Comparison of MMP-2, MMP-9, COX-2, and PGP Expression in Feline Injection-Site and Feline Noninjection-Site Sarcomas-Pilot Study.

Feline injection-site sarcomas (FISSs) are aggressive neoplasms that have been associated mostly with vaccination. Feline noninjection-site sarcomas (non-FISSs) are less frequently observed in cats and may arise in any anatomic site. This study aimed to determine the differences in the expression of the selected proteins (matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), cyclooxygenase-2 (COX-2), and P-glycoprotein (PGP)) and their correlation with the mitotic count in FISS and non-FISS, in order to characterize their immunohistochemical features. A preliminary study of eleven samples of FISS and eight samples of non-FISS was performed using immunohistochemistry. Among all the tested sarcomas, 80.4% of the tumors were positive for COX-2, 90.2% were positive for MMP-9, and 100% were positive for PGP. The results showed that the expressions of COX-2, MMP-9, and PGP were significantly higher in FISS than in non-FISS (COX-2-p ≤ 0.001; MMP-9-p ≤ 0.05; and PGP-p ≤ 0.05). A Spearman rank correlation analysis showed a moderate negative correlation between the expression of COX-2 and MMP-9 in FISS (r = -0.52). A strong negative correlation between COX-2 and PGP (r = -0.81), a moderate positive correlation between MMP-2 and MMP-9 (r = +0.69), and a moderate negative correlation between MMP-2 and PGP (r = -0.44) were observed in non-FISS. In summary, our study presents the immunohistochemical profile of the proteins involved with inflammation and carcinogenesis in FISS and non-FISS, which can contribute to expanding the knowledge of tumor biology.

Crizotinib resistance reversal in ALK-positive lung cancer through zeolitic imidazolate framework-based mitochondrial damage.

Crizotinib (CRZ), one of anaplastic lymphoma kinase tyrosine kinase inhibitors (ALK-TKIs), has emerged as a frontline treatment for ALK-positive (ALK+) lung adenocarcinoma. However, the overexpression of P-glycoprotein (P-gp, a mitochondrial adenosine triphosphate (ATP)-dependent protein) in lung adenocarcinoma lesions causes multidrug resistance and limits the efficacy of CRZ treatment. Herein, a mitochondria-targeting nanosystem, zeolitic imidazolate framework-90@indocyanine green (ZIF-90@ICG), was fabricated to intervene in mitochondria and overcome drug resistance. Due to the zinc ion (Zn2+) interference of ZIF-90 and the photodynamic therapy (PDT) of ICG, this nanosystem is well suited for damaging mitochondrial functions, thus downregulating the intracellular ATP level and inhibiting P-gp expression. In addition, systematic bioinformatics analysis revealed the upregulation of CD44 in CRZ-resistant cells. Therefore, hyaluronic acid (HA, a critical target ligand of CD44) was further modified on the surface of ZIF-90@ICG for active targeting. Overall, this ZIF-90@ICG nanosystem synergistically increased the intracellular accumulation of CRZ and reversed CRZ resistance to enhance its anticancer effect, which provides guidance for nanomedicine design to accurately target tumours and induce mitochondrial damage and represents a viable regimen for improving the prognosis of patients with ALK-TKIs resistance. STATEMENT OF SIGNIFICANCE: The original aim of our research was to combat multidrug resistance (MDR) in highly aggressive and lethal lymphoma kinase-positive (ALK+) lung adenocarcinoma. For this purpose, a cascade-targeted system was designed to overcome MDR, integrating lung adenocarcinoma-targeted hyaluronic acid (HA), mitochondrion-targeted zeolitic imidazolate framework-90 (ZIF-90), the clinically approved drug crizotinib (CRZ), and the fluorescence imaging agent/photosensitizer indocyanine green (ICG). Moreover, using a "two birds with one stone" strategy, ion interference and oxidative stress induced by ZIF-90 and photodynamic therapy (PDT), respectively, disrupt mitochondrial homeostasis, thus downregulating adenosine triphosphate (ATP) levels, inhibiting MDR-relevant P-glycoprotein (P-gp) expression and suppressing tumour metastasis. Overall, this research represents an attempt to implement the concept of MDR reversal and realize the trade-offs between MDR and therapeutic effectiveness.

