Standardization and validation of a high-efficiency liquid chromatography with a diode-array detector (HPLC-DAD) for voriconazole blood level determination

INTRODUCTION

A specialized service for antifungal blood level determination is not available in Colombia. This service is essential for the proper follow-up of antifungal therapies.

OBJECTIVE

To standardize and validate a simple, sensitive, and specific protocol based on high-performance liquid chromatography with a diode array detector for voriconazole blood level quantification.

MATERIALS AND METHODS

We used an Agilent HPLC™ series-1200 equipment with a UVdiode array detector with an analytical column Eclipse XDB-C18 and pre-column Eclipse- XDB-C18 (Agilent). We used voriconazole as the primary control and posaconazole as an internal control. We performed the validation following the Food and Drug Administration (FDA) recommendations.

RESULTS

The best chromatographic conditions were: Column temperature of 25°C, UV variable wavelength detection at 256 nm for voriconazole and 261 nm for posaconazole (internal standard); 50 μl of injection volume, 0,8 ml/min volume flow, 10 minutes of run time, and mobile phase of acetonitrile:water (60:40). Finally, retention times were 3.13 for voriconazole and 5.16 minutes for posaconazole. Quantification range varied from 0.125 μg/ml to 16 μg/ml.

CONCLUSION

The selectivity and chromatographic purity of the obtained signal, the detection limits, and the standardized quantification make this method an excellent tool for the therapeutic monitoring of patients treated with voriconazole.

Replicates Number for Drug Stability Testing during Bioanalytical Method Validation-An Experimental and Retrospective Approach

Background: The stability of a drug or metabolites in biological matrices is an essential part of bioanalytical method validation, but the justification of its sample size (replicates number) is insufficient. The international guidelines differ in recommended sample size to study stability from no recommendation to at least three quality control samples. Testing of three samples may lead to results biased by a single outlier. We aimed to evaluate the optimal sample size for stability testing based on 90% confidence intervals. Methods: We conducted the experimental, retrospective (264 confidence intervals for the stability of nine drugs during regulatory bioanalytical method validation), and theoretical (mathematical) studies. We generated experimental stability data (40 confidence intervals) for two analytes—tramadol and its major metabolite (O-desmethyl-tramadol)—in two concentrations, two storage conditions, and in five sample sizes (n = 3, 4, 5, 6, or 8). Results: The 90% confidence intervals were wider for low than for high concentrations in 18 out of 20 cases. For n = 5 each stability test passed, and the width of the confidence intervals was below 20%. The results of the retrospective study and the theoretical analysis supported the experimental observations that five or six repetitions ensure that confidence intervals fall within 85–115% acceptance criteria. Conclusions: Five repetitions are optimal for the assessment of analyte stability. We hope to initiate discussion and stimulate further research on the sample size for stability testing.

Eco-Friendly, Simple, Fast, and Sensitive UPLC-MS/MS Method for Determination of Pexidartinib in Plasma and Its Application to Metabolic Stability

Pexidartinib is the first drug approved by the U.S. Food and Drug Administration specifically to treat the rare joint tumor tenosynovial giant cell tumor. In the current study, a validated, selective, and sensitive UPLC-MS/MS assay was developed for the quantitative determination of pexidartinib in plasma samples using gifitinib as an internal standard (IS). Pexidartinib and IS were extracted by liquid-liquid extraction using methyl tert-butyl ether and separated on an acquity BEH C18 column kept at 40 °C using a mobile phase of 0.1% formic acid in acetonitrile: 0.1% formic acid in de-ionized water (70:30). The flow rate was 0.25 mL/min. Multiple reaction monitoring (MRM) was operated in electrospray (ESI)-positive mode at the ion transition of 418.06 > 165.0 for the analyte and 447.09 > 128.0 for the IS. FDA guidance for bioanalytical method validation was followed in method validation. The linearity of the established UPLC-MS/MS assay ranged from 0.5 to 1000 ng/mL with r > 0.999 with a limit of quantitation of 0.5 ng/mL. Moreover, the metabolic stability of pexidartinib in liver microsomes was estimated.

Comparison of Two Immunoassay Screening Methods and a LC-MS/MS in Detecting Traditional and Designer Benzodiazepines in Urine

Sensitive and specific immunoassay screening methods for the detection of benzodiazepines in urine represent an important prerequisite for routine analysis in clinical and forensic toxicology. Moreover, emerging designer benzodiazepines force labs to keep their methodologies updated, in order to evaluate the reliability of the immunochemical techniques. This study aimed at evaluating the sensitivity and specificity of two different immunoassay methods for the detection of benzodiazepines in urine, through a comparison with the results obtained by a newly developed liquid chromatographic tandem mass spectrometric (LC-MS/MS) procedure. A cohort of authentic urine samples (N = 501) were processed, before and after a hydrolysis procedure, through two immunoassays and an LC-MS/MS method. The LC-MS/MS target procedure was optimized for monitoring 25 different molecules, among traditional and designer benzodiazepines, including some metabolites. At least one of the monitored substances was detected in 100 out of the 501 samples. A good specificity was observed for the two immunoassays (>0.99), independently of the cut-offs and the sample hydrolysis. The new kit demonstrated a fairly higher sensitivity, always higher than 0.90; in particular, a high cross-reactivity of the new immunoassay was observed for samples that tested positive for lorazepam and 7-aminoclonazepam. The two immunoassays appeared adequate to monitor not only traditional benzodiazepines but also new designer ones.

Review of the Preanalytical Errors That Impact Therapeutic Drug Monitoring

PURPOSE

Preanalytical errors comprise the majority of testing errors experienced by clinical laboratories and significantly impact the accuracy of therapeutic drug monitoring (TDM).

METHODS

Specific preanalytical factors in sample timing, collection, transport, processing, and storage that lead to errors in TDM were reviewed. We performed a literature search using several scientific databases including PubMed, ScienceDirect, Scopus, Web of Science, and ResearchGate for human studies published in the English language from January 1980 to February 2021, reporting on TDM and the preanalytical phase.

RESULTS

Blood collection errors (ie, wrong anticoagulant/clot activator used, via an intravenous line, incorrect time after dosing) delay testing, cause inaccurate results, and adversely impact patient care. Blood collected in lithium heparin tubes instead of heparin sodium tubes produce supertoxic lithium concentrations, which can compromise care. Specimens collected in serum separator gel tubes cause falsely decreased concentrations due to passive absorption into the gel when samples are not processed and analyzed quickly. Dried blood spots are popular for TDM as they are minimally invasive, allowing for self-sampling and direct shipping to a clinical laboratory using regular mail. However, blood collection techniques, such as trauma to the collection site, filter paper fragility, and hematocrit (Hct) bias, can adversely affect the accuracy of the results. Volumetric absorptive microsampling is a potential alternative to dried blood spot that offers fast, volume-fixed sampling, low pain tolerance, and is not susceptible to Hct concentrations.

CONCLUSIONS

The identification of preanalytical factors that may negatively impact TDM is critical. Developing workflows that can standardize TDM practices, align appropriate timing and blood collection techniques, and specimen processing will eliminate errors.

Development and Validation of a Simple and Rapid Ultrahigh-Performance Liquid Chromatography Tandem Spectrometry Method for the Quantification of Hydroxychloroquine in Plasma and Blood Samples in the Emergency Context of SARS-CoV-2 Pandemic

ABSTRACT

Therapeutic drug monitoring of hydroxychloroquine (HCQ) has been recommended to optimize the treatment of patients with COVID-19. The authors describe an ultrahigh-performance liquid chromatography tandem spectrometry method developed in a context of emergency, to analyze HCQ in both human plasma and blood samples. After adding the labeled internal standard and simple protein precipitation, plasma samples were analyzed using a C18 column. Blood samples required evaporation before analysis. The total chromatographic run time was 4 minutes (including 1.5 minutes of column equilibration). The assay was linear over the calibration range (r2 > 0.99) and up to 1.50 mcg/mL for the plasma samples (5.00 mcg/mL for the blood matrix). The limit of quantification was 0.0150 mcg/mL for plasma samples (0.05 mcg/mL blood matrix) with accuracy and precision ranging from 91.1% to 112% and from 0.750% to 11.1%, respectively. Intraday and interday precision and accuracy values were within 15.0%. No significant matrix effect was observed in the plasma or blood samples. This method was successfully applied to patients treated for COVID-19 infection. A simple and rapid ultrahigh-performance liquid chromatography tandem spectrometry method adapted to HCQ therapeutic drug monitoring in the context of SARS-CoV-2 infection was successfully developed and validated.

