Comparative in vitro and in vivo inhibition of cytochrome P450 CYP1A2, CYP2D6, and CYP3A by H2-receptor antagonists

Innovative On-DNA Synthesis of Sulfides and Sulfoximines: Enriching the DEL Synthesis Toolbox

DNA-encoded library (DEL) technologies enable the fast exploration of gigantic chemical space to identify ligands for the target protein of interest and have become a powerful hit finding tool for drug discovery projects. However, amenable DEL chemistry is restricted to a handful of reactions, limiting the creativity of drug hunters. Here, we describe a new on-DNA synthetic pathway to access sulfides and sulfoximines. These moieties, usually contemplated as challenging to achieve through alkylation and oxidation, can now be leveraged in routine DEL selection campaigns.

H2 antihistamines: May be useful for combination therapies in cancer?

Cancer morbimortality is still a great concern despite advances in research and therapies. Histamine and its receptors' ligands can modulate different biological responses according to the cell type and the receptor subtype involved. Besides the wide variety of histamine functions in normal tissues, diverse roles in the acquisition of hallmarks of cancer such as sustained proliferative signaling, resistance to cell death, angiogenesis, metastasis, altered immunity and modified microenvironment have been described. This review summarizes the present knowledge of the various roles of histamine H2 receptor (H2R) ligands in neoplasias. A bioinformatic analysis of human tumors showed dissimilar results in the expression of the H2R gene according to tumor type when comparing malignant versus normal tissues. As well, the relationship between patients' survival parameters and H2R gene expression levels also varied, signaling important divergences in the role of H2R in neoplastic progression in different cancer types. Revised experimental evidence showed multiple effects of H2R antihistamines on several of the cited hallmarks of cancer. Interventional and retrospective clinical studies evaluated different H2R antihistamines in cancer patients with two main adjuvant uses: improving antitumor efficacy (which includes regulation of immune response) and preventing toxic adverse effects produced by chemo or radiotherapy. While there is a long path to go, research on H2R antihistamines may provide new opportunities for developing more refined combination therapeutic strategies for certain cancer types to improve patients' survival and health-related quality of life.

Prediction of Cytochrome P450 Inhibition Using a Deep Learning Approach and Substructure Pattern Recognition

Cytochrome P450 (CYP) is a family of enzymes that are responsible for about 75% of all metabolic reactions. Among them, CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 participate in the metabolism of most drugs and mediate many adverse drug reactions. Therefore, it is necessary to estimate the chemical inhibition of Cytochrome P450 enzymes in drug discovery and the food industry. In the past few decades, many computational models have been reported, and some provided good performance. However, there are still several issues that should be resolved for these models, such as single isoform, models with unbalanced performance, lack of structural characteristics analysis, and poor availability. In the present study, the deep learning models based on python using the Keras framework and TensorFlow were developed for the chemical inhibition of each CYP isoform. These models were established based on a large data set containing 85715 compounds extracted from the PubChem bioassay database. On external validation, the models provided good AUC values with 0.97, 0.94, 0.94, 0.96, and 0.94 for CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4, respectively. The models can be freely accessed on the Web server named CYPi-DNNpredictor (cypi.sapredictor.cn), and the codes for the model were made open source in the Supporting Information. In addition, we also analyzed the structural characteristics of chemicals with CYP450 inhibition and detected the structural alerts (SAs), which should be responsible for the inhibition. The SAs were also made available online, named CYPi-SAdetector (cypisa.sapredictor.cn). The models can be used as a powerful tool for the prediction of CYP450 inhibitors, and the SAs should provide useful information for the mechanisms of Cytochrome P450 inhibition.

A Review of CYP-Mediated Drug Interactions: Mechanisms and In Vitro Drug-Drug Interaction Assessment

Drug metabolism is a major determinant of drug concentrations in the body. Drug-drug interactions (DDIs) caused by the co-administration of multiple drugs can lead to alteration in the exposure of the victim drug, raising safety or effectiveness concerns. Assessment of the DDI potential starts with in vitro experiments to determine kinetic parameters and identify risks associated with the use of comedication that can inform future clinical studies. The diverse range of experimental models and techniques has significantly contributed to the examination of potential DDIs. Cytochrome P450 (CYP) enzymes are responsible for the biotransformation of many drugs on the market, making them frequently implicated in drug metabolism and DDIs. Consequently, there has been a growing focus on the assessment of DDI risk for CYPs. This review article provides mechanistic insights underlying CYP inhibition/induction and an overview of the in vitro assessment of CYP-mediated DDIs.