Impact of V9302, a Competitive Antagonist of Transmembrane Glutamine Flux on Reversal of Resistance in Breast Cancer Cell Lines.

Chemotherapy is a known treatment modality that improves the long-term survival of breast cancer patients. However, due to the resistance to numerous anticancer drugs, alternative chemotherapeutic strategies are required. Regarding antimetabolic drugs, several compounds have proven anticancer properties, such as statins. The present study aimed to investigate the in vitro effects of V9302, a competitive antagonist of glutamine flux, on different subtypes of breast cancers (estrogen, progesterone, and HER2 receptor-positive or negative, and Pgp-negative and Pgp-overexpressing). The interactions of V9302 with standard chemotherapeutic drugs (doxorubicin and cisplatin) were also determined by MTT staining on breast cancer cell lines. Furthermore, the influence of V9302 on the cell cycle of MCF-7 and its Pgp-overexpressing counterpart KCR was monitored by flow cytometry. It was shown that V9302 exerted synergistic interactions with doxorubicin in all breast cancer cell lines. In cell cycle analysis, the KCR cell line was more sensitive to V9302. After 48 h, cell proliferation was completely blocked, and elevated G1, suppressed S, and decreased G2/M could be detected. Inhibition of glutamate transport can be assumed to block resistance related to Pgp.

Solasodine targets NF-κB signaling to overcome P-glycoprotein mediated multidrug resistance in cancer.

P-glycoprotein (P-gp) mediated multidrug resistance (MDR) is the leading cause of chemotherapy failure since it causes the efflux of chemotherapeutic drugs from the cancer cells. Solasodine, a steroidal alkaloid and oxaspiro compound, present in the Solanaceae family showed significant cytotoxic effects on various cancer cells. However, the effect of solasodine on reversing P-gp mediated drug resistance is still unknown. Primarily in this study, the integrative network pharmacology analysis found 71 common targets between solasodine and cancer MDR, among them NF-κB was found as a potential target. The results of immunofluorescence analysis showed that solasodine significantly inhibits NF-κB-p65 nuclear translocation which caused downregulated P-gp expression in KBChR-8-5 cells. Further, solasodine binds to the active sites of the TMD region of P-gp and inhibits P-gp transport activity. Moreover, solasodine significantly promotes doxorubicin intracellular accumulation in the drug resistant cells. Solasodine reduced the fold resistance and synergistically sensitized doxorubicin's therapeutic effects in KBChR-8-5 cells. Additionally, the solasodine and doxorubicin combination treatment increased the apoptotic cell populations and G2/M phase cell cycle arrest in KBChR-8-5 cells. The MDR tumor bearing xenograft mice showed tumor-suppressing characteristics and P-gp downregulation during the combination treatment of solasodine and doxorubicin. These results indicate that solasodine targets NF-κB signaling to downregulate P-gp overexpression, inhibit P-gp transport activity, and enhance chemosensitization in MDR cancer cells. Considering its multifaceted impact, solasodine represents a potent natural fourth-generation P-gp modulator for reversing MDR in cancer.

Pharmacokinetic Modeling of the Effect of Tariquidar on Ondansetron Disposition into the Central Nervous System.

PURPOSE: Serotonin (5-HT3) receptor antagonists are promising agents for treatment of neuropathic pain. However, insufficient drug exposure at the central nervous system (CNS) might result in lack of efficacy. The goal of this study was to evaluate the impact of administration of a Pgp inhibitor (tariquidar) on ondansetron exposure in the brain, spinal cord, and cerebrospinal fluid in a wild-type rat model. METHODS: Ondansetron (10 mg/kg) and tariquidar (7.5 mg/kg) were administered intravenously, plasma and tissue samples were collected and analyzed by HPLC. A mathematical model with brain, spinal cord, cerebrospinal fluid and two systemic disposition compartments was developed to describe the data. RESULTS: The results demonstrate that tariquidar at 7.5 mg/kg resulted in a complete inhibition of Pgp efflux of ondansetron in the brain and spinal cord. The compartmental model successfully captured pharmacokinetics of ondansetron in wild type and Pgp knockout (KO) animals receiving the drug alone or in wild type animals receiving the ondansetron and tariquidar combination. CONCLUSIONS: The study provided important quantitative information on enhancement of CNS exposure to ondansetron using co-administration of Pgp Inhibitor in a rat model, which will be further utilized in conducting a clinical study. Tariquidar co-administration resulted in ondansetron CNS exposure comparable to observed in Pgp KO rats. Results also highlighted the effect of tariquidar on plasma disposition of ondansetron, which may not be dependent on Pgp inhibition, and should be evaluated in future studies.

