Pharmacokinetics of Erythromycin in Rabbit Corneas after Single-Dose Infusion: Role of P-Glycoprotein as a Barrier to in Vivo Ocular Drug Absorption

2004 ◽  
Vol 311 (1) ◽  
pp. 246-255 ◽  
Author(s):  
Surajit Dey ◽  
Sriram Gunda ◽  
Ashim K. Mitra
Keyword(s):  
Single Dose ◽  
Drug Absorption ◽  
P Glycoprotein ◽  
Dose Infusion

Pharmacogenetics of Clozapine: In Vivo Role of Cytochrome P450 Isoforms and P-Glycoprotein

2008 ◽  
Vol 41 (05) ◽  
Author(s):  
E Jaquenoud-Sirot ◽  
B Knezevic ◽  
G Perla Morena ◽  
P Baumann ◽  
CB Eap
Keyword(s):  
Cytochrome P450 ◽  
P Glycoprotein ◽  
Cytochrome P450 Isoforms

scholarly journals In vivo FRET analyses reveal a role of ATP hydrolysis–associated conformational changes in human P-glycoprotein

2020 ◽  
Vol 295 (15) ◽  
pp. 5002-5011 ◽  
Author(s):  
Ryota Futamata ◽  
Fumihiko Ogasawara ◽  
Takafumi Ichikawa ◽  
Atsushi Kodan ◽  
Yasuhisa Kimura ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Drug Transport ◽  
Atp Hydrolysis ◽  
Hek293 Cells ◽  
Atp Binding ◽  
Binding Domains ◽  
P Glycoprotein ◽  
Atp Binding And Hydrolysis

P-glycoprotein (P-gp; also known as MDR1 or ABCB1) is an ATP-driven multidrug transporter that extrudes various hydrophobic toxic compounds to the extracellular space. P-gp consists of two transmembrane domains (TMDs) that form the substrate translocation pathway and two nucleotide-binding domains (NBDs) that bind and hydrolyze ATP. At least two P-gp states are required for transport. In the inward-facing (pre-drug transport) conformation, the two NBDs are separated, and the two TMDs are open to the intracellular side; in the outward-facing (post-drug transport) conformation, the NBDs are dimerized, and the TMDs are slightly open to the extracellular side. ATP binding and hydrolysis cause conformational changes between the inward-facing and the outward-facing conformations, and these changes help translocate substrates across the membrane. However, how ATP hydrolysis is coupled to these conformational changes remains unclear. In this study, we used a new FRET sensor that detects conformational changes in P-gp to investigate the role of ATP binding and hydrolysis during the conformational changes of human P-gp in living HEK293 cells. We show that ATP binding causes the conformational change to the outward-facing state and that ATP hydrolysis and subsequent release of γ-phosphate from both NBDs allow the outward-facing state to return to the original inward-facing state. The findings of our study underscore the utility of using FRET analysis in living cells to elucidate the function of membrane proteins such as multidrug transporters.

Potential Role of Dual NF-κB and Oxidative Stress Pathway Inhibitor, OT-304 as a Novel Drug Resistance-Reversing Agent.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4211-4211
Author(s):  
Shaker A. Mousa ◽  
Ghanshyam Patil ◽  
Abdelhadi Rebbaa
Keyword(s):  
Oxidative Stress ◽  
Drug Resistance ◽  
Tumor Cells ◽  
Genetic Alterations ◽  
Potential Candidate ◽  
Drug Resistant ◽  
P Glycoprotein ◽  
And Oxidative Stress

Abstract The development of resistance to chemotherapy represents an adaptive biological response by tumor cells that leads to treatment failure and patient relapse. During the course of their evolution (intrinsic resistance) or in response to chemotherapy (acquired resistance), tumor cells may undergo genetic alterations to possess a drug resistant phenotype. Dysregulation of membrane transport proteins and cellular enzymes, as well as altered susceptibility to commit to apoptosis are among the mechanisms that contribute to the genesis of acquired drug resistance. Recently, the development of approaches to prevent and/or to reverse this phenomenon has attracted special interest and a number of drug candidates have been identified. Despite strong effects observed for these candidates in vitro, however, most of them fail in vivo. In the present study, we have identified a novel small molecule inhibitor of dual NF-κB and oxidative stress pathways, OT-304, as a potential candidate to reverse drug resistance. Initial investigations indicate that this compound effectively inhibits proliferation of doxorubicin-sensitive and doxorubicin-resistant cells to the same extent, suggesting that it is capable of bypassing the development of drug resistance. Additional experiments reveal that OT-304 enhances cancer cell sensitivity to doxorubicin and to etoposide, particularly in cells characterized by the over-expression of the drug transporter P-glycoprotein. These findings suggest that either the expression/and or the function of P-glycoprotein could be affected by OT-304. In vivo studies using tumor xenografts in nude mice showed that OT-304 is also capable of preventing the growth of drug resistant cancer cells. This later finding further confirms the role of OT-304 as a drug resistance-reversing agent and warrants further pre-clinical and clinical investigation to determine its efficacy in treating aggressive tumors.