Case report: metoclopramide induced acute dystonic reaction in adolescent CYP2D6 poor metabolizers

Metoclopramide is indicated for the management of gastroesophageal reflux, gastric stasis, nausea, and vomiting. Metoclopramide-induced acute dystonic reactions (MIADRs), along with repetitive involuntary protrusion of the tongue, are well-known phenomena in children and young adults that may appear after the first dose. The drug is primarily metabolized via oxidation by the cytochrome P450 enzyme CYP2D6 and to a lesser extent by CYP3A4 and CYP1A2. A recommendation to decrease metoclopramide dosing in patients with severely limited to no CYP2D6 activity (i.e., poor metabolizers, PMs) is included in the drug label. It is important to note, however, that a requirement or recommendation for pre-emptive testing for CYP2D6 metabolizer status is not included in the drug label. We present two cases of acute dystonia in two non-consanguineous male adolescents: one following metoclopramide and cimetidine administration in a 14-year-old to treat gastroesophageal reflux, and another following metoclopramide and pantoprazole administration in a 17-year-old with acute gastroenteritis. A retrospective pharmacogenetic analysis revealed both patients as CYP2D6 PMs.

Evaluation of the pharmacokinetics of trazpiroben (TAK-906) in the presence and absence of the proton pump inhibitor esomeprazole

Trazpiroben, a dopamine D2 /D3 receptor antagonist under development to treat gastroparesis, displays decreasing solubility with increasing pH. This single-sequence, open-label, two-period, crossover study evaluated the effect of esomeprazole, a proton pump inhibitor that raises gastric pH, on the single-dose pharmacokinetics, safety, and tolerability of trazpiroben in healthy adults (NCT03849690). In total, 12 participants were enrolled and entered period 1 (days 1-3), receiving a single oral dose of trazpiroben 25 mg on day 1. After a 4-day washout, participants then entered period 2 (days 8-13) and received esomeprazole 40 mg once daily on days 8-12, with a single oral dose of trazpiroben 25 mg co-administered 1 h post esomeprazole dosing on day 11. Geometric mean area under the curve from time 0 extrapolated to infinity (AUC∞ ) and maximum plasma concentration (Cmax ) values were generally similar when trazpiroben was administered alone versus alongside esomeprazole (AUC∞ , 44.03 vs. 38.85 ng h/ml; Cmax , 19.76 vs. 17.24 ng/ml). Additionally, the associated geometric mean ratio (GMR; co-administration: administration alone) 90% confidence intervals (CIs) suggested no clinically meaningful difference between treatment groups (AUC∞ , GMR 0.88, 90% CI 0.78-1.00; Cmax , 0.87, 90% CI 0.70-1.09). Mean apparent first-order terminal elimination half-life values were similar between treatments, illustrating co-administration with esomeprazole had minimal effect on trazpiroben elimination. Trazpiroben was well-tolerated in healthy adults following administration alone and alongside esomeprazole, with no clinically relevant adverse events reported. The lack of evidence of any clinically meaningful drug-drug interaction supports the co-administration of esomeprazole with trazpiroben.

In Vitro and In Vivo Effect of Xylopic Acid on Cytochrome P450 Enzymes

INTRODUCTION

Xylopic acid (XA), the major constituent of the fruit of Xylopia aethiopica, has shown several pharmacological properties. Traditionally, the plant is used to treat several diseases and is being used in the preparation of several local foods despite the lack of information about its safety, food-drug interaction, and other pharmacokinetic properties. This study, therefore, investigated the effect of XA on rat liver cytochrome P450 (CYP) enzymes in vivo and in vitro.

METHODS

Inhibition or induction of some isoforms of CYP450 enzymes: CYP 1A1/1A2, 1A2, 2B1/2B2, 3A4, 2D6, and 2C9 were investigated using microsomal fractions of the liver obtained from rats pretreated with a low dose of xylopic acid (LDT) 30 mg/kg, high dose of xylopic acid (HDT) 100 mg/kg, phenobarbitone (PC) 80 mg/kg, and ketoconazole (NC) 100 mg/kg, and a no-treatment group received distilled water, with (n = 5) animals in each group. The in vitro inhibition of CYP 3A4 was assessed by treating rat liver microsomes with XA.

RESULTS

Xylopic acid induced CYP 1A1/1A2, 1A2, 2D6, and 2C9, inhibited CYP 3A4, and had no effect on 2B1/2B2.

CONCLUSION

The findings would help mitigate toxicity and therapeutic failure especially in cases of coadministration of medications with food containing XA, with metabolism altered by the latter.

Verification of a cocktail approach for quantitative drug-drug interaction assessment: a comparative analysis between the results of a single drug and a cocktail drug

A cocktail approach is a method to comprehensively evaluate the activity of cytochrome P450 enzymes (CYPs) by co-administering multiple CYP substrates. This is the first report that compares the results from a cocktail study to a single substrate separate administration study (single study) with concomitant administration of CYP inducers/inhibitors. The validity of a cocktail study for use as a quantitative drug-drug interactions (DDIs) assessment was evaluated.We administered a cocktail drug (caffeine, losartan, omeprazole, dextromethorphan, midazolam) with rifampicin, cimetidine or fluvoxamine. A comparative analysis was performed between the results of a cocktail study and single studies. The results of single studies were obtained from a literature review and the trials of single substrate separate administration.A strong positive correlation of the AUC ratio of all drugs between single studies and the cocktail study was obtained. The ratio of AUC change of 12 combinations converged to 0.82-1.09, and 2 combinations ranged between 0.74-1.32.The differences in the degree of interaction between the single studies and cocktail study are acceptable to evaluate DDIs for almost all combinations. Our results indicate that a cocktail study is an adequate and quantitative evaluation method for DDIs.

