MS for the high-throughput quantification. Addition of 0.06 M of ammonium formate and 0.1% formic acid in mobile phase could help reduce the matrix effect. This method uses 100 µl of plasma and covers a linear concentration range from 5 to 10,000 ng/ml. Other validation parameters are also evaluated and meet regulatory expectations by US FDA guidelines. CONCLUSION: The developed HPLC-MS/MS method has been successfully applied to support a clinical pharmacokinetic study. The strategy presented here can be applied elsewhere and may be useful for other amphiphilic drugs.

Simultaneous determination of pirfenidone and its metabolite in human plasma by liquid chromatography-tandem mass spectrometry: application to a pharmacokinetic study.

A simple and rapid analytical method for the simultaneous determination of pirfenidone and its metabolite, 5-carboxy-pirfenidone, in human plasma using liquid chromatography-tandem mass spectrometry has been developed and validated. Aliquots of plasma (0.1 mL) containing pirfenidone and 5-carboxy-pirfenidone, as well as deuterium-labeled internal standards (ISs), were deproteinized using acetonitrile. An Agilent Zorbax Plus C18 column was used for the chromatography, with isocratic elution. The mobile phase was a mixture of acetonitrile and aqueous ammonium formate solution (5 mM) containing 0.1% formic acid (60 : 40, v/v). Using multiple reaction monitoring in positive ionization mode, transitions m/z 186.1 → 65.1, m/z 216.0 → 77.0, m/z 191.1 → 65.1 and m/z 221.0 → 81.0 were chosen to quantify pirfenidone, 5-carboxy-pirfenidone and the two ISs, respectively. The time of analysis was <3 min. The calibration curve was linear over the concentration ranges 0.005-25 µg/mL for pirfenidone, and 0.005-15 µg/mL for 5-carboxy-pirfenidone. The lower limit of quantification for both analytes was 0.005 µg/mL. The intra- and interday precision and relative errors in quality control samples were between -11.7 and 1.3% for pirfenidone and between -5.6 and 2.5% for 5-carboxy-pirfenidone, with mean recoveries ≥90%. The method that has been developed is easy to carry out, sensitive and rapid, and has been successfully used to investigate the pharmacokinetics of pirfenidone in healthy human volunteers.

Simultaneous determination of glimepiride and pioglitazone in human plasma by liquid chromatography-tandem mass spectrometry and its application to pharmacokinetic study.

The rapid, sensitive, and selective liquid chromatography-electrospray ionization-tandem mass spectrometry method (LC-ESI-MS/MS) for the simultaneous estimation and pharmacokinetic investigation of glimepiride and pioglitazone in human plasma has been developed and fully validated. Glimepiride and pioglitazone, compounds which exert synergistic effects on blood glucose control, were investigated in human plasma using deuterium-labeled analogs as internal standards (IS). Liquid-liquid extraction was carried out on 0.2 mL of human plasma using ethyl acetate, and chromatographic separation was performed on an Agilent Eclipse plus C18 column (4.6 mm × 100 mm, 3.5 µm) using a mobile phase consisting of methanol-water-formic acid (95:5:0.1, v/v/v, plus 5mM ammonium acetate) at a flow rate of 0.8 mL/min. To quantify glimepiride, pioglitazone and their IS, multiple reaction monitoring (MRM) transitions of m/z 491.2→352.2, m/z 496.2→357.2, m/z 357.2→134.2 and m/z 361.2→138.2 were performed in positive mode. The total run time was 3.0 min and the elution time was about 2.4 min. The method exhibited good separation of analytes, without interference from endogenous substances. The linear calibration curves were 0.2-250 ng/mL for glimepiride and 0.2-1,250 ng/mL for pioglitazone; the lower limit of quantification (LLOQ) was 0.2 ng/mL for both analytes. Intra- and inter-day reproducibility was less than 10% for glimepiride and less than 5% for pioglitazone, with relative errors ranging from -8.00% to 2.80% at the three concentrations of analytes used for quality control (QC). The matrix effect was negligible and recoveries were similar for each analyte and its IS. Glimepiride and pioglitazone were found to be stable under the assay conditions and the method was successfully applied to the evaluation of pharmacokinetic studies of glimepiride and pioglitazone, following oral doses of 2mg glimepiride tablets and 15 mg pioglitazone tablets to 16 healthy volunteers.

Bayesian analysis of perfusion-weighted imaging to predict infarct volume: comparison with singular value decomposition.

