UPLC–MS/MS assay for quantification of an inhibitor of kinases (Foretinib) in plasma: Application to a pharmacokinetic study in rats

Foretinib, an oral multikinase inhibitor, is known to have anti-tumor effects against cancers. The doses and the levels of foretinib vary based on the type of cancer to be treated. An accurate and precise method is required to determine the level of foretinib and its pharmacokinetics. Here, we developed such a method, which was validated based on the guidelines of the FDA and EMA. Foretinib and ibrutinib (the internal standard (IS)) were extracted using tert-butyl methyl ether. Foretinib and IS were eluted in approximately 1.2 min. Thus, a linear, fast, accurate, and precise method was developed. The calibration curve was linear (r² ˃ 0.997) in the range of 0.5–400.0 ng/mL and the lowest limit of quantitation was 0.5 ng/mL. The average recovery, accuracy, and precision were 87.9%, 88.7%, and ≤7.8%, respectively. The analyte was deemed stable using various stability tests. The validated assay was then fruitfully applied to a pharmacokinetics study in rats, which revealed that foretinib was absorbed and the maximum concentration achieved at 4.0 h after the administration of a single dose of foretinib.     

Silicon switch: Carbon–silicon Bioisosteric replacement as a strategy to modulate the selectivity,physicochemical, and drug-like properties in anticancer pharmacophores

Bioisosterism is one of the leading strategies in medicinal chemistry for the design and modification of drugs, consisting in replacing an atom or a substituent with a different atom or a group with similar chemical properties and an inherent biocompatibility. The objective of such an exercise is to produce a diversity of molecules with similar behavior while enhancing the desire biological and pharmacological properties, without inducing significant changes to the chemical framework. In drug discovery and development, the optimization of the absorption, distribution, metabolism, elimination, and toxicity (ADMETox) profile is of paramount importance. Silicon appears to be the right choice as a carbon isostere because they possess very similar intrinsic properties. However, the replacement of a carbon by a silicon atom in pharmaceuticals has proven to result in improved efficacy and selectivity, while enhancing physicochemical properties and bioavailability. The current review discusses how silicon has been strategically introduced to modulate drug-like properties of anticancer agents, from a molecular design strategy, biological activity, computational modeling, and structure–activity relationships perspectives.     

Gonadotropin-releasing hormone (GnRH) receptors in tumors: a new rationale for the therapeutical application of GnRH analogs in cancer patients?

Gonadotropin-Releasing Hormone (GnRH) is the hypothalamic decapeptide which plays a key role in the control of reproductive functions. By binding to specific receptors present on the pituitary gonadotropes, GnRH regulates gonadotropin release and, consequently, steroid hormone secretion from the gonads. When given continuously and at high doses, GnRH agonists suppress the pituitary gonadal axis through the down-regulation and desensitization of its own receptors. Based on this rationale, pituitary GnRH receptors represent the target for the successful utilization of GnRH agonists (that are more stable than the native peptide) for the treatment of hormone-dependent tumors (e.g., prostate, breast, endometrial, ovarian cancers). The observation that GnRH receptors are expressed in steroid-dependent tumors, and that their activation reduces cell proliferation and metastatic behavior of cancer cell lines, both in vitro and in vivo (when inoculated into nude mice), indicates a possible additional and more direct antitumor activity for these compounds. Interestingly, GnRH receptors have been shown to be expressed also in androgen-independent prostate carcinoma, as well as in tumors that are not classically considered hormone-related (e.g., melanoma), suggesting a clinical utility of the administration of GnRH analogs also in these tumors. More recently, GnRH agonists have been proposed as useful carriers to target cytotoxic drugs or toxins to cancer cells displaying the specific GnRH receptors. A second form of GnRH (designated GnRH-II) has been discovered in most vertebrates, including humans. GnRH-II has been suggested to act through a 'putative' cognate type II GnRH receptor, which is distributed in different tissues, both normal and tumoral. In humans, a full-length functional type II GnRH receptor has not been found. Therefore, its functions as well as its possible utility as a molecular target for a GnRH-II based therapy in oncology still has to be clarified. This review will focus on the role of GnRH receptors in the control of tumor growth, progression and dissemination. It will also be discussed whether the presence of these receptors might represent an additional rationale for the clinical utility of GnRH analogs as anticancer drugs.     