No adverse events were observed in clozapine-treated patients on extended hematologic monitoring intervals during the coronavirus pandemic in four psychiatric centers in Japan

AIM

As an emergency measure during the coronavirus disease pandemic, the monitoring interval for clozapine use was temporarily extended beyond the regulatory requirement in Japan, which is the safest monitoring interval worldwide. In this study, we aimed to explore the effect of this measure on patients undergoing clozapine treatment.

METHODS

This retrospective chart review study included patients with treatment-resistant schizophrenia (TRS) who were undergoing clozapine treatment at four psychiatric institutions in Japan. Demographic characteristics and clinical information of these patients were collected on April 27, 2020, when Japanese psychiatrists were virtually allowed to prescribe clozapine beyond the regulatory requirement. Furthermore, information of adverse events related to the emergency measure was collected and analyzed.

RESULTS

Of the 41 patients with TRS included in this study, 19 patients underwent extended hematological monitoring during clozapine treatment. No psychiatric or hematological adverse events were observed in the patients during the extended monitoring interval.

CONCLUSION

This study suggested that there were few adverse events of clozapine-treated patients related to emergency measures in Japan. However, hematological monitoring intervals during clozapine treatment have been emergently extended worldwide; hence, it is necessary to verify the results of these measures.

Effects of Broad Spectrum Antibiotics on Measurement of Immunosuppressant Drugs

BACKGROUND

Antibiotics used parenterally can affect blood drug level measurements, as measured in diagnostic tests.

OBJECTIVE

To investigate the effect of six different antibiotics commonly used in intensive care units on tacrolimus, sirolimus, everolimus and cyclosporin A levels measured by mass spectrometry.

METHODS

Ampicillin + sulbactam (AB1, IV, 1 g), imipenem + cilastatin sodium (AB2, IV, 500 mg), piperacillin + tazobactam (AB3, 4.5 g, IV), ertapenem (AB4, IV, 1 g), meropenem trihydrate (AB5, 500 mg, IV) and ceftriaxone (AB6, 1 g, IV) antibiotics were used for the interference assay. Measurements were performed on the Shimadzu 8045 (Japan) LC-MS/MS instrument. Bias values were calculated.

RESULTS

The least affected immunosuppressant was cyclosporine A (between -6.88% and 3.40%). The most affected were everolimus and sirolimus. Ertapenem caused negative interference on the level of everolimus at the rate of -27.34% and sirolimus at the rate of -26.79%. Piperacillin + tazobactam and imipenem + cilastatin sodium caused positive interferences on sirolimus at the rate of 24.24% and 22.73%, respectively. Ampicillin + sulbactam, meropenem trihydrate and ceftriaxone affected the sirolimus levels at lower rates (-4.49%, 5.93% and 9.86%). Everolimus levels deviated at the rate of -11.21% to -16.99% due to imipenem + cilastatin sodium, meropenem trihydrate and ceftriaxone.

CONCLUSION

This study demonstrated the potential of antibiotic use affecting immunosuppressant levels. Antibiotic interference, especially in transplant patients, may cause erroneous immunosuppression, increasing the likelihood of rejection.

Sensitive Analysis of Idarubicin in Human Urine and Plasma by Liquid Chromatography with Fluorescence Detection: An Application in Drug Monitoring

A new approach for the sensitive, robust and rapid determination of idarubicin (IDA) in human plasma and urine samples based on liquid chromatography with fluorescence detection (LC-FL) was developed. Satisfactory chromatographic separation of the analyte after solid-phase extraction (SPE) was performed on a Discovery HS C18 analytical column using a mixture of acetonitrile and 0.1% formic acid in water as the mobile phase in isocratic mode. IDA and daunorubicin hydrochloride used as an internal standard (I.S.) were monitored at the excitation and emission wavelengths of 487 and 547 nm, respectively. The method was validated according to the FDA and ICH guidelines. The linearity was confirmed in the range of 0.1-50 ng/mL and 0.25-200 ng/mL, while the limit of detection (LOD) was 0.05 and 0.125 ng/mL in plasma and urine samples, respectively. The developed LC-FL method was successfully applied for drug determinations in human plasma and urine after oral administration of IDA at a dose of 10 mg to a patient with highly advanced alveolar rhabdomyosarcoma (RMA). Moreover, the potential exposure to IDA present in both fluids for healthcare workers and the caregivers of patients has been evaluated. The present LC-FL method can be a useful tool in pharmacokinetic and clinical investigations, in the monitoring of chemotherapy containing IDA, as well as for sensitive and reliable IDA quantitation in biological fluids.

Accuracy of quantitative HIV-1 RNA test methods at 1000 copies/mL and the potential impact of differences in assay calibration on therapy monitoring of patients

The World Health Organization (WHO) recommends the clinical use of a human immunodeficiency virus 1 (HIV-1) viral load (VL) threshold level of 1000 copies (cp)/mL in patients on antiretroviral therapy (ART) to distinguish between viral control (VL < 1000 cp/mL) and viral failure or poor adherence (VL > 1000 cp/mL). The accuracy of five quantitative HIV-1 RNA assays at this level was compared by replicate testing (n = 24) of 1000 cp/mL samples prepared from the Viral Quality Control (VQC) HIV-1 subtype B standard, which is in use for validation of nucleic acid testing methods since 1995. Until 2004 the VL assays reported geometric mean (95% confidence interval [CI]) values ranging between 449 (188-1067) and 3162 (3057-2367) cp/mL when using the Siemens bDNA 3.0 assay as reference method for an assigned value of 1000 (962-1038) cp/mL. In 2018, the following values (95% CI) were found by 24 replicate tests in each of the VL assays on the 1000 cp/mL samples: Abbott RealTime 1084 (784-1572), BioMerieux EasyQ 1110 (533-2230), Roche CAP/CTM 1277 (892-1828), Hologic Aptima 1616 (1324-1973), and Cepheid GeneXpert 2502 (1713-3655) cp/mL. Calibration studies involving three consecutive WHO replacement standards showed a significant drift in the amount of RNA copies per International Unit overtime. Heat inactivation of HIV-1 standards was found to cause a destandardizing effect. Our study underlines the limitations in HIV-1 RNA assay calibration based on frequently replaced WHO international standards. It is therefore proposed that clinicians interpret the recommended 1000 cp/mL alert level in therapy monitoring with an inaccuracy range of 500 to 2000 cp/mL.

Comparison of Two Analytical Methods for Busulfan Therapeutic Drug Monitoring

BACKGROUND AND OBJECTIVES

Busulfan (Bu) is an old drug, but is still well recommended as an alkylating agent during conditioning therapy, before hematopoietic stem cell transplantation. Although its dose administration is standardized and based on patient weight, therapeutic drug monitoring is required in order to maintain its exposure [as area under the concentration-time curve (AUC) from 0 to infinity AUC_0-∞] within a narrow therapeutic range and, if necessary, to adjust the dose with as short a lead time as possible. The aim of the study is to evaluate the agreement (as calculated AUC) between a gold standard analytical method and a new one that is faster and easier.

METHODS

We analyzed 221 plasma samples from 37 children (0.25-16 years; 4-62.5 kg) and 11 adults (21-59 years; 45-80 kg), corresponding to 52 AUC values (ng h/mL). The drug exposure was calculated, simultaneously, by two validated analytical methods. The reference method was a high-performance liquid chromatography (HPLC) assay combined with an ultraviolet detector (UV). The test method had a triple quadrupole mass spectrometer (MS) as detector; the clean-up procedures of the samples were different and faster.

RESULTS

The agreement between the two methods (reference and test) was evaluated in terms of Bu exposure differences based on Lin's concordance correlation coefficient (CCC) and represented by the Bland-Altman plot. The CCC between the AUC of the two methods was excellent (0.868; 95% CI: 0.802-0.935). The precision of the measures (expressed by Pearson's italic "r") was 0.872, and the accuracy (accounted by the bias correction factor) was 0.996.

CONCLUSIONS

We can conclude that the HPLC-MS/MS assay represents a very good alternative to the reference.

