Low Molecular Weight Drugs Research Articles

Composite magnetic microcapsules based on multilayer assembly of ethanol-soluble polyimide brushes and magnetite nanoparticles: preparation and response to magnetic field gradient

Microcapsules consisting of a calcium carbonate core template surrounded by shells containing magnetite nanoparticles and ethanol-soluble polyimide brushes with polymethacrylic acid side chains were assembled using a layer-by-layer technique under nonaqueous conditions. These microcapsules represent a potential solution to the challenging problem of encapsulating water-soluble compounds, particularly low molecular weight drugs. It was possible to move these microcapsules with magnetite nanoparticles in their shells by applying a magnetic field gradient. The novel microcapsules were characterized by optical microscopy, atomic force microscopy, and scanning electron microscopy. Using the brush-like polyanions instead of linear polyanions made it possible to increase the shell thickness gain per ionic assembly cycle by a factor of ~3.

Practice guidelines for monitoring the safety of tofacitinib (according to the proceedings of the Expert Council resolution dated 14 October 2014, Moscow)

The Meeting of the Expert Council considered in detail the key aspects associated with the possible development of adverse reactions during therapy with tofacitinib (TOFA). Active discussion gave rise to a resolution that summarized the main facts concerning the safety of TOFA and gave practical recommendations for the screening and monitoring of infections, cardiovascular diseases and other key areas requiring that exclusive control should be exercised during this therapy. TOFA is the first drug from a new group of immunomodifying and anti-inflammatory drugs, intracellular kinase inhibitors. As of now, it is the only drug that belongs to a class of the so-called small molecules, which is approved for the treatment of rheumatoid arthritis in the Russian Federation and a number of other countries. TOFA is a low molecular weight drug for oral administration; however, its unique mechanism of action brings it close to that of biological agents. A broad spectrum of biological effects of TOFA and its potential effect on a number of important physiological processes demand for special attention to the safety of its therapy.

Inhibition of SERPINe1 reduces rhabdoviral infections in zebrafish.

While exploring the molecular mechanisms behind the fin hemorrhages that follow zebrafish (Danio rerio) early infection with viral haemorrhagic septicemia virus (VHSV), we discovered that most serpin (serine protease inhibitor) gene transcripts were upregulated, except those of serpine1. Surprisingly, only SERPINe1-derived 14-mer peptide and low molecular weight drugs targeting SERPINe1 (i.e. tannic acid, EGCG, tiplaxtinin) inhibited in vitro infections not only of VHSV, but also of other fish rhabdoviruses such as infectious hematopoietic necrosis virus (IHNV) and spring viremia carp virus (SVCV). While the mechanisms that inhibited rhabdoviral infections remain speculative, these and other results suggested that SERPINEe1-derived peptide specifically targeted viral infectivity rather than virions. Practical applications might be developed from these studies since preliminary evidences showed that tannic acid could be used to reduce VHSV-caused mortalities. These studies are an example of how the identification of host genes targeted by viral infections using microarrays might facilitate the identification of novel prevention drugs in aquaculture and illuminate viral infection mechanisms.

Crystallization Kinetics of Indomethacin/Polyethylene Glycol Dispersions Containing High Drug Loadings.

The reproducibility and consistency of physicochemical properties and pharmaceutical performance are major concerns during preparation of solid dispersions. The crystallization kinetics of drug/polyethylene glycol solid dispersions, an important factor that is governed by the properties of both drug and polymer has not been adequately explored, especially in systems containing high drug loadings. In this paper, by using standard and modulated differential scanning calorimetry and X-ray powder diffraction, we describe the influence of drug loading on crystallization behavior of dispersions made up of indomethacin and polyethylene glycol 6000. Higher drug loading increases the amorphicity of the polymer and inhibits the crystallization of PEG. At 52% drug loading, polyethylene glycol was completely transformed to the amorphous state. To the best of our knowledge, this is the first detailed investigation of the solubilization effect of a low molecular weight drug on a semicrystalline polymer in their dispersions. In mixtures containing up to 55% indomethacin, the dispersions exhibited distinct glass transition events resulting from amorphous-amorphous phase separation which generates polymer-rich and drug-rich domains upon the solidification of supercooled polyethylene glycol, whereas samples containing at least 60% drug showed a single amorphous phase during the period in which crystallization normally occurs. The current study demonstrates a wide range in physicochemical properties of drug/polyethylene glycol solid dispersions as a result of the complex nature in crystallization of this system, which should be taken into account during preparation and storage.

