Simple, fast and robust LC-MS/MS method for the simultaneous quantification of canagliflozin, dapagliflozin and empagliflozin in human plasma and urine

Sodium–glucose cotransporter 2 –inhibitors (SGLT2i) are oral glucose-lowering drugs that have also demonstrated cardioprotective and renoprotective effects. SGLT2i play an increasingly important role in the treatment of type 2 diabetes. Here we report a simple and robust liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for the simultaneous quantification of three SGLT2i (canagliflozin, dapagliflozin and empagliflozin) in human plasma, serum and urine with a runtime of 1 min. Methanol was used as protein precipitating agent. Chromatographic separation was accomplished using a Waters ACQUITY UPLC HSS T3 1.8 μm; 2.1 × 50 mm column with a Waters ACQUITY UPLC HSS T3 1.8 μm VanGuard Pre-column; 2.1 × 5 mm, using gradient elution with ammonium acetate 20 mM (pH 5) and acetonitrile as mobile phase at a flow rate of 0.8 ml/min. Mass spectrometric analysis of the acetate adduct ions was carried out using electrospray with negative ionization and SRM mode. The assay was validated according to FDA and EMA guidelines, including selectivity, linearity, accuracy and precision, dilution integrity, stability and recovery. With a sample volume of 200 µl, linear ranges of 10–5000 µg/L, 1–500 µg/L and 2–1000 µg/L for canagliflozin, dapagliflozin and empagliflozin respectively, were achieved. The assay was successfully applied in two pharmacokinetic studies with dapagliflozin and empagliflozin. In conclusion, we developed and validated a simple, fast and robust LC-MS/MS method for the simultaneous quantification of canagliflozin, dapagliflozin and empagliflozin, that allows rapid analysis of large numbers of samples and can be used for both pharmacokinetic studies and biomedical analysis of canagliflozin, dapagliflozin and empagliflozin

The Effects of Exogenous Phospholipids on Airway Function in Asthmatics

The studies described in this thesis examined whether application of lecithin to the oropharyngeal mucosa in asthmatics protected against bronchoconstiction and cough induced by airway challenge with inhaled mannitol powder. An initial study was conducted with 24 physician diagnosed adult asthmatics to determine the safety, convenience and suitability of mannitol airway challenge. Mannitol airway challenge was found to be a safe and convenient type of airway challenge in asthmatics, but marked interindividual variation in the degree of bronchoconstriction evoked by mannitol airway challenge was evident which confirmed previous reports. Twelve suitable adult asthmatics (6 men and 6 women) who showed a fall in the forced expiratory volume in one second (FEV₁) of ≥ 10% after mannitol airway challenge successfully completed the second study. This entailed airway challenges with equivalent doses of inhaled mannitol on two separate days after gargling with water or an aqueous suspension of soy lecithin in random order. Soy lecithin was used because of its high phospholipid content (1,680 mg of phosphatidylcholine, 960 mg of phosphatidylinositol). Prechallenge lung function values were reproducible over the two experimental test days. The results suggest that oropharyngeal application of phospholipids can protect asthmatics against mannitol airway challenge in addition to improving baseline lung function, and that these effects may be sustained for at least an hour. The mechanisms for this protective effect have not been elucidated but it is plausible that attenuated reflex bronchoconstriction and cough resulting from the masking and desensitizing of oropharyngeal neural receptors by adhering phospholipids was responsible. Thus, the findings of this study provide new evidence suggesting that oropharyngeal afferent pathways may be involved in the reflex regulation of airway function and cough during asthmatic exacerbations. The findings also suggest that orpharyngeal phospholipids may have therapeutic potential in the clinical management of asthma by providing the airways with sustained protection against factors that commonly provoke worsening asthmatic symptoms such as inhaling cold dry air and exercise, as well as alleviating upper airway irritation and cough in other common disorders such as viral respiratory tract infections. These findings and the implications arising from them warrant further investigation

Actigraphic Monitoring of Heart Rate and Movement as an Index of Daily Body Energy Expenditure in Health and Disease

