St. John's wort extract with a high hyperforin content does not induce P-glycoprotein activity at the human blood-brain barrier.

St. John's wort (SJW) extract, a herbal medicine with antidepressant effects, is a potent inducer of intestinal and/or hepatic cytochrome P450 (CYP) enzymes and P-glycoprotein (P-gp), which can cause clinically relevant drug interactions. It is currently not known whether SJW can also induce P-gp activity at the human blood-brain barrier (BBB), which may potentially lead to decreased brain exposure and efficacy of certain central nervous system (CNS)-targeted P-gp substrate drugs. In this study, we used a combination of positron emission tomography (PET) imaging and cocktail phenotyping to gain a comprehensive picture on the effect of SJW on central and peripheral P-gp and CYP activities. Before and after treatment of healthy volunteers (n = 10) with SJW extract with a high hyperforin content (3-6%) for 12-19 days (1800 mg/day), the activity of P-gp at the BBB was assessed by means of PET imaging with the P-gp substrate [11C]metoclopramide and the activity of peripheral P-gp and CYPs was assessed by administering a low-dose phenotyping cocktail (caffeine, omeprazole, dextromethorphan, and midazolam or fexofenadine). SJW significantly increased peripheral P-gp, CYP3A, and CYP2C19 activity. Conversely, no significant changes in the peripheral metabolism, brain distribution, and P-gp-mediated efflux of [11C]metoclopramide across the BBB were observed following the treatment with SJW extract. Our data suggest that SJW does not lead to significant P-gp induction at the human BBB despite its ability to induce peripheral P-gp and CYPs. Simultaneous intake of SJW with CNS-targeted P-gp substrate drugs is not expected to lead to P-gp-mediated drug interactions at the BBB.

Chiral Transplacental Pharmacokinetics of Fexofenadine: Impact of P-Glycoprotein Inhibitor Fluoxetine Using the Human Placental Perfusion Model.

PURPOSE: Fexofenadine is a well-identified in vivo probe substrate of P-glycoprotein (P-gp) and/or organic anion transporting polypeptide (OATP). This work aimed to investigate the transplacental pharmacokinetics of fexofenadine enantiomers with and without the selective P-gp inhibitor fluoxetine. METHODS: The chiral transplacental pharmacokinetics of fexofenadine-fluoxetine interaction was determined using the ex vivo human placenta perfusion model (n = 4). In the Control period, racemic fexofenadine (75 ng of each enantiomer/ml) was added in the maternal circuit. In the Interaction period, racemic fluoxetine (50 ng of each enantiomer/mL) and racemic fexofenadine (75 ng of each enantiomer/mL) were added to the maternal circulation. In both periods, maternal and fetal perfusate samples were taken over 90 min. RESULTS: The (S)-(-)- and (R)-(+)-fexofenadine fetal-to-maternal ratio values in Control and Interaction periods were similar (~0.18). The placental transfer rates were similar between (S)-(-)- and (R)-(+)-fexofenadine in both Control (0.0024 vs 0.0019 min-1) and Interaction (0.0019 vs 0.0021 min-1) periods. In both Control and Interaction periods, the enantiomeric fexofenadine ratios [R-(+)/S-(-)] were approximately 1. CONCLUSIONS: Our study showed a low extent, slow rate of non-enantioselective placental transfer of fexofenadine enantiomers, indicating a limited fetal fexofenadine exposure mediated by placental P-gp and/or OATP2B1. The fluoxetine interaction did not affect the non-enantioselective transplacental transfer of fexofenadine. The ex vivo placental perfusion model accurately predicts in vivo placental transfer of fexofenadine enantiomers with remarkably similar values (~0.17), and thus estimates the limited fetal exposure.

Inhibitory effect of terfenadine on Kir2.1 and Kir2.3 channels.

