Pneumatosis intestinalis post steroid use in a patient with immune-related adverse events: Case report, literature review and FAERS analysis.

Introduction: The accurate diagnosis of pneumatosis intestinalis (PI) is increasing despite patients' limited identification of etiologic factors. Recently a patient with lung squamous carcinoma who developed pneumatosis intestinalis following methylprednisolone administration for immune-related adverse events was treated at our hospital. Subsequent a literature review and an analysis of the FDA Adverse Event Reporting System (FAERS) database enabled the identification of additional cases of pneumatosis intestinalis. Methods: A literature review of the MEDLINE/PubMed and Web of Science Core Collection databases using standard pneumatosis intestinalis search terms to identify published cases of immune checkpoint inhibitors (ICIs) or steroids causing pneumatosis intestinalis were performed. A separate retrospective pharmacovigilance study of FAERS enabled the extraction of unpublished cases of pneumatosis intestinalis between the first quarter of 2005 and the third quarter of 2022. Disproportionality and Bayesian analyses were performed to identify signal detection in reported odds ratios, proportional reporting ratios, information components, and empirical Bayesian geometric means. Results: Ten case reports of steroid-related pneumatosis intestinalis were retrieved from six published studies. The implicated drug therapies included pre-treatment with steroids before chemotherapy, combination therapy with cytotoxic agents and steroids, and monotherapy with steroids. In the FAERS pharmacovigilance study, 1,272 cases of immune checkpoint inhibitors or steroid-related pneumatosis intestinalis were incidentally reported. The signal detected in five kinds of immune checkpoint inhibitors and six kinds of steroids implied a positive correlation between the drugs and adverse events. Conclusion: Steroids might be the etiologic factors in the current case of pneumatosis intestinalis. Reports supporting the role of steroids in suspected cases of pneumatosis intestinalis can be found in literature databases and the FAERS database. Even so, as documented in FAERS, immune checkpoint inhibitors-induced pneumatosis intestinalis should not be excluded.

Pharmacovigilance Bibliometrics: Visualizing Thematic Development in the Category of Pharmacology and Pharmacy in Web of Science.

Introduction: Pharmacovigilance studies include monitoring and preventing the occurrence of new, rare, or serious adverse drug reactions, making it possible to discover new safety issues without delay. Bibliometrics could assist scholars to analyze the development of pharmacovigilance. Methods: The MeSH terms of both pharmacovigilance and "adverse drug reaction reporting system" were retrieved in the Science Citation Index Expanded. The articles from 1974 to July 2021 in the pharmacology and pharmacy category were recruited. The citation reports including the publication numbers, h-index, and sum and average cited times in terms of annuals, countries, organizations, authors and journals were tabulated. The coauthorship relations in the analysis units of countries, organizations, and authors; the top 10 burst references; the document citation network; and the author's keywords co-occurrence overlay map were visualized by bibliometric software including the website (https://bibliometric.com/), VOSviewer, CiteSpace, and CitNetExplorer. Results: From 1974 to the present, the most high-yield publication year, country, institute, author, and journal were 2020 (n = 222), France (n = 522), Netherlands Pharmacovigilance Centre Lareb (n = 82), Jean-Louis Montastruc (n = 125), Drug Safety (n = 384), respectively, in all 2,128 articles. Similarly, the United States, Institut National de la Sante et de la Recherche Medicale, and Jean-Louis Montastruc had the most coauthorship strength at the macrolevel (global), mesolevel (local), and microlevel (individual). The topics of burst references covered are the development of methodology, issues of patients reporting and under-reporting, evaluation of methods and databases, assessment of causality, and perspectives in pharmacovigilance. Eight clusters were grouped in the document citation network. "Pharmacovigilance," "adverse drug reactions," "pharmacoepidemiology," "drug safety," and "signal detection" were the research priorities, while "drug-related side effects and adverse reactions," "VigiBase," "disproportionality analysis," "social media," "FAERS," "chemotherapy," "patient safety," "reporting odds ratio," and "preventability" might be the future research hotspots. Conclusion: Positive synergies can be observed in this study by employing the multiple software tools which established the relationship between the units of analysis. The bibliometric analysis can organize the thematic development and guide the hotspots of pharmacovigilance in pharmacology and pharmacy.