Influence of Cation Transporters (OCTs and MATEs) on the Renal and Hepatobiliary Disposition of [11C]Metoclopramide in Mice

PURPOSE

To investigate the role of cation transporters (OCTs, MATEs) in the renal and hepatic disposition of the radiolabeled antiemetic drug [11C]metoclopramide in mice with PET.

METHODS

PET was performed in wild-type mice after administration of an intravenous microdose (<1 μg) of [11C]metoclopramide without and with co-administration of either unlabeled metoclopramide (5 or 10 mg/kg) or the prototypical cation transporter inhibitors cimetidine (150 mg/kg) or sulpiride (25 mg/kg). [11C]Metoclopramide PET was also performed in wild-type and Slc22a1/2(-/-) mice. Radiolabeled metabolites were measured at 15 min after radiotracer injection and PET data were corrected for radiolabeled metabolites.

RESULTS

[11C]Metoclopramide was highly metabolized and [11C]metoclopramide-derived radioactivity was excreted into the urine. The different investigated treatments decreased (~2.5-fold) the uptake of [11C]metoclopramide from plasma into the kidney and liver, inhibited metabolism and decreased (up to 3.8-fold) urinary excretion, which resulted in increased plasma concentrations of [11C]metoclopramide. Kidney and liver uptake were moderately (~1.3-fold) reduced in Slc22a1/2(-/-) mice.

CONCLUSIONS

Our results suggest a contribution of OCT1/2 to the kidney and liver uptake and of MATEs to the urinary excretion of [11C]metoclopramide in mice. Cation transporters may contribute, next to variability in the activity of metabolizing enzymes, to variability in metoclopramide pharmacokinetics and side effects.

Drug-Drug Interactions Involving Intestinal and Hepatic CYP1A Enzymes

Cytochrome P450 (CYP) 1A enzymes are considerably expressed in the human intestine and liver and involved in the biotransformation of about 10% of marketed drugs. Despite this doubtless clinical relevance, CYP1A1 and CYP1A2 are still somewhat underestimated in terms of unwanted side effects and drug–drug interactions of their respective substrates. In contrast to this, many frequently prescribed drugs that are subjected to extensive CYP1A-mediated metabolism show a narrow therapeutic index and serious adverse drug reactions. Consequently, those drugs are vulnerable to any kind of inhibition or induction in the expression and function of CYP1A. However, available in vitro data are not necessarily predictive for the occurrence of clinically relevant drug–drug interactions. Thus, this review aims to provide an up-to-date summary on the expression, regulation, function, and drug–drug interactions of CYP1A enzymes in humans.

Assessing Drug-Drug Interaction Potential among Patients Admitted to Surgery Departments in Three Palestinian Hospitals

Background

Drug-drug interactions (DDIs) are a common issue that leads to adverse drug reactions in hospitals. Patients in the surgical department are expected to have potential DDIs that may lead to morbidity and mortality.

Objectives

To study potential DDI prevalence in the surgery departments in 3 hospitals in Palestine. Moreover, to identify pertinent factors that are associated with drug-drug interactions.

Method

A cross-sectional study in 3 governmental Palestinian hospitals: Palestine Medical Complex, Rafidia Hospital, and Beit Jala Hospital. Patients who are 20 years old or above and admitted to the surgical wards between September 2017 and February 2018 were included in the study. Patient demographics, all medications given in the hospital, and hospitalization period were obtained from medical files. The digital clinical decision support system Micromedex® was used for analysis and classification of possible drug interactions. Bivariate analysis and logistic regression were used to study the risk factors for developing DDIs.

Results

502 patients were included in this report. The prevalence of potential DDIs among patients admitted to surgery wards in three Palestinian hospitals was 56%. The number of detected potential DDIs per patient was 2.22 ± 3.76. The number of prescribed medications (P < 0.001) was found to increase the possibility of having drug interactions.

Conclusions

DDIs in Palestinian hospitals are a prevalent problem, and caution should be taken when ordering medications to hospitalized patients in surgery departments.

The clinical toxicology of caffeine: A review and case study

Caffeine is a widely recognized psychostimulant compound with a long history of consumption by humans. While it has received a significant amount of attention there is still much to be learned with respect to its toxicology in humans, especially in cases of overdose. A review of the history of consumption and the clinical toxicology of caffeine including clinical features, pharmacokinetics, toxicokinetics, a thorough examination of mechanism of action and management/treatment strategies are undertaken. While higher (i.e., several grams) quantities of caffeine are known to cause toxicity and potentially lethality, cases of mainly younger individuals who have experienced severe side effects and death despite consuming doses not otherwise known to cause such harm is troubling and deserves further study. An attempted case reconstruction is performed in an effort to shed light on this issue with a focus on the pharmacokinetics and pharmacodynamics of caffeine.

