Species differences in plasma protein binding of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease inhibitor nirmatrelvir.

Plasma protein binding (PPB) studies on the SARS-CoV-2 main protease inhibitor nirmatrelvir revealed considerable species differences primarily in dog and rabbit, which prompted further investigations into the biochemical basis for these differences.The unbound fraction (fu) of nirmatrelvir in dog and rabbit plasma was concentration (2-200 µM)-dependent (dog fu,p 0.024-0.69, rabbit fu,p 0.010-0.82). Concentration (0.1-100 µM)-dependent binding in serum albumin (SA) (fu,SA 0.040-0.82) and alpha-1-acid glycoprotein (AAG) (fu,AAG 0.050-0.64) was observed in dogs. Nirmatrelvir showed minimal binding to rabbit SA (1-100 µM: fu,SA 0.70-0.79), while binding to rabbit AAG was concentration-dependent (0.1-100 µM: fu,AAG 0.024-0.66). In contrast, nirmatrelvir (2 µM) revealed minimal binding (fu,AAG 0.79-0.88) to AAG from rat and monkeys. Nirmatrelvir showed minimal-to-moderate binding to SA (1-100 µM; fu,SA 0.70-1.0) and AAG (0.1-100 µM; fu,AAG 0.48-0.58) from humans across tested concentrations.Nirmatrelvir molecular docking studies using published crystal structures and homology models of human and preclinical species SA and AAG were used to rationalise the species differences to plasma proteins. This suggested that species differences in PPB are primarily driven by molecular differences in albumin and AAG resulting in differences in binding affinity.

How to advise women on the safe use of medicines while breastfeeding

Medicines use plays an important role in women's decisions to start or continue breastfeeding. Some may stop breastfeeding or the medicine to avoid combining the two, as they feel very strongly about tainting their milk when breastfeeding[10]. Women deserve to be involved in discussions on compatibility, using evidence-based resources presented in a manner in which they can understand. There is a presumption by some healthcare professionals, mothers, families and wider society that formula has benefits over breast milk with a trace of medication in, or that adverse events are likely and serious if this breast milk is consumed. In addition, there is a reticence from healthcare professionals to use professional judgement and go outside the licence application for medicines. This leaves the mother with a dilemma: to interrupt or stop breastfeeding to take the medication, or to delay medication - with chronic diseases, the latter is rarely an acceptable option. In January 2021, the MHRA launched the Safer Medicines Consortium, owing to the "need for reliable and consistent information about medicines used before or during pregnancy and breastfeeding for women and the healthcare professionals who advise them". The vision of the consortium is that "all women will have access to accurate and accessible information to make informed decisions with their healthcare professional about taking medicines before or during pregnancy or breastfeeding"[44]. As experts in medicines, pharmacists should share evidence-based information with the mother and support her in making a decision that is right for her and her baby, as outlined above. Copyright © 2021 Pharmaceutical Press. All rights reserved.

Evaluation of In Vitro Distribution and Plasma Protein Binding of Selected Antiviral Drugs (Favipiravir, Molnupiravir and Imatinib) against SARS-CoV-2.

There are a number of uncertainties regarding plasma protein binding and blood distribution of the active drugs favipiravir (FAVI), molnupiravir (MOLNU) and imatinib (IMA), which were recently proposed as therapeutics for the treatment of COVID-19 disease. Therefore, proton dissociation processes, solubility, lipophilicity, and serum protein binding of these three substances were investigated in detail. The drugs display various degrees of lipophilicity at gastric (pH 2.0) and blood pH (pH 7.4). The determined pKa values explain well the changes in lipophilic character of the respective compounds. The serum protein binding was studied by membrane ultrafiltration, frontal analysis capillary electrophoresis, steady-state fluorometry, and fluorescence anisotropy techniques. The studies revealed that the ester bond in MOLNU is hydrolyzed by protein constituents of blood serum. Molnupiravir and its hydrolyzed form do not bind considerably to blood proteins. Likewise, FAVI does not bind to human serum albumin (HSA) and α1-acid glycoprotein (AGP) and shows relatively weak binding to the protein fraction of whole blood serum. Imatinib binds to AGP with high affinity (logK' = 5.8-6.0), while its binding to HSA is much weaker (logK' ≤ 4.0). The computed constants were used to model the distribution of IMA in blood plasma under physiological and 'acute-phase' conditions as well.