Mechanistic insights into P-glycoprotein ligand transport and inhibition revealed by enhanced molecular dynamics simulations.

P-glycoprotein (P-gp) plays a crucial role in cellular detoxification and drug efflux processes, transitioning between inward-facing (IF) open, occluded, and outward-facing (OF) states to facilitate substrate transport. Its role is critical in cancer therapy, where P-gp contributes to the multidrug resistance phenotype. In our study, classical and enhanced molecular dynamics (MD) simulations were conducted to dissect the structural and functional features of the P-gp conformational states. Our advanced MD simulations, including kinetically excited targeted MD (ketMD) and adiabatic biasing MD (ABMD), provided deeper insights into state transition and translocation mechanisms. Our findings suggest that the unkinking of TM4 and TM10 helices is a prerequisite for correctly achieving the outward conformation. Simulations of the IF-occluded conformations, characterized by kinked TM4 and TM10 helices, consistently demonstrated altered communication between the transmembrane domains (TMDs) and nucleotide binding domain 2 (NBD2), suggesting the implication of this interface in inhibiting P-gp's efflux function. A particular emphasis was placed on the unstructured linker segment connecting the NBD1 to TMD2 and its role in the transporter's dynamics. With the linker present, we specifically noticed a potential entrance of cholesterol (CHOL) through the TM4-TM6 portal, shedding light on crucial residues involved in accommodating CHOL. We therefore suggest that this entry mechanism could be employed for some P-gp substrates or inhibitors. Our results provide critical data for understanding P-gp functioning and developing new P-gp inhibitors for establishing more effective strategies against multidrug resistance.

Treatment with low-dose nintedanib and tacrolimus in patients with progressive fibrosing interstitial lung diseases with anti-ARS antibody-positive dermatomyositis.

Nintedanib has been demonstrated to inhibit the rate of forced vital capacity decline in patients with progressive fibrosing interstitial lung diseases (PF-ILD) at a dose of 200 or 300 mg/day in the INBUILD trial. Although concomitant use of nintedanib with P-glycoprotein inhibitors reportedly increases the plasma concentrations of the former, tacrolimus, a P-glycoprotein inhibitor, is often used to treat connective tissue diseases-related interstitial lung diseases. The optimal dose of nintedanib in combination with tacrolimus for the treatment of PF-ILD with connective tissue disease is unknown. We herein present two patients with PF-ILD with anti-aminoacyl-tRNA synthetase antibody-positive dermatomyositis who were successfully treated with low-dose nintedanib (<200 mg/day) in combination with tacrolimus.

Discovery of pyridoquinoxaline-based new P-gp inhibitors as coadjutant against Multi Drug Resistance in cancer.

Multi-drug resistance (MDR) is a serious challenge in contemporary clinical practice and is mostly responsible for the failure of cancer medication therapies. Several experimental evidence links MDR to the overexpression of the drug efflux transporter P-gp, therefore, the discovery of novel P-glycoprotein inhibitors is required to treat or prevent MDR and to improve the absorption of chemotherapy drugs via the gastrointestinal system. In this work, we explored a series of novel pyridoquinoxaline-based derivatives designed from parental compounds, previously proved active in enhancing anticancer drugs in MDR nasopharyngeal carcinoma (KB). Among them, derivative 10d showed the most potent and selective inhibition of fluorescent dye efflux, if compared to reference compounds (MK-571, Novobiocin, Verapamil), and the highest MDR reversal activity when co-administered with the chemotherapeutic agents Vincristine and Etoposide, at non-cytotoxic concentrations. Molecular modelling predicted the two compound 10d binding mode in a ratio of 2:1 with the target protein. No cytotoxicity was observed in healthy microglia cells and off-target investigations showed the absence of CaV1.2 channel blockade. In summary, our findings indicated that 10d could potentially be a novel therapeutic coadjutant by inhibiting P-gp transport function in vitro, thereby reversing cancer multidrug resistance.