Metabolic interactions between acetaminophen (paracetamol) and two flavonoids, luteolin and quercetin, through in-vitro inhibition studies

OBJECTIVES

Excessive exposure to acetaminophen (APAP, paracetamol) can cause liver injury through formation of a reactive metabolite that depletes hepatic glutathione and causes hepatocellular oxidative stress and damage. Generation of this metabolite is mediated by Cytochrome-P450 (CYP) isoforms, mainly CYP2E1. A number of naturally occurring flavonoids can mitigate APAP-induced hepatotoxicity in experimental animal models. Our objective was to determine the mechanism of these protective effects and to evaluate possible human applicability.

METHODS

Two flavonoids, luteolin and quercetin, were evaluated as potential inhibitors of eight human CYP isoforms, of six UDP-glucuronosyltransferase (UGT) isoforms and of APAP glucuronidation and sulfation. The experimental model was based on in-vitro metabolism by human liver microsomes, using isoform-specific substrates.

KEY FINDINGS

Luteolin and quercetin inhibited human CYP isoforms to varying degrees, with greatest potency towards CYP1A2 and CYP2C8. However, 50% inhibitory concentrations (IC₅₀ values) were generally in the micromolar range. UGT isoforms were minimally inhibited. Both luteolin and quercetin inhibited APAP sulfation but not glucuronidation.

CONCLUSIONS

Inhibition of human CYP activity by luteolin and quercetin occurred with IC₅₀ values exceeding customary in-vivo human exposure with tolerable supplemental doses of these compounds. The findings indicate that luteolin and quercetin are not likely to be of clinical value for preventing or treating APAP-induced hepatotoxicity.

A Two-Period Open-Label, Single-Dose Crossover Study in Healthy Volunteers to Evaluate the Drug-Drug Interaction Between Cimetidine and Inhaled Extrafine CHF 5993

Background and Objectives

CHF 5993 is an extrafine ‘triple therapy’ combination of the long-acting muscarinic antagonist glycopyrronium bromide (GB), the long-acting β₂-agonist formoterol fumarate (FF), and the inhaled corticosteroid beclometasone dipropionate (BDP). It is in development for chronic obstructive pulmonary disease and asthma delivered via pressurised metered-dose inhaler.

Methods

This two-period, open-label, crossover study examined the drug–drug interaction of CHF 5993 and cimetidine. In one period, subjects received cimetidine 800 mg twice daily for 6 days; on the fourth day they also received CHF 5993 (BDP/FF/GB 400/24/100 µg). In the other, they received CHF 5993 alone. Primary objective was to compare the area under the plasma concentration–time curve from time 0 to last quantifiable concentration (AUC_0–t) of GB, with and without cimetidine. Secondary endpoints included GB AUC_0–12h, maximum concentration (C_max), time to C_max (t_max), elimination half-life (t_½) and urinary excretion. Pharmacokinetic parameters of BDP, beclometasone-17-monopropionate (B17MP; active metabolite of BDP) and formoterol were also evaluated.

Results

Twenty-six subjects were randomised; 25 completed. Co-administration of CHF 5993 and cimetidine resulted in small, statistically significant increases in GB AUC_0–t, AUC_0–12h and C_max vs CHF 5993 (ratios 1.16, 1.21 and 1.26, respectively); t_½, t_max and urinary excretion were unaffected. There were small, statistically significant increases in formoterol AUC_0–t, AUC_0–24h and t_½ following co-administration of cimetidine and CHF 5993; urinary excretion was unaffected. There were no significant differences for either BDP or B17MP. There were few adverse events (AEs), and no serious AEs.

Conclusions

Overall, this study indicates that there is no clinically relevant drug–drug interaction between CHF 5993 and cimetidine.

Electronic supplementary material

The online version of this article (doi:10.1007/s13318-016-0345-2) contains supplementary material, which is available to authorized users.

Metformin and cimetidine: Physiologically based pharmacokinetic modelling to investigate transporter mediated drug-drug interactions

Metformin is used as a probe for OCT2 mediated transport when investigating possible DDIs with new chemical entities. The aim of the current study was to investigate the ability of physiologically-based pharmacokinetic (PBPK) models to simulate the effects of OCT and MATE inhibition by cimetidine on metformin kinetics. PBPK models were developed, incorporating mechanistic kidney and liver sub-models for metformin (OCT and MATE substrate) and a mechanistic kidney sub-model for cimetidine. The models were used to simulate inhibition of the MATE1, MATE2-K, OCT1 and OCT2 mediated transport of metformin by cimetidine. Assuming competitive inhibition and using cimetidine Ki values determined in vitro, the predicted metformin AUC ratio was 1.0 compared to an observed value of 1.46. The observed AUC ratio could only be recovered with this model when the cimetidine Ki for OCT2 was decreased 1000-fold or the Ki's for both OCT1 and OCT2 were decreased 500-fold. An alternative description of metformin renal transport by OCT1 and OCT2, incorporating electrochemical modulation of the rate of metformin uptake together with 8-18-fold decreases in cimetidine Ki's for OCTs and MATEs, allowed recovery of the extent of the observed effect of cimetidine on metformin AUC. While the final PBPK model has limitations, it demonstrates the benefit of allowing for the complexities of passive permeability combined with active cellular uptake modulated by an electrochemical gradient and active efflux.