Immune Checkpoint Inhibitor-Associated Tumor Lysis Syndrome: A Real-World Pharmacovigilance Study.

Introduction: Immune checkpoint inhibitors (ICIs) have substantially improved the clinical outcomes of various malignancies. However, the adverse event of tumor lysis syndrome (TLS) has not been included in the National Comprehensive Cancer Network guidelines or drug inserts. In this study, we aimed to establish the relationship between ICI therapies and TLS events using data from a real-world pharmacovigilance database. Methods: The MedDRA terms of TLS and both generic and brand names of ICIs were retrieved from the FDA Adverse Event Reporting System. Four frequentist algorithms were employed to confirm the association between the TLS and the ICI regimens, involving anti-cytotoxic T lymphocyte antigen-4 (anti-CTLA-4), anti-programmed death receptor-1 (PD-1)/programmed cell death 1 ligand 1 (PD-L1), and anti-(CTLA-4 + PD-1). A descriptive and statistical analysis was performed according to the case information. Results: One hundred sixty-four TLS cases, where patients underwent anti-CTLA-4 (n = 14), anti-(PD-1)/(PD-L1) (n = 113), or anti-(CTLA-4 + PD-1) (n = 37) therapies, were collected between the first quarter of 2004 and the fourth quarter of 2020. The most coverage-reporting year, age-group, sex, reporter, region, country, and indication were 2020 (n = 62), 60-74 years (n = 65), males (n = 105), physician (n = 66), Asia (n = 80), Japan (n = 67), and lung and thymus malignancies (n = 40), respectively. The median TLS onset time associated with anti-CTLA-4, anti-(PD-1)/(PD-L1), and anti-(CTLA-4 + PD-1) therapies was 6 (IQR: 2-39.5), 9 (IQR: 2-40), and 20 (IQR: 7.5-37.75) days, respectively. Mortality distribution of 71 reported death outcomes among three groups was statistically significant. All four algorithm signal values of anti-(CTLA-4 + PD-1) were higher than those of anti-CTLA-4 and anti-(PD-1)/(PD-L1). Conclusion: Elderly male patients with lung and thymus malignancies are frequently predisposed to TLS. ICI therapies could induce TLS in both solid and hematological malignancies. The rapid onset time and poor outcomes of patients prompt caution from health-care professionals.

Global publication trends and hotspots of molecular biomarkers in DILI from 1991 to 2020: A 30-year bibliometric analysis.

Drug-induced liver injury (DILI) is one of the common adverse drug reactions and the leading cause of drug development attritions, black box warnings, and post-marketing withdrawals. Current biomarkers are suboptimal in detecting DILI and predicting its outcome. This study aimed to quantitatively and qualitatively investigate the research trends on DILI biomarkers using bibliometric analysis. All relevant publications were extracted from the Web of Science database. An online analysis platform of literature metrology, bibliographic item co-occurrence matrix builder, and CiteSpace software were used to analyze the publication trends. CitNetExplorer was used to construct direct citation networks and VOSviewer was used to analyze the keywords and research hotspots. We found a total of 485 publications related to DILI biomarkers published from 1991 to 2020. Toxicological Sciences had been the most popular journal in this field over the past 30 years. The USA maintained a top position worldwide and provided a pivotal influence, followed by China. Among all the institutions, the University of Liverpool was regarded as a leader for research collaboration. Moreover, Professors Paul B. Watkins and Tsuyoshi Yokoi made great achievements in topic area. We analyzed the citation networks and keywords, therefore identified five and six research hotspot clusters, respectively. We considered the publication information regarding different countries/regions, organizations, authors, journals, et al. by summarizing the literature on DILI biomarkers over the past 30 years. Notably, the subject of DILI biomarkers is an active area of research. In addition, the investigation and discovery of novel promising biomarkers such as microRNAs, keratin18, and bile acids will be future developing hotspots.