PBI-0451 AN ORALLY ADMINISTERED 3CL PROTEASE INHIBITOR of SARS-CoV-2 for COVID-19

Background: The 3CL protease (3CLpro) of coronaviruses (CoV) is responsible for essential & early steps of viral replication. Early treatment of SARS-CoV2 infection with a 3CLpro inhibitor has shown to substantially reduce the rate of hospitalization & death from COVID-19. There is a need for a protease inhibitor that can be used as a stand-alone agent to treat and prevent SARS-CoV-2 infection globally, in the setting of remote testing & healthcare delivery, and as unsupervised outpatient use by a significant number of people who take other medications. Methods: PBI-0451 was assessed in cultures of inducible pluripotent stem cell-derived alveolar type II (iPS-AT2) cells, in nonclinical PK and toxicity studies, and an ongoing randomized, double-blind first-in-human (FIH) study evaluating the tolerability, safety, and PK of single and multiple doses administered as an oral suspension to healthy adult subjects. The effect of food and the potential for a drug-drug interaction (DDI) with ritonavir were also explored. Results: PBI-0451 potently inhibited SARS-CoV-2 replication in iPS-AT2 cells with multi-log reductions in viral titer and mean (SD) IC50 & EC90 values of 32 (25) & 106 (90) nM, respectively. No clinically relevant adverse effects of PBI-0451 were observed in 14-day GLP toxicity studies in mice and dogs, including on the cardiovascular, CNS, or respiratory systems. PBI-0451 was not genotoxic in Ames and micronucleus tests. In the ongoing FIH study to date, study treatments were generally well tolerated with no study drug or study discontinuations. No Grade 2, 3, 4, or severe adverse events were reported. Preliminary single-dose concentration-time profile of PBI-0451 following administration with food demonstrated a 2-compartment PK profile with a median terminal elimination t1/2 ranging from 11-14 hours. PBI-0451 demonstrated good oral bioavailability and a linear increase in exposure over a 10-fold dose range when administered with food, achieving concentrations >1-, 3-& 10-fold the plasma protein binding-adjusted EC90 value (374 ng/mL) against SARS-CoV-2 at doses of 100, 300 & 1050 mg, respectively. The PK of PBI-0451 was unaffected by coadministration with ritonavir. Conclusion: PBI-0451 has shown favorable nonclinical properties and early clinical safety & PK that supports its continued evaluation as a stand-alone agent. Ongoing multiple-dose evaluation will further elucidate its clinical profile and inform the dose & dosing regimen selection for potential Phase II/III studies.

Advantages of Allometric Scaling Methods for Predicting Human Pharmacokinetics of Novel JAK Inhibitor -Baricitinib and Dose Extrapolation

The primary motive of this study was to examine advantages of allometry scaling strategies for correct prediction of pharmacokinetics of Baricitinib in human from preclinical species. Baricitinib is basically Janus kinase (JAK) inhibitor used for the treatment of rheumatoid arthritis. Currently approved by FDA in combination with remdesivir for treatment of COVID-19 hospitalized patient. The literature published pharmacokinetic parameters (Cl and Vd) of preclinical species (Rat, Dog and monkey) were utilized for the allometry scaling of Baricitinib. The connection among the primary pharmacokinetic parameters [Volume of distribution (Vd) and clearance (Cl)] and body weight (BW) were studied across three preclinical species, we used the double logarithmic plots for prediction of the human pharmacokinetic parameters i.e. Cl and Vd with use of simple allometry and with additional correction factors for better prediction. The dose extrapolation of baricitinib was carried out by FDA guidelines. By application of the allometric scaling methods and principles correlation was found to be satisfactory for the prediction of intravenous human Cl and Vd for baricitinib. The volume of distribution (Vd) predicted by simple allometry (65.3 L) was found to be in agreement with the reported value (75.5 L);clearance (Cl) prediction by simple allometry was found to be at least 1.06 -closer to the reported value (245 mL/min);CF were used to predict the clearance. Both brain weight (B.W) and maximum life span potential (MLP) predicted the Cl with 0.52- and 0.61 -fold difference. The application of monkey liver blood flow predicted Cl with 0.81 fold which was also in close agreement with reported value. The Cl prediction was also extrapolated using LBF (Liver blood flow) method and observed that the higher species (Dog and Monkey) have predicted Cl with better accuracy than rat. Overall, the simple allometry (SA), monkey liver blood flow (MLBF) and application of liver blood flow (LBF) methods showed excellent correlation with human. The time vs. plasma concentration simulated graph also showed the similar closeness with human profile. The inclusion of plasma protein binding factor didn't improve the prediction accuracy. The FIH dose extrapolation were showed that PK guided approach and exponent for BSA based approach was found closer to actual human dose of 4.0 mg/Kg. Oriental Scientific Publishing Company