Environmental monitoring of urban streams using a primary fish gill cell culture system (FIGCS)

The primary fish gill cell culture system (FIGCS) is an in vitro technique which has the potential to replace animals in whole effluent toxicity tests. In the current study FIGCS were transported into the field and exposed to filtered (0.2μm) river water for 24h from 4 sites, on 2 different sampling dates. Sites 1 and 2 are situated in an urban catchment (River Wandle, London, UK) with site 1 downstream of a sewage treatment work; site 3 is located in a suburban park (River Cray, Kent, UK), and site 4 is more rural (River Darent, Kent, UK). The change in transepithelial electrical resistance (TER), the expression of the metal responsive genes metallothionein A (mta) and B (mtb), cytochrome P450 1A1 (cyp1a1) and 3A27 (cyp3a27), involved in phase 1 metabolism, were assessed following exposure to sample water for 24h. TER was comparable between FIGCS exposed to 0.2μm filtered river water and those exposed to synthetic moderately soft water for 24h. During the first sampling time, there was an increase in mta, cyp1a1 and cyp3a27 gene expression in epithelium exposed to water from sites 1 and 2, and during the second sampling period an increase in cyp3a27 gene expression at sites 1 and 4. Urban river water is a complex mixture of contaminants (e.g., metals, pesticides, pharmaceuticals and polyaromatic hydrocarbons) and the increase in the expression of genes encoding mta, cyp1a1 and cyp3a27 in FIGCS is indicative of the presence of biologically active pollutants.

Repurposing drugs in oncology (ReDO)-cimetidine as an anti-cancer agent

Cimetidine, the first H₂ receptor antagonist in widespread clinical use, has anti-cancer properties that have been elucidated in a broad range of pre-clinical and clinical studies for a number of different cancer types. These data are summarised and discussed in relation to a number of distinct mechanisms of action. Based on the evidence presented, it is proposed that cimetidine would synergise with a range of other drugs, including existing chemotherapeutics, and that further exploration of the potential of cimetidine as an anti-cancer therapeutic is warranted. Furthermore, there is compelling evidence that cimetidine administration during the peri-operative period may provide a survival benefit in some cancers. A number of possible combinations with other drugs are discussed in the supplementary material accompanying this paper.

Paroxetine markedly increases plasma concentrations of ophthalmic timolol; CYP2D6 inhibitors may increase the risk of cardiovascular adverse effects of 0.5% timolol eye drops

Although ophthalmic timolol is generally well tolerated, a significant fraction of topically administered timolol can be systemically absorbed. We investigated the effect of the strong CYP2D6 inhibitor paroxetine on the pharmacokinetics of timolol after ophthalmic administration. In a four-phase crossover study, 12 healthy volunteers ingested either paroxetine (20 mg) or placebo daily for 3 days. In phases 1-2, timolol 0.1% gel, and in phases 3-4, timolol 0.5% drops were administered to both eyes. Paroxetine increased the plasma concentrations of timolol with both timolol formulations to a similar degree. The geometric mean ratio (95% confidence interval) of timolol peak concentration was 1.53-fold (1.23-1.91) with 0.1% timolol and 1.49-fold (0.94-2.36) with 0.5% timolol, and that of timolol area under the plasma concentration-time curve (AUC) from time 0 to 12 hours was 1.61-fold (1.26- to 2.06-fold) and 1.78-fold (1.21-2.62), respectively. During paroxetine administration, six subjects on 0.5% timolol drops, but none on 0.1% timolol gel, had plasma timolol concentrations exceeding 0.7 ng/ml, which can cause systemic adverse effects in patients at risk. There was a positive correlation between the AUC from time 0 to 13 hours of paroxetine and the placebo phase AUC from time 0 to infinity of timolol after timolol 0.5% drops (P < 0.05), and a nonsignificant trend after timolol 0.1% gel, consistent with the role of CYP2D6 in the metabolism of both agents. In the orthostatic test, heart rate immediately after upright standing was significantly lower (P < 0.05) during the paroxetine phase than during the placebo phase at 1 and 3 hours after 0.5% timolol dosing. In conclusion, paroxetine and other CYP2D6 inhibitors can have a clinically important interaction with ophthalmic timolol, particularly when patients are using 0.5% timolol formulations.