Analysis of hemorrhagic drug-drug interactions between P-gp inhibitors and direct oral anticoagulants from the FDA Adverse Event Reporting System.

BACKGROUND: Limited understanding exists regarding the hemorrhagic risk resulting from potential interactions between P-glycoprotein (P-gp) inhibitors and direct oral anticoagulants (DOACs). Utilizing the Food and Drug Administration Adverse Event Reporting System (FAERS) data, we analyzed hemorrhagic adverse events (AEs) linked with the co-administration of P-gp inhibitors and DOACs, aiming to offer guidance for their safe and rational use. METHODS: Hemorrhagic events associated with P-gp inhibitors in combination with DOACs were scrutinized from the FAERS database. Hemorrhagic signals mining was performed by estimating the reported odds ratios (RORs), corroborated by additive and multiplicative models and a combination risk ratio (PRR) model. RESULTS: Our analysis covered 4,417,195 cases, revealing 11,967 bleeding events associated with P-gp inhibitors. We observed a significantly higher risk of bleeding with the combination of apixaban and felodipine (ROR 118.84, 95% CI 78.12-180.79, additive model 0.545, multiplicative model 1.253, PRR 22.896 (2450.141)). Moreover, consistent associations were found in the co-administration analyzes of rivaroxaban with dronedarone and diltiazem, and apixaban with losartan, telmisartan, and simvastatin. CONCLUSION: Our FAERS data analysis unveils varying degrees of bleeding risk associated with the co-administration of P-gp inhibitors and DOACs, underscoring the importance of vigilance about them in clinical practice.

A hybrid evaluation of the intestinal absorption performance of compounds from molecular structure.

Intestinal absorption of compounds is significant in drug research and development. To evaluate this efficiently, a method combining mathematical modeling and molecular simulation was proposed, from the perspective of molecular structure. Based on the quantitative structure-property relationship study, the model between molecular structure and their apparent permeability coefficients was successfully constructed and verified, predicting intestinal absorption of drugs and interpreting decisive structural factors, such as AlogP98, Hydrogen bond donor and Ellipsoidal volume. The molecules with strong lipophilicity, less hydrogen bond donors and receptors, and small molecular volume are more easily absorbed. Then, the molecular dynamics simulation and molecular docking were utilized to study the mechanism of differences in intestinal absorption of drugs and investigate the role of molecular structure. Results indicated that molecules with strong lipophilicity and small volume interacted with the membrane at a lower energy and were easier to penetrate the membrane. Likewise, they had weaker interaction with P-glycoprotein and were easier to escape from it and harder to export from the body. More in, less out, is the main reason these molecules absorb well.

Effect of ABCB1 most frequent polymorphisms on the accumulation of bictegravir in recombinant HEK293 cell lines.

Bictegravir, a key second-generation integrase strand transfer inhibitor in the treatment of HIV, is subject to active efflux transport mediated by ABCB1 (P-glycoprotein). Several coding variants of ABCB1 have been described and associated with variable effects on substrate drugs pharmacokinetics. Here, we investigated the effect of the four most common coding ABCB1 single nucleotide polymorphisms (i.e., c.1199G > A, c.1236C > T, c.2677G > T and c.3435C > T) on the intracellular accumulation of bictegravir. Using a previously validated HEK293 recombinant cell line model, we found decreased bictegravir intracellular concentrations in cell lines overexpressing ABCB1 as compared to control cell lines, in line with the known role of ABCB1 in bictegravir transport. However, we were unable to demonstrate any significant difference in bictegravir intracellular accumulation when comparing HEK293 cells overexpressing the wild type (1236C-2677G-3435C, 1199G) or the variant (1236C-2677G-3435T, 1236T-2677T-3435T or 1199A) proteins. These findings suggest that the ABCB1 c.1199G > A and c.1236C > T-c.2677G > T-c.3435C > T variants have no or at least limited impact on the active transport of bictegravir by ABCB1.

Advances in nano-preparations for improving tetrandrine solubility and bioavailability.