Terfenadine is a second-generation H1-antihistamine that despite potentially can produce severe side effects it has recently gained attention due to its anticancer properties. Lately, the subfamily 2 of inward rectifier potassium channels (Kir2) has been implicated in the progression of some tumoral processes. Hence, we characterized the effects of terfenadine on Kir2.x channels expressed in HEK-293 cells. Terfenadine inhibited Kir2.3 channels with a strikingly greater potency (IC50 = 1.06 ± 0.11 µmol L-1) compared to Kir2.1 channels (IC50 = 27.8 ± 4.8 µmol L-1). The Kir2.3(I213L) mutant, possessing a larger affinity for phosphatidylinositol 4,5-bisphosphate (PIP2) than the wild-type Kir2.3, was less sensitive to terfenadine inhibition (IC50 = 13.0 ± 2.9 µmol L-1). Additionally, the PIP2 intracellular application had largely reduced the inhibition of Kir2.1 channels by terfenadine. Our data support that Kir2.x channels are targets of terfena-dine by affecting their interaction with PIP2, which could be regarded as a mechanism of the antitumor properties of terfenadine.

Urticaria and angioedema as a prodromal cutaneous manifestation of SARS-CoV-2 (COVID-19) infection.

This is a case of a patient who presented with an urticarial rash 48 hours before developing symptoms of fever and a continuous cough. She subsequently developed angioedema of her lips and hands before testing positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Urticarial rashes occurring 48 hours before other symptoms of COVID-19 infection have been documented. This case demonstrates the importance of heightened awareness that not all urticarial rashes represent spontaneous urticaria and as a consequence, this may result in misdiagnosis and ultimately delayed diagnosis. This is the first reported case in the literature of urticaria with angioedema as a prodromal phenomenon of COVID-19.

Chiral Discrimination of P-glycoprotein in Parturient Women: Effect of Fluoxetine on Maternal-Fetal Fexofenadine Pharmacokinetics.

BACKGROUND AND OBJECTIVE: Fluoxetine, antidepressant widely-used during pregnancy, is a selective inhibitor for P-glycoprotein (P-gp). Fexofenadine, an in vivo P-gp probe, is an antihistamine drug for seasonal allergic rhinitis and chronic urticaria treatment during pregnancy and it is available as a racemic mixture. This study evaluated the chiral discrimination of P-gp investigating the effect of fluoxetine on maternal-fetal pharmacokinetics of fexofenadine. METHODS: Healthy parturient women received either a single oral dose of 60 mg racemic fexofenadine (Control group; n = 8) or a single oral dose of 40 mg racemic fluoxetine 3 h before a single oral dose of 60 mg racemic fexofenadine (Interaction group; n = 8). Maternal blood and urine samples were collected up to 48 h after fexofenadine administration. At delivery, maternal-placental-fetal blood samples were collected. RESULTS: The maternal pharmacokinetics of fexofenadine was enantioselective (AUC0-∞R-(+)/S-(-) ~ 1.5) in both control and interaction groups. Fluoxetine increased AUC0-∞ (267.7 vs 376.1 ng.h/mL) and decreased oral total clearance (105.1 vs 74.4 L/h) only of S-(-)-fexofenadine, whereas the renal clearance were reduced for both enantiomers, suggesting that the intestinal P-gp-mediated transport of S-(-)-fexofenadine is influenced by fluoxetine to a greater extent that the R-(+)-fexofenadine. However, the transplacental transfer of fexofenadine is low (~16%), non-enantioselective and non-influenced by fluoxetine. CONCLUSIONS: A single oral dose of 40 mg fluoxetine inhibited the intestinal P-gp mediated transport of S-(-)-fexofenadine to a greater extent than R-(+)-fexofenadine in parturient women. However, the placental P-gp did not discriminate fexofenadine enantiomers and was not inhibited by fluoxetine.

The macrolide drug erythromycin does not protect the hERG channel from inhibition by thioridazine and terfenadine.

