Therapeutic efficacy of generic artemether-lumefantrine in the treatment of uncomplicated malaria in Ghana: assessing anti-malarial efficacy amidst pharmacogenetic variations.

BACKGROUND: Despite efforts made to reduce morbidity and mortality associated with malaria, especially in sub-Saharan Africa, malaria continues to be a public health concern that requires innovative efforts to reach the WHO-set zero malaria agenda. Among the innovations is the use of artemisinin-based combination therapy (ACT) that is effective against Plasmodium falciparum. Generic artemether-lumefantrine (AL) is used to treat uncomplicated malaria after appropriate diagnosis. AL is metabolized by the cytochrome P450 family of enzymes, such as CYP2B6, CYP3A4 and CYP3A5, which can be under pharmacogenetic influence. Pharmacogenetics affecting AL metabolism, significantly influence the overall anti-malarial activity leading to variable therapeutic efficacy. This study focused on generic AL drugs used in malarial treatment as prescribed at health facilities and evaluated pharmacogenomic influences on their efficacy. METHODS: Patients who have been diagnosed with malaria and confirmed through RDT and microscopy were recruited in this study. Blood samples were taken on days 1, 2, 3 and 7 for parasite count and blood levels of lumefantrine, artemisinin, desbutyl-lumefantrine (DBL), and dihydroartemisinin (DHA), the active metabolites of lumefantrine and artemether, respectively, were analysed using established methods. Pharmacogene variation analysis was undertaken using iPLEX microarray and PCR-RFLP. RESULTS: A total of 52 patients completed the study. Median parasite density from day 1 to 7 ranged from 0-2666/µL of blood, with days 3 and 7 recording 0 parasite density. Highest median plasma concentration for lumefantrine and desbutyl lumefantrine, which are the long-acting components of artemisinin-based combinations, was 4123.75 ng/mL and 35.87 ng/mL, respectively. Day 7 plasma lumefantrine concentration across all generic ACT brands was ≥ 200 ng/mL which potentially accounted for the parasitaemia profile observed. Monomorphism was observed for CYP3A4 variants, while there were observed variations in CYP2B6 and CYP3A5 alleles. Among the CYP3A5 genotypes, significant differences in genotypes and plasma concentration for DBL were seen on day 3 between 1/*1 versus *1/*6 (p = 0.002), *1/*3 versus *1/*6 (p = 0.006) and *1/*7 versus *1/*6 (p = 0.008). Day 7 plasma DBL concentrations showed a significant difference between *1/*6 and *1/*3 (p = 0.026) expressors. CONCLUSIONS: The study findings show that CYP2B6 and CYP3A5 pharmacogenetic variations may lead to higher plasma exposure of AL metabolites.

Introducing an lsoprenaline Eluting Guidewire: Report on its Design and the Results of the Dose-Determining Pilot Study.

Introduction: Retrograde intrarenal surgery (RIRS) is associated with complications, many of which are related to the intrarenal pressure (IRP). We aim to describe the design of a novel isoprenaline-eluting guidewire ("IsoWire") and present the results from the first in vitro release studies and the first animal studies showing its effect on IRP. Materials and Methods: The IsoWire comprises a Nitinol core surrounded by a stainless-steel wire wound into a tight coil. The grooves created by this coil provided a reservoir for adding a hydrogel coating into which isoprenaline, a beta-agonist, was loaded. Animal studies were performed using a porcine model. For the control, IRP, heart rate (HR), and mean arterial pressure (MAP) were measured continuously for 6 minutes with a standard guidewire in place. For the experiment, the standard hydrophilic guidewire was removed, the IsoWire was inserted into the renal pelvis, and the same parameters were measured. Results: In vitro analysis of the isoprenaline release profile showed that most (63.9 ± 5.9%) of the loaded drug mass was released in the 1st minute, and almost all of the drug was released in the first 4 minutes exponentially. Porcine studies showed a 25.1% reduction in IRP in the IsoWire that released 10 µg in the 1st minute; however, there was a marked increase in HR. The average percentage reduction in IRP was 8.95% and 21.3% in the IsoWire that released 5 and 7.5 µg of isoprenaline, respectively, with no changes in HR or MAP. Conclusions: The IsoWire, which releases 5 and 7.5 µg of isoprenaline in the 1st minute, appears to be safe and effective in reducing the IRP. Further studies are needed to establish whether the isoprenaline-induced ureteral relaxation will render easier insertion of a ureteral access sheath, reduce IRP during sheathless RIRS, or even promote the practice of sheathless RIRS.