Tetrandrine (TET) is a natural bis-benzylisoquinoline alkaloid isolated from Stephania species with a wide range of biological and pharmacologic activities; it mainly serves as an anti-inflammatory agent or antitumor adjuvant in clinical applications. However, limitations such as prominent hydrophobicity, severe off-target toxicity, and low absorption result in suboptimal therapeutic outcomes preventing its widespread adoption. Nanoparticles have proven to be efficient devices for targeted drug delivery since drug-carrying nanoparticles can be passively transported to the tumor site by the enhanced permeability and retention (EPR) effects, thus securing a niche in cancer therapies. Great progress has been made in nanocarrier construction for TET delivery due to their outstanding advantages such as increased water-solubility, improved biodistribution and blood circulation, reduced off-target irritation, and combinational therapy. Herein, we systematically reviewed the latest advancements in TET-loaded nanoparticles and their respective features with the expectation of providing perspective and guidelines for future research and potential applications of TET.

The role of drug efflux and uptake transporters in the plasma pharmacokinetics and tissue disposition of morphine and its main metabolites.

Morphine is a widely used opioid for the treatment of pain. Differences in drug transporter expression and activity may contribute to variability in morphine pharmacokinetics and response. Using appropriate mouse models, we investigated the impact of the efflux transporters ABCB1 and ABCG2 and the OATP uptake transporters on the pharmacokinetics of morphine, morphine-3-glucuronide (M3G), and M6G. Upon subcutaneous administration of morphine, its plasma exposure in Abcb1a/1b-/-;Abcg2-/--, Abcb1a/1b-/-;Abcg2-/-;Oatp1a/1b-/-;Oatp2b1-/- (Bab12), and Oatp1a/1b-/-;Oatp2b1-/- mice was similar to that found in wild-type mice. Forty minutes after dosing, morphine brain accumulation increased by 2-fold when mouse (m)Abcb1 and mAbcg2 were ablated. Relative recovery of morphine in small intestinal content was significantly reduced in all the knockout strains. In the absence of mOatp1a/1b and mOatp2b1, plasma levels of M3G were markedly increased, suggesting a lower elimination rate. Moreover, Oatp-deficient mice displayed reduced hepatic and intestinal M3G accumulation. Mouse Oatps similarly affected plasma and tissue disposition of subcutaneously administered M6G. Human OATP1B1/1B3 transporters modestly contribute to the liver accumulation of M6G. In summary, mAbcb1, in combination with mAbcg2, limits morphine brain penetration and its net intestinal absorption. Variation in ABCB1 activity due to genetic polymorphisms/mutations and/or environmental factors might, therefore, partially affect morphine tissue exposure in patients. The ablation of mOatp1a/1b increases plasma exposure and decreases the liver and small intestinal disposition of M3G and M6G. Since the contribution of human OATP1B1/1B3 to M6G liver uptake was quite modest, the risks of undesirable drug interactions or interindividual variation related to OATP activity are likely negligible.

P-glycoprotein inhibitors as an adjunct therapy for TB.

The primary challenge in TB treatment is the emergence of multidrug-resistant TB (MDR-TB). One of the major factors responsible for MDR is the upregulation of efflux pumps. Permeation-glycoprotein (P-gp), an efflux pump, hinders the bioavailability of the administered drugs inside the infected cells. Simultaneously, angiogenesis, the formation of new blood vessels, contributes to drug delivery complexities. TB infection triggers a cascade of events that upregulates the expression of angiogenic factors and P-gp. The combined action of P-gp and angiogenesis foster the emergence of MDR-TB. Understanding these mechanisms is pivotal for developing targeted interventions to overcome MDR in TB. P-gp inhibitors, such as verapamil, and anti-angiogenic drugs, including bevacizumab, have shown improvement in TB drug delivery to granuloma. In this review, we discuss the potential of P-gp inhibitors as an adjunct therapy to shorten TB treatment.

Potency and mechanism of p-glycoprotein chemosensitizers in rainbow trout (Oncorhynchus mykiss) hepatocytes.