The macrolide antibiotic erythromycin has been associated with QT interval prolongation and inhibition of the hERG-encoded channels responsible for the rapid delayed rectifier K+ current I(Kr ). It has been suggested that low concentrations of erythromycin may have a protective effect against hERG block and associated drug-induced arrhythmia by reducing the affinity of the pore-binding site for high potency hERG inhibitors. This study aimed to explore further the notion of a potentially protective effect of erythromycin. Whole-cell patch-clamp experiments were performed in which hERG-expressing mammalian (Human Embryonic Kidney; HEK) cells were preincubated with low to moderate concentrations of erythromycin (3 or 30 µM) prior to whole-cell patch clamp recordings of hERG current (IhERG ) at 37°C. In contrast to a previous report, exposure to low concentrations of erythromycin did not reduce pharmacological sensitivity of hERG to the antipsychotic thioridazine and antihistamine terfenadine. The IC50 value for IhERG tail inhibition by terfenadine was decreased by ~32-fold in the presence of 3 µM erythromycin (p < .05 vs. no preincubation). Sensitivity to thioridazine remained unchanged (p > .05 vs. no preincubation). The effects of low concentrations of erythromycin were investigated for a series of pore blocking drugs, and the results obtained were consistent with additive and/or synergistic effects. Experiments with the externally acting blocker BeKm-1 on WT hERG and a pore mutant (F656V) were used to explore the location of the binding site for erythromycin. Our data are inconsistent with the use of erythromycin for the management of drug-induced QT prolongation.

Utilization of the chronic atrioventricular block cynomolgus monkey as an in vivo model to evaluate drug interaction-associated torsade de pointes.

It has been difficult to experimentally reproduce synergistic effects of ketoconazole on terfenadine-induced torsade de pointes. We assessed proarrhythmic effects of terfenadine (30 mg/kg, p.o.) with/without ketoconazole (100 mg/kg, p.o.) pretreatment using the chronic atrioventricular block cynomolgus monkeys with repeated-measured design (n = 4). Terfenadine with ketoconazole pretreatment repeatedly induced non-sustained torsade de pointes in each animal, although terfenadine alone did not induce it at all. Thus, the chronic atrioventricular block cynomolgus monkeys can be used for studying drug interaction-associated torsade de pointes, providing a non-clinical strategy to circumvent untoward drug interactions in patients specially under polypharmacy.

Fexofenadine and Rosuvastatin Pharmacokinetics in Mice with Targeted Disruption of Organic Anion Transporting Polypeptide 2B1.

Organic anion transporting polypeptide 2B1 (OATP2B1) is a widely expressed membrane transporter with diverse substrate specificity. In vitro and clinical studies suggest a role for intestinal OATP2B1 in the oral absorption of medications. Moreover, OATP2B1 is highly expressed in hepatocytes where it is thought to promote liver drug clearance. However, until now, a shortcoming of studies implicating OATP2B1 in drug disposition has been a lack of in vivo models. Here, we report the development of a knockout (KO) mouse model with targeted, global disruption of the Slco2b1 gene to examine the disposition of two confirmed mOATP2B1 substrates, namely, fexofenadine and rosuvastatin. The plasma pharmacokinetics of intravenously administered fexofenadine was not different between KO and wild-type (WT) mice. However, after oral fexofenadine administration, KO mice had 70% and 41% lower maximal plasma concentration (C max) and area under the plasma concentration-time curve (AUC0-last) than WT mice, respectively. In WT mice, coadministration of fexofenadine with grapefruit juice (GFJ) or apple juice (AJ) was associated with reduced C max by 80% and 88%, respectively, while the AUC0-last values were lower by 35% and 70%, respectively. In KO mice, AJ coadministration reduced oral fexofenadine C max and AUC0-last values by 67% and 59%, respectively, while GFJ had no effects. Intravenous and oral rosuvastatin pharmacokinetics were similar among WT and KO mice. We conclude that intestinal OATP2B1 is a determinant of oral fexofenadine absorption, as well as a target for fruit juice interactions. OATP2B1 does not significantly influence rosuvastatin disposition in mice. SIGNIFICANCE STATEMENT: A novel mouse model with targeted disruption of the Slco2b1 gene revealed that OATP2B1 is a determinant of oral absorption but not systemic disposition of fexofenadine, as well as a target of fruit juice interactions. Rosuvastatin oral and intravenous pharmacokinetics were not dependent on OATP2B1. These findings support the utility of the Slco2b1 KO mouse model for defining mechanisms of drug disposition at the intersection of in vitro and clinical pharmacology.