scholarly journals A novel in vivo regulatory role of P-glycoprotein in alloimmunity

2010 ◽  
Vol 394 (3) ◽  
pp. 646-652 ◽  
Author(s):  
Atsushi Izawa ◽  
Tobias Schatton ◽  
Natasha Y. Frank ◽  
Takuya Ueno ◽  
Kazuhiro Yamaura ◽  
...  
Keyword(s):  
Regulatory Role ◽  
P Glycoprotein

scholarly journals Cellular Accumulation and Pharmacodynamic Evaluation of the Intracellular Activity of CEM-101, a Novel Fluoroketolide, against Staphylococcus aureus, Listeria monocytogenes, and Legionella pneumophila in Human THP-1 Macrophages

2009 ◽  
Vol 53 (9) ◽  
pp. 3734-3743 ◽  
Author(s):  
Sandrine Lemaire ◽  
Françoise Van Bambeke ◽  
Paul M. Tulkens
Keyword(s):  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Legionella Pneumophila ◽  
Critical Role ◽  
Intracellular Accumulation ◽  
Cellular Accumulation ◽  
Intracellular Activity ◽  
P Glycoprotein

ABSTRACT CEM-101 is a novel fluoroketolide with lower MICs than those of telithromycin and macrolides. Our aim was to assess the cellular accumulation and intracellular activity of CEM-101 using models developed for analyzing the pharmacokinetics and pharmacological properties of antibiotics against phagocytized bacteria. We used THP-1 macrophages and Staphylococcus aureus (ATCC 25923 [methicillin (meticillin) sensitive]), Listeria monocytogenes (strain EGD), and Legionella pneumophila (ATCC 33153). CEM-101 reached cellular-to-extracellular-concentration ratios of about 350 within 24 h (versus approximately 20, 30, and 160 for telithromycin, clarithromycin, and azithromycin, respectively). This intracellular accumulation was suppressed by incubation at a pH of ≤6 and by monensin (proton ionophore) and was unaffected by verapamil (P-glycoprotein inhibitor; twofold accumulation increase for azithromycin) or gemfibrozil. While keeping with the general properties of the macrolide antibiotics in terms of maximal efficacy (E max; approximately 1-log10-CFU decrease compared to the postphagocytosis inoculum after a 24-h incubation), CEM-101 showed significantly greater potency against phagocytized S. aureus than telithromycin, clarithromycin, and azithromycin (for which the 50% effective concentration [EC50] and static concentrations were about 3-, 6-, and 15-fold lower, respectively). CEM-101 was also about 50-fold and 100-fold more potent than azithromycin against phagocytized L. monocytogenes and L. pneumophila, respectively. These differences in EC50s and static concentrations between drugs were minimized when data were expressed as multiples of the MIC, demonstrating the critical role of intrinsic drug activity (MIC) in eliciting the antibacterial intracellular effects, whereas accumulation per se was unimportant. CEM-101 should show enhanced in vivo potency if used at doses similar to those of the comparators tested here.

Assessment of Pharmacokinetic Drug–Drug Interactions in Humans: In Vivo Probe Substrates for Drug Metabolism and Drug Transport Revisited

2019 ◽  
Vol 59 (1) ◽  
pp. 507-536 ◽  
Author(s):  
Uwe Fuhr ◽  
Chih-hsuan Hsin ◽  
Xia Li ◽  
Wafaâ Jabrane ◽  
Fritz Sörgel
Keyword(s):  
Drug Transport ◽  
Quantitative Prediction ◽  
Pharmacokinetic Parameters ◽  
Glycoprotein P ◽  
Therapeutic Drugs ◽  
P Glycoprotein ◽  
Clinical Drug ◽  
Pharmacokinetic Drug