The membrane efflux transporter P-glycoprotein (P-gp, [ABCB1, MDR1]) exports a wide range of xenobiotic compounds, resulting in a continuous first line of defense against toxicant accumulation at basal expression levels, and contributing to the multixenobiotic resistance (MXR) phenotype at elevated expression levels. Relatively little information exists on P-gp inhibition in fish by chemosensitizers, compounds which lower toxicity thresholds for harmful P-gp substrates in complex mixtures. The effects of four known mammalian chemosensitizers (cyclosporin A [CsA], quinidine, valspodar [PSC833], and verapamil) on the P-gp-mediated transport of rhodamine 123 (R123) and cortisol in primary cultures of rainbow trout (Oncorhynchus mykiss) hepatocytes were examined. Competitive accumulation assays using 25 µM R123 or cortisol and varying concentrations of chemosensitizers (0-500 µM) were used. CsA, quinidine, and verapamil inhibited R123 export (IC50 values ± SE: 132 ± 60, 83.3 ± 27.2, and 43.2 ± 13.6 µM, respectively). CsA and valspodar inhibited cortisol export (IC50 values: 294 ± 106 and 92.2 ± 34.9 µM, respectively). In an ATP depletion assay, hepatocytes incubated with all four chemosensitizers resulted in lower free ATP concentrations, suggesting that they act via competitive inhibition. Chemosensitizers that inhibit MXR transporters are an important class of environmental pollutant, and these results show that rainbow trout transporters are inhibited by similar chemosensitizers (and mostly at similar concentrations) as seen in mammals and other fish species.

[P-glycoprotein activity in vivo in older adults: physiological, -pathophysiological and pharmacokinetic interplay at the blood-brain barrier]. / Activité de la p-glycoprotéine in vivo chez la personne âgée : intrications physiologique, physiopathologique et pharmacocinétique au niveau de la barrière hémato-encéphalique.

p-glycoprotein (P-gp) is an efflux transporter of xenobiotic and endogenous compounds across the blood-brain barrier (BBB). P-gp plays an essential role by limiting passage of these compounds into the brain tissue. It is susceptible to drug-drug interactions when interactors drugs are co-administrated. The efficiency of P-gp may be affected by the aging process and the development of neurodegenerative diseases. Studying this protein in older adults is therefore highly relevant for all these reasons. Understanding P-gp activity in vivo is essential when considering the physiological, pathophysiological, and pharmacokinetic perspectives, as these aspects seem to be interconnected to some extent. In vivo exploration in humans is based on neuroimaging techniques, which have been improving over the last years. The advancement of exploration and diagnostic tools is opening up new prospects for understanding P-gp activity at the BBB.

Investigating how HIV-1 antiretrovirals differentially behave as substrates and inhibitors of P-glycoprotein via molecular dynamics simulations.

HIV-1 can rapidly infect the brain upon initial infection, establishing latent reservoirs that induce neuronal damage and/or death, resulting in HIV-Associated Neurocognitive Disorder. Though anti-HIV-1 antiretrovirals (ARVs) suppress viral load, the blood-brain barrier limits drug access to the brain, largely because of highly expressed efflux proteins like P-glycoprotein (P-gp). While no FDA-approved P-gp inhibitor currently exists, HIV-1 protease inhibitors show promise as partial P-gp inhibitors, potentially enhancing drug delivery to the brain. Herein, we employed docking and molecular dynamics simulations to elucidate key differences in P-gp's interactions with several antiretrovirals, including protease inhibitors, with known inhibitory or substrate-like behaviors towards P-gp. Our results led us to hypothesize new mechanistic details of small-molecule efflux by and inhibition of P-gp, where the "Lower Pocket" in P-gp's transmembrane domain serves as the primary initial site for small-molecule binding. Subsequently, this pocket merges with the more traditionally studied drug binding site-the "Upper Pocket"-thus funneling small-molecule drugs, such as ARVs, towards the Upper Pocket for efflux. Furthermore, our results reinforce the understanding that both binding energetics and changes in protein dynamics are crucial in discerning small molecules as non-substrates, substrates, or inhibitors of P-gp. Our findings indicate that interactions between P-gp and inhibitory ARVs induce bridging of transmembrane domain helices, impeding P-gp conformational changes and contributing to the inhibitory behavior of these ARVs. Overall, insights gained in this study could serve to guide the design of future P-gp-targeting therapeutics for a wide range of pathological conditions and diseases, including HIV-1.

Effect of carvedilol on pharmacokinetics of sofosbuvir and its metabolite GS-331007: role of P-glycoprotein.