Thin-layer chromatography/matrix-assisted laser desorption/ionisation mass spectrometry and matrix-assisted laser desorption/ionisation mass spectrometry imaging for the analysis of phospholipids in LS174T colorectal adenocarcinoma xenografts treated with the vascular disrupting agent DMXAA.

5,6-Dimethylxanthenone-4-acetic acid (DMXAA) is a low molecular weight drug of the flavonoid group, which has an anti-vascular effect in tumours causing endothelial cell apoptosis and activation of cytokines. Flavonoid-based compounds have been reported to lead to an upregulation in the expression of lysophosphatidylcholines (LPC)-type lipids in solid tumours. A study employing TLC/MALDI-MS and MALDI-MS imaging to examine LS174T colorectal adenocarcinoma xenografts following administration of DMXAA has been conducted into this effect. LS174T colorectal adenocarcinoma xenografts grown in male immune-deficient mice were treated with 27.5 mg/kg DMXAA. The control (before treatment) and 4 h and 24 h post-treatment tumours were excised and divided into two. MALDI-MS imaging experiments were carried out on 12 µm cryosections sections taken from one half of the tumours and from the other half the lipids were extracted and analysed by TLC/MALDI-MS. These experiments were carried out in triplicate. Statistical analysis of the MALDI-MS imaging data set indicated an increased amount of LPC in the 24 h post-treated sample and a decreased amount of PC in the 24 h post-treated sample, compared with the 4 h post-treated sample and the control. These effects were confirmed by the TLC/MALDI-MS data. The lipid extracts were separated into six spots on the TLC plate. These were identified as arising from different lipids classes, i.e. LPC, sphingomyelins (SM), phosphatidylcholines (PC) and phosphatidylethanolamines (PE). The TLC/MALDI-MS data indicated that LPC were highly expressed in the 4 h and 24 h post-treated tumour samples compared with the control. Examination of the mass spectrometric images confirms this increase and demonstrates additionally that the increase in the signals arising from LPC appears to be localised primarily within the central areas of the xenograft. An increase in expression of LPC lipids in solid tumours treated with DMXAA has been demonstrated and shown to be localised in the central area of the tumour.

Polymeric biomaterials and nanomedicines

This overview intends to demonstrate the close relationship between the design of smart biomaterials and water-soluble polymer–drug conjugates. First, the discovery and systematic studies of hydrogels based on crosslinked poly(meth)acrylic acid esters and substituted amides is described. Then, the lessons learned for the design of water-soluble polymers as drug carriers are highlighted. The current state-of-the-art in water-soluble, mainly poly[N-(2-hydroxypropyl)methacylamide (HPMA), polymer–drug conjugates is shown including the design of backbone degradable HPMA copolymer carriers. In the second part, the modern design of hybrid hydrogels focuses on the self-assembly of hybrid copolymers composed from the synthetic part (backbone) and biorecognizable grafts (coiled-coil forming peptides or morpholino oligonucleotides) is shown. The research of self-assembling hydrogels inspired the invention and design of drug-free macromolecular therapeutics – a new paradigm in drug delivery where crosslinking of non-internalizating CD20 receptors results in apoptosis in vitro and in vivo. The latter is mediated by biorecognition of complementary motifs; no low molecular weight drug is needed.

Regioselective Ring-Opening Polymerization of a Polyhydroxycarboxylic Acid for the Synthesis of a Nanoscale Carrier Material with pH-Dependent Stability and Sustained Drug Release.