PURPOSE: We compared the performances of a Bayesian estimation method and oscillation index singular value decomposition (oSVD) deconvolution for predicting final infarction using data previously obtained from 10 cynomolgus monkeys with permanent unilateral middle cerebral artery (MCA) occlusion. METHODS: We conducted baseline perfusion-weighted imaging 3 hours after MCA occlusion and generated time to peak, first moment of transit, cerebral blood flow, cerebral blood volume, and mean transit time maps using Bayesian and oSVD methods. Final infarct volume was determined by follow-up diffusion-weighted imaging (DWI) scanned 47 hours after MCA occlusion and from histological specimens. We used a region growing technique with various thresholds to determine perfusion abnormality volume. The best threshold was defined when the mean perfusion volume matched the mean final infarct volume, and Pearson's correlation coefficients (r) and intraclass correlations (ICC) were calculated between perfusion abnormality and final infarct volume at that threshold. These coefficients were compared between Bayesian and oSVD using Wilcoxon's signed rank test. P-value < 0.05 was considered a statistically significant difference. RESULTS: The Pearson's correlation coefficients were larger but not significantly different for the Bayesian technique than oSVD in 4 of 5 perfusion maps when final infarct was determined by specimen volume (P = 0.104). When final infarct volume was defined by DWI volume, all perfusion maps had a significantly higher correlation coefficient by Bayesian technique than oSVD (P = 0.043). For ICC, all perfusion maps had higher value in Bayesian than oSVD calculation, and significant differences were observed both on specimen- and DWI-defined volumes (P = 0.043 for both). CONCLUSION: The Bayesian method is more reliable than oSVD deconvolution in estimating final infarct volume.

Determination of allopurinol and oxypurinol in human plasma and urine by liquid chromatography-tandem mass spectrometry.

Allopurinol is used widely for the treatment of gout, but its pharmacokinetics is complex and some patients show hypersensitivity, necessitating careful monitoring and improved detection methods. In this study, a sensitive and reliable liquid chromatography-tandem mass spectrometry method was developed to determine the concentrations of allopurinol and its active metabolite oxypurinol in human plasma and urine using 2,6-dichloropurine as the internal standard (IS). Analytes and the IS were extracted from 0.5ml aliquots of plasma or urine using ethyl acetate and separated on an Agilent Eclipse Plus C18 column using methanol and ammonium formate-formic acid buffer containing 5mM ammonium formate and 0.1% formic acid (95:5, v/v) as the mobile phase (A) for allopurinol or methanol plus 5mM ammonium formate aqueous solution (95:5, v/v) as the mobile phase (B) for oxypurinol. Allopurinol was detected in positive ion mode and the analysis time was about 7min. The calibration curve was linear from 0.05 to 5µg/mL allopurinol in plasma and 0.5-30µg/mL in urine. The lower limit of quantification (LLOQ) was 0.05µg/mL in plasma and 0.5µg/mL in urine. The intra- and inter-day precision and relative errors of quality control (QC) samples were ≤11.1% for plasma and ≤ 8.7% for urine. Oxypurinol was detected in negative mode with an analysis time of about 4min. The calibration curve was linear from 0.05 to 5µg/mL in plasma (LLOQ, 0.05µg/mL) and from 1 to 50µg/mL in urine (LLOQ, 1µg/mL). The intra- and inter-day precision and relative errors were ≤7.0% for plasma and ≤9.6% for urine. This method was then successfully applied to investigate the pharmacokinetics of allopurinol and oxypurinol in humans.

Prediction of infarct volume and neurologic outcome by using automated multiparametric perfusion-weighted magnetic resonance imaging in a primate model of permanent middle cerebral artery occlusion.

By optimizing thresholds, we identified the perfusion-weighted magnetic resonance imaging (PWI) parameters that accurately predict final infarct volume and neurologic outcome in a primate model of permanent middle cerebral artery (MCA) occlusion. Ten cynomolgus monkeys underwent PWI and diffusion-weighted imaging (DWI) at 3 and 47 hours, respectively, after right MCA occlusion using platinum coils, and were killed at 48 hours. Volumes of the hypoperfused areas on PWI were automatically measured using different thresholds and 11 parametric maps to determine the optimum threshold (at which least difference was found between the average volumes on PWI and those determined using specimens or DWI). In the case of arrival time (AT), cerebral blood volume (CBV), time to peak (TTP), time to maximum (T(max)), and cerebral blood flow (CBF) determined using deconvolution techniques, the volume of the hypoperfused area significantly correlated with the infarct volumes and the neurologic deficit scores with small variations, whereas in the case of mean transit time and nondeconvolution CBF, relatively poor correlations with large variations were seen. At optimum threshold, AT, CBV, TTP, T(max), and deconvolution CBF can accurately predict the final infarct volume and neurologic outcome in monkeys with permanent MCA occlusion.