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Aim: This study aimed to identify DPYD variants and the related but previously unexplored phenotype (plasma uracil, dihydrouracil [DHU], and the DHU-to-uracil ratio) in a healthy adult Indian population. Methods: Healthy adult volunteers (n = 100) had their uracil and DHU levels measured and were genotyped for selected variants. Results: Among the nine variants studied, c.1906-14763G>A and c.85T>C were the most prevalent. Participants with any of the variants except for c.85T>C and c.1627A>G had a significantly lower DHU-to-uracil ratio and those with c.1905+1G>A variant had significantly increased uracil concentration compared with wild-type. Conclusion: Participants with five variants were identified as having altered phenotypic measures, and 40% of the intermediate metabolizers had their phenotype in the terminal population percentiles.

Serial monitoring of tacrolimus and serum creatinine after renal transplantation is of vital importance. In this study, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for the estimation of tacrolimus and creatinine, obtained from dried blood spots (DBS) or by volumetric absorptive microsampling (VAMS) was validated and the two sampling strategies were compared with traditional venous sampling.The LC-MS/MS assay was validated using a shared extract for the estimation of tacrolimus and creatinine from DBS and VAMS independently. The relationship between the concentrations in DBS/VAMS specimens and in venous samples was assessed using Passing-Bablok (PB) analysis and the bias between the two methods was determined by the Bland Altman (BA) analysis.The imprecision and bias of tacrolimus and creatinine estimated from DBS and VAMS samples was12% and was independent of the hematocrit (Hct). Samples were stable for five days at ambient temperature. From the PB regression analysis, correction equations were generated for the prediction of tacrolimus and creatinine values from DBS and VAMS samples. In a separate cohort of patients for validation, the corrected DBS and VAMS concentrations had a mean (95% CI) bias for tacrolimus of -0.64 (-2.98 to 1.70)% and -0.92 (-3.69 to 1.85)% respectively and for creatinine of 1.00 (-2.73 to 4.72)% and -0.71 (-3.74 to 2.32)% respectively. Using DBS and VAMS respectively, for tacrolimus, 91.8 and 89.8% of patient values and for creatinine, 69.4 and 81.6% of patient values were within the limits of clinical acceptance (within 15% agreement against the venous samples).We conclude that VAMS is the preferred single sampling option for estimating tacrolimus and creatinine in renal transplant patients.

Aim: To determine the concentration of 6-thioguanine nucleotide (6-TGN) and 6-methylmercaptopurine (6-MMP), the interpatient variability, and the relationship with disease activity in patients with Chron’s disease on long-term stable doses of azathioprine (AZA). Methods: This is a prospective, tertiary care single-center hospital study in adult Chron’s disease patients treated with AZA. The quantification of phenotypic thiopurine methyltransferase enzyme activity in red blood cells and the estimation of the concentration of 6-TGN and 6-MMP in whole blood was performed using the HPLC-UV detector method. A clinical response was categorized as remission (Harvey-Bradshaw Index [HBI] < 5) or improvement (drop from baseline of at least three points of HBI) based on HBI. Exposure to metabolite concentrations and the clinical response to AZA treatment was observed. Results: Study analysis included 30 patients who were initiated on AZA, and they were followed up with an estimation of metabolite concentrations to determine their clinical outcome. At six months, 93% of ( n = 28) patients continued to be on AZA and had clinical improvement. All the patients achieved remission of Chron’s disease. Only two patients developed adverse effects such as joint pain and thrombocytopenia. Conclusion: AZA is a safe and effective therapy in managing Chron’s disease when administered after determining thiopurine methyltransferase phenotype and with dose optimization performed using therapeutic drug monitoring of 6-TGN and 6-MMP.

A significant proportion of patients with Rhino-orbito-cerebral mucormycosis (ROCM) develop oroantral fistulas. Due to the unclear efficacy of crushed delayed-release posaconazole tablets (DRPT) via nasogastric tube in this group of patients, clinicians often use inferior alternatives like posaconazole suspension. In this prospective study, we report good plasma concentrations (median, 2,639 ng/mL; interquartile range [IQR], 1,690 to 3,575 ng/mL; and range, 1,004 to 4,835ng/mL) and complete cure and survival at 3 and 6 months in 19 such patients.

Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are the most common intensive care unit (ICU) infections. We aimed to evaluate the association of early and cumulative beta-lactam pharmacokinetic/pharmacodynamic (PK/PD) parameters with therapy outcomes in pneumonia. Adult ICU patients who received cefepime, meropenem, or piperacillin-tazobactam for HAP or VAP and had its concentration measured were included. Beta-lactam exposure was generated for every patient for the entire duration of therapy, and the time free concentration remained above the MIC (fT(>MIC)) and the time free concentration remained above four multiples of the MIC (fT(>4×MIC)) were calculated for time frames of 0 to 24 h, 0 to 10 days, and day 0 to end of therapy. Regression analyses and machine learning were performed to evaluate the impact of PK/PD on therapy outcomes. A total of 735 patients and 840 HAP/VAP episodes (47% HAP) were included. The mean age was 56 years, and the mean weight was 80 kg. Sequential organ failure assessment (SOFA), hemodialysis, age, and weight were significantly associated with the clinical outcomes and kept in the final model. In the full cohort including all pneumonia episodes, PK/PD parameters at different time windows were associated with a favorable composite outcome, clinical cure, and mechanical ventilation (MV)-free days. In patients who had positive cultures and reported MICs, almost all PK/PD parameters were significant predictors of therapy outcomes. In the machine learning analysis, PK/PD parameters ranked high and were the primary overall predictors of clinical cure. Early target attainment and cumulative target attainment have a great impact on pneumonia outcomes. Beta-lactam exposure should be optimized early and maintained through therapy duration.

Aims 5-Fluorouracil (5-FU) is widely used in combination chemotherapy, and literature suggests pharmacokinetic-guided dosing to improve clinical efficacy and reduce toxicity. This study aimed to determine the pharmacokinetic exposure of both 5-FU and its metabolite, 5,6-dihydrofluorouracil (DHFU), in patients with gastrointestinal malignancy and to establish a simplified strategy to assist in therapeutic drug management for dose optimization. Methods This was a prospective, observational study, performed in 27 patients diagnosed with gastrointestinal malignancy who were prescribed 5-FU. Multiple samples were collected per patient over the slow bolus (15-20 min) and continuous infusion period (over 44 h) in doses 1 and 3, and the concentrations of 5-FU and DHFU were measured. Results A higher proportion of patients had exposures within the therapeutic range in dose 3 (50%) as compared to dose 1 (37.5%) with 5-FU. There was an association between delayed time to maximum concentration of DHFU and a high maximum concentration of 5-FU. A limited sampling strategy was developed with 4 samples, 2 during the bolus period and 2 during the continuous period (at 18 h and the end of infusion), which accurately predicted the total area under the curve of 5-FU. Conclusion Using body surface area-based dosing with 5-FU, 50-60% of patients were outside of the therapeutic range. In the absence of genotype testing, measurement of the metabolite DHFU could be a phenotypical measure of dihydropyrimidine dehydrogenase enzyme activity. A limited sampling strategy was developed in patients who were prescribed a combination regimen of slow bolus, followed by a 44-hour continuous infusion of 5-FU to assist in the therapeutic drug management of patients.

Adequate colistin exposure is important for microbiological clearance. This study was performed in critically ill patients18 years old to develop a simplified nonparametric pharmacokinetic (PK) model of colistin for routine clinical use and to determine the role of dose optimization. The Non-Parametric Adaptive Grid algorithm within the Pmetrics software package for R was used to develop a PK model from 47 patients, and external validation of the final model was performed in 13 patients. A 1-compartment multiplicative gamma error model with 0-order input and first-order elimination of colistin was developed with creatinine clearance and serum albumin as covariates on elimination rate constant. An R