Pre-clinical evaluation of NEOS-223, an (S)-valine-thiazole derived peptidomimetic N-heterocycle, as an anticancer agent and P-glycoprotein inhibitor

The ability to control the proliferation and cell death by inhibiting specific target kinase offers the opportunity to apply targeted therapies in the treatment of cancer. It has been found that (S)-valine-thiazole-derived compounds such as NEOS-223 are effective inhibitors of one or more of these kinases. NEOS 223 was developed, synthesized, and tested in the NCI 60 human tumor cell-screening panel demonstrating inhibition of colon (-53%), melanoma (-41%), and breast cancers (-9%). Microsomal clearance was determined in mouse, rat, dog, and human, and analyzed by LC-MS/MS by percent of parent material. IC50 values for CYP inhibition of >10 μM were calculated for 1A2, 2C19, and 3A4 with IC50 values of 4.86, 4.31, and 7.84 μM for 2C9 and 2D6. Microsomal clearance was high in all species with clearance rates ranging from 69-136 mL/min/kg. Plasma protein binding was determined by Rapid Equilibrium Dialysis in mice, rats, dogs, and humans. High plasma protein binding (>70%) was observed across all species. Based on the NCI results several cell lines were assayed in an MTT assay (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) to determine cell viability in the presence of NEOS-223 resulting in <20% viability in colon, breast, melanoma, pancreatic and prostate human cancer cell lines at a 10 uM concentration. Maximum tolerated dose studies were conducted by both intraperitoneal and oral administration in mice. NEOS-223 delivered up to 80 mg/kg was well tolerated. Minimal or no toxicity was observed in acute and repeat dose animal studies. Pharmacokinetics of oral administration demonstrated adequate systemic exposure at therapeutic levels in mice, rats, and dogs. Preliminary in vivo mouse xenograft studies were performed on colon (COLO 205, HT-29 red FLUC), breast (MDA-Sumathi Chittamuru;Timothy M. Murphy;Sara A. Little;Andrew A. Taylor;Roseanne Wexler;Laxman Desai MB-468), melanoma (M-14), pancreatic (PANC-1), and prostate (PC3) human cancer cells with significant tumor inhibition observed compared to positive control agent groups with twice daily dosing of NEOS-223. In addition, a five-day pilot oral toxicity study in rats with dose range-finding studies and a 28-day repeat dose toxicity study performed in both rats and dogs provided favorable results. NEOS-223 has demonstrated active in vitro activity along with a favorable safety profile. in vivo efficacy resulted in inhibition of growth of multiple cell line. As a novel effective structure possibly targeting multiple kinases and transporters in one hybrid molecule, NEOS-223 may be a preferred monotherapy or combined therapy for multiple cancers. If upon further development, this drug is effective in humans, it would advance clinical practice and could improve current therapy significantly.

Phytoconstituents from ten natural herbs as potent inhibitors of main protease enzyme of SARS-COV-2: In silico study.

Background: Lack of treatment of novel Coronavirus disease led to the search of specific antivirals that are capable to inhibit the replication of the virus. The plant kingdom has demonstrated to be an important source of new molecules with antiviral potential. Purpose: The present study aims to utilize various computational tools to identify the most eligible drug candidate that have capabilities to halt the replication of SARS-COV-2 virus by inhibiting Main protease (Mpro) enzyme. Methods: We have selected plants whose extracts have inhibitory potential against previously discovered coronaviruses. Their phytoconstituents were surveyed and a library of 100 molecules was prepared. Then, computational tools such as molecular docking, ADMET and molecular dynamic simulations were utilized to screen the compounds and evaluate them against Mpro enzyme. Results: All the phytoconstituents showed good binding affinities towards Mpro enzyme. Among them laurolitsine possesses the highest binding affinity i.e. -294.1533 kcal/mol. On ADMET analysis of best three ligands were simulated for 1.2 ns, then the stable ligand among them was further simulated for 20 ns. Results revealed that no conformational changes were observed in the laurolitsine w.r.t. protein residues and low RMSD value suggested that the Laurolitsine-protein complex was stable for 20 ns. Conclusion: Laurolitsine, an active constituent of roots of Lindera aggregata, was found to be having good ADMET profile and have capabilities to halt the activity of the enzyme. Therefore, this makes laurolitsine a good drug candidate for the treatment of COVID-19.