Validation of a LC-MS/MS method to simultaneously quantify thiafentanil and naltrexone in plasma for pharmacokinetic studies in wildlife.

Thiafentanil is a popular opioid agonist that is fully reversed by administering naltrexone. This agonist-antagonist combination is administered to a wide variety of wildlife species for chemical immobilisation, however plasma concentrations for thiafentanil remain unreported. This report describes a method that was developed and validated using human plasma and cross-validated for the analysis of goat plasma. Samples were extracted using a simple protein precipitation and analysed using LC-MS/MS. The assay was validated over the calibration range 4.38 - 1120 ng/mL for thiafentanil and 15.63 - 4000 ng/mL for naltrexone. The mean inter-day accuracies for QCs prepared in human plasma (n = 18) ranged from 94.8 - 103.8 % for thiafentanil and 94.8 - 95.9 % for naltrexone with corresponding precisions of 3.4 - 7.9 % and 2.8 - 11.4 %, respectively. The mean accuracies for QCs prepared in goat plasma (n = 6) ranged from 89.0 - 100.5 % for thiafentanil and 89.0 - 98.0 % for naltrexone with the associated precisions ranging from 7.1 - 11.6 % and 4.8 - 12.3 %, respectively. Both analytes were stable on bench for six hours and for three freeze-thaw cycles. The impact of heat-inactivation, necessary for the inactivation of potential foot-and-mouth disease, on analyte stability, matrix effect and recovery were evaluated, and a correction factor was established to determine the original analyte concentrations. The method was applied to pharmacokinetic samples collected from goats. The use of goats as a model species provides the first insight into the plasma concentrations of thiafentanil.

In vitro optimization of crushed drug-sensitive antituberculosis medication when administered via a nasogastric tube.

IMPORTANCE: The incidence of tuberculosis (TB) in intensive care units (ICUs) can be as high as 3% in high-burden settings, translating to more than 7,500 patients admitted to the ICU annually. In resource-limited settings, the lack or absence of intravenous formulations of drug-sensitive antituberculosis medications necessitates healthcare practitioners to crush, dissolve, and administer the drugs to critically ill patients via a nasogastric tube (NGT). This off-label practice has been linked to plasma concentrations below the recommended target concentrations, particularly of rifampicin and isoniazid, leading to clinical failure and the development of drug resistance. Optimizing the delivery of crushed drug-sensitive antituberculosis medication via the NGT to critically ill patients is of utmost importance.

An LC-MS/MS method for the simultaneous quantitation of sulfasalazine and sulfapyridine in human placenta.

Sulfasalazine has been identified as a candidate molecule to be investigated as an intervention to treat preterm pre-eclampsia during pregnancy. However, placental exposure of sulfasalazine and its systemically absorbed metabolite, sulfapyridine, is unknown. A robust liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated to simultaneously quantitate these analytes in human placenta with an application to a pilot clinical trial. The placental tissue was homogenised using a water:methanol (1:1, v/v) mixture, followed by sample extraction using both protein precipitation and solid phase extraction. Sulfasalazine-d4 and sulfapyridine-d4 were used as internal standards. An Agilent Poroshell EC-C18 (3.0 ×100 mm, 2.7 µm) column was used for chromatographic separation, with gradient elution employed at a flow rate of 0.450 mL/min over a total run time of seven minutes. The mobile phases consisted of water with 0.1% formic acid (mobile phase A) and acetonitrile:methanol (90:10, v/v) with 0.1% formic acid (mobile phase B). A Shimadzu-8040 mass spectrometer was operated in multiple reaction monitoring (MRM) mode using positive electrospray ionisation (ESI). For both analytes, the assay was validated over the range 30-30,000 ng/mL, or 150-150,000 ng/g. During inter-day validations (n = 18), the average accuracies of quality controls ranged from 101.6% to 112.7% with corresponding precisions of 4.4-6.7% for sulfasalazine, and from 97.4% to 108.4%, with corresponding precisions of 3.7-10.0% for sulfapyridine. No significant matrix effects were observed, and the method proved to be sensitive and specific for both analytes. This study presents the first validated analytical method for quantifying sulfasalazine and sulfapyridine in human placenta as part of a pilot clinical trial to generate preliminary data on its pharmacokinetics and efficacy as in intervention for preterm pre-eclampsia.