Synthetic polyesters are usually composed of monohydroxycarboxylic acids to avoid the problem of regioselectivity during ring-opening polymerization. In contrast, the linear polyester BICpoly contains four secondary OH groups and is nevertheless esterified regioselectively at only one of these positions. Neither the synthesis of the tricyclic monomers nor the ring-opening polymerization requires protecting groups, making BICpoly an attractive novel and biocompatible polymer. BICpoly nanoparticles can be loaded with low-molecular weight drugs or coated onto surfaces as thin films. The release of loaded compounds makes BICpoly an attractive depot for drug release, as shown herein by loading BICpoly with dyes or the cytostatic drug doxorubicin. BICpoly is distinguishable from other polymers by its characteristic pH-dependent degradation.

Некоторые вопросы регулирования обращения небиологических лекарственных средств сложного химического строения

Представлен аналитический обзор широко обсуждаемых в настоящее время в мире вопросов классификации лекарственных средств (ЛС), основанной на методах/источниках получения и сложности строения с выделением 3 типов: а) низкомолекулярных синтетических полностью охарактеризованных химически «обычных» ЛС; б) биологических ЛС сложного, не полностью охарактеризованного химического строения (БП); в) небиологических/синтетических ЛС сложного не полностью охарактеризованного химического строения (НБЛССХС). Данная классификация имеет не только научное, но и прикладное значение в связи с тем, что НБЛССХС (липосомальные препараты, комплексные железо-углеводные комплексы, глатирамоиды, низкомолекулярные гепарины) имеют сходство с БП по структуре (смеси прочно связанных друг с другом высокомолекулярных фрагментов, не поддающихся выделению и полной идентификации), а также биологическим/фармакологическим эффектам (иммуногенность, недостаточно полная информация о механизме действия др.). Практика последних лет свидетельствует о том, что генерические версии НБЛССХС также, как и в случае биоподобных препаратов, из-за различий в процессе производства не являются идентичными оригинальным препаратам. В этой связи представляется недостаточной сокращенная процедура экспертизы и регистрации этих ЛС, используемая в случае «обычных» низкомолекулярных ЛС.

The iron chelator deferasirox affects redox signalling in haematopoietic stem/progenitor cells.

The iron chelator deferasirox (DFX) prevents complications related to transfusional iron overload in several haematological disorders characterized by marrow failure. It is also able to induce haematological responses in a percentage of treated patients, particularly in those affected by myelodysplastic syndromes. The underlying mechanisms responsible for this feature, however, are still poorly understood. In this study, we investigated the effect of DFX-treatment in human haematopoietic/progenitor stem cells, focussing on its impact on the redox balance, which proved to control the interplay between stemness maintenance, self-renewal and differentiation priming. Here we show, for the first time, that DFX treatment induces a significant diphenyleneiodonium-sensitive reactive oxygen species (ROS) production that leads to the activation of POU5F1 (OCT4), SOX2 and SOX17 gene expression, relevant in reprogramming processes, and the reduction of the haematopoietic regulatory proteins CTNNB1 (β-Catenin) and BMI1. These DFX-mediated events were accompanied by decreased CD34 expression, increased mitochondrial mass and up-regulation of the erythropoietic marker CD71 (TFRC) and were compound-specific, dissimilar to deferoxamine. Our findings would suggest a novel mechanism by which DFX, probably independently on its iron-chelating property but through ROS signalling activation, may influence key factors involved in self-renewal/differentiation of haematopoietic stem cells.

Mild hyperthermia influence on Herceptin(®) properties.