Sofosbuvir (SOF) is a P-glycoprotein (P-gp) substrate, and carvedilol (CAR) is an inhibitor of P-gp, suggesting that it may affect the oral pharmacokinetics and safety of SOF. The current study investigated the pharmacokinetic interaction of CAR with SOF and its metabolite, GS-331007, and the possible consequent toxicities in rats. To assess the pharmacokinetics of SOF and GS-331007, rats were divided into three groups; all received a single oral dose of SOF preceded with saline (SAL), verapamil (VER) as a standard P-gp inhibitor, or CAR, respectively. The serosal, plasma, and hepatic tissue contents of SOF and GS-331007 were assessed using LC-MS/MS. Renal and hepatic toxicities were assessed using biochemical and histopathological tests. Serosal and plasma concentrations of SOF and GS-331007 were increased in the presence of CAR, suggesting a significant inhibitory effect of CAR on intestinal P-gp. Simultaneously, the pharmacokinetic profile of SOF showed a significant increase in the Cmax, AUC(0-t), AUC (0-∞), t1/2, and a reduction in its apparent oral clearance. While the pharmacokinetic profile of GS-331007 was not significantly affected. However, this notable elevation in drug oral bioavailability was corroborated by a significant alteration in renal functions. Hence, further clinical investigations are recommended to ensure the safety and dosing of CAR/SOF combination.

[P-glycoprotein activity in vivo in older adults: physiological, pathophysiological and pharmacokinetic interplay at the blood-brain barrier]. / Activité de la p-glycoprotéine in vivo chez la personne âgée : intrications physiologique, physiopathologique et pharmacocinétique au niveau de la barrière hémato-encéphalique.

p-glycoprotein (P-gp) is an efflux transporter of xenobiotic and endogenous compounds across the blood-brain barrier (BBB). P-gp plays an essential role by limiting passage of these compounds into the brain tissue. It is susceptible to drug-drug interactions when interactors drugs are co-administrated. The efficiency of P-gp may be affected by the aging process and the development of neurodegenerative diseases. Studying this protein in older adults is therefore highly relevant for all these reasons. Understanding P-gp activity in vivo is essential when considering the physiological, pathophysiological, and pharmacokinetic perspectives, as these aspects seem to be interconnected to some extent. In vivo exploration in humans is based on neuroimaging techniques, which have been improving over the last years. The advancement of exploration and diagnostic tools is opening up new prospects for understanding P-gp activity at the BBB.

Comparison of P-glycoprotein gene expression of two Haemonchus contortus isolates from Yucatan, Mexico, with resistant or susceptible phenotype to ivermectin in relation to a susceptible reference strain.

The variability in the expression of different P-glycoprotein (P-gp) genes in parasitic nematodes of ruminants such as Haemonchus contortus (Hco-pgp) may be caused by different factors including nematode biology, geographical region and anthelmintic pressure. This study analysed the relative expression level of 10 P-gp genes in two H. contortus (Hco-pgp) field isolates from Yucatan, Mexico: 1) PARAISO (IVM-resistant) and 2) FMVZ-UADY (IVM-susceptible). These isolates were compared with a susceptible reference isolate from Puebla, Mexico, namely "CENID-SAI". In all cases H. contortus adult males were used. The Hco-pgp genes (1, 2, 3, 4, 9, 10, 11, 12, 14 and 16) were analysed for each isolate using the RT-qPCR technique. The Hco-pgp expressions were pairwise compared using the 2-ΔΔCt method and a t-test. The PARAISO isolate showed upregulation compared to the CENID-SAI isolate for Hco-pgp 1, 3, 9, 10 and 16 (P < 0.05), and the PARAISO isolate showed upregulation vs. FMVZ-UADY isolate for Hco-pgp 2 and 9 (P < 0.05), displaying 6.58- and 5.93-fold differences (P < 0.05), respectively. In contrast, similar Hco-pgp gene expression levels were recorded for FMVZ-UADY and CENID-SAI isolates except for Hco-pgp1 (P <0.1), which presented a significant upregulation (6.08-fold). The relative expression of Hco-pgp allowed confirming the IVM-resistant status of the PARAISO isolate and the IVM-susceptible status of the FMVZ-UADY isolate when compared to the CENID-SAI reference isolate. Therefore, understanding the association between the Hco-pgp genes expression of H. contortus and its IVM resistance status could help identifying the genes that could be used as molecular markers in the diagnosis of IVM resistance. However, it is important to consider the geographic origin of the nematode isolate and the deworming history at the farm of origin.