Combination of Mangifera indica L. extract supplementation plus methotrexate in rheumatoid arthritis patients: a pilot study

The purpose of the present study was to evaluate the possible therapeutic effects and the safety of Mangifera indica extract (Vimang tablets, 300 mg) combined with methotrexate (MTX) on reducing disease activity in rheumatoid arthritis (RA). Twenty patients with active RA underwent a year of treatment with MTX (12.5 mg/week) associated to non-steroidal anti-inflammatory drugs (NSAIDs) and/or prednisone (5-10 mg/day) were randomly allocated to the experimental group (n=10), that received the extract supplementation (900 mg/day) or preceding usual treatment (n=10) during 180 days. RA activity was evaluated using the tender and swollen joint counts, erythrocyte sedimentation rate, disease activity score-28 (DAS 28), visual analogue scale (VAS) and health assessment questionnaire (HAQ). Treatment's efficacy was demonstrated with ACR criteria. Only the patients of MTX-Vimang group revealed statistically significant improvement in DAS 28 parameters with respect baseline data but no differences were observed between groups. ACR improvements amounted 80% only in MTX-Vimang group at the 90 days (p<0.001). In MTX-Vimang group, 100% of patients decreased NSAIDs administration (p<0.01) and 70% of those eradicated gastrointestinal side effects (p<0.01) ensuing of the preceding treatment. Other adverse effects were not reported.

Predictors of the clinical effects of pirfenidone on idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease with a poor prognosis. Recently, pirfenidone was reported to slow the rate of decline in vital capacity and improve progression-free survival in IPF. The purpose of this study was to clarify the factors that predicted a good response to pirfenidone, as well as its adverse effects.

METHODS

Forty-one IPF cases, treated with pirfenidone from January 2009 to January 2011, were enrolled in this investigation. Disease severity was classified into grades I-IV, as defined by the Japanese Respiratory Society (JRS). Short-term responsiveness to pirfenidone was evaluated by the modified criteria of the JRS. Predictors of nausea, anorexia, or both that represented important adverse effects were examined by multivariate Cox proportional hazard analyses. Predictors of short-time responsiveness were examined by multivariate logistic regression analyses.

RESULTS

Diagnosed by a surgical lung biopsy (SLB), the mild cases of grade I/II were predictors of good, short-term responsiveness. Patients taking acid-secretion inhibitors, including proton pump inhibitors and histamine H2-receptor antagonists, showed less anorexia, nausea, or both. Only 1 case was administered drugs to activate gastrointestinal motility.

CONCLUSIONS

We concluded that IPF patients with a mild disease, diagnosis by SLB, or both showed indications of a good response to pirfenidone. In addition, acid-secretion inhibitors may reduce the frequency of anorexia, nausea, or both from pirfenidone.

Effect of meal and antisecretory agents on the pharmacokinetics of danoprevir/ritonavir in healthy volunteers

OBJECTIVES

To evaluate the effect of a low- and high-fat meal and co-administration of ranitidine or omeprazole on the pharmacokinetics of ritonavir-boosted danoprevir (DNVr).

METHODS

In this randomised, open-label, cross-over study, healthy subjects received a single dose of DNVr. In group 1, DNVr was administered while fasting or with a low-fat or high-fat meal. In group 2, DNVr was administered alone or with ranitidine 150 mg (single dose) or omeprazole 40 mg (multiple doses).

KEY FINDINGS

Group 1 (n = 16): relative to fasting conditions, food slightly prolonged absorption but did not alter the extent of absorption. DNV area under the plasma concentration-time curve extrapolated to infinity (AUC0-∞), maximum plasma concentration (C(max)), and plasma concentration 12 h after administration (C12h) geometric mean ratios (GMR%) (90% confidence interval (CI)) with a low-fat meal were 92.3 (80.2-106), 61.8 (51.0-74.9) and 95.2 (80.9-112), versus fasting conditions, and with a high-fat meal 99.5 (86.4-115), 58.9 (48.5-71.6) and 101 (86.0-119). Group 2 (n = 13): ranitidine or omeprazole had no clinically significant effect on DNV pharmacokinetics. DNV AUC0-∞, Cmax and C12h GMR% (90% CI) with ranitidine: 81.9 (68.3-98.1), 104 (86.9-123) and 87.5 (69.3-111), and with omeprazole: 83.0 (67.4-102), 92.7 (70.6-122) and 93.3 (65.6-133).

CONCLUSIONS

The absence of clinically relevant effects of food, ranitidine or omeprazole on DNVr pharmacokinetics suggests that DNVr can be administered without regard to meals and in combination with H2 antagonists or proton pump inhibitors.

An Overview of Analytical Determination of Diltiazem, Cimetidine, Ranitidine, and Famotidine by UV Spectrophotometry and HPLC Technique

This review article recapitulates the analytical methods for the quantitative determinations of diltiazem and three H2receptor antagonists (cimetidine, ranitidine, and famotidine) by one of the spectroscopic technique (UV spectrophotometery) and separation technique such as high-performance liquid chromatography (HPLC). The clinical and pharmaceutical analysis of these drugs requires effective analytical procedures for quality control, pharmaceutical dosage formulations, and biological fluids. An extensive survey of the literature published in various analytical and pharmaceutical chemistry-related journals has been compiled in its review. A synopsis of reported spectrophotometric and high-performance liquid chromatographic methods for individual drug is integrated. This appraisal illustrates that majority of the HPLC methods reviewed are based on the quantitative analysis of drugs in biological fluids, and they are appropriate for therapeutic drug monitoring purpose.