Refereed/Peer-reviewed Individualization of vancomycin dosing based on therapeutic drug monitoring (TDM) data is known to improve patient outcomes compared with fixed or empirical dosing strategies. There is increasing evidence to support area-under-the-curve (AUC24)-guided TDM to inform vancomycin dosing decisions for patients receiving therapy for more than 48 hours. It is acknowledged that there may be institutional barriers to the implementation of AUC24-guided dosing, and additional effort is required to enable the transition from trough-based to AUC24-based strategies. Adequate documentation of sampling, correct storage and transport, accurate laboratory analysis, and pertinent data reporting are required to ensure appropriate interpretation of TDM data to guide vancomycin dosing recommendations. Ultimately, TDM data in the clinical context of the patient and their response to treatment should guide vancomycin therapy. Endorsed by the International Association of Therapeutic Drug Monitoring and Clinical Toxicology, the IATDMCT Anti-Infectives Committee, provides recommendations with respect to best clinical practice for vancomycin TDM.

Individualization of vancomycin dosing based on therapeutic drug monitoring (TDM) data is known to improve patient outcomes compared with fixed or empirical dosing strategies. There is increasing evidence to support area-under-the-curve (AUC24)-guided TDM to inform vancomycin dosing decisions for patients receiving therapy for more than 48 hours. It is acknowledged that there may be institutional barriers to the implementation of AUC24-guided dosing, and additional effort is required to enable the transition from trough-based to AUC24-based strategies. Adequate documentation of sampling, correct storage and transport, accurate laboratory analysis, and pertinent data reporting are required to ensure appropriate interpretation of TDM data to guide vancomycin dosing recommendations. Ultimately, TDM data in the clinical context of the patient and their response to treatment should guide vancomycin therapy. Endorsed by the International Association of Therapeutic Drug Monitoring and Clinical Toxicology, the IATDMCT Anti-Infectives Committee, provides recommendations with respect to best clinical practice for vancomycin TDM.

Objective: To determine thiopurine S-methyltransferase (TPMT) activity and the range of TPMT activity values for the Indian population. Methods: An isocratic reversed-phase high-performance liquid chromatography method with ultraviolet detection for the determination of TPMT activity in red blood cells was developed and validated. TPMT activity (nmol of 6-methylmercaptopurine [6-MMP]/h/ml erythrocytes) was measured based on the conversion of 6-mercaptopurine to 6-MMP with S-adenosyl-l-methionine. The stability of erythrocyte lysate at −20°C and the whole-blood specimens for TPMT activity were determined at 4°C. TPMT enzyme activity was measured in 150 patients who were not on azathioprine (AZA), and population difference in TPMT enzyme activity was evaluated. Results: The assay was linear from 1.0 to 60.14 nmol 6-MMP concentrations. The chromatogram peaks obtained were baseline separated for 6-MMP and the internal standard. The bias and precision of low-, medium-, and high-quality controls (QC) were within acceptable limits. Stock and lysate specimens were found to be stable in −20°C. The Indian populations have a considerable number of patients with low- and intermediate-TPMT activity. The wide range of TPMT activity in the study population (3.85–35.68 nmol/h/ml erythrocytes) is suggestive of high inter-individual variability in the formation of 6-thioguanine nucleotide formation, and therefore clinical efficacy and safety of AZA. Conclusion: A simple isocratic method was developed and validated for measuring TPMT activity in erythrocytes. Measuring TPMT activity before initiating AZA may help to decide the initial dose of AZA in patient management.

A robust and economical assay for routine determination of indocyanine green pharmacokinetics was developed and validated using high-performance liquid chromatography with a photodiode array detector. Plasma specimens from critically ill patients and those with hepatitis on various co-medications were used as blanks for validation of this assay. Extraction of indocyanine green was performed by simple protein precipitation with acetonitrile, and the supernatant was separated using an octadecyl column with detection at 784 nm. Blanks were found to have no interference for 40 blanks of patients who were on 56 different medications. The precision for LLOQ (0.5 µg/ml) as determined by the percentage coefficient of variation was 1.19. Stability of plasma calibration standards and stock were determined over a period of 61 days, and ICG was found to be stable for 20 days. Stability of whole blood specimens containing ICG was determined at 4°C for a period of 4 hours.