A simple and sensitive LC-MS/MS method for the quantitation of sertraline and N-desmethylsertraline in human plasma.

A simple and sensitive LC-MS/MS method for the simultaneous quantification of the second-generation antidepressant sertraline, and its active metabolite, N-desmethylsertraline, in human plasma was developed and validated. The analytes were extracted from 200 µL human plasma using a simple protein precipitation method. A gradient elution mode of water and 0.1% formic acid and acetonitrile was used for chromatographic separation on a Poroshell EC-C18 column (3 × 100 mm, 2.7 µm) at a flow rate of 0.450 mL/min. MS/MS analysis was performed in positive ionization mode using the transitions of m/z 306.1 â†’ 159.1, 309.1 â†’ 275.2, 292.1 â†’ 159.1, and 296.2 â†’ 279.0 for sertraline, sertraline-d3, N-desmethylsertraline, and N-desmethylsertraline-d4, respectively. The calibration curves for sertraline and N-desmethylsertraline in human plasma ranged from 2.50-320 ng/mL and 10.0-1280 ng/mL, respectively, with correlation coefficients (r) of ≥ 0.9992. The intra- and inter-assay precisions for both analytes at four concentrations (LLOQ, QCL, QCM, and QCH) ranged between 2.2% and 12.2%, respectively, while their accuracies ranged between 92.0 and 111.7%, with the exception of LLOQ, which ranged between 84.3 and 106.0%. The mean percentage recovery and process efficiency at three concentrations (QCL, QCM, and QCH) was 94.2 and 87.9% for sertraline, and 95.7 and 95.2% for N-desmethylsertraline, respectively. Both analytes were stable in plasma at room temperature for 2 h, at -80 °C for 28 days and through three freeze/thaw cycles. This method was successfully applied to a clinical study investigating the use of sertraline during pregnancy.

Urine tenofovir-monitoring predicts HIV viremia in patients treated with high genetic-barrier regimens.

OBJECTIVE: Access to viral load measurements is constrained in resource-limited settings. A lateral flow urine tenofovir (TFV) rapid assay (UTRA) for patients whose regimens include TFV offers an affordable approach to frequent adherence monitoring. DESIGN: We conducted a cross-sectional study of patients to assess the utility of UTRA to predict virologic failure, defined as a viral load greater than 400 copies/ml. METHODS: We assessed urine TFV among 113 participants at increased risk of viral failure (who had previous viral failure on this regimen or had previously been ≥30 days out of care), comparing low genetic-barrier efavirenz (EFV) regimens (n = 60) to dolutegravir (DTG)-boosted or ritonavir-boosted protease inhibitor (PI/r)-based high genetic-barrier regimens (n = 53). Dried blood spots (DBS) for TFV-diphosphate and plasma for TFV concentrations were collected, with drug resistance assessed if viral failure present. RESULTS: Among 113 participants, 17 of 53 received DTG or PI/r had viral failure at the cross-sectional visit, with 11 (64.7%) demonstrating an undetectable urine TFV; the negative-predictive value (NPV) of undetectable UTRA for viral failure was 85% (34/40); none of the 16 sequenced had dual class drug resistance. In those treated with EFV regimens the sensitivity was lower, as only 1 (4.8%) of 21 with viral failure had an undetectable UTRA (P < 0.001). CONCLUSIONS: Urine tenofovir-testing had a high negative-predictive value for viral failure in patients treated with DTG or ritonavir-boosted protease inhibitor regimens, where viral failure was largely explained by poor drug adherence. Frequent monitoring with inexpensive lateral flow urine TFV testing should be investigated prospectively in between viral load visits to improve viral load suppression on DTG-based first-line therapy in resource-limited settings.