Oral H1 antihistamines as 'add-on' therapy to topical treatment for eczema.

BACKGROUND: The symptoms of eczema can lead to sleeplessness and fatigue and may have a substantial impact on quality of life. Use of oral H1 antihistamines (H1 AH) as adjuvant therapy alongside topical agents is based on the idea that combining the anti-inflammatory effects of topical treatments with the blocking action of histamine on its receptors in the skin by H1 AH (to reduce the principal symptom of itch) might magnify or intensify the effect of treatment. Also, it would be unethical to compare oral H1 AH alone versus no treatment, as topical treatment is the standard management for this condition. OBJECTIVES: To assess the effects of oral H1 antihistamines as 'add-on' therapy to topical treatment in adults and children with eczema. SEARCH METHODS: We searched the following databases up to May 2018: the Cochrane Skin Group Specialised Register, CENTRAL, MEDLINE, Embase, and the GREAT database (Global Resource of EczemA Trials; from inception). We searched five trials registers and checked the reference lists of included and excluded studies for further references to relevant randomised controlled trials (RCTs). We also searched the abstracts of four conference proceedings held between 2000 and 2018. SELECTION CRITERIA: We sought RCTs assessing oral H1 AH as 'add-on' therapy to topical treatment for people with eczema compared with topical treatment plus placebo or no additional treatment as add-on therapy. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methodological procedures. Primary outcome measures were 'Mean change in patient-assessed symptoms of eczema' and 'Proportion of participants reporting adverse effects and serious adverse events'. Secondary outcomes were 'Mean change in physician-assessed clinical signs', 'Mean change in quality of life', and 'Number of eczema flares'. MAIN RESULTS: We included 25 studies (3285 randomised participants). Seventeen studies included 1344 adults, and eight studies included 1941 children. Most studies failed to report eczema severity at baseline, but they were conducted in secondary care settings, so it is likely that they recruited patients with more severe cases of eczema. Trial duration was between three days and 18 months. Researchers studied 13 different H1 AH treatments. We could not undertake pooling because of the high level of diversity across studies in terms of duration and dose of intervention, concomitant topical therapy, and outcome assessment. Risk of bias was generally unclear, but five studies had high risk of bias in one domain (attrition, selection, or reporting bias). Only one study measured quality of life, but these results were insufficient for statistical analysis.Although this review assessed 17 comparisons, we summarise here the results of three key comparisons in this review.Cetirizine versus placeboOne study compared cetirizine 0.5 mg/kg/d against placebo over 18 months in 795 children. Study authors did not report patient-assessed symptoms of eczema separately for pruritus. Cetirizine is probably associated with fewer adverse events (mainly mild) (risk ratio (RR) 0.68, 95% confidence interval (CI) 0.46 to 1.01) and the need for slightly less additional H1 AH use as an indication of eczema flare rate (P = 0.035; no further numerical data given). Physician-assessed clinical signs (SCORing Atopic Dermatitis index (SCORAD)) were reduced in both groups, but the difference between groups was reported as non-significant (no P value given). Evidence for this comparison was of moderate quality.One study assessed cetirizine 10 mg/d against placebo over four weeks in 84 adults. Results show no evidence of differences between groups in patient-assessed symptoms of eczema (pruritus measured as part of SCORAD; no numerical data given), numbers of adverse events (RR 1.11, 95% CI 0.50 to 2.45; mainly sedation, other skin-related problems, respiratory symptoms, or headache), or physician-assessed changes in clinical signs, amount of local rescue therapy required, or number of applications as an indicator of eczema flares (no numerical data reported). Evidence for this comparison was of low quality.Fexofenadine versus placeboCompared with placebo, fexofenadine 120 mg/d taken in adults over one week (one study) probably leads to a small reduction in patient-assessed symptoms of pruritus on a scale of 0 to 8 (mean difference (MD) -0.25, 95% CI -0.43 to -0.07; n = 400) and a greater reduction in the ratio of physician-assessed pruritus area to whole body surface area (P = 0.007; no further numerical data given); however, these reductions may not be clinically meaningful. Results suggest probably little or no difference in adverse events (mostly somnolence and headache) (RR 1.05, 95% CI 0.74 to 1.50; n = 411) nor in the amount of 0.1% hydrocortisone butyrate used (co-intervention in both groups) as an indicator of eczema flare, but no numerical data were given. Evidence for this comparison was of moderate quality.Loratadine versus placeboA study of 28 adults compared loratadine 10 mg/d taken over 4 weeks versus placebo. Researchers found no evidence of differences between groups in patient-assessed pruritus, measured by a 100-point visual analogue scale (MD -2.30, 95% CI -20.27 to 15.67); reduction in physician-assessed clinical signs (SCORAD) (MD -4.10, 95% CI -13.22 to 5.02); or adverse events. Study authors reported only one side effect (folliculitis with placebo) (RR 0.25, 95% CI 0.01 to 5.76). Evidence for this comparison was of low quality. Number of eczema flares was not measured for this comparison. AUTHORS' CONCLUSIONS: Based on the main comparisons, we did not find consistent evidence that H1 AH treatments are effective as 'add-on' therapy for eczema when compared to placebo; evidence for this comparison was of low and moderate quality. However, fexofenadine probably leads to a small improvement in patient-assessed pruritus, with probably no significant difference in the amount of treatment used to prevent eczema flares. Cetirizine was no better than placebo in terms of physician-assessed clinical signs nor patient-assessed symptoms, and we found no evidence that loratadine was more beneficial than placebo, although all interventions seem safe.The quality of evidence was limited because of poor study design and imprecise results. Future researchers should clearly define the condition (course and severity) and clearly report their methods, especially participant selection and randomisation; baseline characteristics; and outcomes (based on the Harmonising Outcome Measures in Eczema initiative).