The studies in this thesis were prompted by the rapidly emerging field of actigraphy which can provide nonintrusive measurements of physical activity over prolonged periods in free-living conditions. These features offer a unique opportunity to investigate daily activities and how such activities can be impaired by clinical disorders. A series of investigations were carried out to evaluate the accuracy of actigraphic based estimates of body energy expenditure made with an Actiheart system at rest and during exercise in healthy individuals (Studies 1 and 2 described in Chapters 2 and 3). A subsequent study (Study 3 described in Chapter 4) examined Actiheart based measurements of daily body energy expenditure in obstructive sleep apnoea (OSA) patients, how body energy expenditure varied throughout the day in these patients, and whether daily body energy expenditure and the daily body energy expenditure profile changed after commencement of nightly treatment with continuous positive airway pressure (CPAP). A central hypothesis in the OSA study (Study 3 described in Chapter 4) was that reversal of excessive daytime sleepiness by CPAP would result in increased daily activities and increased body energy expenditure. As shown in Study 2, the Actiheart system provided accurate estimates of body energy expenditure in healthy men under resting conditions and during mild and moderate levels of 3 types of exercise (arm ergometry, bicycle ergometry and treadmill walking) performed at matched workloads. This study is the first to demonstrate that the accuracy of Actiheart based BEE estimates at matched mechanical workloads remains high over a range of different modes of exercises which involved different body movements utilising different muscle groups. As predicted, the heart rate response to arm exercise was higher than during bicycle and treadmill exercise at matched workloads. However, this did not impair the Actiheart's ability to provide accurate estimates of body energy expenditure

Pharmacokinetic Modeling, Simulation, and Development of a Limited Sampling Strategy of Cycloserine in Patients with Multidrug-/Extensively Drug-Resistant Tuberculosis

BACKGROUND AND OBJECTIVE: Multidrug-resistant tuberculosis has much poorer treatment outcomes compared with drug-susceptible tuberculosis because second-line drugs for treating multidrug resistant tuberculosis are less effective and are frequently associated with side effects. Optimization of drug treatment is urgently needed. Cycloserine is a second-line tuberculosis drug with variable pharmacokinetics and thus variable exposure when programmatic doses are used. The objective of this study was to develop a population pharmacokinetic model of cycloserine to assess drug exposure and to develop a limited sampling strategy for cycloserine exposure monitoring. MATERIAL AND METHODS: Patients with multidrug-/extensively drug-resistant tuberculosis who were treated for > 7 days with cycloserine were eligible for inclusion. Patients received cycloserine 500 mg (body weight ≤ 50 kg) or 750 mg (body weight > 50 kg) once daily. MW/Pharm 3.83 (Mediware, Groningen, The Netherlands) was used to parameterize the population pharmacokinetic model. The model was compared with pharmacokinetic values from the literature and evaluated with a bootstrap analysis, Monte Carlo simulation, and an external dataset. Monte Carlo simulations were used to develop a limited sampling strategy. RESULTS: Cycloserine plasma concentration vs time curves were obtained from 15 hospitalized patients (nine male, six female, median age 35 years). Mean dose/kg body weight was 11.5 mg/kg (standard deviation 2.04 mg/kg). Median area under the concentration-time curve over 24 h (AUC0-24 h) of cycloserine was 888 h mg/L (interquartile range 728-1252 h mg/L) and median maximum concentration of cycloserine was 23.31 mg/L (interquartile range 20.14-33.30 mg/L). The final population pharmacokinetic model consisted of the following pharmacokinetic parameters [mean (standard deviation)]: absorption constant Ka_po of 0.39 (0.31) h-1, distribution over the central compartment (Vd) of 0.54 (0.26) L/kg LBM, renal clearance as fraction of the estimated glomerular filtration rate of 0.092 (0.038), and metabolic clearance of 1.05 (0.75) L/h. The population pharmacokinetic model was successfully evaluated with a bootstrap analysis, Monte Carlo simulation, and an external dataset of Chinese patients (difference of 14.6% and 19.5% in measured and calculated concentrations and AUC0-24 h, respectively). Root-mean-squared-errors found in predicting the AUC0-24 h using a one- (4 h) and a two- (2 h and 7 h) limited sampling strategy were 1.60% and 0.14%, respectively. CONCLUSIONS: This developed population pharmacokinetic model can be used to calculate cycloserine concentrations and exposure in patients with multidrug-/extensively drug-resistant tuberculosis. This model was successfully validated by internal and external validation methods. This study showed that the AUC0-24 h of cycloserine can be estimated in patients with multidrug-/extensively drug-resistant tuberculosis using a 1- or 2-point limited sampling strategy in combination with the developed population pharmacokinetic model. This strategy can be used in studies to correlate drug exposure with clinical outcome. This study also showed that good target attainment rates, expressed by time above the minimal inhibitory concentration, were obtained for cycloserine with a minimal inhibitory concentration of 5 and 10 mg/L, but low rates with a minimal inhibitory concentration of 20 and 32.5 mg/L