Montmorillonite/poly-(ε-caprolactone) composites as versatile layered material: reservoirs for anticancer drug and controlled release property

This work evaluates intercalation of tamoxifen (Tmx) in interlayer gallery of Na(+)-MMT (Montmorillonite, MMT) (Tmx-MMT), which is further compounded with poly-(ε-caprolactone) (PCL) (Tmx-MMT/PCL, MPs), for oral chemotherapy of breast cancer. The X-ray diffraction patterns, thermal and spectroscopic analyses indicated the intercalation of Tmx into the MMT interlayer that stabilized in the longitudinal monolayer mode by electrostatic interaction. No significant change in structural and functional properties of Tmx was found in the MMT layers. In vitro study of drug release profiles showed controlled release pattern. The genotoxic effect of drug was in vitro evaluated in human lymphocyte cell culture by comet assay, and results indicated moderate reduction in DNA damage when pristine Tmx was intercalated with MMT and formulated in composites. The Tmx-MMT hybrid efficacy was also confirmed on HeLa and A549 cancer cells by in vitro cell viability assay. In vivo pharmacokinetics (PK) of formulated Tmx in rats was examined and the results showed that plasma Tmx levels were within therapeutic window as compared to pristine Tmx. Therefore, Tmx-MMT hybrid and microcomposite particles (MPs) can be of considerable value in chemotherapy of malignant neoplastic disease with reduced side effects. This study clearly indicated that MMT not only plays a role as a delivery matrix for drug, but also facilitates significant increase in the delivery proficiency.     

Curcumin–Zn(II) complex for enhanced solubility and stability: an approach for improved delivery and pharmacodynamic effects

Objective: The aim of present investigation was to prepare Curcumin–Zn(II) complex in a view to enhance solubility, stability and pharmacodynamic effect in experimentally induced ulcerative colitis.

Method: Curcumin–Zn(II) complex was prepared by stirring curcumin with anhydrous zinc chloride at a molar ratio of 1:1. The prepared curcumin metallocomplex was characterized by TLC, FTIR, UV spectroscopy and ¹H NMR. In vitro kinetic degradation and solubility of Curcumin and Curcumin–Zn(II) complex was analyzed spectrophotometrically. Pharmacodynamic evaluation of curcumin and its metal complex was assessed in ulcerative colitis in mice.

Results: Curcumin showed chelation with zinc ion as confirmed by the TLC, FTIR, UV spectroscopy and ¹H NMR. The results of TLC [R_f value], IR Spectroscopy [shifting of stretching vibrations of υ(C=C) and υ(C=O)], UV spectra [deconvoluted with absorption band at 432–466.4 nm] of Curcumin–Zn(II) complex compared to curcumin confirmed the formation of metallocomplex. ¹HNMR spectra of Curcumin–Zn(II) showed the upfield shift of H_a and H_b. Kinetic stability studies showed metallocomplex with zinc exhibited good stability. In vivo study revealed significant reduction in severity and extent of colonic damage with Curcumin–Zn(II) which were further confirmed by histopathological study.

Conclusion: This study recognizes higher solubility and stability of Curcumin–Zn(II) complex and suggested better pharmacodynamic effects.     

Inhibition of protein kinases by anticancer DNA intercalator, 4-butylaminopyrimido[4′,5′:4,5]thieno(2,3-b)quinoline

Targeting protein kinases (PKs) has been a promising strategy in treating cancer, as PKs are key regulators of cell survival and proliferation. Here in this study, we studied the ability of pyrimido[4′,5′:4,5]thieno(2,3-b)quinolines (PTQ) to inhibit different PKs by performing computational docking and in vitro screening. Docking studies revealed that 4-butylaminopyrimido[4′,5′:4,5]thieno(2,3-b)quinoline (BPTQ) has a higher order of interaction with the kinase receptors than other PTQ derivatives. In vitro screening confirms that BPTQ inhibits VEGFR1 and CHK2, with the IC₅₀ values of 0.54 and 1.70 µmol/L, respectively. Further, cytotoxicity of BPTQ was measured by trypan blue assay. Treatment with BPTQ decreased the proliferation of HL-60 cells with an IC₅₀ value of 12 µmol/L and induces apoptosis, as explicated by the fall in the mitochondrial membrane potential, annexin V labeling and increased expression of caspase-3. Taken together, these data suggest that BPTQ possess ability to inhibit PKs and to induce cell death in human promyelocytic leukemia cells.     