LC-MS/MS analysis of the plasma concentrations of a cocktail of 5 cytochrome P450 and P-glycoprotein probe substrates and their metabolites using subtherapeutic doses.

Drug transporters and CYP enzymes are important sources of pharmacokinetics (PK) variability in drug responses and can cause various pharmacological and toxicological consequences, leading to either toxicity or an insufficient pharmacological effect. In recent years, the cocktail approach was developed to determine in vivo CYP and transporters activities, but these approaches are somewhat limited. We described the development and validation of three sensitive and specific LC-MS/MS assays for the determination of P-gp and major human CYP isoenzyme activities following oral administration of a drug cocktail of subtherapeutic doses (lower than 10 times) of caffeine (CAF), omeprazole (OME), losartan (LOS), midazolam (MDZ), metoprolol (METO) and fexofenadine (FEX) in healthy volunteers. The three validated methods were selective for all tested analytes. No interference or matrix effect was observed for the mass transition and retention times for all compounds monitored. Additionally, assays were linear over a wide range, and limits of quantification varied between 0.01-5 ng/mL plasma. The coefficients of variation obtained in the precision studies and the inter- and intra-assay accuracies were less than 15%, guaranteeing the reproducibility and repeatability of the results. All substrates and metabolites were stable in plasma during freeze-thaw cycles. Three healthy volunteers were selected based on genotyping for CYP2C9, CYP2C19 and CYP2D6. One volunteer was genotyped as an extensive metabolizer (EM) for all tested CYP isoforms, one volunteer was genotyped as a poor metabolizer (PM) for the CYP2C9 isoform (CYP2C9*3/*3), and one volunteer was genotyped as a PM for the CYP2D6 isoform (CYP2D6*4/*4). The methods allowed the quantification of all analytes over the entire sampling period (12 h) in all studied genotypes. Thus, the analytical methods described here were sufficiently sensitive for use in low-dose pharmacokinetic studies.

Quantitative Assessment of the Physiological Parameters Influencing QT Interval Response to Medication: Application of Computational Intelligence Tools.