[Direct oral anticoagulants: In which indications? Which one to prescribe? For or against their use in frail patients and in atypical cases? Which monitoring and management haemorrhage complications?]

Since their approval, the direct oral anticoagulants have been widely used in the management of venous thromboembolism, for stroke and systemic embolism prevention in non valvular atrial fibrillation, and in venous thromboembolism prophylaxis after surgical hip or knee replacement. Because they are easy to use, with oral fixed doses and no biological monitoring need, they are more and more prescribed. New indications are rising in cancer associated thrombosis in France beyond the 6 first months of treatment, and to prevent cardiovascular events after an acute coronary syndrome, or in stable coronary or peripheral arterial disease in Europe. The efficacity and safety of direct oral anticoagulants in frail patients or in unusual pathological contexts are not entirely known, but further data are coming and will probably bring new answers.

When is it OK to Stop Anti-Programmed Death 1 Receptor (PD-1) Therapy in Metastatic Melanoma?

Systemic therapy for metastatic melanoma has been revolutionized over the past decade with the development of highly effective immune checkpoint inhibition, specifically anti-Programmed Death 1 receptor (PD-1) therapy. However, even though one-third of patients will have durable response to single-agent or combination therapy, the optimal duration of therapy is unknown. Identifying the optimal duration of therapy is important, as exposure to anti-PD-1 therapy increases the risk of developing immune-mediated toxicities that can have significant morbidity and are, at times, fatal. It has long been understood that patients with complete responses to high-dose interleukin-2 and ipilimumab typically maintain their responses after a brief treatment course; thus, it is important to better understand the data to help understand the optimal management of melanoma patients treated with anti-PD-1 therapy. The clinical data with anti-PD-1-based therapy and published data on the duration of therapy suggest that patients may not require a full 2 years of anti-PD-1 therapy and that the risk of toxicity may be mitigated by further understanding the mechanisms and kinetics of response to therapy. Although novel markers to help guide therapeutic decision making are under investigation, there is an ongoing need to improve our tools to monitor response to therapy and disease activity.

Optimizing Isotretinoin Treatment of Acne: Update on Current Recommendations for Monitoring, Dosing, Safety, Adverse Effects, Compliance, and Outcomes

Acne vulgaris is the most common skin disease treated by dermatologists. It can be severe and result in permanent scars. Isotretinoin is the most effective treatment for acne and has the potential for long-term clearance. Prescribing and monitoring protocols can vary widely among prescribers. Recent studies, reports, and consensus statements help shed light on optimizing the use of isotretinoin for acne. A recent literature review is summarized in this article to help the practitioner optimize isotretinoin use for acne. The article outlines the advantages and disadvantages of standard, high-dose, and low-dose isotretinoin regimens; discusses the current status of controversies surrounding isotretinoin (including depression/suicide, pregnancy, and inflammatory bowel disease); reviews monitoring recommendations and treatment for hypertriglyceridemia and elevated transaminase levels; and discusses common adverse effects seen with isotretinoin, along with their treatment and prevention.

Are monitoring instructions provided in direct healthcare professional communications (DHPCs) of sufficient quality? A retrospective analysis of DHPCs sent out between 2007 and 2018

OBJECTIVE

To assess whether direct to healthcare professional communications (DHPCs) are of sufficient quality to be applicable in clinical practice and study how the quality differs according to safety concerns and type of monitoring.

DESIGN

Retrospective cohort study.

SETTING

DHPCs containing monitoring instructions were identified among all DHPC issued in Denmark between 2007 and 2018.

INTERVENTION

Quality of information of monitoring instructions was assessed according to the Systematic Information for Monitoring (SIM) score. Associations between different characteristics of instructions and the SIM score were compared with analysis of variance and the post hoc test Tukey's honestly significant difference if significant.

RESULTS

In total, 297 DHPCs were issued, of which 97 contained 134 monitoring instructions. For 95% of these DHPCs the European Medicines Agency was involved. The average SIM score was 2.6±1.6 (ranging 0-6) and only 47% were considered of sufficient quality (SIM score ≥3). In addition, even fewer (11%) instructions were considered a 'adequate instruction' which also reported about facts and risks. Differences between quality of information according to type of monitoring were observed, specifically between clinical monitoring (average SIM score 1.9) and biomarker monitoring (physical average SIM score 2.9, p=0.029 and laboratory average SIM score 3.4, p<0.0001).

CONCLUSIONS

Monitoring instructions were found not to be of sufficient quality to be applicable in clinical practice according to the SIM score. Our study concludes the need for further research and regulatory steps to ensure improve quality of information in safety communications.

Quantification of T Cell Binding Polyclonal Rabbit Anti-thymocyte Globulin in Human Plasma with Liquid Chromatography Tandem-Mass Spectrometry

The addition of rabbit anti-human thymocyte globulin (ATG) to the conditioning regimen prior to allogeneic hematopoietic cell transplantation has significantly reduced the risk of graft-versus-host disease (GvHD) and graft failure. However, ATG has a small therapeutic window. Overexposure of ATG post-HCT hampers T cell immune reconstitution and has been associated with increased relapse rates and viral reactivations, whereas underexposure has been associated with an increased incidence of GvHD, both of which lead to increased mortality. Therapeutic drug monitoring of T cell binding ATG plasma levels provides a means to optimize dosing for patients at high risk for graft failure to ensure timely T cell immune reconstitution and subsequently increase survival chances. This manuscript describes the first liquid chromatography tandem-mass spectrometry (LC-MS/MS) method to quantify the pharmacologically active fraction of polyclonal ATG in plasma. This was achieved through immunoaffinity purification of active ATG from plasma with Jurkat T cells. After the binding and washing, samples were eluted, denatured, and trypsin-digested. Signature peptides originating from the IgG constant chain were measured with LC-MS/MS. Critical method parameters were optimized, and the method was successfully validated following European Medicines Agency (EMA) guidelines. The method covered the therapeutic range of ATG and was validated at a lower limit of quantification (LLOQ) of 1 AU/mL with an overall CV and bias of 11.8% and - 2.5%, respectively. In conclusion, we developed a LC-MS/MS-based method to quantify active polyclonal rabbit ATG in human plasma. We suggest that this novel assay can be used to monitor and optimize dosing of ATG in clinical practice.

A randomized evaluation of on-site monitoring nested in a multinational randomized trial

BACKGROUND

Evidence from prospectively designed studies to guide on-site monitoring practices for randomized trials is limited. A cluster randomized study, nested within the Strategic Timing of AntiRetroviral Treatment (START) trial, was conducted to evaluate on-site monitoring.

METHODS

Sites were randomized to either annual on-site monitoring or no on-site monitoring. All sites were centrally monitored, and local monitoring was carried out twice each year. Randomization was stratified by country and projected enrollment in START. The primary outcome was a participant-level composite outcome including components for eligibility errors, consent violations, use of antiretroviral treatment not recommended by protocol, late reporting of START primary and secondary clinical endpoints (defined as the event being reported more than 6 months from occurrence), and data alteration and fraud. Logistic regression fixed effect hierarchical models were used to compare on-site versus no on-site monitoring for the primary composite outcome and its components. Odds ratios and 95% confidence intervals comparing on-site monitoring versus no on-site monitoring are cited.

RESULTS

In total, 99 sites (2107 participants) were randomized to receive annual on-site monitoring and 97 sites (2264 participants) were randomized to be monitored only centrally and locally. The two monitoring groups were well balanced at entry. In the on-site monitoring group, 469 annual on-site monitoring visits were conducted, and 134 participants (6.4%) in 56 of 99 sites (57%) had a primary monitoring outcome. In the no on-site monitoring group, 85 participants (3.8%) in 34 of 97 sites (35%) had a primary monitoring outcome (odds ratio = 1.7; 95% confidence interval: 1.1-2.7; p = 0.03). Informed consent violations accounted for most outcomes in each group (56 vs 41 participants). The largest odds ratio was for eligibility violations (odds ratio = 12.2; 95% confidence interval: 1.8-85.2; p = 0.01). The number of participants with a late START primary endpoint was similar for each monitoring group (23 vs 16 participants). Late START grade 4 and unscheduled hospitalization events were found for 34 participants in the on-site monitoring group and 19 participants in the no on-site monitoring group (odds ratio = 2.0; 95% confidence interval: 1.1-3.7; p = 0.02). There were no cases of data alteration or fraud. Based on the travel budget for on-site monitoring and the hours spent conducting on-site monitoring, the estimated cost of on-site monitoring was over US$2 million.

