Polimery w medycynie最新文献

Background: Levocetirizine, active R (-) enantiomer of cetirizine, is an orally active and selective H1 receptor antagonist used medically as an anti-allergic. Allergic rhinitis is a symptomatic disorder of the nose induced by inflammation mediated by immunoglobulin E (IgE) in the membrane lining the nose after allergen exposure.

Objectives: The purpose of the present study was to prepare rapidly disintegrating tablets of levocetirizine after its complexation with β-cyclodextrin (β-CD).

Material and methods: Levocetirizine-β-CD complex tablets were prepared by direct compression technique using 3 synthetic superdisintegrants in different proportions. Development of the formulation in the present study was mainly based on the concentration of superdisintegrants and the properties of the drug. Nine batches of tablets were formulated and evaluated for various parameters: drug content, weight variation, water absorption ratio, wetting time, in vitro disintegration, hardness, friability, thickness uniformity, and in vitro dissolution.

Results: A Fourier-transform infrared spectroscopy (FTIR) study showed that there were no significant interactions between the drug and the excipients. The prepared tablets were good in appearance and showed acceptable results for hardness and friability. The in vitro disintegrating time of the formulated tablet batches was found to be 15-35 s percentage and the drug content of tablets in all formulations was found to be between 90-102%, which complied with the limits established in the United States Pharmacopeia.

Conclusions: Complexation of levocetirizine with β-CD significantly improves the solubility of the drug. The disintegration time of the tablets was decreased with an increase in superdisintegrant amount. The tablets (batch CPX5) had a minimum disintegration time of 20 s and 99.99% of the drug was released within 10 min.

Background: Solid dispersions are among the techniques successfully employed to enhance the dissolution of poorly water-soluble drugs. Microwave (MW)-assisted evaporative crystallization has been used to prepare solid dispersions of drugs and polymers.

Objectives: The aim of the study was to investigate the solubility of apremilast (APM) in water by exploring the effect of MW-assisted solid dispersion technology.

Material and methods: In the present study, solid dispersions of APM, a poorly water-soluble drug, were prepared. The solid dispersions were prepared using the conventional method (CM) and the MW-based solvent evaporation technique. Microwave energy was used to enhance the solubility and dissolution rate of APM. The physical mixture and solid dispersions were characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Apremilast tablets containing MW-assisted solid dispersions were prepared by the direct compression technique and compared with the marketed formulation (Aprezo tablets).

Results: The results obtained confirmed the conversion of crystalline APM to an amorphous form. The XRPD pattern of the MW-assisted formulation at a 2:1 ratio suggests the amorphous structure of APM within the formulation. Based on solubility studies results, Syloid® 244FP was selected as the best carrier. The dissolution study results suggested that the APM tablet prepared using MW-assisted solid dispersions at a 2:1 carrier/drug ratio improved the APM dissolution rate compared to the marketed formulation.

Conclusions: Based on the results, it can be concluded that the MW-assisted solid dispersion technique may be an effective approach to enhancing the dissolution profile of other poorly water-soluble drugs.

Dialysis membranes are the basic element of a hemodialyzer. Synthetic and natural materials characterized by various fiber arrangements are used in their production. The most up-to-date ones are made of synthetic polymers such as polyamide, phosphatidylserine (PS), polyacrylonitrile-based fiber (PAN), polyarylethersulfone, polyethersulfone, or polymethylmethacrylate. Dialysis membranes are characterized by the ability to remove uremic molecules, which can be divided into small water-soluble compounds, protein-bound compounds and larger "middle molecules". Newer membranes such as medium cut off membranes (MCO) allow the removal of a wider spectrum of uremic molecules, which reduces the risk of late complications of dialysis. Dialysis membranes are used in therapy methods such as low flux, high flux or HDx therapy. An important aim in dialysis membrane development is to increase their biocompatibility. Insufficient biocompatibility can result in complement activation or platelet activation, which can lead to an increased risk of cardiovascular complications. The aim of the study is to discuss the latest reports on dialysis membranes.