Human heart electrophysiology is complex biological phenomenon, which is indirectly assessed by the measured ECG signal. ECG trace is further analyzed to derive interpretable surrogates including QT interval, QRS complex, PR interval, and T wave morphology. QT interval and its modification are the most commonly used surrogates of the drug triggered arrhythmia, but it is known that the QT interval itself is determined by other nondrug related parameters, physiological and pathological. In the current study, we used the computational intelligence algorithms to analyze correlations between various simulated physiological parameters and QT interval. Terfenadine given concomitantly with 8 enzymatic inhibitors was used as an example. The equation developed with the use of genetic programming technique leads to general reasoning about the changes in the prolonged QT. For small changes of the QT interval, the drug-related IKr and ICa currents inhibition potentials have major impact. The physiological parameters such as body surface area, potassium, sodium, and calcium ions concentrations are negligible. The influence of the physiological variables increases gradually with the more pronounced changes in QT. As the significant QT prolongation is associated with the drugs triggered arrhythmia risk, analysis of the role of physiological parameters influencing ECG seems to be advisable.

Histamine receptor 1 inhibition enhances antitumor therapeutic responses through extracellular signal-regulated kinase (ERK) activation in breast cancer.

Histamine receptor 1 (HRH1) belongs to the rhodopsin-like G-protein-coupled receptor family. Its activation by histamine triggers cell proliferation, embryonic development, and tumor growth. We recently established that HRH1 is up-regulated in basal and human epidermal growth factor receptor 2 (HER2)-enriched human breast tumors and that its expression correlates with a worse prognosis. Nevertheless, the functional role of HRH1 in basal and HER2-targeted therapy-resistant breast cancer (BC) progression has not yet been addressed. Using terfenadine, a selective chemical inhibitor of HRH1, we showed that the inhibition of HRH1 activity in basal BC cells leads to sub-G0 cell accumulation, suppresses proliferation, promotes cell motility and triggers the activation of extracellular signal-regulated kinase (ERK) signaling, initiating the mitochondrial apoptotic pathway. Furthermore, HER2-targeted therapy-resistant cells express higher levels of HRH1 and are more sensitive to terfenadine treatment. Moreover, in vivo experiments showed that terfenadine therapy reduced the tumor growth of basal and trastuzumab-resistant BC cells. In conclusion, our results suggest that targeting HRH1 is a promising new clinical approach to consider that could enhance the effectiveness of current therapeutic treatment in patients with basal and BC tumors resistant to HER2-targeted therapies.

A sensitive method for the quantitation of the peptide-based glucagon-like peptide-1 receptor agonist liraglutide in plasma using microfluidics chromatography tandem MS.

AIM: An LC-MS/MS assay for the quantitation of liraglutide, a peptide-based injectable glucagon-like peptide-1 receptor agonist, has been developed as a convenient alternative to the enzyme-linked immunosorbent assay, and used to characterize liraglutide pharmacokinetics in cynomolgus monkeys. RESULTS: Assay calibration curves exhibited a linear dynamic range of 10-5000 ng/ml and correlation coefficient ≥0.98. Following a 30 µg/kg intravenous dose, liraglutide demonstrated low plasma clearance and distribution volume, which led to a terminal half-life of 6.59 h in monkeys. CONCLUSION: The dynamic range of our LC-MS/MS assay provides sufficient coverage of the average efficacious liraglutide concentrations in human plasma, and can be used for pharmacokinetics/pharmacodynamics studies in animals and potentially in humans.

Enzalutamide inhibits testosterone-induced growth of human prostate cancer xenografts in zebrafish and can induce bradycardia.

