Development and validation of a liquid chromatography coupled to tandem mass spectrometry method for the monitoring of temsavir plasma concentrations in people living with HIV.

A majority of people living with HIV (PLWH) now have access to HIV treatment with high antiviral potency and favorable tolerability profile. However, in some treatment experienced PLWH viral strains resistant to major current classes of antiretrovirals have emerged, usually due to periods with continued virus replication in the presence of failing drug regimens and thus selection pressure. In such context, new treatment options are therefore needed. Fostemsavir (RUKOBIA®) is the prodrug of temsavir, a first-in-class oral attachment inhibitor approved for the treatment of heavily treatment-experienced adults with multidrug-resistant HIV-1 infection. In this case RUKOBIA® is part of a complex regimen of antiretroviral drugs, often in addition to other drugs for chronic co-morbidities (e.g., heart disease, diabetes mellitus, hepatic and renal impairment, etc). In such a multi-drug regimen context, therapeutic drug monitoring (TDM) of temsavir can be necessary to exclude or adjust for relevant drug-drug interactions. A highly selective assay by liquid chromatography method coupled to tandem mass spectrometry (LC-MS/MS) was therefore developed for the quantification of temsavir in human plasma. A convenient sample preparation using protein precipitation with acetonitrile followed by supernatant dilution was carried out. Temsavir and fostemsavir were separated in less than 2 min using a multi-step UPLC gradient, thus ensuring adequate quantification of temsavir. The assay for the quantification of temsavir was extensively validated over the large range of clinically relevant concentrations from 1 to 10,000 ng/mL, in accordance with international bioanalytical method guidelines. The method achieves excellent performance in terms of trueness (99.7 - 105.3%), repeatability and intermediate precision (both from 1.6% to 5.8%). This LC-MS/MS method is now part of the routine analyses of the Laboratory of the Service of Clinical Pharmacology of Lausanne (CHUV), Switzerland, as an integrated part of our general TDM Service for antiretrovirals

Levetiracetam circulating concentrations and response in status epilepticus.

Intravenous levetiracetam (LEV) is broadly used in the treatment of status epilepticus (SE). A loading dose is usually infused, aiming to reach quickly the range of plasma concentrations considered as therapeutic (12-46 mg/l). The aim of the study was to evaluate the response to LEV in SE, correlated exposure assessed by plasma concentration monitoring, as well as calculated exposure parameters. We retrospectively analyzed a SE registry, including patients since 2015 with at least one available LEV plasma level measured less than 36 h after loading. A Bayesian maximum likelihood approach based on a population pharmacokinetic model was used to estimate LEV exposure parameters. We compared plasma levels and pharmacokinetics parameter estimates between responders and nonresponders. Therapeutic response was defined as SE cessation within 24 h following LEV introduction without a need for additional antiepileptic drug (AED). We included 29 patients (45 plasma levels). Variability was salient in LEV loading doses (ranging between 17 and 38 mg/kg) and monitoring practice. There was no difference in median plasma concentrations (19.5 versus 21.5 mg/l; p = 0.71), median estimated LEV exposure (25.8 versus 37.0 mg/l; p = 0.61), peak (30.4 versus 41.5 mg/l; p = 0.36), or residual levels after loading dose (14.4 versus 20.5 mg/l; p = 0.07) between responders and nonresponders. Levetiracetam exposure does not seem to differ significantly between responders and nonresponders; greater exposure was not associated with better outcome. Loading doses of 30 mg/kg seem, however, appropriate to quickly reach the target exposure level. The short LEV half-life makes standardized sampling measurement necessary to obtain directly interpretable LEV levels

Sofosbuvir and ribavirin before liver re-transplantation for graft failure due to recurrent hepatitis C: a case report.