Aurora kinase inhibitor patents and agents in clinical testing: an update (2009 – 10)

Introduction: Mitosis is a key step in the cell cycle and is controlled by several cell cycle regulators, including aurora kinases. Aurora family members A, B and C are essential for spindle assembly, centrosome maturation, chromosomal segregation and cytokinesis. Overexpression/amplification of aurora kinases has been implicated in oncogenic transformation, including the development of chromosomal instability in cancer cells. Hence, the use of aurora kinase small molecule inhibitors as a potential molecular-targeted therapeutic intervention for cancer is being pursued by various researchers.

Area covered: This review provides an update on aurora kinase inhibitors based on developments from 2009 to 2010. The medicinal chemistry aspects of aurora kinase inhibitors, with a particular emphasis on the patent literature, are reviewed. Databases such as PubMed, SCOPUS, Scifinder and www.clinicaltrials.gov database were used to search for literature in the preparation of this review.

Expert opinion: Around a dozen aurora kinase inhibitors are currently undergoing various Phase I – II evaluations for different human cancers. Instead of being applied as a monotherapy, combinations of aurora kinase inhibitors and existing chemotherapeutic compounds seem to give better therapeutic outcomes and are, therefore, a promising future cancer therapy.     

γH2AX as a novel endpoint to detect DNA damage: Applications for the assessment of the in vitro genotoxicity of cigarette smoke

Histone H2AX is rapidly phosphorylated to become γH2AX after exposure to DNA-damaging agents that cause double-strand DNA breaks (DSBs). γH2AX can be detected and quantified by numerous methods, giving a direct correlation with the number of DSBs. This relationship has made γH2AX an increasingly utilised endpoint in multiple scientific fields since its discovery in 1998. Applications include its use in pre-clinical drug assessment, as a biomarker of DNA damage and in in vitro mechanistic studies.Here, we review current in vitro regulatory and non-regulatory genotoxicity assays proposing the γH2AX assay as a potential complement to the current test battery.Additionally, we evaluate the use of the γH2AX assay to measure DSBs in vitro in tobacco product testing.     

Synthesis of silica chemisorbed bis(hydrogensulphato)benzene (SiO2–BHSB) as a new hybrid material and it's utility as an efficient,recyclable catalyst for the green synthesis of bis(indolyl)methanes

Synthesis of silica chemisorbed bis(hydrogensulphato)benzene (SiO₂-BHSB) was achieved as a new hybrid catalytic material, its structure, stoichiometry and stability was established using modern analytical techniques such as CP-MAS ¹³C NMR, CP-MAS ²⁹Si NMR, EDX, FT-IR, TGA and DTG. The synthesised material SiO₂–BHSB was observed as an environmentally benign, recyclable catalyst for the synthesis of bis(indolyl)methanes (BIMs) via an electrophilic substitution reaction of indoles by aldehydes or ketones under solvent free grinding condition. A range of structurally diverse aldehydes, ketones and indoles were smoothly undergone the developed catalytic protocol to offer good to excellent yields of corresponding bis(indolyl)methane derivatives in shorter reaction times. The synthesised material SiO₂–BHSB showed a sustained catalytic activity up to five cycles of its reuse for the synthesis of BIMs. The catalytic protocol offered a chemo-selective route for the synthesis of BIMs, in which aldehydes are pushed exclusively in presence of ketones to undergo the reaction. Simple working procedure, ease of isolation of the catalyst, environmentally compatible energy conditions and no side products are the additional salient features of this protocol.     

Photosensitization of thymine nucleobase by benzophenone derivatives as models for photoinduced DNA damage: Paterno-Büchi vs energy and electron transfer processes

Time-resolved and product studies have shown that there is a strong interaction between drugs containing the benzophenone chromophore and the free thymidine nucleoside. In quantitative terms, such an interaction is stronger for the lowest lying npi* triplet states (S-ketoprofen) than for mixed npi*-pipi* triplets (fenofibrate and fenofibric acid), as indicated by the quenching rate constants. This is consistent with a Paterno-Büchi photoreaction, where the initial step is the formation of a new bond between the excited carbonyl oxygen and one of the thymine olefinic carbons. Actually, oxetanes are obtained as photoproducts when benzophenone is irradiated in the presence of thymidine. Hence, triplet-triplet energy transfer resulting in formation of cyclobutane pyrimidine dimers, which would be thermodynamically disfavored, does not seem to play a major role. However, in DNA, the contribution of energy transfer could be higher, due to the lower energy of the thymine triplet in the biomacromolecule. These results are discussed in connection with the observed DNA damage upon photosensitization with ketoprofen, fenofibrate, and fenofibric acid.     