The zebrafish has become a popular human tumour xenograft model, particularly for solid tumours including prostate cancer (PCa). To date PCa xenotransplantation studies in zebrafish have not been performed in the presence of testosterone, even when employing androgen-dependent cell models, such as the LNCaP cell line. Thus, with the goal of more faithfully modelling the hormonal milieu in which PCa develops in humans, we sought to determine the effects of exogenous testosterone on the growth of LNCaP, or androgen-independent C4-2 cells xenografted into zebrafish embryos. Testosterone significantly increased engrafted LNCaP proliferation compared to control xenografts, which could be inhibited by co-administration of the anti-androgen receptor drug, enzalutamide. By contrast, C4-2 cell growth was not affected by either testosterone or enzalutamide. Enzalutamide also induced bradycardia and death in zebrafish embryos in a dose-dependent manner and strongly synergized with the potassium-channel blocking agent, terfenadine, known to induce long QT syndrome and cardiac arrhythmia. Together, these data not only indicate that testosterone administration should be considered in all PCa xenograft studies in zebrafish but also highlights the unique opportunity of this preclinical platform to simultaneously evaluate efficacy and toxicity of novel therapies and/or protective agents towards developing safer and more effective PCa treatments.

Effect of Garlic, Gingko, and St. John's Wort Extracts on the Pharmacokinetics of Fexofenadine: A Mechanistic Study.

The aim of this study was to determine the effects of garlic and ginkgo herbal extracts on the pharmacokinetics of the P-glycoprotein (P-gp)/organic anion-transporting polypeptides (Oatps) substrate fexofenadine. Male rats were dosed orally with garlic (120 mg/kg), ginkgo (17 mg/kg), St. John's wort (SJW; 1000 mg/kg; positive control), or Milli-Q water for 14 days. On day 15, rats either were administered fexofenadine (orally or i.v.), had their livers isolated and perfused with fexofenadine, or had their small intestines divided into four segments (SI-SIV) and analyzed for P-gp and Oatp1a5. In vivo, SJW increased the clearance of i.v. administered fexofenadine by 28%. Garlic increased the area under the curve0-∞ and maximum plasma concentration of orally administered fexofenadine by 47% and 85%, respectively. Ginkgo and SJW had no effect on the oral absorption of fexofenadine. In the perfused liver, garlic, ginkgo, and SJW increased the biliary clearance of fexofenadine with respect to perfusate by 71%, 121%, and 234%, respectively. SJW increased the biliary clearance relative to the liver concentration by 64%. The ratio of liver to perfusate concentrations significantly increased in all treated groups. The expression of Oatp1a5 in SI was increased by garlic (88%) and SJW (63%). There were no significant changes in the expression of P-gp. Induction of intestinal Oatp1a5 by garlic may explain the increased absorption of orally administered fexofenadine. Ginkgo had no effect on the expression of intestinal P-gp or Oatp1a5. A dual inductive effect by SJW on opposing intestinal epithelial transport by Oatp1a5 and P-gp remains a possibility.

Capsaicin pretreatment enhanced the bioavailability of fexofenadine in rats by P-glycoprotein modulation: in vitro, in situ and in vivo evaluation.

BACKGROUND AND OBJECTIVE: Capsaicin is the main pungent principle present in chili peppers has been found to possess P-glycoprotein (P-gp) inhibition activity in vitro, which may have the potential to modulate bioavailability of P-gp substrates. Therefore, purpose of this study was to evaluate the effect of capsaicin on intestinal absorption and bioavailability of fexofenadine, a P-gp substrate in rats. METHODS: The mechanistic evaluation was determined by non-everted sac and intestinal perfusion studies to explore the intestinal absorption of fexofenadine. These results were confirmed by an in vivo pharmacokinetic study of oral administered fexofenadine in rats. RESULTS: The intestinal transport and apparent permeability (Papp) of fexofenadine were increased significantly by 2.8 and 2.6 fold, respectively, in ileum of capsaicin treated rats when compared to control group. Similarly, absorption rate constant (Ka), fraction absorbed (Fab) and effective permeability (Peff) of fexofenadine were increased significantly by 2.8, 2.9 and 3.4 fold, respectively, in ileum of rats pretreated with capsaicin when compared to control group. In addition, maximum plasma concentration (Cmax) and area under the concentration-time curve (AUC) were increased significantly by 2.3 and 2.4 fold, respectively, in rats pretreated with capsaicin as compared to control group. Furthermore, obtained results in rats pretreated with capsaicin were comparable to verapamil (positive control) treated rats. CONCLUSIONS: Capsaicin pretreatment significantly enhanced the intestinal absorption and bioavailability of fexofenadine in rats likely by inhibition of P-gp mediated cellular efflux, suggesting that the combined use of capsaicin with P-gp substrates may require close monitoring for potential drug interactions.