Pharmacokinetics and Safety of Dabigatran Etexilate after Single and Multiple Oral Doses in Healthy Chinese Subjects.

BACKGROUND AND OBJECTIVE: Dabigatran etexilate is a non-vitamin K antagonist oral anticoagulant (NOAC) that is used to prevent stroke and systemic embolism in adults with nonvalvular atrial fibrillation (NVAF) and one or more risk factors. Pharmacokinetic data on this anticoagulant in Chinese subjects are limited. This study aimed to provide further information on the pharmacokinetic profile of dabigatran in healthy Chinese subjects, together with its safety profile. METHODS: This was an open-label, single-centre, phase I study. Subjects were randomized into 110 and 150 mg dabigatran etexilate treatment groups. Each subject received 7 days of treatment: a single dose on day 1, no dose on days 2-3, and then multiple doses on days 4-10. Blood samples were collected to analyze the pharmacokinetic profile of dabigatran. All adverse events (AEs) were recorded. Routine clinical laboratory tests, a physical examination, vital signs, and 12-lead electrocardiogram (ECG) measurements were performed. RESULTS: A total of 28 subjects (14 males and 14 females) were randomized in this trial. The plasma concentration of total dabigatran reached its maximum measured concentration at a median time of 3-4 h from the dose of interest (either the initial single dose on day 1 or the final dose on day 10) under fed conditions, and declined with an elimination half-life of 10.7-10.9 h following the dose of interest. There was a modest difference in pharmacokinetic profile between male and female subjects. None of the subjects experienced a serious adverse event (SAE) or an AE of moderate or severe intensity. The investigator reported that 17 of the 28 subjects had mild treatment-emergent AEs that resolved without any concomitant treatment or intervention. No clinically significant changes in vital signs or ECG parameters were observed. CONCLUSIONS: This study revealed the pharmacokinetic characteristics and good safety profile of dabigatran in healthy Chinese subjects.

A validated HPLC-MS/MS method for the quantification of caderofloxacin in human plasma and its application to a clinical pharmacokinetic study.

A simple, selective and rapid HPLC-MS/MS method was developed and validated for the determination of caderofloxacin in human plasma. Sparfloxacin was used as the internal standard (IS). After precipitation with methanol and dilution with the mobile phase, the samples were injected into the HPLC-MS/MS system. The chromatographic separation was performed on a Zorbax XDB Eclipse C18 column (150 × 4.6 mm, 5 µm) with a mobile phase of ammonium acetate buffer (20 mm, pH 3.0)-methanol, 45:55 (v/v). The MS/MS analysis was done in positive mode. The multiple reaction monitoring transitions monitored were m/z 412.3 → 297.1 for caderofloxacin and m/z 393.2 → 292.2 for the IS. The calibration curve was linear over the range of 50.0-8000 ng/mL with an aliquot of 100 µL plasma. The precision of the assay was 2.0-9.4 and 6.6-11.5% for the intra- and inter-run variability, respectively. The intra- and inter-run accuracy (relative error) was 4.4-10.0 and -1.2-4.0%. The total run time was 3.5 min. The assay was fully validated in accordance with the US Food and Drug Administration guidance. It was successfully applied to a pharmacokinetic study of caderofloxacin in healthy Chinese volunteers.

Development and validation of a sensitive liquid chromatography-tandem mass spectrometry method for the determination of naringin and its metabolite, naringenin, in human plasma.

A sensitive and specific method was developed for the simultaneous determination of naringin and its metabolite, naringenin, in human plasma by liquid chromatography-tandem mass spectrometry. Hesperidin was used as the internal standard, plasma samples were extracted with ethyl acetate and the analytes were chromatographically separated by using acetonitrile-0.1% formic acid (gradient elution) as the mobile phase. Detection was performed by electrospray ionization mass spectrometry in negative ion mode with multiple reaction monitoring. The lower limit of quantification was 0.5 ng/mL for naringin and naringenin and the linear calibration curves ranged from 0.5 to 200 ng/mL. The intra-run and inter-run precision values were within 8.6 and 7.7% for naringin and between 13.1 and 10.3% for naringenin. The accuracy ranged from 91.3 to 98.2% for naringin and from 90.2 to 97.6 % for naringenin. The validated method was successfully applied to determine concentrations of naringin and naringenin in clinical patients.