BACKGROUND: Recurrent hepatitis C virus infection after liver transplantation is associated with reduced graft and patient survival. Re-transplantation for graft failure due to recurrent hepatitis C is controversial and not performed in all centers. CASE PRESENTATION: We describe a 54-year-old patient with hepatitis C virus genotype 1b infection and a null response to pegylated interferon-α and ribavirin who developed decompensated graft cirrhosis 6 years after a first liver transplantation. Treatment with sofosbuvir and ribavirin allowed for rapid negativation of serum HCV RNA and was well tolerated despite advanced liver and moderate renal dysfunction. Therapeutic drug monitoring did not reveal any clinically significant drug-drug interactions. Despite virological response, the patient remained severely decompensated and re-transplantation was performed after 46 days of undetectable serum HCV RNA. The patient is doing well 12 months after his second liver transplantation and remains free of hepatitis C virus. CONCLUSIONS: The use of directly acting antivirals may allow for successful liver re-transplantation for recipients who remain decompensated despite virological response and is likely to improve the outcome of liver re-transplantation for end-stage recurrent hepatitis C

Therapeutic drug monitoring of newer generation antiseizure medications at the point of treatment failure.

The benefit of therapeutic drug monitoring (TDM) of newer generation antiseizure medications (ASM) has been little studied. A recent randomized study suggested that TDM at each medical visit did not bring a significant benefit, but the study did not investigate TDM in cases of treatment failure. Accordingly, we realized a post hoc analysis of this trial. We analyzed 282 TDMs in 136 patients. We compared TDM performed at visits after treatment failure versus without treatment failure, reporting the proportion of drug levels out of range and the prescriber's adherence to dosage recommendations according to measured drug levels. There was no statistical difference in terms of proportion of out of range plasma drug levels (47% vs 50%, p = 0.7) or adherence of prescribers to the clinical pharmacologists' dosage recommendations (21% vs 30%, p = 0.6) between visits after treatment failure and visits without treatment failure, respectively. Knowledge of prior drug levels did not modify the results. Systematic TDM at appointments following treatment failure showed similar results to TDM at visits without treatment failure. The prescribers' adherence with dosage recommendations was low in both cases. It is not clear whether better prescriber adherence would improve patient outcome. Furthermore, the ability to detect poor patient compliance is limited in a planned outpatient appointment. The study setting does not reflect on the general usefulness of TDM

Therapeutic Drug Monitoring of Newer Antiepileptic Drugs: A Randomized Trial for Dosage Adjustment.

Therapeutic drug monitoring (TDM) of antiepileptic drugs (AEDs) is widely established for older generation AEDs, whereas there is limited evidence about newer AEDs. Our aim is to assess the benefit of TDM of newer generation AEDs in epilepsy. We performed a randomized, controlled trial comparing systematic with rescue TDM of lamotrigine, levetiracetam, oxcarbazepine, topiramate, brivaracetam, zonisamide, or pregabalin. Participants were adults with epilepsy, in whom treatment with newer generation AEDs was initiated or needed adjustment. In the systematic TDM arm, AED plasma levels were available at each appointment, whereas in the rescue TDM arm, levels were known only if a study endpoint was reached (inefficacy or adverse events). The primary outcome was the proportion of participants followed 1 year without reaching one of the predefined endpoints. A total of 151 participants were enrolled; global retention in the study was similar in both arms (56% overall, 58% in the systematic, and 53% in the rescue TDM arm, p = 0.6, Cox regression). There was no difference in terms of outcome regarding treatment efficacy or tolerability. Partial adherence of clinicians to TDM (adjusting or not AED dosage based on blood levels) did not explain this lack of benefit. This study provides class A evidence that systematic drug level monitoring of newer generation AEDs does not bring tangible benefits in the management of patients with epilepsy. Poor correlation between clinical effects and drug levels likely accounts for this finding. However, TDM is useful in several situations, such as pregnancy, as well as when there are compliance issues. ANN NEUROL 2020;87:22-29

An inhibitor of HIV-1 protease modulates constitutive eIF2α dephosphorylation to trigger a specific integrated stress response.