BackgroundMild hyperthermia (mHT) increases the tumor perfusion and vascular permeability, and reduces the interstitial fluid pressure, resulting in better intra-tumoral bioavailability of low molecular weight drugs. This approach is potentially also attractive for delivery of therapeutic macromolecules, such as antibodies. Here, we investigated the effects of mHT on the stability, immunological and pharmacological properties of Herceptin®, a clinically approved antibody, targeting the human epidermal growth factor receptor 2 (HER-2) overexpressed in breast cancer.ResultsHerceptin® was heated to 37°C (control) and 42°C (mHT) for 1 hour. Formation of Herceptin® aggregates was measured using Nile Red assay. mHT did not result in additional Herceptin® aggregates compared to 37°C, showing the Herceptin® stability is unchanged. Immunological and pharmacological properties of Herceptin® were evaluated following mHT using HER-2 positive breast cancer cells (BT-474). Exposure of Herceptin® to mHT preserved recognition and binding affinity of Herceptin® to HER-2. Western-blot and cell proliferation assays on BT-474 cells showed that mHT left the inhibitory activities of Herceptin® unchanged.ConclusionsThe stability, and the immunological and pharmacological properties of Herceptin® are not negatively affected by mHT. Further in-vivo studies are required to evaluate the influence of mHT on intra-tumoral bioavailability and therapeutic effectiveness of Herceptin®.

Effect ofBacillus cereusHemolysin II on Hepatocyte Cells

We investigated the efficiency of increasing the permeability (permeabilization) of cell membranes in primary liver cells by Bacillus cereus hemolysin II. An assessment of the degree of permeabilization was car ried out by measuring the fluorescence intensity of various low molecular weight dyes, which enter through pores into hepatocyte cells cultivated with hemolysin. We uncovered a high efficacy of hemolysin HlyII action on hepatocyte cell walls, which exceeded the effect of nonionic detergent, digitonin, which is commonly employed for pore formation in various cell membranes. Our results also point to the reversibility of membrane permeabilization in primary hepatocytes. The data obtained in this study can be utilized for assessments of pore-forming activity, in studies of hepatic mechanisms of action, and also the determination of the liver toxicity for different low molecular weight drugs.

Conjugates of degraded and oxidized hydroxyethyl starch and sulfonylureas: synthesis, characterization, and in vivo antidiabetic activity.

Orally administered drugs usually face the problem of low water solubility, low permeability, and less retention in bloodstream leading to unsatisfactory pharmacokinetic profile of drugs. Polymer conjugation has attracted increasing interest in the pharmaceutical industry for delivering such low molecular weight (Mw) drugs as well as some complex compounds. In the present work, degraded and oxidized hydroxyethyl starch (HES), a highly biocompatible semisynthetic biopolymer, was used as a drug carrier to overcome the solubility and permeability problems. The HES was coupled with synthesized N-arylsulfonylbenzimidazolones, a class of sulfonylurea derivatives, by creating an amide linkage between the two species. The coupled products were characterized using GPC, FT-IR, (1)H NMR, and (13)C NMR spectroscopy. The experiments established the viability of covalent coupling between the biopolymer and N-arylsulfonylbenzimidazolones. The coupled products were screened for their in vivo antidiabetic potential on male albino rats. The coupling of sulfonylurea derivatives with HES resulted in a marked increase of the hypoglycemic activity of all the compounds. 2,3-Dihydro-3-(4-nitrobenzensulfonyl)-2-oxo-1H-benzimidazole coupled to HES10100 was found most potent with a 67% reduction in blood glucose level of the rats as compared to 41% reduction produced by tolbutamide and 38% by metformin.

Biocompatibility of poly(d,l-lactic-co-hydroxymethyl glycolic acid) microspheres after subcutaneous and subcapsular renal injection