Development and validation of a sensitive and robust LC-MS/MS with electrospray ionization method for simultaneous quantitation of quetiapine and its active metabolite norquetiapine in human plasma.

BACKGROUND: Quetiapine is an atypical antipsychotic agent for the treatment of schizophrenia, acute mania, and acute bipolar depression. The antidepressive response is considered to be mediated by the metabolite norquetiapine (N-desalkylquetiapine), and the aim of this study was to develop an LC-MS/MS method to measure concentrations of these compounds in human plasma. METHODS: Following one step liquid-liquid extraction, the analytes were separated using an isocratic mobile phase on a Sunfire C18 column (50mm×2.1mm, 5µm). The retention times were 2.12, 2.24, 2.12 and 2.19min for quetiapine, norquetiapine and their respective stable labeled internal standards, respectively. Cycle time was 4min. Selected reaction monitoring (SRM) in positive ion mode was used for quantitation. RESULTS: The present method exhibited a linear dynamic range of 0.5-500ng/ml for quetiapine and 0.6-600ng/ml for norquetiapine. The applicable range was extended by dilution up to 5-fold with blank matrix. The accuracy and precision for quetiapine were <103.0% and 8.8%, for norquetiapine were <108.8% and 11.1%, respectively. CONCLUSIONS: A rapid, sensitive, and robust LC-MS/MS method for quantifying quetiapine and its metabolite norquetiapine levels in human plasma was validated and successfully applied to samples from schizophrenic patients in clinical pharmacokinetics studies.

Validation of a fast and reliable liquid chromatography-tandem mass spectrometry (LC-MS/MS) with atmospheric pressure chemical ionization method for simultaneous quantitation of voriconazole, itraconazole and its active metabolite hydroxyitraconazole in human plasma.

BACKGROUND: Voriconazole and itraconazole are two broad-spectrum antifungal triazole derivates administered for the prevention and in the treatment of invasive fungal infections. Their broad inter- and intra-individual pharmacokinetic variability and the high probability of drug-drug interactions justify therapeutic drug monitoring. METHODS: After liquid-liquid extraction with tert-butyl methyl ether, chromatographic separation was achieved on a Zorbax Eclipse XDB-C18 column using gradient elution with 10 mM ammonium formate and acetonitrile. Detection was performed by a tandem mass spectrometer coupled to LC via an atmospheric pressure chemical ionization (APCI) and quantification was performed using selected reaction monitoring (SRM) transitions RESULTS: Total run time was 4.5 min. The method was validated for concentrations ranging from 0.05 to 10 µg/mL for voriconazole and from 0.025 to 5 µg/mL for itraconazole and hydroxyitraconazole, respectively. The intra- and inter-day correlation coefficients of variation were <7.7%-<9.2%, respectively. The accuracy ranged from 92.6% to 109%. CONCLUSIONS: A rapid and simple liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (LC-APCI-MS/MS) method has been developed and validated to measure voriconazole itraconazole and hydroxyitraconazole in human plasma. This method is successfully applied to samples from patients receiving antifungal treatment.

Population pharmacokinetics of naringin in total flavonoids of Drynaria fortunei (Kunze) J. Sm. in Chinese women with primary osteoporosis.

