Development and validation of a paper spray mass spectrometry method for the rapid quantitation of remdesivir and its active metabolite, GS-441524, in human plasma

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Rapid PS-MS/MS quantification of remdesivir and its active metabolite, GS-441524, directly from plasma.

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No sample preparation, short turn-around time, use of stable isotope-labeled internal standards.

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Robust stability data are presented.

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Suitable for adjusting remdesivir dosage for optimal efficacy and minimal toxicity.

Introduction

Remdesivir (GS-5734) is a nucleoside analog prodrug with antiviral activity against several single-stranded RNA viruses, including the novel severe respiratory distress syndrome virus 2 (SARS-CoV-2). It is currently the only FDA-approved antiviral agent for the treatment of individuals with COVID-19 caused by SARS-CoV-2. However, remdesivir pharmacokinetics/pharmacodynamics (PK/PD) and toxicity data in humans are extremely limited. It is imperative that precise analytical methods for the quantification of remdesivir and its active metabolite, GS-441524, are developed for use in further studies. We report, herein, the first validated anti-viral paper spray-mass spectrometry (PS-MS/MS) assay for the quantification of remdesivir and GS-441524 in human plasma. We seek to highlight the utility of PS-MS/MS technology and automation advancements for its potential future use in clinical research and the clinical laboratory setting.

Methods

Calibration curves for remdesivir and GS-441524 were created utilizing seven plasma-based calibrants of varying concentrations and two isotopic internal standards of set concentrations. Four plasma-based quality controls were prepared in a similar fashion to the calibrants and utilized for validation. No sample preparation was needed. Briefly, plasma samples were spotted on a paper substrate contained within pre-manufactured plastic cassette plates, and the spots were dried for 1 h. The samples were then analyzed directly for 1.2 min utilizing PS-MS/MS. All experiments were performed on a Thermo Scientific Altis triple quadrupole mass spectrometer utilizing automated technology.

Results

The calibration ranges were 20 – 5000 and 100 – 25000 ng/mL for remdesivir and GS-441524, respectively. The calibration curves for the two antiviral agents showed excellent linearity (average R² = 0.99–1.00). The inter- and intra-day precision (%CV) across validation runs at four QC levels for both analytes was less than 11.2% and accuracy (%bias) was within ± 15%. Plasma calibrant stability was assessed and degradation for the 4 °C and room temperature samples were seen beginning at Day 7. The plasma calibrants were stable at −20 °C. No interference, matrix effects, or carryover was discovered during the validation process.

Conclusions

PS-MS/MS represents a useful methodology for rapidly quantifying remdesivir and GS-441524, which may be useful for clinical PK/PD, therapeutic drug monitoring (TDM), and toxicity assessment, particularly during the current COVID-19 pandemic and future viral outbreaks.

Cutting Instruments to Cut Costs: A Simple Initiative with Breast Surgical Operating Room Trays that Resulted in Substantial Savings

BACKGROUND

A substantial expense in surgical care is incurred in the operating room (OR). We evaluated the financial impact of a systematic reduction in instrument tray contents on charges for breast surgery procedures.

METHODS

A catalog of OR trays historically used for breast procedures (excisional biopsy, segmental and total mastectomy with or without axillary staging) was reviewed by four dedicated breast surgeons and downsized to a single tray accommodating all surgeon preferences. A matched-case comparison was performed pre- and post-downsizing. Cost analysis for salary and benefits (S&B) and unit supply cost (USC) pre- and post-downsizing were carried out. Instrument number, OR tray weights, set-up, and breakdown times were also compared.

RESULTS

Post-downsizing, OR tray counts were reduced from 132 to 67 instruments (49%) and tray weight decreased from 30 to 20 pounds (33%). Scrub technician set-up and breakdown times were shorter by 22% and 25%, respectively. Comparing 449 matched cases (239 pre- and 210 post-downsizing), S&B and USC post-downsizing were decreased collectively for all procedures (p < 0.0001). With an average variance of S&B and USC (pre- to post-intervention) of $354, and an annualized case load of 813 operations, this could translate into S&B and USC savings of $287,802 per year.