Poly(d,l-lactic-co-hydroxymethyl glycolic acid) (PLHMGA) is a biodegradable copolymer with potential as a novel carrier in polymeric drug delivery systems. In this study, the biocompatibility of PLHMGA microspheres (PLHMGA-ms) was investigated both in vitro in three different cell types (PK-84, HK-2 and PTECs) and in vivo at two implantation sites (by subcutaneous and subcapsular renal injection) in rats. Both monodisperse (narrow size distribution) and polydisperse PLHMGA-ms were prepared with volume weight mean diameter of 34 and 17μm, respectively. Mono and polydisperse PLHMGA-ms showed good cytocompatibility properties upon 72h incubation with the cells (100μg microspheres/600μL/cell line). A mild foreign body reaction was seen shortly after subcutaneous injection (20mg per pocket) of both mono and polydisperse PLHMGA-ms with the presence of mainly macrophages, few foreign body giant cells and myofibroblasts. This transient inflammatory reaction diminished within 28 days after injection, the time-point at which the microspheres were degraded. The degradation profile is comparable to the in vitro degradation time of the microspheres (i.e., within 35 days) when incubated at 37°C in phosphate buffered saline. Subcapsular renal injection of monodisperse PLHMGA-ms (10mg) in rats was characterized with similar inflammatory patterns compared to the subcutaneous injection. No cortical damage was observed in the injected kidneys. In conclusion, this study demonstrates that PLHMGA-ms are well tolerated after in vivo injection in rats. This makes them a good candidate for controlled delivery systems of low-molecular weight drugs as well as protein biopharmaceuticals.

Visualization and analysis of adverse reactions of molecularly targeted anticancer agents using the self-organizing map (SOM)

Molecularly targeted anticancer agents cause a variety of adverse reactions compared with conventional anticancer agents because of their unique mechanisms of action. Sources of drug information such as package inserts (PIs) provide primarily document-based and numerical information. Therefore it is not easy to obtain a complete picture of drugs with similar effects, or to understand differences among drugs. In this study we used the self-organizing map (SOM) technique to visualize the adverse reactions indicated on PIs of 23 molecularly targeted anticancer agents as of March 2013. In both the presence/absence version and the frequency version, SOM was divided into domains according to mechanism of action, antibody drug or low-molecular weight drug, and molecular target. The component planes of the 753 adverse reaction items in the frequency version enabled us to grasp all available information and differences among the drugs. In some component planes in the presence/absence version, an adverse reaction that had not been reported for a drug but had already been reported for its proximally positioned drug(s) as of March 2013, was found to be reported thereafter by the Drug Safety Update (DSU) or the Adverse Event Report Search System "CzeekV," which is based on FDA Adverse Event Reporting System (FAERS). Our results suggest that visualization of the adverse reactions of molecularly targeted anticancer agents by the SOM technique is useful not only to acquire all available information and differences among drugs, but also to predict the appearance of adverse reactions.

Folate receptor-β in activated macrophages: ligand binding and receptor recycling kinetics.

Activated macrophages overexpress a receptor for the vitamin folic acid termed the folate receptor β (FR-β). Because conjugation of folate to low molecular weight drugs, genes, liposomes, nanoparticles, and imaging agents has minor effects on FR binding, the vitamin can be exploited to target both therapeutic and imaging agents to activated macrophages without promoting their uptake by other healthy cells. In this paper, we characterize the binding, internalization, and recycling kinetics of FR-β on activated macrophages in inflamed tissues of rats with adjuvant-induced arthritis. Our results demonstrate that saturation of macrophage FR is achieved at injection doses of ∼150-300 nmol/kg, with more rapidly perfused tissues saturating at lower doses than inflamed appendages. After binding, FR-β internalizes and recycles back to the cell surface every ∼10-20 min, providing empty receptors for additional folate conjugate uptake. Because the half-life of low molecular weight folate conjugates in the vasculature is usually <1 h, these data suggest that targeting of folate conjugates to activated macrophages in vivo can be maximized by frequent dosing at conjugate concentrations that barely saturate FR (∼150 nmol/kg), thereby minimizing nonspecific binding to receptor-negative tissues and maximizing the probability that unoccupied cell surface receptors will be exposed to folate-drug conjugate.

Spatial distribution of theobromine--a low MW drug--in tissues via matrix-free NALDI-MS imaging.

The ability of nano-assisted laser desorption-ionization mass spectrometry imaging (NALDI-IMS) to provide selective chemical monitoring with appropriate spatial distribution of a low molecular drug in a biological tissue was investigated. NALDI-IMS is a matrix-free laser desorption ionization (LDI) protocol based on imprinting of tissue constituents on a nanostructured surface. Using the accumulation of theobromine in rat kidney as a model, NALDI-IMS was found to provide well-resolved images of the special distribution of this low molecular weight (MW) drug in tissue.