OBJECTIVE: To evaluate the effect of covariates on the pharmacokinetic profiles of naringin in the total flavonoids of Drynaria fortunei (Kunze) J. Sm. in the Qianggu Capsule () by evaluating Chinese women with primary osteoporosis. METHODS: A total of 98 female patients from the communities of Jingshan, Beixinqiao, Jiaodaokou, Chaoyangmen, and Donghuamen in Beijing, China, aged 40 to 80 years, were included in this study. Blood samples were collected before and 0.5, 1, 2, 3, 4, 6, 8, 10, 12, and 24 h after a single oral dose of Qianggu Capsule. The concentration in blood samples from 32 patients before and 0.5, 1, 2, 3, and 4 h after drug administration were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, and full set of pharmacokinetic data was analyzed with nonlinear mixed-effect modeling (NONMEM) software. The mean of population parameters clearance (C1), central distribution volume (V), absorption rate constant (Ka1), inter-compartmental clearance (C2), peripheral distribution volume (V2) were set as parameters and estimated through base model, covariate model, and final model. Age, height, weight, blood urea nitrogen (BUN), serum creatinine (Scr), alanine transaminase (ALT), aspartate transaminase (AST), hyperlipidemia, Liver (Gan) Kidney (Shen) yin insufficiency (GSYI), Kidney (Shen) yang insufficiency (SYI) were set as covariates. RESULTS: The relationships between these parameters and covariates were analyzed. The results showed that C1 was the main parameter influenced by the selected covariates among the population parameters, and the relationships between the covariates and C1 were analyzed, among the selected covariates hyperlipidemia was identified as significant covariate of C1. CONCLUSION: The pharmacokinetic behaviors of naringin are altered with hyperlipidemia in Chinese women with primary osteoporosis.

Role of arachidonoylethanolamine in blood pressure regulation in volume-resistant patients on peritoneal dialysis.

In this study we explored the possible role of arachidonoylethanolamine (AEA) in regulating blood pressure in patients on continuous ambulatory peritoneal dialysis (CAPD). One hundred and five patients on CAPD were enrolled. Volume status was evaluated by the overhydration (OH) value obtained by bioimpedance analysis. OH<2.0 kg was defined as normal volume (NV) and OH≥2.0 kg as high volume (HV). Home mean systolic blood pressure<130 mmHg was defined as controlled hypertension (CHT) and ≥130 mmHg as uncontrolled hypertension (UHT). The patients were divided into four subgroups: (1) controlled hypertension with normal volume (CHT-NV), (2) controlled hypertension with high volume (CHT-HV), (3) uncontrolled hypertension with normal volume (UHT-NV), and (4) uncontrolled hypertension with high volume (UHT-HV). AEA was measured by ultra performance liquid chromatography-tandem mass spectrometry. AEA was significantly higher in the HV group as compared with the NV group (P<0.05). In addition, AEA was also significantly higher in the CHT-HV group as compared with the UHT-NV group (P<0.05). These results may suggest a compensatory function of AEA and TRPV1 pathway to lower blood pressure during volume expansion in CAPD patients.

Pharmacokinetics of single and multiple oral doses of valsartan/amlodipine (80/5 mg) in healthy Chinese subjects.

OBJECTIVE: The efficacy and safety of valsartan/amlodipine combination have been demonstrated for the treatment of hypertension. In China, where the prevalence of hypertension is increasing the pharmacokinetic study of valsartan, amlodipine assumes significance. The aim of this study was to characterize the pharmacokinetics (PK) of valsartan and amlodipine following single- and multiple-dose oral administrations of valsartan/ amlodipine 80/5 mg fixed-dose combination in healthy Chinese subjects. MATERIALS AND METHODS: This was an open-label, two-period (single-dose treatment followed by a multiple-dose (once-daily for 9 days), with a 7-day intertreatment washout period) study conducted in 18 subjects. Serial blood samples were collected at pre-defined time points, and the plasma concentrations of valsartan and amlodipine were measured using LC-MS/MS. Safety was evaluated after single- and multiple-dose drug administration. RESULTS: Following the single-dose oral administration of valsartan/amlodipine 80/5 mg, valsartan and amlodipine plasma concentrations reached peak levels at median tmax of 3 and 6 h, respectively. These concentrations declined thereafter, with mean elimination half-lives of 7.7 h (single dose) and 8.6 h (multiple dose) for valsartan, and 47 h (single dose) and 45 h (multiple dose) for amlodipine. After a 9-day multiple-dose treatment (at steady state), accumulation of valsartan and amlodipine was consistent with their half-lives. The single- and multiple-dose administration of valsartan/amlodipine 80/5 mg was associated with asymptomatic hypotension, consistent with the pharmacological activity of the combination of these two blood pressure-lowering drugs when co-administered in healthy subjects. CONCLUSION: The PK of valsartan and amlodipine are linear following oral administration of valsartan/amlodipine fixed-dose combination.