CONCLUSION

Simply downsizing OR breast trays resulted in decreased combined S&B and USC per procedure, leading to a substantial cost savings for the healthcare system. This measure aligns with a value and quality-based approach to patient care and could be easily replicated across institutions and specialties.

Clinical Features of Critical Coronavirus Disease 2019 in Children

OBJECTIVES

We sought to describe the presentation, course, and outcomes of hospitalized pediatric coronavirus disease 2019 patients, with detailed description of those requiring mechanical ventilation, and comparisons between critically ill and noncritical hospitalized pediatric patients.

DESIGN

Observational cohort study.

SETTING

Riley Hospital for Children at Indiana University Health in Indianapolis in the early weeks of the coronavirus disease 2019 pandemic.

PATIENTS

All hospitalized pediatric patients with confirmed coronavirus disease 2019 as of May 4, 2020, were included.

INTERVENTIONS

Patients received therapies including hydroxychloroquine, remdesivir, tocilizumab, and convalescent serum and were managed according to an institutional algorithm based on evidence available at the time of presentation.

MEASUREMENTS AND MAIN RESULTS

Of 407 children tested for severe acute respiratory syndrome-coronavirus 2 at our hospital, 24 were positive, and 19 required hospitalization. Seven (36.8%) were critically ill in ICU, and four (21%) required mechanical ventilation. Hospitalized children were predominantly male (14, 74%) and African-American or Hispanic (14, 74%), with a bimodal distribution of ages among young children less than or equal to 2 years old (8, 42%) and older adolescents ages 15-18 (6, 32%). Five of seven (71.4%) of critically ill patients were African-American (n = 3) or Hispanic (n = 2). Critical illness was associated with older age (p = 0.017), longer duration of symptoms (p = 0.036), and lower oxygen saturation on presentation (p = 0.016); with more thrombocytopenia (p = 0.015); higher C-reactive protein (p = 0.031); and lower WBC count (p = 0.039). Duration of mechanical ventilation averaged 14.1 days. One patient died.

CONCLUSIONS

Severe, protracted coronavirus disease 2019 is seen in pediatric patients, including those without significant comorbidities. We observed a greater proportion of hospitalized children requiring mechanical ventilation than has been reported to date. Older children, African-American or Hispanic children, and males may be at risk for severe coronavirus disease 2019 requiring hospitalization. Hypoxia, thrombocytopenia, and elevated C-reactive protein may be useful markers of critical illness. Data regarding optimal management and therapies for pediatric coronavirus disease 2019 are urgently needed.

A statistical approach to optimizing paper spray mass spectrometry parameters

RATIONALE

Paper spray mass spectrometry (PS-MS) was used to analyze and quantify ampicillin, a hydrophilic compound and frequently utilized antibiotic. Hydrophilic molecules are difficult to analyze via PS-MS due to their strong binding affinity to paper substrates and low ionization efficiency, among other reasons.

METHODS

Solvent and paper parameters were optimized to increase the extraction of ampicillin from the paper substrate. After optimizing these key parameters, a Resolution IV 1/16 fractional factorial design with two center points was employed to screen eight different design parameters simultaneously.

RESULTS

Pore size, sample volume, and solvent volume were the most significant factors affecting average peak area under the curve (AUC) and the signal-to-blank (S/B) ratio for the 1 μg/mL ampicillin calibrant. After optimizing the key parameters, a linear calibration curve with a range of 0.2 μg/mL to 100 μg/mL was generated (R²  = 0.98) and the limit of detection (LOD) and lower limit of quantification (LLOQ) were calculated to be 0.07 μg/mL and 0.25 μg/mL, respectively.

CONCLUSIONS

The statistical optimization procedure undertaken here increased the mass spectral signal intensity by more than a factor of 40. This statistical method of screening followed by optimization experiments proved faster and more efficient, and produced more drastic improvements than typical one-factor-at-a-time experiments.