Concentrations of Efavirenz, Tenofovir, and Emtricitabine in Obesity: A Cross-Sectional Study.

BACKGROUND: Obesity is increasing worldwide including in people living with HIV (PLWH). Antiretroviral pharmacokinetic data in obesity are limited. OBJECTIVES: To measure antiretroviral drug concentrations in obese and nonobese PLWH treated with the fixed-dose combination of efavirenz-tenofovir-emtricitabine. To determine pharmacokinetic differences across indicators of obesity and their associated immunovirological outcomes. METHODS: We conducted a cross-sectional sample analysis of 2 cohort studies. We measured mid-dose efavirenz, 8-hydroxy-efavirenz, tenofovir, and emtricitabine concentrations. Antiretroviral drug concentrations were analyzed by body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR). RESULTS: We performed a study of 213 participants: General obesity was detected in 20.4% using BMI and abdominal obesity in 53.6% using WC and 62.4% using WHR, respectively. The median concentrations of all antiretroviral drugs were lower among obese participants determined by BMI and WC, with efavirenz showing greater differences than tenofovir or emtricitabine. For BMI, results were most striking for efavirenz (1752.3 vs 2342.9 ng/mL, P = 0.002) with lower concentrations in obese participants. Using WC, efavirenz (1845.8 vs 2571.2 ng/mL, P < 0.001), tenofovir (65.8 vs 73.2 ng/mL, P = 0.036), and emtricitabine (159.5 vs 221.0 ng/mL, P = 0.005) concentrations were lower in obese participants. Eight-hydroxyefavirenz concentrations were similar in nonobese and obese participants for WC. Using WHR, the concentrations of all antiretroviral drugs were lower in the obese population, most strikingly for emtricitabine (173.5 vs 229.0 ng/mL, P = 0.015). There were no immunovirological associations. CONCLUSION: We found lower antiretroviral concentrations in all obese groups, most strikingly in participants with abdominal obesity determined by WC. Lower drug concentrations had no immunovirological associations.

Validation and application of a quantitative liquid chromatography tandem mass spectrometry assay for the analysis of rifapentine and 25-O-desacetyl rifapentine in human milk.

A robust analytical method based on liquid chromatography coupled to tandem mass spectrometry was developed and validated to quantify rifapentine and 25-O-desacetyl rifapentine in human breast milk to aid in determining the breastfed infant risk to the excreted drug in human milk. Samples were extracted by a combination of protein precipitation and solid phase extraction using rifampicin-d3 as an internal standard. An Agilent® Poroshell 120 EC-C18 (4.6 mm × 50 mm, 2.7 µm) column was used for chromatographic separation employing an isocratic mobile phase consisting of acetonitrile: methanol: 0.1% formic acid (55/5/40, v/v/v) at a flow rate of 450 µL/min, and with a total run time of four minutes. Mass detection was on an AB Sciex API 4000 mass spectrometer using electrospray ionization in the positive mode and based on multiple reaction monitoring data acquisition. Rifapentine was accurately quantified across a concentration range of 2.00-2000 ng/mL and 25-O-desacetyl rifapentine from 4.00 to 2000 ng/mL. During validation, the inter- and intra-day accuracy and precision at the tested QC concentrations (N = 18) for rifapentine were between 97.4% and 100.6%, and 3.1% and 8.3%, respectively. The inter- and intra-day accuracy and precision for 25-O-desacetyl rifapentine were between 96.4% and 106.3%, and 6.7% and 11.8%, respectively. No significant matrix effects were observed, and the method was shown to be specific for rifapentine and 25-O-desacetyl rifapentine. Human milk samples (N = 22) generated during a phase I/II clinical trial were successfully analysed for rifapentine and 25-O-desacetyl rifapentine using this validated method. Concentrations for rifapentine and 25-O-desacetyl rifapentine in human milk samples (N = 22) ranged from 11.2-1180 ng/mL and 7.11-573 ng/mL, respectively.

Drug Resistance, Rather than Low Tenofovir Levels in Blood or Urine, Is Associated with Tenofovir, Emtricitabine, and Efavirenz Failure in Resource-Limited Settings.