Pharmacokinetic parameters of selective probe substrates are used to quantify the activity of an individual pharmacokinetic process (PKP) and the effect of perpetrator drugs thereon in clinical drug–drug interaction (DDI) studies. For instance, oral caffeine is used to quantify hepatic CYP1A2 activity, and oral dagibatran etexilate for intestinal P-glycoprotein (P-gp) activity. However, no probe substrate depends exclusively on the PKP it is meant to quantify. Lack of selectivity for a given enzyme/transporter and expression of the respective enzyme/transporter at several sites in the human body are the main challenges. Thus, a detailed understanding of the role of individual PKPs for the pharmacokinetics of any probe substrate is essential to allocate the effect of a perpetrator drug to a specific PKP; this is a prerequisite for reliably informed pharmacokinetic models that will allow for the quantitative prediction of perpetrator effects on therapeutic drugs, also in respective patient populations not included in DDI studies.

scholarly journals Anti-Trypanosoma cruzieffects of cyclosporin A derivatives: possible role of a P-glycoprotein and parasite cyclophilins

Parasitology ◽  
2007 ◽  
Vol 135 (2) ◽  
pp. 217-228 ◽  
Author(s):  
J. BÚA ◽  
L. E. FICHERA ◽  
A. G. FUCHS ◽  
M. POTENZA ◽  
M. DUBIN ◽  
...  
Keyword(s):  
Cyclosporin A ◽  
Mammalian Cells ◽  
Isomerase Activity ◽  
P Glycoprotein ◽  
Demethylase Activity ◽  
Target Molecules ◽  
Intracellular Amastigote

SUMMARYCyclophilins are target molecules for cyclosporin A (CsA), an immunosuppressive antimicrobial drug. We have previously reported thein vitroanti-Trypanosoma cruziactivity of H-7-94 and F-7-62 non-immunosuppressive CsA analogues. In this work, we continue the study of the parasiticidal effect of H-7-94 and F-7-62 CsA analoguesin vitroandin vivoand we analyse 3 new CsA derivatives: MeIle-4-CsA (NIM 811), MeVal-4-CsA (MeVal-4) and D-MeAla-3-EtVal-4-CsA, (EtVal-4). The most efficient anti-T. cruzieffect was observed with H-7-94, F-7-62 and MeVal-4 CsA analogues evidenced as inhibition of epimastigote proliferation, trypomastigote penetration, intracellular amastigote development andin vivo T. cruziinfection. This trypanocidal activity could be due to inhibition of the peptidyl prolylcis-transisomerase activity on theT. cruzirecombinant cyclophilins tested. Furthermore, CsA and F-7-62 derivative inhibited the efflux of rhodamine 123 fromT. cruziepimastigotes, suggesting an interference with a P-glycoprotein activity. Moreover, H-7-94 and F-7-62 CsA analogues were not toxic as shown by cell viability and by aminopyrine-N-demethylase activity on mammalian cells. Our results show that H-7-94, F-7-62 and MeVal-4 CsA analogues expressed the highest inhibiting effects onT. cruzi, being promissory parasiticidal drugs worthy of further studies.

scholarly journals The Influence of Fed State Lipolysis Inhibition on the Intraluminal Behaviour and Absorption of Fenofibrate from a Lipid-Based Formulation

Pharmaceutics ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 119
Author(s):  
Marlies Braeckmans ◽  
Joachim Brouwers ◽  
Danny Riethorst ◽  
Cécile Servais ◽  
Jan Tack ◽  
...  
Keyword(s):  
Drug Absorption ◽  
Lipid Phase ◽  
Proximal Jejunum ◽  
Fenofibric Acid ◽  
Lipophilic Drugs ◽  
Fed State ◽  
Different Levels ◽  
Lipid Based Formulation

The bioavailability of lipophilic drugs may or may not be increased when administered with food due to increased solubilisation in fed state gastrointestinal (GI) fluids. The in vivo interplay between drug solubilisation, lipid phase digestion and drug absorption is complex and remains poorly understood. This study aimed to investigate the role of fed state GI lipolysis on the intraluminal behaviour and absorption of fenofibrate, formulated as the lipid-based formulation Fenogal. Therefore, a crossover study was performed in healthy volunteers using orlistat as lipase inhibitor. Fenofibrate concentrations were determined in the proximal jejunum and linked to simultaneously assessed systemic fenofibric acid concentrations. Inhibition of lipolysis by orlistat resulted in a faster onset of absorption in 4 out of 6 volunteers, reflected by a decrease in systemic Tmax between 20 and 140 min. In addition, the increase of undigested lipids present in the small intestine upon orlistat co-administration sustained drug solubilisation for a longer period, resulting in higher fenofibrate concentrations in the jejunum and improved absorption in 5 out of 6 volunteers (median AUC0–8h 8377 vs. 5832 μM.min). Sustaining drug solubilisation in the lipid phase may thus contribute to the absorption of lipophilic drugs. More research into the different mechanisms underlying lipophilic drug absorption from fed state media at different levels of digestion is warranted.

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