Melioidosis is an emerging infectious disease of major public health importance. We describe a patient who presented with septicaemic melioidosis with multi-organ dysfunction. He had only marginal response on standard doses of meropenem. Therapeutic drug monitoring (TDM) revealed suboptimal concentration of meropenem following which drug dose was increased, with which he showed rapid clinical improvement and microbiological clearance. Melioidosis presents with multisystem involvement with disseminated abscess, standard dosing of meropenem may not be sufficient in achieving therapeutic levels and TDM with increased dosing in these critically ill patients will improve outcome.

Pharmacokinetics of meropenem differ widely in the critically ill population. It is imperative to maintain meropenem concentrations above the inhibitory concentrations for most of the interdose interval. A population pharmacokinetic/pharmacodynamic model was developed to determine the probability of target attainment for 3-hour and 30-minute infusion regimens in this population.This study was performed in an intensive care setting among adult patients who were initiated on meropenem at a dose of 1000 mg. Multiple blood specimens were collected at predetermined time points during the interdose period, and meropenem concentrations were measured using high performance liquid chromatography. Using Pmetrics, a pharmacokinetic/pharmacodynamic model was developed and validated. Monte Carlo simulation was performed, and probability of target attainment (100% Tminimum inhibitory concentration (MIC), with a probability0.9) for doubling MICs was determined for different regimens of meropenem.A 2-compartment multiplicative gamma error model best described the population parameters from 34 patients. The pharmacokinetic parameters used in the final model were Ke (elimination rate constant from the central compartment), Vc (volume of distribution of central compartment), KCP and KPC (intercompartmental rate constants), and IC2 (the fitted amount of meropenem in the peripheral compartment). Inclusion of creatinine clearance (CLcreat) and body weight as covariates improved the model prediction (Ke = Ke0 × (Equation is included in full-text article.), Vc = Vc0 × Weight). The Ke and Vc [geometric mean (range)] of the individuals were 0.54 (0.01-2.61)/h and 9.36 (4.35-21.62) L, respectively. The probability of attaining the target, TMIC of 100%, was higher for 3-hour infusion regimens compared with 30-minute infusion regimens for all ranges of CLcreat.This study emphasizes that extended regimens of meropenem are preferable for treating infections caused by bacteria with higher MICs. The nonparametric analysis using body weight and CLcreat as covariate adequately predicted the pharmacokinetics of meropenem in critically ill patients with a wide range of renal function.

ObjectiveAdequate data on fentanyl pharmacokinetics in neonates are lacking. The study was performed to compare serum concentrations and clinical outcome between continuous infusion (CI) and intermittent bolus (IB) doses of fentanyl for analgesia and sedation in neonates.MethodsIn this open-label randomised controlled trial, neonates requiring 24–48 hours of mechanical ventilation and fentanyl administration were recruited. In CI regimen, 1 mcg/kg loading dose was followed by 1 mcg/kg/hour infusion. In IB regimen, 1mcg/kg/dose was administered every 4 hours.Maximum six blood samples were collected in 48 hours from each baby at prespecified time points for estimating serum fentanyl concentration. Secondary outcomes were pain scores (Neonatal Infant Pain Scale and Neonatal Pain, Agitation and Sedation Scale for acute and ongoing pain, respectively) and incidence of adverse effects of fentanyl.Results100 neonates were recruited, 53 in CI and 47 in IB group. In CI regimen, median (IQR) serum fentanyl concentration was 0.42 (0.35, 0.46) to 0.61 (0.47, 0.89) ng/mL throughout the infusion period. In IB regimen, median (IQR) peak concentration ranged from 2.21 (1.82, 3.55) to 3.61 (2.91, 4.51) ng/mL and trough concentration 0.41 (0.33, 0.48) to 0.97 (0.56, 1.25) ng/mL for various doses.Median (IQR) peak concentration (Cmax, 3.06 (1.09, 4.50) vs 0.78 (0.49, 1.73) ng/mL; p0–24, 19.6 (10.4, 33.5) vs 13.2 (10.8, 22.6) µg·hour/L; p=0.12) was higher (though not statistically significant) in IB than CI regimen. Pain scores and adverse effects were comparable between the two regimens.ConclusionCI regimen of fentanyl produces steady serum concentrations, whereas IB regimen produces wide fluctuations in serum concentration with high-peak concentrations. A serum fentanyl concentration of 0.4–0.6 ng/mL produces adequate analgesia and sedation in neonates.Trial registration numberCTRI/2014/11/005190.

