Up-regulation of P-glycoprotein reduces intracellular accumulation of beta amyloid: Investigation of P-glycoprotein as a novel therapeutic target for Alzheimer\u27s disease

Objectives: Several studies have suggested the efflux transporter P-glycoprotein (P-gp) to play a role in the etiology of Alzheimer\u27s disease through the clearance of amyloid beta (Aβ) from the brain. In this study, we aimed to investigate the possibility of P-gp as a potential therapeutic target for Alzheimer\u27s disease by examining the impact of P-gp up-regulation on the clearance of Aβ, a neuropathological hallmark of Alzheimer\u27s disease. Methods: Uptake studies for 125I-radiolabelled Aβ 1-40, and fluorescent immunostaining technique for P-gp and fluorescent imaging of Aβ 1-40 were carried out in LS-180 cells following treatment with drugs known to induce P-gp expression. Key findings: Approximately 10-35% decrease in 125I-Aβ 1-40 intracellular accumulation was observed in cells treated with rifampicin, dexamethasone, caffeine, verapamil, hyperforin, β-estradiol and pentylenetetrazole compared with control. Also, fluorescent micrographs showed an inverse relationship between levels of P-gp expression and 5-carboxyfluorescein labelled Aβ (FAM-Aβ 1-40) intracellular accumulation. Quantitative analysis of the micrographs revealed that the results were consistent with those of the uptake studies using 125I-Aβ 1-40. Conclusions: The investigated drugs were able to improve the efflux of Aβ 1-40 from the cells via P-gp up-regulation compared with control. Our results elucidate the importance of targeting Aβ clearance via P-gp up-regulation, which will be effective in slowing or halting the progression of Alzheimer\u27s disease. © 2011 The Authors JPP © 2011 Royal Pharmaceutical Society

In vivo incorporation of fenfluramine and norfenfluramine into pigmented and nonpigmented hair of rats measured by HPLC-fluorescence detection

The incorporation profiles for fenfluramine (Fen) and its metabolite norfenfluramine (Norf) into black hair and white hair of Zucker rats and into white hair of Wistar rats after intraperitoneal (i.p.) administration of Fen or N-nitrosofenfluramine (N-Fen) were studied in great detail. The target compounds were determined by high-performance liquid chromatography with fluorescence detection using 4-(4,5-diphenyl-1 H-imidazol-2-yl)benzoyl chloride as a derivatization reagent. After repeated i.p. administration of Fen (5 mg/kg) for 4 days to Zucker rats, shaft and root samples of black and white hair were obtained 1 week after the first administration. It was surprising that Fen and Norf levels in root samples of white hair were much higher than those in shaft or root samples of black hair, strongly suggesting that unknown mechanisms other than the action of melanin take place in the white hair root. Time course profiles for Fen and Norf after administration of a single i.p. dose of Fen or N-Fen were constructed for Zucker and Wistar rats. The percent level of Fen or Norf in white hair was 15-50% of that in black hair at any interval within 600 min after a single administration of Fen in Zucker rats. Even with Wistar rats having only white hair, we could demonstrate the time courses for incorporation of Fen and Norf into white hair. Finally, time course profiles for Fen and Norf were also followed after a single i.p. administration of N-Fen; this experiment showed that the levels of Norf were much higher than those of Fen for both black and white hair samples of Zucker rats at any interval tested

Comment on López-Yerena et al. “Absorption and Intestinal Metabolic Profile of Oleocanthal in Rats” Pharmaceutics 2020, 12, 134

This comment is intended to discuss errors observed in the title paper, doi:10.3390/pharmaceutics12020134. When this paper was published, the authors of this commentary were excited to read it. However, the more we read, the more pitfalls were observed, which necessitated a response to revise the many errors and misleading information included in this publication

Development of Physiologically Based Pharmacokinetic/Pharmacodynamic Model for Indomethacin Disposition in Pregnancy.