Muscle from grass- and grain-fed cattle differs energetically

Insufficient acidification results in dark, firm, and dry beef. While this defect is often indicative of a stress event antemortem, muscle tissue may change in response to feeding regime. Longissimus dorsi muscle samples from 10 grain-fed and 10 grass-fed market weight, angus-crossbred beef cattle were collected postmortem. Lower (P < .05) L* and a* values were recorded for steaks from grass-fed cattle. Higher (P < .05) ultimate pH values were noted in lean of grass-fed cattle compared to grain-fed cattle, yet differences in lactate, glycogen and glucose were not detected. Further, increased (P < .05) ultimate pH values and lower (P < .05) lactate accumulations were noted when samples from grass-fed cattle were subjected to an in vitro glycolysis system. Muscle from grass-fed beef possessed nearly two-fold more (P < .05) succinate dehydrogenase and (P < .001) myoglobin than that of grain-fed cattle. These data show lean from grass-fed beef has greater enzymes reflective of oxidative metabolism and suggest dark lean from grass-fed cattle may be a function of more oxidative metabolism rather than a stress-related event antemortem.

Muscle from grass- and grain-fed cattle differs energetically

Insufficient acidification results in dark, firm, and dry beef. While this defect is often indicative of a stress event antemortem, muscle tissue may change in response to feeding regime. Longissimus dorsi muscle samples from 10 grain-fed and 10 grass-fed market weight, angus-crossbred beef cattle were collected postmortem. Lower (P < .05) L* and a* values were recorded for steaks from grass-fed cattle. Higher (P < .05) ultimate pH values were noted in lean of grass-fed cattle compared to grain-fed cattle, yet differences in lactate, glycogen and glucose were not detected. Further, increased (P < .05) ultimate pH values and lower (P < .05) lactate accumulations were noted when samples from grass-fed cattle were subjected to an in vitro glycolysis system. Muscle from grass-fed beef possessed nearly two-fold more (P < .05) succinate dehydrogenase and (P < .001) myoglobin than that of grain-fed cattle. These data show lean from grass-fed beef has greater enzymes reflective of oxidative metabolism and suggest dark lean from grass-fed cattle may be a function of more oxidative metabolism rather than a stress-related event antemortem.

Nonclinical safety assessment of PF614: A novel TAAP prodrug of oxycodone for chronic pain indication

PF614, a novel trypsin activated abuse protection (TAAP) prodrug of oxycodone, is being studied as chronic pain analgesic with extended release and abuse resistant properties. A series of nonclinical safety studies were conducted to support PF614 introduction to clinical trials. Ames assays (PF614 and its metabolites), comet assay (PF614 ≤ 50 mg/kg/day oral gavage in rats) and micronucleus assay (PF614 ≤ 175 mg/kg/day oral gavage in rats) were negative. hERG assay IC₅₀ for PF614 was ≥300 μM. PF614 (0.1 and 10 μM) showed a low permeability in Caco-2 cells (≤1.17 x 10-6 cm/s) and was not a P-gp or BCRP substrate or inhibitor. The mean percent unbound PF614 among all concentrations in plasma ranged from 91.2 to 98.4, 79.4 to 100, and 52.9-79.9% in rat, dog, and human, respectively. Also, PF614 was metabolically stable in rat, dog, and human hepatocytes with no metabolites identified. Safety pharmacology study in dog indicated moderately lower heart rate at ≥ 2 mg/kg oral gavage doses. Toxicity studies of PF614 in rat and dog with daily oral doses of 25 and 18 mg/kg, respectively, for 14 Days were well tolerated with favorable safety profile supporting its further clinical evaluation.