Context: Kv7 potassium channels are expressed in several types of smooth muscles and could mediate physiological responses in the tissues expressed. Flupirtine is an analgesic that acts by opening Kv7 potassium channels. It has been shown to inhibit the contractility of several types of isolated smooth muscle. Aims: This study investigated the ability of flupirtine to inhibit the spontaneous contractility of isolated distal caprine (goat) ureter. Settings and Design: Spontaneous contractility of the isolated goat ureter was recorded using a physiograph. Materials and Methods: The ability of 1, 3, 10, 30, and 90 μM concentrations of flupirtine maleate to inhibit the spontaneous contractility of isolated distal goat ureter was investigated. The ability of the nonspecific potassium channel blocker 4-aminopyridine (4-AP; 1 mM) and the specific Kv7 channel blocker XE-991 (100 μM) to reverse the inhibitory effect of flupirtine on ureteric contractility was also investigated. Statistical Analysis Used: Both parametric and nonparametric statistical tests were used. Results: At 10, 30, and 90 μM concentrations, flupirtine significantly inhibited the spontaneous contractility of the isolated goat ureter. The EC50 of flupirtine for a contact period of 10 min was 17.7 μM. The inhibitory effect of flupirtine on ureteric contractility was significantly reversed by 4-AP and XE-991. Conclusions: Flupirtine inhibits the spontaneous contractility of the isolated goat ureter by opening Kv7 channels.

Context: Benidipine is a calcium channel blocker that blocks all the major types (L, N, and T) of calcium channels. It has been shown to inhibit the contractility of many isolated smooth muscles but not isolated ureter. Aims: This study evaluated the ability of benidipine to inhibit the spontaneous contractility of isolated proximal and distal caprine (goat) ureter. Settings and Design: Spontaneous contractility of isolated goat ureter was recorded using a physiograph. Materials and Methods: Benidipine at concentrations in the range of 1 nM to 10 μM was analyzed for its inhibitory effects on the spontaneous contractility of the isolated proximal and distal caprine ureter. Statistical Analysis Used: Both parametric and nonparametric statistical tests were used. Results: The EC50 of benidipine for inhibiting contractility in the distal ureter was found to be 54.68 nM. Benidipine was found to have a greater inhibitory effect on the distal ureter than on the proximal ureter. It was also found to inhibit amplitude of spontaneous ureteric contractility more readily than the frequency of spontaneous ureteric contractility. Conclusions: These results suggest that benidipine has differential inhibitory effects on the spontaneous contractility of the isolated ureter. Benidipine could be useful in the management of clinical conditions like ureteric colic due to its inhibitory effects on the contractility of the ureter.

Lipoprotein-Associated Phospholipase A2 (Lp-PLA2) is a 45-kDa protein of 441 amino acids encoded by the pla2g7 gene in the humans. In the blood it is associated mainly with Low Density Lipoprotein (LDL) and less than 20% is associated with High Density Lipoprotein (HDL). This enzyme is characterized by its ability to specifically hydrolyze PAF as well as glycerophospholipids containing short, truncated, and/or oxidized fatty acyl groups at the sn-2 position of the glycerol backbone. Genetic studies conducted in humans harboring an inactivating mutation at this locus suggest that loss of Lp-PLA2 function is a risk factor for inflammatory and vascular conditions. Consistently, overexpression of Lp-PLA2 has anti-inflammatory or pro-inflammatory actions and anti-atherogenic properties in animal models. This article discusses two simple techniques to estimate Lp-PLA2 activity. New therapeutic agents inhibiting the activity of Lp-PLA2 are being investigated for curative purpose.