Underreporting in pharmacovigilance: an intervention for Italian GPs (Emilia–Romagna region)

Purpose

Underreporting is a major limitation of spontaneous reporting systems for suspected adverse drug reactions (ADRs). Several interventions to increase the ADR reporting rate have been proposed, but their efficacy remains poorly investigated.

Methods

This was a questionnaire study aimed at assessing the knowledge, attitudes, and behavior of general practitioners (GPs) regarding ADR reporting and at evaluating whether a monthly e-mail-based newsletter on drug safety could affect the rate and the quality of the ADR reports submitted by these GPs. Three local health authorities (LHAs) of the Emilia–Romagna region were chosen on the basis of their ADR reporting rate during the period preceding the study: Rimini (high), Ferrara (average), and Piacenza (low reporting rate). All GPs (n?=?737) associated with these three LHAs were recruited. The pooled number of ADR reports sent by GPs in the remaining seven LHAs of the region was used as controls. The study covered a period of 3 years and was divided into: (1) identification of the reasons leading to underreporting through a questionnaire (Phase I); (2) the intervention, i.e., sending a newsletter for a 10-month period (Phase II); (3) evaluation of the intervention outcomes during the 10 months following the period in which the newsletter had been received (Phase III).

Results

Among GPs involved, 22.8 % returned the questionnaire. Over 94 % of the respondents considered the spontaneous reporting of suspected ADRs to be part of their professional obligations, but only 6.5 % had submitted at least one report in the previous 6 months. Following the completion of Phase II, the overall number of reports coming from the LHAs subjected to the intervention rose by 49.2 % compared to 2009, while the number of reports coming from the control LHAs increased by 8.8 %. Rimini and Piacenza showed a 200 % increase in the number of ADR reports submitted by GPs, while the number of ADR reported submitted by the control group decreased by 25.5 %. In 2011, the number of overall ADRs reports from the LHAs subjected to the intervention decreased by 6.8 %; this decrease reached 50.0 % of the GPs. Control HLAs showed an overall decline of 4.3 %, while the total number of ADRs from GPs increased by 63.3 %. Ferrara was excluded from the analysis due to confounding factors.

Conclusions

The periodic e-mail update on the safety of drugs represents an effective and inexpensive way to raise the awareness of GPs on the importance of spontaneous ADR reporting. Since the outcome of the intervention seemed to disappear after the intervention was stopped, there appears to be a need to adopt a policy of regular updates and educational strategies for health professionals.     

Small molecules and antibodies for the treatment of psoriasis: a patent review (2010–2015)

Introduction: Psoriasis is a chronic condition whose therapeutic armamentarium is increasingly being discussed, particularly when compared to past decades. The use of biologic agents has profoundly changed the history of this disease, as well as the management of psoriatic patients. Due to the enormous interest in psoriasis, as demonstrated within the scientific community and pharmaceuticals, new therapeutic targets have been identified and novel patented therapeutics are being tested.

Areas covered: This review sought to give an overview of small molecules and antibodies patented in the last five years for the treatment of psoriasis. Therapeutic agents either in the early or advanced phase of development have been described, primarily based on a systematic search using the PubMed Medline database.

Expert opinion: Though the recent introduction of new antipsoriatic agents has facilitated the management of long-term psoriasis, there is still a strong desire for alternative therapeutic options. Indeed, there remain unmet needs regarding safety and efficacy of psoriasis treatment that should be addressed. In this context, recently patented drugs may prove valid, interesting, and promising within the therapeutic paradigm.     