Inhibitors of the HIV aspartyl protease [HIV protease inhibitors (HIV-PIs)] are the cornerstone of treatment for HIV. Beyond their well-defined antiretroviral activity, these drugs have additional effects that modulate cell viability and homeostasis. However, little is known about the virus-independent pathways engaged by these molecules. Here we show that the HIV-PI Nelfinavir decreases translation rates and promotes a transcriptional program characteristic of the integrated stress response (ISR). Mice treated with Nelfinavir display hallmarks of this stress response in the liver, including α subunit of translation initiation factor 2 (eIF2α) phosphorylation, activating transcription factor-4 (ATF4) induction, and increased expression of known downstream targets. Mechanistically, Nelfinavir-mediated ISR bypassed direct activation of the eIF2α stress kinases and instead relied on the inhibition of the constitutive eIF2α dephosphorylation and down-regulation of the phophatase cofactor CReP (Constitutive Repressor of eIF2α Phosphorylation; also known as PPP1R15B). These findings demonstrate that the modulation of eIF2α-specific phosphatase cofactor activity can be a rheostat of cellular homeostasis that initiates a functional ISR and suggest that the HIV-PIs could be repositioned as therapeutics in human diseases to modulate translation rates and stress responses

Precision oncology by point-of-care therapeutic drug monitoring and dosage adjustment of conventional cytotoxic chemotherapies: A perspective.

Therapeutic drug monitoring (TDM) of conventional cytotoxic chemotherapies is strongly supported yet poorly implemented in daily practice in hospitals. Analytical methods for the quantification of cytotoxic drugs are instead widely presented in the scientific literature, while the use of these therapeutics is expected to keep going for longer. There are two main issues hindering the implementation of TDM: turnaround time, which is incompatible with the dosage profiles of these drugs, and exposure surrogate marker, namely total area under the curve (AUC). Therefore, this perspective article aims to define the adjustment needed from current to efficient TDM practice for cytotoxics, namely point-of-care (POC) TDM. For real-time dose adjustment, which is required for chemotherapies, such POC TDM is only achievable with analytical methods that match the sensitivity and selectivity of current methods, such as chromatography, as well as model-informed precision dosing platforms to assist the oncologist with dose fine-tuning based on quantification results and targeted intervals

Antibiotic stability over six weeks in aqueous solution at body temperature with and without heat treatment that mimics the curing of bone cement.

Thermal stability is a key property in determining the suitability of an antibiotic agent for local application in the treatment of orthopaedic infections. Despite the fact that long-term therapy is a stated goal of novel local delivery carriers, data describing thermal stability over a long period are scarce, and studies that avoid interference from specific carrier materials are absent from the orthopaedic literature. In this study, a total of 38 frequently used antibiotic agents were maintained at 37°C in saline solution, and degradation and antibacterial activity assessed over six weeks. The impact of an initial supplementary heat exposure mimicking exothermically curing bone cement was also tested as this material is commonly used as a local delivery vehicle. Antibiotic degradation was assessed by liquid chromatography coupled to mass spectrometry, or by immunoassays, as appropriate. Antibacterial activity over time was determined by the Kirby-Bauer disk diffusion assay. The heat exposure mimicking curing bone cement had minimal effect on stability for most antibiotics, except for gentamicin which experienced approximately 25% degradation as measured by immunoassay. Beta-lactam antibiotics were found to degrade quite rapidly at 37°C regardless of whether there was an initial heat exposure. Excellent long-term stability was observed for aminoglycosides, glycopeptides, tetracyclines and quinolones under both conditions. This study provides a valuable dataset for orthopaedic surgeons considering local application of antibiotics, and for material scientists looking to develop next-generation controlled or extended-release antibiotic carriers.Cite this article: E. Samara, T. F. Moriarty, L. A. Decosterd, R. G. Richards, E. Gautier, P. Wahl. Antibiotic stability over six weeks in aqueous solution at body temperature with and without heat treatment that mimics the curing of bone cement. Bone Joint J 2017;6:296-306. DOI: 10.1302/2046-3758.65.BJR-2017-0276.R1