Fast and reliable determination of voriconazole in human plasma by LC-APCI-MS/MS.

A fast and reliable liquid chromatography coupled with atmospheric pressure chemical ionization tandem mass spectrometry (LC-APCI-MS/MS) method was developed and validated for the quantification of voriconazole in human plasma. The proposed method was validated in a linear range of 50-10,000 ng/ml, and the total run time was 1.5 min. This method was successfully used to support routine therapeutic drug monitoring of voriconazole.

Performance of tiloronoxim and tilorone determination in human blood by HPLC-MS/MS: method validation, uncertainty assessment and its application to a pharmacokinetic study.

A highly sensitive and selective HPLC-MS/MS method is presented for the quantitative determination of tiloronoxim and its metabolite tilorone in human blood. An aliquot of 200 microl human blood was extracted with a mixture of chloroform/ethyl ether (1/2, v/v), using metoprolol as the internal standard (the IS). Separation was achieved on an Xterra MS C18 column (50 mm x 2.1 mm, 5 microm) with a gradient mobile phase of methanol/water containing 15 mM ammonium bicarbonate (pH 10.5). Detection was performed using positive MRM mode on a TurboIonSpray source. The mass transitions monitored were m/z 426.3-->100.0, m/z 411.3-->100.0 and m/z 268.3-->116.1 for tiloronoxim, tilorone and the IS, respectively. The method was fully validated using total error theory, which is based on beta-expectation tolerance intervals and include trueness and intermediate precision. The method was found to be accurate over a concentration range of 1-100 ng/ml for both compounds. The measurement uncertainty based on beta-expectation tolerance intervals was assessed at each concentration level of the validation standards. This method was successively applied to a pharmacokinetic study of tiloronoxim in healthy volunteers.

Two-stage analysis of pharmacokinetics of sufentanil administered by target-controlled infusion in Chinese patients.

BACKGROUND: Sufentanil is a suitable choice for target-controlled infusion (TCI) because of its shorter context-sensitive half-time. The current study was to estimate the pharmacokinetics of sufentanil TCI in Chinese patients using the two-stage analysis. METHODS: Twelve adult patients with American Society of Anesthesiologists (ASA) physical status I or II undergoing elective surgery under general anesthesia were included. Anesthesia was induced with propofol, rocuronium and sufentanil administered by TCI lasting for 30 minutes, with target effect-site concentration of sufentanil 4 or 6 ng/ml. Frequent arterial blood samples (1.5 ml) were taken during and up to 24 hours after sufentanil TCI. Before the end of surgery, another arterial blood sample (1.0 ml) was drawn for the blood-gas analysis. Plasma sufentanil concentrations were determined by liquid chromatography-tandem mass spectrometry (limit of quantitation was 5 pg/ml). The data were analyzed with the two-stage approach, linear regression and correlation analysis. RESULTS: The pharmacokinetics of sufentanil TCI were adequately described by a three-compartment model. The variables were derived as follows: the volume of central compartment (V(1)) was 5.4 L, volume of distribution at steady-state (Vdss) was 222.6 L, metabolic clearance (Cl(1)) was 0.84 L/min and elimination half-life (t(1/2Y)) was 389 minutes. Patients' age, gender and PaCO2 correlated significantly with the pharmacokinetic parameters. The Vdss, volume of slowly equilibrating compartment (V(3)) and t(1/2Y) increased, and rapid distribution clearance (Cl(2)) decreased with increasing patient age. Male patients had larger values of Vdss, volume of rapidly equilibrating compartment (V(2)) and V(3) than female patients. The Vdss and V(3) increased with higher PaCO2 values. There were no significant correlations between the pharmacokinetic variables and body weight, height, lean body mass, plasma albumin, sufentanil dose, duration of surgery, pH or base excess of blood (BE-B). CONCLUSIONS: The pharmacokinetics of sufentanil TCI in Chinese patients can be optimally described by a three-compartment model. The pharmacokinetic analysis technique may affect the pharmacokinetic parameters and correlations.