Investigating Drug Repositioning Approach to Design Novel Prodrugs for Colon-specific Release of Fexofenadine for Ulcerative Colitis.

BACKGROUND: Recent immunologic data implicates involvement of mucosal immune cells of the intestine like eosinophils and mast cells to be functionally involved in the pathogenesis of UC. Mast cell activation is followed by increased secretion and elevated tissue concentration of histamine. Inhibition of mucosal histamine release in colon may be an effective therapeutic approach to treat UC. Some studies report that intestinal inflammation associated with acute and chronic colitis has been ameliorated by fexofenadine in mice. OBJECTIVE: In the present work, we investigated the effect of colon- specific prodrugs of antihistaminic fexofenadine on TNBS- induced colitis in Wistar rats, applying the principle of drug repositioning. METHOD: Amino acid- appended amide prodrugs of fexofenadine were designed and characterized spectrally. In vitro kinetics and protective effect of prodrugs were studied on TNBS-induced colitis in Wistar rats. RESULTS: Conjugation with amino acids improved the hydrophilicity of fexofenadine (log P: 0.037 to 0.082) to enable efficient delivery to colon. Prodrugs were chemically and enzymatically stable in aqueous buffers (pH 1.2 and7.4) and stomach homogenates/intestinal homogenates, respectively. Prodrugs were substantially cleaved to release 60-70% of fexofenadine in homogenates of colon in 12 h. Prodrug of fexofenadine with L-glutamine additively and significantly suppressed TNBS-induced colitis showing comparable effects to orally administered 5-aminosalicylic acid. CONCLUSION: The outcome of this preliminary work emphasizes involvement of mast cells that release histamine as one of the important pathological inducers of UC. These promising, dual acting, colontargeting fexofenadine prodrugs could be explored further for repositioning fexofenadine in the treatment of UC and its relapse.

Efficacy and safety of bilastine in Japanese patients with perennial allergic rhinitis: A multicenter, randomized, double-blind, placebo-controlled, parallel-group phase III study.

BACKGROUND: Bilastine, a novel non-sedating second-generation H1 antihistamine, has been approved in most European countries since 2010. This study aimed to evaluate the superiority of bilastine over placebo in Japanese patients with perennial allergic rhinitis (PAR). METHODS: This randomized, double-blind, placebo-controlled, parallel-group, phase III study (trial registration number JapicCTI-142600) evaluated the effect of a 2-week treatment period with bilastine (20 mg once daily), fexofenadine (60 mg twice daily), or a matched placebo (double dummy) in patients with PAR. All patients were instructed to record individual nasal and ocular symptoms in diaries daily. The primary endpoint was the mean change in total nasal symptom scores (TNSS) from baseline to Week 2 (Days 10-13). RESULTS: A total of 765 patients were randomly allocated to receive bilastine, fexofenadine, or placebo (256, 254, and 255 patients, respectively). The mean change in TNSS from baseline at Week 2 was significantly decreased by bilastine (-0.98) compared to placebo (-0.63, P = 0.023). Bilastine and fexofenadine showed no significant difference in the primary endpoint. However, the mean change in TNSS from baseline on Day 1 was more significantly decreased by bilastine (-0.99) than by placebo (-0.28, P < 0.001) or fexofenadine (-0.62, P = 0.032). The active drugs also improved instantaneous TNSS 1 h after the first and before the second drug administration on Day 1 (P < 0.05). The study drugs were well tolerated. CONCLUSIONS: After 2-week treatment period, bilastine 20 mg once daily was effective and tolerable in Japanese patients with PAR, and exhibited a rapid onset of action.