Substituent Effects on the Reactivity of the 2,4,6-Tridehydropyridinium Cation, an Aromatic σ,σ,σ-Triradical

2,4,6-Tridehydropyridinium cation (7) undergoes three consecutive atom or atom group abstractions from reagent molecules in the gas phase. By placing a π-electron-donating hydroxyl group between two radical sites, their reactivity can be quenched by enhancing their through-space coupling via a favorable resonance structure. Indeed, 3-hydroxy-2,4,6-tridehydropyridinium cation (8) abstracts only one atom or group of atoms from reagents. On the other hand, an electron-withdrawing cyano group between two of the radical sites (9) destabilizes the analogous resonance structure and diminishes through-space coupling between the radical sites, resulting in abstraction of three atoms, just like 7. However, the cyano-substituent also increases acidity to the point that 9 reacts pre-dominantly via proton transfer instead of undergoing radical reactions. Therefore, acidic triradicals may undergo nonradical, barrierless proton transfer reactions faster than radical reactions, which are usually accompanied by barriers. Examination of the analogous cyano-substituted mono-and biradicals revealed behavior similar to that of the corresponding unsubstituted species, with the exception of substantially greater reactivities due to their greater (calculated) vertical electron affinities. Finally, the 3-cyano-2,6-didehydropyridinium cation with a singlet ground state (S-T splitting: -11.9 kcal mol-1) was found to react exclusively from the lowest-energy triplet state by fast proton transfer reactions.

Uveal Melanoma UK National Guidelines

The United Kingdom (UK) uveal melanoma guideline development group used an evidence based systematic approach (Scottish Intercollegiate Guidelines Network (SIGN)) to make recommendations in key areas of uncertainty in the field including: the use and effectiveness of new technologies for prognostication, the appropriate pathway for the surveillance of patients following treatment for primary uveal melanoma, the use and effectiveness of new technologies in the treatment of hepatic recurrence and the use of systemic treatments. The guidelines were sent for international peer review and have been accredited by NICE. A summary of key recommendations is presented. The full documents are available on the Melanoma Focus website.

Results from phase Ib studies of PX-12, a thioredoxin inhibitor in patients with advanced solid malignancies

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Background: PX-12, a small-molecule inhibitor of Thioredoxin-1 (Trx-1) stimulates apoptosis, down-regulates HIF- 1α, VEGF in animal models. High levels of Trx-1 have been linked to chemoresistance in lung cancers. The phase 2 dose of PX-12 was 226 mg/m2 given by 3-h infusion IV x 5 days, q 21d (Ramanathan RK et al. CCR 13; 2109; 2007). Two Phase 1b trials of PX-12 in patients with advanced solid tumors have been completed to determine the safety, tolerability and optimal biologic dose when delivered by prolonged infusion. Methods: PX-12 was administered as a 24-h infusion every q7- 14d starting at 150 mg/m2/day (n=18); or a 72-h infusion q 21d, starting at 300 mg/m2/day (n=14) using a portable delivery pump. Results: Both the 24- or 72-h infusion of PX-12 were well tolerated in patients at doses up to 400 mg/m2/day. Common grade 1/2 AE's included fatigue, taste alteration, and odor caused by expired drug metabolite. In the 24 h study the maximal dose evaluated was 450 mg/m2. No DLTs were observed in this study. Since no MTD was reached on 24-h infusion up to 450 mg/m2 dose level, additional higher doses were explored utilizing 72-h infusion. DLT in the 72-h study at the highest dose administered (500 mg/m2/day) included reversible hypoxia with or without pneumonitis. Best response was stable disease in 3 pts (SD): liver cancer and colon cancer (24-h infusion) and rectal cancer (72-h infusion). Pharmacodynamics (PD): PX- 12 lowered circulating Trx-1 levels in patients who had starting Trx-1 levels 3-fold greater than that of the normal population (5.4 ng/mL) including all three SD. Circulating VEGF and FGF-2 levels were also lowered over multiple courses of treatment in these patients. The pharmacokinetics of PX-12 showed a dose dependent increase of Cmax and no accumulation over multiple cycles following a 24 h infusion. Conclusions: Dosing at 400 mg/m2/day appears safe and tolerable as a 24–72-h infusion. Extending the infusion time to 72h appears to decrease the intensity of cough and odor compared to bolus 1–3 h infusion. The PD effect produced by PX-12 was apparent only in those patients with elevated plasma Trx-1 levels. Patients with elevated TRX-1 levels appear to have the best probability of having SD. Supported by ProlX Pharmaceuticals/Oncothyreon through an award from the NCI.