CONCLUSION

On-site monitoring led to the identification of more eligibility and consent violations and START clinical events being reported more than 6 months from occurrence as compared to no on-site monitoring. Considering the nature of the excess monitoring outcomes identified at sites receiving on-site monitoring, as well as the cost of on-site monitoring, the value to the START study was limited.

Novel "Matrix-Corrected Calibration" study for the detection of polyunsaturated fatty acids (PUFAs) in plasma and erythrocytes by means of a gas chromatography-mass spectrometry approach optimized to follow up long-term parental patients

An accurate and specific gas chromatography-mass spectrometry (GC-MS) method was optimized to quantify specific polyunsaturated fatty acids (PUFAs) in plasma and in erythrocyte membranes for clinical purposes. The developed and fully-validated method showed optimal linearity in addition to adequate results in terms of accuracy, intra-day and inter-day precision. By adopting the Matrix-Corrected Calibration approach on all the biological matrices tested, both the constant and the proportional errors of the developed analytical methodology were considered to assure that the method was not affected by matrix bias. Moreover, a pilot study involving patients in parental nutrition with two different compositions of the administered fat emulsion was performed. The comparison of results obtained in these patients with a group of healthy subjects (i.e. control population) showed significant differences in the collected values of PUFAs in both plasma and erythrocyte membranes, thus providing evidence that the described GC-MS method could be employed as a simple tool for fast and accurate PUFAs analysis aimed at optimizing parenteral nutrition protocols.

An isotope dilution LC-MS/MS based candidate reference method for the quantification of cyclosporine A, tacrolimus, sirolimus and everolimus in human whole blood

An isotope dilution LC-MS/MS based candidate reference measurement procedure for the quantification of cyclosporine A, tacrolimus, sirolimus and everolimus in human whole blood is presented to be used for evaluation and standardization of routine assays applied for therapeutic drug monitoring. The assay allows baseline separation of the four immunosuppressive drugs within a total runtime of 9 minutes using a C4 reversed phase column. Sample preparation is based on protein precipitation with zinc sulphate followed by purification with solid phase extraction. Reference materials used in this reference measurement procedure were characterized by qNMR and an absolute content of analytes calculated to guarantee traceability to SI units. As internal standards the corresponding deuterated and ¹³C-labelled analytes were used. The method allows the measurement of cyclosporine A in the range of 5 ng/mL to 2100 ng/mL; tacrolimus, sirolimus and everolimus were analysed in the range of 0.25 ng/mL to 50 ng/mL. Imprecision for inter-day measurements were found to be ≤3.5% for cyclosporine A and ≤4.4% for tacrolimus, sirolimus and everolimus. Accuracy was found to be within 101% and 108% for cyclosporine A and between 95% and 104% for the macrolide compounds. The uncertainty was evaluated according to the GUM. Expanded measurement uncertainties were found to be ≤7.2% for cyclosporine A, ≤6.8% for tacrolimus, ≤9.0% for sirolimus and ≤8.9% for everolimus (k = 2).

Beyond HbA1c : using continuous glucose monitoring metrics to enhance interpretation of treatment effect and improve clinical decision-making

Assessment of glycaemic outcomes in the management of Type 1 and Type 2 diabetes has been revolutionized in the past decade with the increasing availability of accurate, user-friendly continuous glucose monitoring (CGM). This advancement has brought a need for new techniques to appropriately analyse and understand the voluminous and complex CGM data for application in research-related goals and clinical guidance for individuals. Traditionally, HbA_1c was established using the Diabetes Control and Complications Trial (DCCT) and other trials as the ultimate measure of glycaemic control in terms of efficacy and, by default, risk of microvascular complications of diabetes. However, it is acknowledged that HbA_1c alone is inadequate at describing an individual's daily glycaemic variation and risks for hypo- and hyperglycaemia, and it does not provide the guidance needed to decrease those risks. CGM data provide means by which to characterize an individual's daily glycaemic excursions on a different time scale measured in minutes rather than months. As a consequence, clinical reports, such as the ambulatory glucose profile, increasingly include summary statistics related to averages (mean glucose, time in range) as well as markers related to glycaemic variability (coefficient of variation, standard deviation). However, there is a need to translate those metrics into specific risks that can be addressed in an actionable plan by individuals with diabetes and providers. This review presents several clinical scenarios of glycaemic outcomes from CGM data that can be analysed to describe glycaemic variability and its attendant risks of hyperglycaemia and hypoglycaemia, moving towards relevant interpretation of the complex CGM data streams.

Laboratory assay measurement of modified clotting factor concentrates: a review of the literature and recommendations for practice

Over the past several years, novel modified clotting factor concentrates (CFCs) have been introduced into practice and are now widely prescribed in the countries where they are licensed. These products allow for less frequent infusions of CFC, thereby providing improved convenience and/or higher trough levels. They have been extensively studied for prophylaxis, episodic treatment of bleeding and for surgical prophylaxis. One issue that has emerged regarding the clinical application of these products revolves around the measurement of infused CFC in the clinical coagulation laboratory. Recent studies have demonstrated significant problems with the measurement of correct FVIII/IX levels following infusion of novel CF VIII/IX concentrates. The source of this problem appears to be related to the tremendous variability of the APTT reagents that are used in the one-stage clotting assay, the most commonly used assay for determining factor levels. More specifically, the issue is related to the type of activator used in the reagents. Depending on the combination of the CFC and the APTT activator, the observed results may be either under- or overestimated to degrees that would be clinically relevant. Recommendations based on a review of published information regarding the potential for incorrect measurements of factor VIII/IX levels following infusion of recently developed, novel factor VIII/IX CFCs are presented for the clinician to use in clinical practice.

Rationale for Raising Current Clinical Practice Guideline Target for Serum 25-Hydroxyvitamin D in Chronic Kidney Disease

BACKGROUND

Vitamin D repletion is recommended for secondary hyperparathyroidism (SHPT) and associated vitamin D insufficiency (VDI) in chronic kidney disease (CKD), but optimal levels of serum total 25-hydroxyvitamin D remain undefined. Clinical practice guidelines target sufficiency, whereas recent data indicate that higher levels are required to control the elevation of intact parathyroid hormone (iPTH) as CKD advances. This secondary analysis of 2 randomized controlled trials seeks to identify the minimum level of mean serum 25-hydroxyvitamin D required to control SHPT arising from VDI in stage 3 or 4 CKD.

METHODS

Adult subjects (n = 429) with SHPT, VDI, and stage 3 or 4 CKD were stratified by stage and treated daily with either extended-release calcifediol (ERC) or placebo in 2 identical, parallel, randomized, double-blind studies. After treatment for 26 weeks, all subjects were ranked by the level of serum total 25-hydroxyvitamin D and divided into quintiles in order to examine the relationships between the degree of vitamin D repletion and the associated changes in plasma iPTH, serum bone turnover markers, calcium, phosphorus, intact fibroblast growth factor 23 (FGF23) and vitamin D metabolites, estimated glomerular filtration rate (eGFR), and urine calcium:creatinine (Ca:Cr) ratio.

RESULTS

Progressive increases in serum 1,25-dihydroxyvitamin D and reductions in plasma iPTH and serum bone turnover markers were observed as mean posttreatment serum 25-hydroxyvitamin D rose from 13.9 ng/mL (in Quintile 1) to 92.5 ng/mL (in Quintile 5), irrespective of CKD stage. Mean serum calcium, phosphorus and FGF23, eGFR, and urine Ca:Cr ratio (collectively "safety parameters") did not significantly change from Quintile 1. Suppression of iPTH and bone turnover markers was not observed until serum 25-hydroxyvitamin D rose to at least 50.8 ng/mL (Quintile 3).

CONCLUSION

ERC therapy produced exposure-dependent reductions in plasma iPTH and bone turnover markers only when mean serum total 25-hydroxyvitamin D reached at least 50.8 ng/mL, indicating that current targets for vitamin D repletion therapy in CKD are too low. Gradual elevation of mean serum 25-hydroxyvitamin D to 92.5 ng/mL was not associated with significant adverse changes in safety parameters.