Pharmacokinetics of sufentanil administered by target-controlled infusion in Chinese surgical patients.

BACKGROUND: Target-controlled infusion (TCI) has been recently developed and successfully implemented in clinical practice. This study was conducted to determine the pharmacokinetics of TCI administered sufentanil in Chinese surgical patients. METHODS: The pharmacokinetics of sufentanil was investigated in 12 adult patients, aged 23-76 years, scheduled for prolonged surgery under general anesthesia. Anesthetic induction was carried out with propofol, rocuronium and TCI administered sufentanil aiming for target effect-site concentration of sufentanil 4 or 6 ng/ml. Sufentanil TCI lasted for 30 minutes. Frequent arterial blood samples (1.5 ml) were drawn during and up to 24 hours after sufentanil TCI. Plasma sufentanil concentrations were measured by liquid chromatography-tandem mass spectrometry; limit of sensitivity of mass spectrometry was 5 pg/ml. The data were analyzed with the nonlinear mixed-effect model program. RESULTS: The pharmacokinetics of TCI administered sufentanil were optimally described by a three-compartment model with the following parameters: the central volume of distribution (V(1))=5.4 L, the volume of distribution at steady-state (Vdss)=195.4 L, systemic clearance (Cl(1))=1.10 L/min, and elimination half-life (t(1/2) gamma)=271.8 minutes. Both age and gender affected the pharmacokinetic parameters. The rapid distribution clearance (Cl(2)) was negatively correlated with patient age, and the volume of slowly equilibrating compartment (V(3)) was positively correlated with age. The Cl(2) and the volume of rapidly equilibrating compartment (V(2)) were influenced by gender with male patients showing higher values of Cl(2) and V(2) than female patients. There was no relationship of body weight, lean body mass, plasma albumin, or target effect-site concentration of sufentanil with any of the pharmacokinetic parameters studied. CONCLUSIONS: The pharmacokinetics of TCI administered sufentanil in Chinese patients can be adequately described by a three-compartment model. Pharmacokinetics adjusted to the individual patient should improve the accuracy of TCI systems.

Clinical evaluation of target controlled infusion system for sufentanil administration.

BACKGROUND: Sufentanil target controlled infusion (TCI) provides stable analgesia, better hemodynamic control than a bolus injection of intravenous anesthetics, anticipated recovery and improved quality of anesthesia during perioperative period. This study evaluated the accuracy and feasibility of TCI system for sufentanil at high concentrations in Chinese surgical patients. METHODS: Twelve low risk adult patients undergoing elective surgery under general anesthesia were included in this study. Sufentanil was administered with a specific TCI system incorporating the population pharmacokinetic data of sufentanil previously reported, using a target effect-site concentration of sufentanil 4 or 6 ng/ml. Sufentanil TCI duration was 30 minutes. Frequent arterial blood samples were taken during and up to 24 hours after sufentanil TCI for determination of plasma sufentanil concentrations by liquid chromatography-mass spectrometry/mass spectrometry. The changes of circulatory system function during the procedure, recovery profile and adverse effects were recorded. Measured plasma sufentanil concentrations were compared with the values predicted by the TCI system. The bias (median performance error, MDPE), precision (median absolute performance error, MDAPE) and wobble (variability of performance error) of the sufentanil TCI system were determined. RESULTS: All patients had stable cardiovascular variables during induction and maintenance of anesthesia. Time to eye opening and extubation were (5.6 + or - 1.7) minutes when TCI set to 4 ng/ml and (7.2 + or - 2.3) minutes when set to 6 ng/ml. There was no episode of agitation, muscle rigidity or intraoperative awareness. The bias (MDPE), precision (MDAPE) and wobble of the sufentanil TCI system were -3.7%, 18.9% and 19.6% respectively during TCI, and the MDPE, MDAPE and wobble were -29.1%, 31.7% and 15.0% respectively after TCI (up to 8 hours). CONCLUSIONS: The TCI system programmed for sufentanil at 4 or 6 ng/ml was considered acceptable for clinical use in low risk Chinese surgical patients. But the relatively larger MDPE and MDAPE after TCI suggest improvements of the pharmacokinetic model are needed.