Findings of a recent clinical study showed indomethacin has lower plasma levels and higher steady-state apparent clearance in pregnant subjects when compared to those in non-pregnant subjects reported in separate studies. Thus, in the current work we developed a pregnancy physiological based pharmacokinetic/pharmacodynamic (PBPK/PD) model for indomethacin to explain the differences in indomethacin pharmacokinetics between pregnancy and non-pregnancy. A whole-body PBPK model with key pregnancy-related physiological changes was developed to characterize indomethacin PK in pregnant women and compare these parameters to those in non-pregnant subjects. Data related to maternal physiological and biological changes were obtained from literature and incorporated into the structural PBPK model that describes non-pregnant PK data. Changes in indomethacin area under the curve (AUC), maximum concentration (Cmax) and average steady-state concentration (Cave) in pregnant women were predicted. Model-simulated PK profiles were in agreement with observed data. The predicted mean ratio (non-pregnant:second trimester (T2)) of indomethacin Cave was 1.6 compared to the observed value of 1.59. In addition, the predicted steady-state apparent clearance (CL/Fss) ratio was almost similar to the observed value (0.46 vs. 0.42). Sensitivity analysis suggested changes in CYP2C9 activity, and to a lesser extent UGT2B7, as the primary factor contributing to differences in indomethacin disposition between pregnancy and non-pregnancy. The developed PBPK model which integrates prior physiological knowledge, in vitro and in vivo data, allowed the successful prediction of indomethacin disposition during T2. Our PBPK/PD model suggested a higher indomethacin dosing requirement during pregnancy

Structure of pregnancy physiologically based pharmacokinetic (p-PBPK) model.

<p>Structure of pregnancy physiologically based pharmacokinetic (p-PBPK) model.</p

Indomethacin observed and predicted PK parameters after oral dosing in non-pregnant and pregnant subjects.

<p>* Reported values in pregnant subjects receiving chronic administration of 25mg of indomethacin four times daily.</p><p>** Reported values in non-pregnant, healthy subjects receiving chronic administration of 25mg of indomethacin three times daily.</p><p>Indomethacin observed and predicted PK parameters after oral dosing in non-pregnant and pregnant subjects.</p

Tissue-to-Plasma Partition Coefficients (K_p) of indomethacin used in non-pregnant and pregnant (2^nd Trimester) subjects PBPK models.

<p>Tissue-to-Plasma Partition Coefficients (K_p) of indomethacin used in non-pregnant and pregnant (2^nd Trimester) subjects PBPK models.</p

Indomethacin PK parameters after oral dosing in non-pregnant subjects.

<p>* Reported values in non-pregnant, healthy subjects [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0139762#pone.0139762.ref022" target="_blank">22</a>].</p><p>**Reported values in non-pregnant subjects [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0139762#pone.0139762.ref002" target="_blank">2</a>].</p><p>Indomethacin PK parameters after oral dosing in non-pregnant subjects.</p

Sensitivity analysis to evaluate mechanism(s) primarily contributes to differences in indomethacin levels in pregnancy.

<p>Contribution of changes in metabolism (CYP2C9 and UGT2B7 activities), plasma protein binding (PB), glomular filtration rate (GFR), and volume of distribution (V_d) to variation in C_ave (Black columns) and CL/F_ss (Grey columns) during pregnancy.</p

Simulated and observed PD effect-time profiles for indomethacin presented as % decrease in PGEM (13, 14-dihydro-15-ketoprostaglandin E2) plasma concentration vs. time after single oral administration of 25mg.

<p>The solid line represents predicted mean indomethacin profile in non-pregnant subjects. The dashed line represents predicted mean indomethacin profile in pregnant subjects. Mean observed data are overlaid for 25 mg dose in non-pregnant subjects [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0139762#pone.0139762.ref039" target="_blank">39</a>]. The green and blue shaded areas represent the 90% confidence interval for the simulated data, and error bars represent ± SD.</p