[¹¹C]Rhodamine-123: synthesis and biodistribution in rodents

INTRODUCTION

Rhodamine-123 is a known substrate for the efflux transporter, P-glycoprotein (P-gp). We wished to assess whether rhodamine-123 might serve as a useful substrate for developing probes for imaging efflux transporters in vivo with positron emission tomography (PET). For this purpose, we aimed to label rhodamine-123 with carbon-11 (t(1/2)=20.4min) and to study its biodistribution in rodents.

METHODS

[¹¹C]Rhodamine-123 was prepared by treating rhodamine-110 (desmethyl-rhodamine-123) with [¹¹C]methyl iodide. The biodistribution of this radiotracer was studied with PET in wild-type mice and rats, in efflux transporter knockout mice, in wild-type rats pretreated with DCPQ (an inhibitor of P-gp) or with cimetidine (an inhibitor of organic cation transporters; OCT), and in P-gp knockout mice pretreated with cimetidine. Unchanged radiotracer in forebrain, plasma and peripheral tissues was also measured ex vivo at 30min after radiotracer administration to wild-type and efflux transporter knockout rodents.

RESULTS

[(¹¹C]Rhodamine-123 was obtained in 4.4% decay-corrected radiochemical yield from cyclotron-produced [¹¹C]carbon dioxide. After intravenous administration of [¹¹C]rhodamine-123 to wild-type rodents, PET and ex vivo measurements showed radioactivity uptake was very low in brain, but relatively high in some other organs such as heart, and especially liver and kidney. Inhibition of P-gp increased uptake in brain, heart, kidney and liver, but only by up to twofold. Secretion of radioactivity from kidney was markedly reduced by OCT knockout or pretreatment with cimetidine.

CONCLUSIONS

[¹¹C]Rhodamine-123 was unpromising as a PET probe for P-gp function and appears to be a strong substrate of OCT in kidney. Cimetidine appears effective for blocking OCT in kidney in vivo.

Fetal serotonin reuptake inhibitor antidepressant exposure: maternal and fetal factors

Prenatal serotonin reuptake inhibitor exposure is common and neonatal outcomes vary greatly, often leading to confusion about whether to use or even continue antenatal use of these antidepressants. Importantly, some but not all infants are affected, which raises questions about how maternal drug metabolism contributes to fetal drug exposure. To address this key question, our paper reviews the role of key maternal, fetal, and placental pharmacokinetic, metabolic, and genetic factors that affect the extent of fetal drug exposure. Considering the role of these factors may further our understanding of variables that may assist in optimizing maternal psychopharmacotherapy during pregnancy and neonatal outcomes.

Concurrent use of proton pump inhibitors or H2 blockers did not adversely affect nilotinib efficacy in patients with chronic myeloid leukemia

PURPOSE

The impact of proton pump inhibitors (PPIs) and histamine H2 receptor antagonists (H2 blockers) on the efficacy of nilotinib was evaluated.

METHODS

Retrospective analyses were performed in patients with newly diagnosed Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia in chronic phase (CML-CP; N = 492) and in patients with imatinib-resistant or imatinib-intolerant Ph+ CML-CP (N = 256) treated with nilotinib.

RESULTS

In the newly diagnosed population, 87 (17.7 %) and 49 (10.0 %) patients received PPIs and H2 blockers, respectively. Major molecular response at 12 months was achieved by 59 (49.6 %) patients who received at least one PPI or H2 blocker (n = 119) and 153 (41.0 %) patients who did not receive any comedication (n = 373; P = 0.13). PPIs and H2 blockers were used by 77 (30.1 %) and 17 (6.6 %) patients with imatinib-resistant or imatinib-intolerant CML-CP, respectively. Major cytogenetic response by 12 months was achieved by 55 (64.0 %) patients who received at least one PPI or H2 blocker (n = 86) versus 98 (57.6 %) patients who did not receive any comedication (n = 170; P = 0.40); 39 (45.3 %) versus 65 (38.2 %), respectively, achieved complete cytogenetic response by 12 months (P = 0.34). Similar findings were observed in patients who received comedication for >50 % of the time on nilotinib therapy. Nilotinib steady-state trough concentration was not affected by the presence of PPIs or H2 blockers.

CONCLUSIONS

Concurrent use of PPIs or H2 blockers did not affect the pharmacokinetics and efficacy of nilotinib in patients with Ph+ CML-CP.

Validated Method for the Simultaneous Determination of Gemifloxacin and H2‐receptor Antagonists in Bulk, Pharmaceutical Formulations and Human Serum by RP‐HPLC; In‐vitro Applications

Simple, isocratic and rapid RP‐HPLC method has been developed for the simultaneous analysis of gemifloxacin and H2‐receptor antagonists i.e. Cimetidine, Famotidine and Ranitidine, in bulk, pharmaceutical formulation and human serum. Separation was achieved on the RP‐Mediterranea column [C18 (250 × 4.6 mm, 5 μ)] at ambient temperature using mobile phase consisting of acetonitrile: methanol: water (20:28:52 v/v/v pH 2.8 adjusted by phosphoric acid). Flow rate was 1.0 mL/min with an average operating pressure of 180 kg/cm2. Gatifloxacin (GATI) was used as an internal standard (IS). Quantitation was achieved with UV detection at 221, 256 and 267 nm, respectively. Linear calibration curves, at concentration ranges of 0.05‐37.5 μgmL‐L with a correlation coefficient of ±0.9994. The detection and quantification limits were in the ranges of 0.023‐0.250 μgmL‐L and 0.071‐0.756 μgmL‐L, respectively. Friedman's and Student's t‐test were applied to correlate these results. Method was validated in terms of selectivity, linearity, precision, robustness, recovery, limits of detection and quantitation and is applicable to the routine analysis of GFX and H2‐receptor antagonists, alone or in combination.