Risk factors contributing to a low darunavir plasma concentration

Darunavir is an efficacious drug; however, pharmacokinetic variability has been reported. The objective of this study was to find predisposing factors for low darunavir plasma concentrations in patients starting the once- or twice-daily dosage. Darunavir plasma concentrations from January 2010 till December 2014 of human immunodeficiency virus-infected individuals treated in the outpatient clinic of the University Medical Center Groningen were retrospectively reviewed. The first darunavir plasma concentration of patients within 8weeks after initiation of darunavir therapy was selected. A dichotomous logistic regression analysis was conducted to select the set of variables best predicting a darunavir concentration below median population pharmacokinetic curve. In total 113 patients were included. The variables best predicting a darunavir concentration besides food intake included age together with estimated glomerular filtration rate (Hosmer-Lemeshow test P=0.945, Nagelkerke R-2=0.284). Systematic evaluation of therapeutic drug monitoring results may help to identify patients at risk for low drug exposure

Ganciclovir Therapeutic Drug Monitoring:A Case Series

This paper presents three cases of immunocompromised patients for whom therapeutic drug monitoring (TDM) of ganciclovir in combination with cytomegalovirus (CMV) viral load measurement was used to guide treatment. The first patient is diagnosed with Thymoma A, the second is a heart transplant recipient and the third is an HIV positive patient. These patients were all diagnosed with CMV and treated with ganciclovir. Our case studies illustrate how TDM guided dosing can be helpful in the management of these complex cases.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal

Treatment outcomes of patients with MDR-TB in Nepal on a current programmatic standardised regimen:retrospective single-centre study

OBJECTIVES: The objectives of this study were to evaluate treatment in patients on current programmatic multidrug-resistant tuberculosis (MDR-TB) regimen and verify eligibility for the 9-month regimen and therapeutic drug monitoring (TDM). METHODS: We performed a retrospective chart review of patients with MDR-TB receiving standardised regimen at the German Nepal TB Project Clinic, Nepal, between 2014 and 2016. Eligibility for the 9-month regimen and indications for TDM were evaluated. RESULTS: Out of 107 available patients' medical records, 98 were included. In this centre, the MDR-TB treatment success rates were 69.0% in 2015, 86.6% in 2016 and 86.5% in 2017. The median time to sputum smear conversion was 60 days (60-90 IQR) and culture conversion was 60 days (60-90 IQR). Observed side effects did not impact treatment outcomes. No difference in treatment success rates was observed between patients with predisposing risk factors and those without. Only 49% (36/74) of patients were eligible for the 9-month regimen and 23 patients for TDM according to American Thoracic Society guideline criteria. CONCLUSIONS: Nepalese patients with MDR-TB on ambulatory care had good treatment outcome after programmatic treatment. Implementation of the new WHO oral MDR-TB treatment regimen may further improve treatment results. The 9-month regimen and TDM should be considered as part of programmatic care