Simultaneous quantification of tiloronoxim and tilorone in human urine by liquid chromatography-tandem mass spectrometry.

A simple, sensitive and specific HPLC method with tandem mass spectrometry (HPLC/MS/MS) detection has been developed and validated for the simultaneous quantification of tiloronoxim and its major active metabolite, tilorone, in human urine. The analytes, together with metoprolol, which was employed as an internal standard (IS), were extracted with a mixture solvent of chloroform/ethyl ether (1/2, v/v). The chromatographic separation was performed on a narrow-bore reversed phase HPLC column with a gradient mobile phase of methanol/water containing 15 mM ammonium bicarbonate (pH 10.5). The API 3,000 mass spectrometer was equipped with a TurboIonSpray interface and was operated on positive-ion, multiple reaction-monitoring (MRM) mode. The mass transitions monitored were m/z 426.3-->100.0, m/z 411.3-->100.0 and m/z 268.3-->116.1 for tiloronoxim, tilorone and the IS, respectively. The assay exhibited a linear dynamic range of 1-100 ng/ml for both tiloronoxim and tilorone based on the analysis of 0.2 ml aliquots of urine. The lower limit of quantification was 1 ng/ml for both compounds. Acceptable precision and accuracies were obtained for concentrations over the standard curve ranges. Run time of 8 min for each injection made it possible to analyze a high throughput of urine samples. The assay has been successfully used to analyze human urine samples from healthy volunteers.

Sensitive quantification of rifaximin in human plasma by liquid chromatography-tandem mass spectrometry.

A liquid chromatography-mass spectrometry method (LC-MS/MS) for the quantitative determination of rifaximin in human plasma was developed and validated. In the developed procedure, metoprolol was added to human plasma as an internal standard (IS) and acetonitrile was used to precipitate the plasma proteins before LC-MS/MS analysis. Chromatographic separation was obtained on a RESTEK Pinnacle C18 column (50 mm x 2.1mm, 5 microm) with a mobile phase consisted of ammonium acetate solution (15 mM, pH 4.32) as buffer A and methanol as mobile phase B. Quantification was performed in positive mode using multiple reaction monitoring (MRM) of the transitions m/z 786.1-->754.1 for rifaximin and m/z 268.3-->116.1 for the IS. The assay has been validated over the concentration range of 0.5-10 ng/ml (r=0.9992) based on the analysis of 0.2 ml of plasma. The assay accuracy was between 98.2% and 109%. The within-day and between-day precision was better than 3.9% and 8.9% at three concentration levels. The freeze-thaw stability was also investigated and it was found that both rifaximin and the IS were quite stable. This method provides a rapid, sensitive, specific and robust tool for the quantitative determination of rifaximin in human plasma, which is especially useful for the pharmacokinetic study of rifaximin.

Improvement of cyclosporin A determination in whole blood by reversed-phase high-performance liquid chromatography.

A chromatographic method was developed for the determination of cyclosporin A in human whole blood using reversed-phase HPLC at room temperature. Most previous reports carried out this liquid chromatographic separation at temperatures above 70 degrees C. The present procedure greatly improves the detection limit by controlling peak broadening effects, as well as the lifetime of the column at room temperature. Under optimal conditions and using ketoconazole as an internal standard, the calibration graph was linear in the range of 16-1000 microg/L with a relative standard deviation of 3.72% at 150 microg/L and 2.45% at 300 microg/L (n = 11) of cyclosporin A. The detection limit was of 5.0 microg/L cyclosporin A. By this procedure, cyclosporin A pharmacokinetic parameters in healthy Chinese subjects were studied. The developed method could be applied to the quantification of cyclosporin A in human blood samples and allows the study of its pharmacokinetics in routine laboratories.