Drug interactions with the tyrosine kinase inhibitors imatinib, dasatinib, and nilotinib

Several cancer treatments are shifting from traditional, time-limited, nonspecific cytotoxic chemotherapy cycles to continuous oral treatment with specific protein-targeted therapies. In this line, imatinib mesylate, a selective tyrosine kinases inhibitor (TKI), has excellent efficacy in the treatment of chronic myeloid leukemia. It has opened the way to the development of additional TKIs against chronic myeloid leukemia, including nilotinib and dasatinib. TKIs are prescribed for prolonged periods, often in patients with comorbidities. Therefore, they are regularly co-administered along with treatments at risk of drug-drug interactions. This aspect has been partially addressed so far, calling for a comprehensive review of the published data. We review here the available evidence and pharmacologic mechanisms of interactions between imatinib, dasatinib, and nilotinib and widely prescribed co-medications, including known inhibitors or inducers of cytochromes P450 or drug transporters. Information is mostly available for imatinib mesylate, well introduced in clinical practice. Several pharmacokinetic aspects yet remain insufficiently investigated for these drugs. Regular updates will be mandatory and so is the prospective reporting of unexpected clinical observations.

Effects of Flos carthami on CYP2D6 and on the Pharmacokinetics of Metoprolol in Rats

Flos carthami is a traditional Chinese herbal medicine. Clinically, the Flos carthami Injection has been used concomitantly with other Western drugs and may be used concomitantly with β-blockers, such as metoprolol, to treat cerebrovascular and coronary heart diseases, in China. Metoprolol is a CYP2D6 substrate and is predominantly metabolized by this isozyme. However, we do not know whether there is an effect of Flos carthami on CYP2D6 and the consequences of such an effect. Concern is raised regarding the possible herb-drug interaction. In this report, the effects of Flos carthami on the activity of CYP2D6 in vivo and in vitro and on the pharmacokinetics of metoprolol, in rats, are investigated. To assess the inhibitory potency of Flos carthami, the concentration associated with 50% inhibition (IC₅₀) of dextromethorphan metabolism was determined based on the concentration-inhibition curves. The inhibitory effect of Flos carthami on CYP2D6 was also compared with cimetidine in vitro. Flos carthami could significantly inhibit CYP2D6 in rats both in vitro and in vivo (P < .05) and could slow down the metabolic rate of metoprolol as suggested by prolonged t_1/2 (67.45%), by increased C_max (74.51%) and AUC_0−∞ (76.89%). These results suggest that CYP2D6 is a risk factor when Flos carthami is administered concomitantly with metoprolol or other CYP2D6 substrates.

Structure, function, regulation and polymorphism and the clinical significance of human cytochrome P450 1A2

Human CYP1A2 is one of the major CYPs in human liver and metabolizes a number of clinical drugs (e.g., clozapine, tacrine, tizanidine, and theophylline; n > 110), a number of procarcinogens (e.g., benzo[a]pyrene and aromatic amines), and several important endogenous compounds (e.g., steroids). CYP1A2 is subject to reversible and/or irreversible inhibition by a number of drugs, natural substances, and other compounds. The CYP1A gene cluster has been mapped on to chromosome 15q24.1, with close link between CYP1A1 and 1A2 sharing a common 5'-flanking region. The human CYP1A2 gene spans almost 7.8 kb comprising seven exons and six introns and codes a 515-residue protein with a molecular mass of 58,294 Da. The recently resolved CYP1A2 structure has a relatively compact, planar active site cavity that is highly adapted for the size and shape of its substrates. The architecture of the active site of 1A2 is characterized by multiple residues on helices F and I that constitutes two parallel substrate binding platforms on either side of the cavity. A large interindividual variability in the expression and activity of CYP1A2 has been observed, which is largely caused by genetic, epigenetic and environmental factors (e.g., smoking). CYP1A2 is primarily regulated by the aromatic hydrocarbon receptor (AhR) and CYP1A2 is induced through AhR-mediated transactivation following ligand binding and nuclear translocation. Induction or inhibition of CYP1A2 may provide partial explanation for some clinical drug interactions. To date, more than 15 variant alleles and a series of subvariants of the CYP1A2 gene have been identified and some of them have been associated with altered drug clearance and response and disease susceptibility. Further studies are warranted to explore the clinical and toxicological significance of altered CYP1A2 expression and activity caused by genetic, epigenetic, and environmental factors.