Development of dual-responsive chitosan–collagen scaffolds for pulsatile release of bioactive molecules

Advancement in polymer science and engineering has led to the development of new polymeric systems for well-controlled delivery of therapeutic agents. In this work, thermo and pH responsive chitosan–collagen (CHT–CLG) scaffolds were prepared using a non-residue strategy. CHT–CLG scaffolds (pH sensitive) were produced by freeze drying method, cross-linked with glutaraldehyde, and coated with poly(N,N′-diethylacrylamide) (PDEAAm) in supercritical media to confer the thermoresponsive behavior. This green and integrated process generated a wide range of porous structures with different mechanical properties, reversible swelling ability and controlled biodegradability, depending on the scaffold composition and cross-linking degree. Microarchitectural analysis by scanning electron microscopy and mercury intrusion porosimetry demonstrated that the coating of the pores inner surface was efficiently achieved without compromising the porosity. The ability of these dual sensitive structures to control the release of a low molecular weight drug (ibuprofen, Ibu) and a model protein (BSA) was investigated. Additionally, a mathematical model was adjusted to the experimental release profiles in order to quantitatively describe the drug release and elucidate the underlying drug release mechanisms. The tunable morphological and mechanical properties together with the well-controlled pulsatile release of bioactive molecules make these structures attractive ON–OFF systems in biomedical and pharmaceutical fields.

A novel protocol allowing oral delivery of a protein complement inhibitor that subsequently targets to inflamed colon mucosa and ameliorates murine colitis.

While there is evidence of a pathogenic role for complement in inflammatory bowel disease, there is also evidence for a protective role that relates to host defence and protection from endotoxaemia. There is thus concern regarding the use of systemic complement inhibition as a therapeutic strategy. Local delivery of a complement inhibitor to the colon by oral administration would ameliorate such concerns, but while formulations exist for oral delivery of low molecular weight drugs to the colon, they have not been used successfully for oral delivery of proteins. We describe a novel pellet formulation consisting of cross-linked dextran coated with an acrylic co-polymer that protects the complement inhibitor CR2-Crry from destruction in the gastrointestinal tract. CR2-Crry containing pellets administered by gavage, were characterized using a therapeutic protocol in a mouse model of dextran sulphate sodium (DSS)-induced colitis. Oral treatment of established colitis over a 5-day period significantly reduced mucosal inflammation and injury, with similar therapeutic benefit whether or not the proton pump inhibitor, omeprazole, was co-administered. Reduction in injury was associated with the targeting of CR2-Crry to the mucosal surface and reduced local complement activation. Treatment had no effect on systemic complement activity. This novel method for oral delivery of a targeted protein complement inhibitor will reduce systemic effects, thereby decreasing the risk of opportunistic infection, as well as lowering the required dose and treatment cost and improving patient compliance. Furthermore, the novel delivery system described here may provide similar benefits for administration of other protein-based drugs, such as anti-tumour necrosis factor-α antibodies.

Carbohydrate PEGylation, an approach to improve pharmacological potency.

Conjugation with polyethylene glycol (PEG), known as PEGylation, has been widely used to improve the bioavailability of proteins and low molecular weight drugs. The covalent conjugation of PEG to the carbohydrate moiety of a protein has been mainly used to enhance the pharmacokinetic properties of the attached protein while yielding a more defined product. Thus, glycoPEGylation was successfully applied to the introduction of a PEGylated sialic acid to a preexisting or enzymatically linked glycan in a protein. Carbohydrates are now recognized as playing an important role in host–pathogen interactions in protozoal, bacterial and viral infections and are consequently candidates for chemotherapy. The short in vivo half-life of low molecular weight glycans hampered their use but methods for the covalent attachment of PEG have been less exploited. In this review, information on the preparation and application of PEG-carbohydrates, in particular multiarm PEGylation, is presented.

ChemInform Abstract: Screening and Confirmation Methods for GHB Determination in Biological Fluids

AbstractReview: 128 refs.