Medically assisted recovery from opiate dependence within the context of the UK drug strategy: Methadone and Suboxone (buprenorphine–naloxone) patients compared

The focus of drug policy in the UK has shifted markedly in the past 5 years to move beyond merely emphasising drug abstinence towards maximising individuals' opportunities for recovery. The UK government continues to recognise the prescribing of narcotic medications indicated for opiate dependence as a key element of these individuals' recovery journey. This article describes a small, naturalistic comparison of the efficacy of the two most commonly prescribed opiate substitute medications in the UK—methadone hydrochloride (methadone oral solution) and Suboxone (buprenorphine–naloxone sublingual tablets)—for reducing current heroin users' (n = 34) days of heroin use, and preventing short-term abstainers (n = 37) from relapsing to regular heroin use. All patients had been prescribed either methadone or Suboxone for maintenance for 6 months prior to intake. Results showed that when controlling for a number of patient-level covariates, both methadone and Suboxone significantly reduced current users' days of heroin use between the 90 days prior to intake and at the 8-month follow-up, with Suboxone yielding a significantly larger magnitude reduction in heroin use days than methadone. Methadone and Suboxone were highly and equally effective for preventing relapse to regular heroin use, with all but 3 of 37 (91.9%) patients who were abstinent at intake reporting past 90-day point prevalence heroin abstinence at the 8-month follow-up. Overall, prescribing methadone or Suboxone for eight continuous months was highly effective for initiating abstinence from heroin use, and for converting short-term abstinence to long-term abstinence. However, the study design, which was based on a relatively small sample size and was not able randomise patients to medication and so could not control for the effects of potential prognostic factors inherent within each patient group, means that these conclusions can only be made tentatively. These positive but preliminary indications of the comparative efficacy of methadone and Suboxone for treating opiate dependence now require replication in a well-powered, randomised controlled trial.     

Mechanism-based PK–PD model for the prolactin biological system response following an acute dopamine inhibition challenge: quantitative extrapolation to humans

The aim of this investigation was to develop a mechanism-based pharmacokinetic-pharmacodynamic (PK-PD) model for the biological system prolactin response following a dopamine inhibition challenge using remoxipride as a paradigm compound. After assessment of baseline variation in prolactin concentrations, the prolactin response of remoxipride was measured following (1) single intravenous doses of 4, 8 and 16?mg/kg and (2) following double dosing of 3.8?mg/kg with different time intervals. The mechanistic PK-PD model consisted of: (i) a PK model for remoxipride concentrations in brain extracellular fluid; (ii) a pool model incorporating prolactin synthesis, storage in lactotrophs, release into- and elimination from plasma; (iii) a positive feedback component interconnecting prolactin plasma concentrations and prolactin synthesis; and (iv) a dopamine antagonism component interconnecting remoxipride brain extracellular fluid concentrations and stimulation of prolactin release. The most important findings were that the free brain concentration drives the prolactin release into plasma and that the positive feedback on prolactin synthesis in the lactotrophs, in contrast to the negative feedback in the previous models on the PK-PD correlation of remoxipride. An external validation was performed using a dataset obtained in rats following intranasal administration of 4, 8, or 16?mg/kg remoxipride. Following simulation of human remoxipride brain extracellular fluid concentrations, pharmacodynamic extrapolation from rat to humans was performed, using allometric scaling in combination with independent information on the values of biological system specific parameters as prior knowledge. The PK-PD model successfully predicted the system prolactin response in humans, indicating that positive feedback on prolactin synthesis and allometric scaling thereof could be a new feature in describing complex homeostatic mechanisms.     

Inhibitors of the kynurenine pathway as neurotherapeutics: a patent review (2012–2015)

Introduction: The proven pathological alterations in the kynurenine pathway of tryptophan metabolism, either in preclinical models of neurological and psychiatric disorders or in human samples themselves, elicited numerous attempts to restore the altered balance via pharmaceutical manipulation of the pathway.

Areas covered: The aim of the authors was to conduct a review of relevant scientific data on enzyme inhibitors of the kynurenine pathway, with special attention to pipeline drug development strategies based on relevant patent literature, covering the period of 2012–2015. Considering the magnitude of the topic, only the most prominent examples of lead compounds and substances necessary to enlighten structure activity relationships were reported.

Expert opinion: Although the clinical and preclinical data are reassuring, there is a lack of applicable drugs in daily clinical practice. However, the recent determination of enzyme structures considerably promoted the development of potent inhibitors, most of them having been designed as a structural analog of the natural enzyme substrate. Especially, the inhibition of indolamine 2,3-dioxygenase in central nervous system tumors, the inhibition of kynurenine aminotransferase in cognitive dysfunction, and the inhibition of kynurenine 3-monooxygenase in neurodegenerative disorders, such as Huntington’s disease, each show great promise.