New Zealand Society of Gastroenterology Guidelines on Therapeutic Drug Monitoring in Inflammatory Bowel Disease

The incidence of inflammatory bowel disease (IBD) in New Zealand has increased over the last several decades. The management of IBD has been transformed since the introduction of monoclonal antibody drugs. Other medications used in the treatment of IBD include amino-salicylates, steroids, thiopurines and methotrexate. Therapeutic drug monitoring (TDM) involves the measurement of serum drug levels or active metabolites and anti-drug antibodies. TDM is essential for a personalised approach to the management of patients with IBD and is used to optimise drug efficacy and reduce the risk of toxicity. In IBD, TDM can be used for checking adherence, evaluating drug toxicity, identifying hypermethylators, assessing loss of response and in decisions regarding treatment escalation or de-escalation. Management decisions in patients on a thiopurine are facilitated by checking TPMT enzyme activity and thiopurine metabolite levels. Measurement of drug trough levels and anti-drug antibodies can result in individualised treatment decisions in patients on biologics. In addition to using TDM in patients who fail therapy, proactive TDM can potentially facilitate early treatment decisions, albeit more work is needed in this area. The clinical benefits of reactive TDM are well documented and this has been shown to be cost effective. Studies have shown that combination therapy in patients on a biologic leads to better clinical outcomes. Effective use of drugs in the treatment of IBD is even more imperative in the New Zealand setting due to relatively fewer options of funded treatment, and the limitations on the use of available drugs. This document represents the current guidelines of the New Zealand Society of Gastroenterology on TDM in IBD.

Growth Hormone (GH) Therapy During the Transition Period: Should We Think About Early Retesting in Patients with Idiopathic and Isolated GH Deficiency?

To investigate growth hormone (GH) secretion at the transition age, retesting of all subjects who have undergone GH replacement therapy is recommended when linear growth and pubertal development are complete to distinguish between transitional and persistent GH deficiency (GHD). Early retesting of children with idiopathic and isolated GHD (i.e., before the achievement of final height and/or the adult pubertal stage) can avoid possible over-treatment. Here, we report data from our population with idiopathic and isolated GHD to encourage changes in the management and timing of retesting. We recruited 31 patients (19 males) with idiopathic GHD who received recombinant GH (rGH) for at least 2 years. All of the patients were retested at the transition age at least 3 months after rGH discontinuation. Permanent GHD was defined as a GH peak of <19 ng/mL after administration of growth hormone–releasing hormone (GHRH) + arginine as a provocative test. Permanent GHD was confirmed in only five of 31 patients (16.13%). None of these patients presented low serum insulin-like growth factor (IGF)-1 levels (<−2 standard deviation score (SDS)). Only one male patient with an IGF-1 serum level lower than −2 SDS showed a normal GH stimulation response, with a GH peak of 44.99 ng/mL. Few patients with idiopathic and isolated GHD demonstrated persistence of the deficit when retested at the transition age, suggesting that the timing of retesting should be anticipated to avoid overtreatment.

Quantification of Designer Opioids by Liquid Chromatography-Tandem Mass Spectrometry

Opioids including heroin and commonly prescribed drugs such as oxycodone and fentanyl are among the most commonly abused drugs. In recent years, the abuse of opioids has spread beyond these commonly encountered analytes and now includes novel psychoactive drugs such as AH-7921 and U47700 and a variety of fentanyl-related compounds such as acetyl fentanyl and furanyl fentanyl. The assay described is for the quantitative determination of 19 designer opioids in serum, plasma, and whole blood. Also included is a discussion on the challenges of keeping an analytical method current as new analytes appear on the illicit drug market.

An Introduction to Drug Testing: The Expanding Role of Mass Spectrometry

Measurement of drugs and their metabolites in biological fluids is the foundation of both therapeutic drug monitoring (TDM) and toxicology. The introduction of methods based on mass spectrometry (MS), coupled with gas or liquid chromatography, has revolutionized these areas. This chapter will introduce the reader to the application of MS to TDM and toxicology, the steps that should be considered during implementation and the processes that should be implemented to assure continued quality. Points of emphasis include advances and recent trends since the publication of the first edition of this book, such as high-resolution mass spectrometry and increased interest in alternate matrices.

Analysis of Synthetic Cannabinoid Metabolites by Liquid Chromatography-Tandem Mass Spectrometry

The analysis of synthetic cannabinoid compounds in a urine sample is currently one of the more complex tasks facing toxicologists. The list of prevalent compounds in circulation at any given time is constantly in flux, changing at a rapid rate to avoid legal control and to a lesser extent to avoid detection. Even with knowledge of the chemical entities, their detection in urine is complicated by the fact that they are present exclusively as both phase I metabolites and phase II conjugates. With proper knowledge of the correct analytical targets, relatively simple procedures are capable of extracting and analyzing synthetic cannabinoids. Following enzymatic hydrolysis, compounds can be extracted through liquid partitioning procedures, and the extracts are analyzed via LC-MS/MS.

Therapeutic Drug Monitoring of Lacosamide by LC-MS/MS

High-performance liquid chromatography tandem mass spectrometry (LC-MS/MS) has become a primary analytical methodology in therapeutic drug monitoring of antiepileptic drugs (AEDs). To demonstrate the utility of LC-MS/MS in measuring drug concentrations in serum or plasma, analysis of lacosamide (Vimpat^™) is discussed in this chapter. Lacosamide is an example of the newer-generation AEDs. The drug is extracted by protein precipitation and dilution of the serum specimen. A small volume of the extracted specimen is injected into a reversed-phase chromatography column, and lacosamide is identified by positive electrospray ionization (ESI) mass spectrometry in the multiple reaction monitoring (MRM) mode, which provides selectivity for quantitative analysis. A deuterated internal standard is used to correct for any loss of analyte during the process of extraction and analysis. A seven-point calibration curve and two levels of quality controls are included in each batch.

Proactively Optimized Infliximab Monotherapy Is as Effective as Combination Therapy in IBD

BACKGROUND

Infliximab (IFX) discontinuation is not uncommon during the first year of treatment due to inadequate drug concentrations and anti-IFX antibodies (ATI). Both combination therapy and proactive therapeutic drug monitoring (pTDM) are used to decrease ATI and increase IFX durability. We proposed that monotherapy (Mono) is as effective as combination therapy (Combo) if the first maintenance infusion is dosed based on week 10 pTDM.

METHODS

In a retrospective cohort of 83 patients with inflammatory bowel disease (IBD), we examined the frequency of IFX discontinuation, ATI, infusion reactions, and IFX concentrations during the first year of treatment in patients receiving week 10 pTDM-guided IFX monotherapy (Mono pTDM; n = 16) compared with patients on mono (n = 32) or combination therapy (n = 35) in whom TDM was introduced at or after week 14, per standard of care (SOC).

RESULTS

The frequency of IFX discontinuation was lower with Mono pTDM compared with Mono SOC (P = 0.04) but did not differ with Combo SOC (P = 1). At first TDM, no patient in the pTDM strategy had ATI, vs 41% in Mono SOC (P = 0.002) and 6% in Combo SOC (P = 1). Of the 13 subjects with ATI in Mono SOC, 7 (47%) had ATI already at week 14. IFX trough concentrations with Mono pTDM were higher during maintenance compared with Mono SOC (9.5 vs 6.4 µg/mL, P = 0.04) but not Combo SOC.

CONCLUSIONS

Infliximab durability did not differ between patients on IFX monotherapy dosed based on p-TDM and patients receiving combination therapy. In the absence of concomitant immunosuppression, proactive TDM may improve IFX durability by maintaining higher IFX concentrations entering into maintenance. Further studies are needed to confirm our findings.

Perioperative management of patients who are receiving antiplatelet therapy: a case-based, evidence-informed approach

Addressing the optimal management approach for patients who are receiving single or dual antiplatelet therapy is a common and sometimes challenging clinical problem, especially for patients with coronary stents who are receiving dual antiplatelet therapy with acetylsalicylic acid (ASA) combined with a P2Y12 inhibitor. Using a case-based format, we summarize the findings of recent clinical trials and key observational studies which help inform best practices for the perioperative antiplatelet management of noncardiac surgery and coronary artery bypass graft surgery. In this review, we explore the evidence to address 3 key questions: What is the minimum duration that a surgery should be delayed after coronary stent implantation? In patients who are receiving single antiplatelet therapy with ASA, how to manage patients who require noncardiac and cardiac surgery? In patients who are receiving dual antiplatelet therapy for a coronary stent, how to manage patients who require noncardiac and cardiac surgery?