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The generation of a conditional Fmr1 knock out mouse model to study Fmrp function in vivo

The FMR1 gene, mutated in Fragile X syndrome patients, has been modeled in mice with a neomycin cassette inserted in exon 5 of the mouse Fmr1 gene creating an Fmr1 knockout (Fmr1 KO) allele. This results in animals lacking Fmr1 protein (Fmrp) expression in all tissues. We have created a new, more versatile Fmr1 in vivo KO model (Fmr1 KO2) and generated conditional Fmr1 KO (CKO) mice by flanking the promoter and first exon of Fmr1 with lox P sites. This enables us to create a null allele in specific cell types and at specific time points by crossing Fmr1 CKO mice with tissue specific or inducible cre-recombinase expressing mice. The new Fmr1 KO2 line does not express any Fmrp and also lacks detectable Fmr1 transcripts. Crossing the Fmr1 CKO line with a Purkinje cell-specific cre-recombinase expresser produces mice that are null for Fmr1 in Purkinje neurons but wild type in all other cell types.

A comparison of laparoscopic supracervical hysterectomy vs laparoscopically assisted vaginal hysterectomy

BACKGROUND

We set out to compare the length of stay, costs, and morbidity associated with laparoscopic supracervical hysterectomy (LSH) with laparoscopically assisted vaginal hysterectomy (LAVH).

METHODS

We performed a cohort analysis of consecutive patients at a university-based medical center from April 1997 through October 1999.

RESULTS

A total of 145 patients were identified initially; however, 13 cases were excluded because of concomitant procedures (retropubic urethropexy, lymphadenectomy, paravaginal repair). Of the 132 patients included in the study, 27 underwent LSH and 105 underwent LAVH. The two groups were similar with respect to gravidity, parity, uterine weight, and preoperative diagnosis. Patients undergoing LSH had significantly shorter operating times (median, 181 vs 220 min, p = 0.007), briefer hospital stays (median, 1.0 vs 2.0 days, p = 0.0001), and less blood loss (median, 125 vs 400 ml, p = 0.0001). None of the patients submitted to LSH experienced morbidity, as compared with a 13% morbidity rate for LAVH (bladder injury, n = 3; blood loss >1000 ml, n = 7; vaginal cuff hematoma, n = 4; 0% vs 13%; p = 0.04).

CONCLUSIONS

Patients undergoing laparoscopic supracervical hysterectomy had shorter operating times, shorter hospital stays, and less morbidity than those who underwent laparoscopically assisted vaginal hysterectomy. The practice of routine cervicectomy at laparoscopic hysterectomy should be reconsidered.

Surgery trends change nursing care: operating room nurses share new procedures that will affect home healthcare

The word "surgery" does not mean what is used to. Community nursing care means something different now, too.

The influence of physical properties and lipid content of bile on the human blood/bile ethanol ratio

The relationship between ethanol levels in blood and bile was determined in human postmortem specimens. The influences of several physical properties--surface tension, specific gravity and viscosity--and bile lipid content on the blood/bile ethanol ratio were evaluated. A gas chromatographic direct injection technique was employed to determine the ethanol concentrations in postmortem blood and bile specimens. A positive correlation was established between the levels in the two fluids. No correlation could be found between the blood/bile ethanol ratios and the aforementioned physical properties of bile. Correction of the observed bile ethanol for lipid content had an insignificant effect on the ratio. The average blood/bile ethanol ratio was 1.03 +/- 0.29 (range: 0.32-2.91). The wide range observed makes it undesirable to use bile ethanol concentrations to predict specific blood ethanol concentrations. However, under certain conditions, bile ethanol levels may be used to estimate blood concentrations within a range of values.