The high cost of viral load (VL) testing limits its use for antiretroviral therapy (ART) adherence support. A low-cost lateral flow urine tenofovir (TFV) rapid assay predicts pre-exposure prophylaxis breakthroughs, but has not yet been investigated in HIV treatment. We therefore evaluated its utility in a pilot cross-sectional study of TFV-containing ART recipients at an increased risk of virologic failure (VF). Participants who had a treatment interruption ≥30 days or had ≥1 episode of viremia (VL ≥400 copies/mL) in the previous year were recruited from a public health setting in Cape Town, South Africa. Self-reported adherence data were collected, the urine TFV assay performed, and concurrent TFV-diphosphate analyzed in dried blood spots. VL testing was done concurrently and, if viremic, genotypic HIV drug resistance testing was performed. Of 48 participants, 18 (37.5%) had VL (>400 copies/mL) at the time of the study, including 16 of 39 receiving efavirenz (EFV), 2 of 6 receiving protease inhibitors, and 0 of 3 receiving dolutegravir. Resistance testing succeeded in 17/18, of which 14 had significant mutations compromising ≥2 agents of the current EFV-based regimen. Of these 14, all had detected urine TFV. Urine TFV was undetectable in two out of three without regimen-relevant resistance; p = .02. In participants on EFV-based regimens returning to care, VF was largely due to viral resistance, where detectable urine TFV had 100% sensitivity (14/14 participants) in predicting resistance. Conversely, when undetectable, the urine-based assay could be used to preclude participants with poor adherence from undergoing costly HIV drug resistance testing.

Pharmacogenetics of the Late-Onset Efavirenz Neurotoxicity Syndrome (LENS).

BACKGROUND: The late-onset efavirenz neurotoxicity syndrome (LENS) presents as ataxia and/or encephalopathy with supratherapeutic efavirenz plasma concentrations (>4 µg/mL). Efavirenz is primarily metabolized by cytochrome P450 2B6 (CYP2B6), with CYP2A6 as an accessory pathway. We hypothesized that participants with LENS would predominantly be CYP2B6 slow metabolizers. The aim of our study was to determine the frequency of CYP2B6 slow metabolizers in participants with LENS. METHODS: Adult HIV-positive participants on efavirenz-based antiretroviral therapy presenting with LENS were prospectively enrolled. Genetic polymorphisms known to be associated with increased efavirenz plasma concentrations in CYP2B6 (rs3745274, rs28399499, rs4803419) and CYP2A6 (rs28399433) were selected and used to determine proportions of slow metabolizers. Pharmacokinetic analyses were performed using liquid chromatography-tandem mass spectrometry. Median (IQR) plasma efavirenz and 8-hydroxyefavirenz were described. RESULTS: Fifteen participants were enrolled. Thirteen (13/15) were Black-African and 13 were female. Median weight was 49.9kg with a median duration on efavirenz of 2.2 years. All 15 participants were successfully genotyped as slow CYP2B6 metabolizers, with 6 participants additionally having CYP2A6 heterozygous genotype. Thirteen were receiving the CYP2A6 enzyme inhibitor isoniazid, and all 15 were genotypic NAT2 slow or intermediate acetylators. Efavirenz plasma concentration was markedly increased at 50.5 (47.0-65.4) µg/mL; 8-hydroxyefavirenz concentration was markedly decreased at 0.10 (0.07-0.15) µg/mL. CONCLUSIONS: Our cohort provides definitive evidence that LENS is associated with the CYP2B6 slow metabolizer genotype, with a median efavirenz plasma concentration >12-fold higher than the defined upper limit of the therapeutic range. Isoniazid and low body weight are important contributors to LENS development.

A validated liquid chromatography tandem mass spectrometry assay for the analysis of pretomanid in plasma samples from pulmonary tuberculosis patients.