Evolution of haemostatic parameters and risk of bleeding during treatment with cefazolin

In 2017, five cases of severe haemorrhages during treatment with cefazolin occurred in France. The aim of this study was to assess the risk of haemorrhage related to treatment with cefazolin by evaluating haemostatic parameters and bleeding events. A retrospective study was conducted from January 2016 to December 2017. Two populations were analysed: (i) overall population, which included all patients treated with cefazolin during this period and (ii) coagulation study population, which included all patients treated with cefazolin with available coagulation parameters (activated partial thromboplastin time (aPTT) and international normalised ratio (INR) at baseline and at the end of treatment or EoT). Values of either aPTT or INR at baseline and at EoT were compared. Cases of severe haemorrhages were reported and correlated with values of aPTT and INR. Overall, 132 patients received cefazolin and 59/132 (45%) were included in the coagulation study group. A significant increase of median aPTT was observed from baseline to EoT (39.5 and 44.3 sec; p = 0.004, respectively). Overall, severe haemorrhage occurred in 7/132 (5%) patients. Coagulation parameters were available in three of them, and no correlation was observed between bleeding events and aPTT increase. This study showed that bleeding is probably more frequent than ever reported before during cefazolin treatment. The significant increase of aPTT observed during cefazolin treatment was not correlated with risk of haemorrhage. Further studies are needed to explore the possible physio-pathological pathways behind the modification of haemostatic parameters and risk of haemorrhage.

Methods for the assessment of selection bias in drug safety during pregnancy studies using electronic medical data

Electronic health data are routinely used for population drug studies. Due to the ethical dilemma in carrying out experimental drug studies on pregnant women, the effects of medication usage during pregnancy on fetal and maternal outcomes are largely evaluated using this data collection medium. One major limitation in this type of study is the delayed inclusion of pregnancies in the cohort. For example, in the province of Quebec, Canada, a major pregnancy cohort only captured pregnancies after 20 weeks gestation. The purpose of this study was to demonstrate three methods that can be used to assess the extent of selection bias due to the delayed inclusion of pregnancies. We use causal directed acyclic graphs to explain the source of this selection bias. In an example involving a cohort of pregnant asthmatic women reconstructed from the linkage of administrative health databases from the province of Quebec, we use numerical derivations, a simulation study and a sensitivity analysis to investigate the potential for bias and loss of power due to the delayed inclusion. We find that this selection bias can be partially mitigated by controlling for variables related to (spontaneous or therapeutic) abortion and the outcome of interest. The three proposed methods allow for the pre and post hoc ascertainment of the bias. While delayed pregnancy inclusion selection bias (which includes "live birth bias") can produce substantial bias in pregnancy drug studies, all three methods are effective at producing estimates of the size of the bias.

Efficacy and tolerability of novel triple combination therapy in drug-naïve patients with type 2 diabetes from the TRIPLE-AXEL trial: protocol for an open-label randomised controlled trial

INTRODUCTION

Patients with type 2 diabetes are at risk of microvascular and macrovascular complications. Intensive glycaemic control, especially in patients with short duration of diabetes, is the mainstay of management of type 2 diabetes to lower the risk of complications. However, despite the improvement in the understanding of the pathophysiology of type 2 diabetes and development of novel glucose-lowering agents, long-term durable glycaemic control remains a difficult goal to achieve. Several challenging clinical trials proved that an early combination therapy with a variety of glucose-lowering agents had a more favourable effect than conventional stepwise therapy in terms of glycaemic control. We aim to evaluate the efficacy and tolerability of a novel, initial triple combination therapy with metformin, sodium glucose cotransporter 2 inhibitor (dapagliflozin) and dipeptidyl peptidase-4 inhibitor (saxagliptin) compared with conventional stepwise add-on therapy in drug-naïve patients with recent-onset type 2 diabetes.

METHODS AND ANALYSIS

This study is a multicentre, prospective, randomised, open-label, parallel group, comparator-controlled trial. A total of 104 eligible participants will be randomised to either the initial combination therapy group or the conventional stepwise add-on therapy group for 104 weeks. The primary endpoint is the proportion of patients who achieved haemoglobin A1c level<6.5% without hypoglycaemia, weight gain or discontinuation due to adverse events at 104 weeks. This trial will determine whether a novel triple combination therapy with metformin, dapagliflozin and saxagliptin has a beneficial effect on durable glycaemic control compared with conventional therapy in drug-naïve patients with type 2 diabetes.

ETHICS AND DISSEMINATION

This study protocol was approved by the local institutional review boards and independent ethics committees over the recruitment sites. Results of this study will be disseminated in scientific journals and scientific conferences.

TRIAL REGISTRATION NUMBER

NCT02946632; Pre-results.

Applying U.S. national guidelines for ototoxicity monitoring in adult patients: perspectives on patient populations, service gaps, barriers and solutions

OBJECTIVES

To promote establishment of effective ototoxicity monitoring programs (OMPs), this report reviews the U.S. national audiology guidelines in relation to "real world" OMP application. Background is provided on the mechanisms, risks and clinical presentation of hearing loss associated with major classes of ototoxic medications.

DESIGN

This is a non-systematic review using PubMed, national and international agency websites, personal communications between ototoxicity experts, and results of unpublished research. Examples are provided of OMPs in various healthcare settings within the U.S. civilian sector, Department of Defense (DoD), and Department of Veterans Affairs (VA).

STUDY SAMPLE

The five OMPs compared in this report represent a convenience sample of the programs with which the authors are affiliated. Their opinions were elicited via two semi-structured teleconferences on barriers and facilitators of OMP, followed by a self-administered questionnaire on OMP characteristics and practices, with responses synthesized herein. Preliminary results are provided from an ongoing VA clinical trial at one of these OMP sites. Participants were 40 VA patients who received cisplatin chemotherapy in 2014-2017. The study arms contrast access to care for OMP delivered on the treatment unit versus usual care as provided in the audiology clinic.

RESULTS

Protocols of the OMPs examined varied, reflecting their diverse settings. Service delivery concerns included baseline tests missed or completed after the initial treatment, and monitoring tests done infrequently or only after cessation of treatment. Perceived barriers involved logistics related to accessing and testing patients, such as a lack of processes to help patients enter programs, patients' time and scheduling constraints, and inconvenient audiology clinic locations. Use of abbreviated or screening methods facilitated monitoring.

CONCLUSIONS

The most effective OMPs integrated audiological management into care pathways of the clinical specialties that prescribe ototoxic medications. More OMP guidance is needed to inform evaluation schedules, outcome reporting, and determination of actionable ototoxic changes. Guidance is also lacking on the use of hearing conservation approaches suitable for the mass testing needed to support large-scale OMP efforts. Guideline adherence might improve with formal endorsement from organizations governing the medical specialty stakeholders in OMP such as oncologists, pulmonologists, infectious disease specialists, ototolaryngologists and pharmacists.

Practical fluorimetric assay for the detection of anticancer drug SN-38 in human plasma

The implementation of therapeutic drug monitoring in the routine clinical practice in oncology is mainly limited by the lack of therapeutic indexes for the majority of the anticancer drugs, and by the absence of suitable analytical tools, which can accurately quantify in real time the concentration of the administered drugs and their relevant metabolites in biological fluids. In this work, a simple and efficient fluorimetric determination of SN-38, the active metabolite of the anticancer drug irinotecan, was developed and applied to human plasma samples. The intrinsic fluorescence of SN-38 allowed its quantification in the range 10-500 ng mL^-1 with a LOQ of 5.0 ng mL^-1 and a LOD of 1.5 ng mL^-1. Low interferences due to main metabolites of irinotecan and comedications, commonly associated with administration of irinotecan, were observed. A validation study, according to FDA and EMA guidelines for bioanalytical method validation, was carried out and, finally, blind samples were analyzed in parallel with a HPLC-MS method obtaining an excellent agreement between the two techniques.

Appropriateness of vancomycin therapeutic drug monitoring and its outcomes among non-dialysis patients in a tertiary hospital in Singapore

Background Vancomycin therapeutic drug monitoring (TDM) is commonly performed to ensure safe and effective use of the antibiotic. Aim of Study To evaluate appropriateness of vancomycin TDM and its outcomes in Singapore General Hospital. Method A retrospective, cross-sectional study was conducted between 1 January 2014 and 28 February 2014 involving patients who received ≥ 1 dose of intravenous vancomycin with TDM. Patient demographics and relevant vancomycin TDM data were collected from medical records. Results Of 746 vancomycin troughs measured among 234 patients, 459 troughs (61.5%) were taken inappropriately, with a median time of 2.6 h (interquartile range 1.1-4.3) before the next scheduled dose. Inappropriate interpretation of vancomycin troughs resulted in 41 unnecessary dose suspensions, 24 dose changes, and 102 unchanged vancomycin doses. The cost incurred due to inappropriate interpretation and measurement after discontinuation of treatment was US$7286. No differences in rates of vancomycin related nephrotoxicity, ototoxicity, recurrent infection, development of infection secondary to vancomycin resistant microorganism and mortality were observed (p > 0.05). Conclusion This study highlighted a high incidence of inappropriate vancomycin TDM which has led to increased healthcare cost.

Pharmacist Impact on Tacrolimus Serum Concentrations in Liver Transplant Patients

Objective The purpose of this quality-improvement project was to determine if a pharmacist consultation following a liver transplant is associated with an increased percentage of drug levels in range after the patient sees the pharmacist. Setting Tertiary care, multispecialty medical clinic, and hospital providing solid-organ transplant. Practice Description Pharmacist consult service in a tertiary care, multispecialty medical clinic and hospital providing solid-organ transplant. Practice InnovationProvision of liver post-transplant consultations, not required by the Centers for Medicare & Medicaid Services, that results in therapeutic drug level improvement. Main Outcome MeasureTacrolimus therapeutic drug levels in range. Results A 96% improvement in quantity of therapeutic tacrolimus levels was seen in liver post-transplant patients after pharmacist post-transplant consultation. Results revealed 59 out of 74 (79.7%) post-liver transplant patients, 25 to 77 years of age (average 59.7 years), had an increased number of therapeutic tacrolimus levels after pharmacist post-transplant consultation. ConclusionWithout a pharmacist consultation following a liver transplant, patients may have a higher number of tacrolimus levels out of therapeutic range, placing them at increased risk for possible graft loss from low tacrolimus levels or toxicity resulting from high tacrolimus levels. Improvement in therapeutic tacrolimus levels after liver transplant was observed after patients received consultation and education from a clinical pharmacist. This finding creates an opportunity for pharmacists to implement services for patients after liver transplants to improve therapeutic tacrolimus levels.

The Impact of Prescription Drug Monitoring Programs and Prescribing Guidelines on Emergency Department Opioid Prescribing: A Multi-Center Survey

Objective

Emergency department (ED) providers are high volume but low quantity prescribers of opioid analgesics (OA). Few studies have examined differences in opioid prescribing decisions specifically among ED providers. The aim of this study was to describe OA prescribing decisions of ED providers at geographically diverse centers, including utilization of prescribing guidelines and prescription drug monitoring programs (PDMP).

Methods

This was a multi-center cross-sectional Web-based survey of ED providers who prescribe OA. Respondents were asked about their OA prescribing decisions, their use of PDMPs, and their use of prescribing guidelines. Data was analyzed using descriptive statistics and chi-square tests of association were used to assess the relationship between providers' opioid prescribing decisions and independent covariates.

Results

The total survey population was 957 individuals and 515 responded to the survey for an overall response rate of 54%. The frequency respondents prescribed different types of pain medication was variable between centers. of respondents were registered to access a PDMP, and were not aware whether their state had a PDMP. Forty percent (172/426) of respondents used OA prescribing guidelines, while 24% (103/426) did not, and 35% (151/426) were unaware of prescribing guidelines. No significant differences in OA prescribing decisions were found between groups either by use of PDMP or by guideline adherence.

Conclusions

In this multi-center survey study of ED clinicians, OA prescribing varied between centers The utilization of prescribing guidelines and PDMPs was not associated with differences in OA prescribing decisions.

Reference ranges for antiepileptic drugs revisited: a practical approach to establish national guidelines

BACKGROUND AND OBJECTIVE

Laboratories sometimes use different reference ranges for the same antiepileptic drug (AED), particularly for new and poorly investigated drugs. This may contribute to misunderstandings, concerns or inappropriate dose changes, which in turn may affect therapeutic effect, drug safety or treatment adherence. Therefore, the Norwegian Association of Clinical Pharmacology wished to update and harmonize the reference ranges for AEDs and establish national guidelines for Norway.

METHODS

A working group collected information on the reference ranges used by Norwegian laboratories for all commonly used AEDs. These reference ranges were compared to recent recommendations by the International League Against Epilepsy, current literature, applicable clinical studies, reference ranges used by leading Northern European epilepsy centers outside of Norway, and routine data derived from Norwegian laboratory databases.

RESULTS

Reference ranges varied between laboratories for four of 23 available AEDs (lamotrigine, valproate, eslicarbazepine and oxcarbazepine). For four AEDs (brivaracetam, perampanel, stiripentol and sulthiame), reference ranges had not previously been established. In total, 13 reference ranges were either harmonized, updated or newly established. No changes were applied to the remaining 10 AEDs.

CONCLUSION

Updated and harmonized reference ranges are now available for 22 of the 23 AEDs available in Norway. The exception is vigabatrin (reference range not applicable). Revision of reference ranges is an important part of pharmacovigilance of AEDs and must be a continuous process based on current literature and clinical experience.

International collaborative study for the calibration of proposed International Standards for thromboplastin, rabbit, plain, and for thromboplastin, recombinant, human, plain

Essentials Two candidate International Standards for thromboplastin (coded RBT/16 and rTF/16) are proposed. International Sensitivity Index (ISI) of proposed standards was assessed in a 20-centre study. The mean ISI for RBT/16 was 1.21 with a between-centre coefficient of variation of 4.6%. The mean ISI for rTF/16 was 1.11 with a between-centre coefficient of variation of 5.7%.

SUMMARY

Background The availability of International Standards for thromboplastin is essential for the calibration of routine reagents and hence the calculation of the International Normalized Ratio (INR). Stocks of the current Fourth International Standards are running low. Candidate replacement materials have been prepared. This article describes the calibration of the proposed Fifth International Standards for thromboplastin, rabbit, plain (coded RBT/16) and for thromboplastin, recombinant, human, plain (coded rTF/16). Methods An international collaborative study was carried out for the assignment of International Sensitivity Indexes (ISIs) to the candidate materials, according to the World Health Organization (WHO) guidelines for thromboplastins and plasma used to control oral anticoagulant therapy with vitamin K antagonists. Results Results were obtained from 20 laboratories. In several cases, deviations from the ISI calibration model were observed, but the average INR deviation attributabled to the model was not greater than 10%. Only valid ISI assessments were used to calculate the mean ISI for each candidate. The mean ISI for RBT/16 was 1.21 (between-laboratory coefficient of variation [CV]: 4.6%), and the mean ISI for rTF/16 was 1.11 (between-laboratory CV: 5.7%). Conclusions The between-laboratory variation of the ISI for candidate material RBT/16 was similar to that of the Fourth International Standard (RBT/05), and the between-laboratory variation of the ISI for candidate material rTF/16 was slightly higher than that of the Fourth International Standard (rTF/09). The candidate materials have been accepted by WHO as the Fifth International Standards for thromboplastin, rabbit plain, and thromboplastin, recombinant, human, plain.

Point of care monitoring of oral anticoagulant therapy in children: comparison of CoaguChek Plus and Thrombotest methods with venous international normalised ratio

This paper reports the outcome of a research protocol aimed at optimising warfarin monitoring in a tertiary pediatric centre. The Thrombotest™ INR was the standard monitoring test employed to manage oral anticoagulant therapy in children at the Royal Children’s Hospital (RCH), Melbourne. This study compares the results of this standard method to the novel CoaguChek® INR monitor and the “gold standard” technique of venous INR sampling. The objectives were to determine 1) if point-of-care techniques of measuring the INR (Thrombotest and CoaguChek) are accurate and reliable compared to INR results obtained from venous sampling, processed in an accredited laboratory, and 2) if INR results generated by POC devices can be safely used to manage oral anticoagulant therapy in children. 18 children (10 females and 8 males) participated in the study. Ages ranged from 9 months to 21 years (Mean 11.9 years; SD 5.03 years). The agreement between CoaguChek and venous INR measurements (r = 0.885) was shown to be higher compared to Thrombotest and venous INR (r = 0.700). Compared to the venous INR, values obtained with Coaguchek and Thrombotest crossed into or out of the therapeutic range in 25% and 36% of cases respectively. In 88% of the CoaguChek cases and 57% Thrombotest cases, the difference from the venous result was less than 0.5. The CoaguChek method of INR monitoring is a more accurate and reliable method compared to Thrombotest, in the pediatric population tested, and can be safely used to manage oral anticoagulant therapy in children.