A method for the extraction and quantification of pretomanid in 40 µL of human plasma, by high performance liquid chromatography with tandem mass spectrometry (LC-MS/MS) detection was developed and validated. Samples were prepared using liquid-liquid extraction and chromatographic separation was achieved on an Agilent Poroshell C18 column using an isocratic elution at a flow rate of 400 µL/min. Electrospray ionization with mass detection at unit resolution in the multiple reaction monitoring (MRM) mode on an AB Sciex API 3200 mass spectrometer was used. Over the validation period, accuracy, precision, selectivity, sensitivity, recovery and stability were assessed. The calibration range was 10 - 10 000 ng/mL. Inter- and intra-day precision, expressed as the coefficient of variation (%CV), was shown to be lower than 9% at all concentrations tested with accuracies between 95.2 and 110 %. The recovery was 72.4 % overall and reproducible at the low, medium and high end of the calibration range. The method was shown to be specific for pretomanid with no significant matrix effects observed. The validated method facilitated the analysis of pretomanid in plasma collected from adults with pulmonary TB as part of a clinical pharmacokinetic study.

The determination of capreomycin in human plasma by LC-MS/MS using ion-pairing chromatography and solid-phase extraction.

A bioanalytical method was developed and validated for the quantification of capreomycin (Cm) analogs, Cm IA and Cm IB, in human plasma. This implemented ion-pairing solid phase extraction, followed by ion-pairing high-performance liquid chromatography, with tandem mass spectrometry detection. Chromatographic separation was achieved using a Discovery C18 , 5 µm, 4.6 × 50 mm analytical column. An isocratic mobile phase consisting of water and acetonitrile with 0.1% formic acid and 4mm heptafluorobutyric acid (80:20; v/v) was used at a flow-rate of 500 µL/min. An AB Sciex API 3000 mass spectrometer at unit resolution, in multiple reaction monitoring mode, was used for detection. Electrospray ionization was used for ion production. The method was successfully validated for the range 469-30,000 ng/mL for Cm IA and for Cm IB, with cefotaxime as the internal standard. The within- and between-day precision determinations for Cm IA and IB, expressed as the percentage coefficient of variation, were < 20.0% at the lower limit of quantification (LLOQ) and < 8.2% at all other test concentrations. Recovery of both analogs was > 72.3% and reproducible at the low, medium and high end of the calibration range. No significant matrix effects were observed for the analyte. The assay performed well when applied to clinical samples generated from children in a clinical multidrug resistant tuberculosis research study in South Africa.

Pharmacokinetics and safety of rifabutin in young HIV-infected children receiving rifabutin and lopinavir/ritonavir.

OBJECTIVES: Co-treatment of HIV and TB in young children is complicated by limited treatment options and complex drug-drug interactions. Rifabutin is an alternative to rifampicin for adults receiving a ritonavir-boosted PI. We aimed to evaluate the short-term safety and pharmacokinetics of rifabutin when given with lopinavir/ritonavir in children. PATIENTS AND METHODS: We conducted an open-label study of rifabutin dosed at 5 mg/kg three times a week in HIV-infected children≤5 years of age receiving lopinavir/ritonavir. Intensive steady-state pharmacokinetic sampling was conducted after six doses. The Division of AIDS 2004, clarification 2009, table for grading severity of adverse events was used to classify drug toxicities. The study was registered with ClinicalTrials.gov, number NCT01259219. RESULTS: Six children completed the study prior to closure by institutional review boards. The median (range) AUC0-48 of rifabutin was 6.91 (3.52-8.67) µg ·â€Šh/mL, the median (range) Cmax of rifabutin was 0.39 (0.19-0.46) µg/mL, the median (range) AUC0-48 of 25-O-desacetyl rifabutin was 5.73 (2.85-9.13) µg ·â€Šh/mL and the median (range) Cmax of 25-O-desacetyl rifabutin was 0.17 (0.08-0.32) µg/mL. The neutrophil count declined in all children; two children experienced grade 4 neutropenia, which resolved rapidly without complications. There was strong correlation between AUC0-48 measures and neutrophil counts. CONCLUSIONS: Rifabutin dosed at 5 mg/kg three times per week resulted in lower AUC0-48, AUC0-24 and Cmax values for rifabutin and 25-O-desacetyl rifabutin compared with adults receiving 150 mg of rifabutin daily, the current recommended dose. We observed high rates of severe transient neutropenia, possibly due to immaturity of CYP3A4 in young children. It remains unclear whether a safe and effective rifabutin dose exists for treatment of TB in children receiving lopinavir/ritonavir.