Transition from argatroban to oral anticoagulation with phenprocoumon or acenocoumarol: effects on prothrombin time, activated partial thromboplastin time, and Ecarin Clotting Time

Treatment with the direct thrombin inhibitor argatroban (ARG) is often followed by vitamin K-antagonist treatment (VKA). Phenprocoumon (PC) and acenocoumarol (AC) are frequently used in Europe. The standard monitoring test for VKA, prothrombin time (PT), is prolonged by direct thrombin inhibitors. Therefore the International Normalized Ratio (INR) obtained during combined treatment does not reflect the true effect of the VKA. A similar interference of the VKA on the activated partial thromboplastin time (aPTT), a monitoring assay for direct thrombin inhibitors, can occur. In 39 healthy volunteers the effect of ARG alone or combined with PC or AC on PT, INR, aPTT, and Ecarin Clotting Time (ECT) was investigated. 6 groups each of 6-8 volunteers received a 5-hour infusion of either 1.0, 2.0 or 3.0 µg/kg/min ARG (days 1, 3, 4 and 5) before initiation of either PC or AC (day 1) and during continued VKA dosing (target INR 2-3). A linear relationship (INR ARG+VKA = intercept + slope * INR VKA alone) was observed between the INR measured “on” and “off” ARG.The slope depended on the argatroban dose and on the International Sensitivity Index (ISI) of the PT reagent, the steepest slope (i.e., the largest difference between INR ARG+VKA and INR VKA alone) was seen with the highest ARG dose and the PT reagent with an ISI of 2.13.There was a close correlation between plasma levels of ARG and aPTT or ECT. Under VKA the ARG-aPTT relationship indicated an increased sensitivity of the aPTT to ARG, VKA treatment had no effect on the prolongation of the ECT induced by argatroban. In conclusion, ARG at doses up to 2 µg/kg/min can be discontinued at an INR of 4.0 on combined therapy with VKA, as this would correspond to an INR between 2.2 and 3.7 for the VKA. If it is necessary to monitor ARG in the critical transition period, the ECT which is not influenced by VKA can be used as an alternative to the aPTT.

High Performance Liquid Chromatographic Method for Direct Determination of Diazepam in Whole Blood and Serum - Optimization of Solid-Phase Extraction Method

Herein, we present a simple and rapid high performance liquid chromatographic (HPLC) method with UV-detection for the direct determination of diazepam in whole blood and serum that can be used for monitoring diazepam levels in clinical samples analysis. The isolation of diazepam and the internal standard bromazepam from serum and whole blood samples was performed using solid phase extraction method with RP select B cartridges. The analytes were separated employing a reversed phase C8 column with a mobile phase composed of 0.1 % (V/V) triethylamine in water (pH 3.5) and acetonitrile (63:37, V/V). UV detection was carried out at 240 nm. Linearity was achieved in the range from 10.0-1000.0 ng/ml for serum and whole blood. The method was applied to spiked and real biological samples after an oral administration of 10 mg diazepam. In conclusion, the proposed method is simple, rapid and provides efficient clean-up of the complex biological matrix and high recovery of diazepam.

[Prevalence of oral anticoagulation and quality of its management in primary healthcare: A study by the Health Sentinel Network of the Region of Valencia (Spain)]

OBJECTIVE

To estimate the prevalence of patients with oral anticoagulant therapy (OAT) in the Region of Valencia and to evaluate the quality of management of OAT with vitaminK antagonists (VKA) carried out in primary healthcare.

DESIGN

Observational cross-sectional study conducted through the Health Sentinel Network of the Region of Valencia, which includes a survey and the retrospective analysis of OAT monitoring.

SETTING

Primary healthcare, Region of Valencia, Spain.

SUBJECTS

All patients aged 18years or older on OAT who consulted during the year 2014. The population covered by the 59 doctors of the Health Sentinel Network constitutes 2.2% of the adult population of the Region of Valencia, and it is representative of it.

KEY MEASUREMENTS

Demographic, socioeconomic and health data as well as information concerning OAT. Quality of OAT management with VKA was assessed by means of the percentage of time in therapeutic range (TTR), computed using the Rosendaal method.

RESULTS

A total of 1,144 patients were recorded (mean age 74.5±11 years; 49.7% women). Prevalence of OAT in the Region of Valencia is 1.3 cases per 100 population. The characteristic profile of these patients is an old person, with several comorbidities and a low level of education, who lives accompanied. Atrial fibrillation is the most common indication. 82.8% of patients on OAT with VKA were monitored in primary healthcare. The average TTR was 65.0%, and 53.9% of patients had a TTR ≥65%. Among inadequately controlled patients, 74.4% were perceived as well-controlled by their primary care doctor.

CONCLUSIONS

Prevalence of OAT is high, and it is expected to increase. The degree of control achieved meets the generally accepted quality standard (mean TTR ≥65%), and it is comparable to that observed in other national and international studies. However, there is wide scope for improvement. It is crucial to optimize the management of this therapy in the most effective and cost-effective way. Among other measures, access of physicians to their patients' clinical information should be improved.

Qualification of a select one-stage activated partial thromboplastin time-based clotting assay and two chromogenic assays for the post-administration monitoring of nonacog beta pegol

Essentials Nonacog beta pegol (N9-GP) is an extended half-life, recombinant human factor IX (FIX). One-stage clotting (OSC) and chromogenic FIX activity assays were assessed for N9-GP recovery. OSC STA® -Cephascreen® , ROX FIX and BIOPHEN FIX chromogenic assays were qualified for N9-GP. Other extended half-life factor products should be assessed in a similar way prior to approval.

SUMMARY

Background Nonacog beta pegol (N9-GP) is an extended half-life, glycoPEGylated recombinant human factor IX that is under development for the prophylaxis and treatment of bleeding episodes in hemophilia B patients. Considerable reagent-dependent variability has been observed when one-stage clotting assays are used to measure the recovery of recombinant FIX products, including N9-GP. Objective To qualify select one-stage clotting and chromogenic FIX activity assays for measuring N9-GP recovery. Methods The accuracy and precision of the one-stage clotting assay (with the STA-Cephascreen activated partial thromboplastin [APTT] reagent) and the ROX Factor IX and BIOPHEN Factor IX chromogenic assays for measuring N9-GP recovery were assessed in N9-GP-spiked hemophilia B plasma samples in a systematic manner at three independent sites, with manufacturer-recommended protocols and/or site-specific assay setups, including different instruments. Results For each of the three FIX activity assays qualified on five different reagent-instrument systems, acceptable intra-assay and interassay accuracy and precision, dilution integrity, reagent robustness and freeze-thaw and short-term sample stabilities were demonstrated. The STA-Cephascreen assay showed a limited reportable range at one of the three qualification sites, and the BIOPHEN Factor IX assay showed suspect low-end sensitivity at one of the three qualification sites. An individual laboratory would account for these limitations by adjusting the assay's reportable range; thus, these findings are not considered to impact the respective assay qualifications. Conclusion The one-stage clotting assay with the STA-Cephascreen APTT reagent, the ROX Factor IX chromogenic assay and the BIOPHEN Factor IX chromogenic assay are considered to be qualified for the measurement of N9-GP in 3.2% (0.109 m) citrated human plasma.

European Association of Urology Position Statement on the Role of the Urologist in the Management of Male Hypogonadism and Testosterone Therapy

Testosterone is a crucial sex hormone important for the health and development of men of all ages. It plays a role in the integrity and maintaining the function of several systems and organs. Testosterone deficiency is linked to a number of signs and symptoms potentially affecting every man in his complexity and masculinity, and is therefore of strong urological interest. For this reason, urologists should attach importance to the need for knowledge, vocational education, and training in this specific area.