The uptake and specificity of drugs and the bioavailability of poorly soluble drugs has been improved by means of targeted drug delivery using nanoparticles. Many platforms have been used for nanoparticulate drug delivery and these include liposomes, polymer conjugates, metallic nanoparticles, polymeric micelles, dendrimers, nanoshells, and protein and nucleic acid-based nanoparticles. Starch is the 2nd most abundant natural polymer and has found wide use in drug delivery systems as binder, disintegrant and filler. However, its application is limited by the poor functional properties of native starch. Starch nanocrystals of different shapes and sizes can be obtained based on the starch origin and isolation process involved. Nanocrystals with varying morphology have been reported; from nanocrystals of platelet-like shaped waxy maize starch with 5-7 nm thickness and 15-40 nm diameters, to those with round and grape-like shape from potato starch granules, with sizes ranging from 40 nm to 100 nm. This review describes different methods of obtaining starch nanoparticles, their modification and application in drug delivery.

Background: Presently, most of receptacles used in medicine are made of polymeric materials. This is due to, e.g., low price, low weight, and aesthetic values of these materials. The important issue is to ensure long life of polymer in order to protect the medicines closed in the boxes. However, all materials during exploitation are exposed to many factors, which can cause degradation of polymer materials. Degradation processes lead to deterioration of thermomechanical properties of polymers.

Objectives: The aim of this syudy was to examine the influence of electrochemical ageing on properties of polymeric materials used in production of receptacles for drugs and boxes for medical use.

Material and methods: We conducted comparative analysis of samples before and after electrochemical ageing, cut out of receptacles for drugs made from polyethylene, as well as from boxes for medical use and Eppendorf tube made from polypropylene. Investigating methods included differential scanning calorimetry (DSC) and imaging of microstructure ×400 magnification.

Results: We noticed different value of the degree of crystallinity for the aged samples in comparison to not aged samples. The change in value of temperature of physical transformation was also detected. In the aged samples defragmentation of crystal structure was observed.

Conclusions: Electrochemical ageing results in changes of properties of polymeric materials used in production of medical receptacles.

Background: Ciprofloxacin is a broad-spectrum fluoroquinolone antibacterial drug to which most Gram-negative and many Gram-positive bacteria are highly susceptible. Fluoroquinolones are administered repeatedly, twice a day for 5 days, during the course of therapy. Hence, they require repeated administration. Ciprofloxacin qualifies as a drug candidate for a controlled-release drug delivery system.

Objectives: The present work was aimed to develop ciprofloxacin hydrochloride-containing matrix tablets by the wet granulation method.

Material and methods: The tablets were prepared using EthocelTM 100 Premium and Eudragit® RS PO (Evonik Laboratory, Mumbai, India) as a rate-controlling polymer. Granular dioctyl phthalate (DCP) was used as a diluent. An isopropyl alcohol and dichloromethane (1:1) mixture was used as a granulating agent. The effect of the formulation variables on tablet performance was examined based on weight variation, hardness, friability, thickness, and drug release profiles. The results suggested that the tablets had good integrity.

Results: The tablets were stable for 18 months. Formulation F7 gave a linear release pattern up to 12 h. The release of ciprofloxacin from formulation F7 followed zero-order kinetics. The release mechanism was found to be diffusion-controlled as the Higuchi equation was obeyed.

Conclusions: Ciprofloxacin hydrochloride-containing matrix tablets were prepared successfully. The tablets had good integrity and were found stable for 18 months.

Background: Natural polymers have been used in medical, pharmaceutical, cosmetic and food industry. They should be characterized before their possible applications in different industries.

Objectives: The objective of this study was to characterize Kheri (Acacia chundra, family: Mimosaceae) gum using analytical, mathematical and pharmaceutical approaches.

Material and methods: Crude Kheri gum (KG) was purified using distilled water as a solvent and ethanol as a precipitating agent. KG was characterized in terms of phytochemical screening, micromeritic properties, microbial load, ash value, rheological behavior, solid state 1H nuclear magnetic resonance (NMR), mass spectra and Fourier-transform infrared spectroscopy (FTIR) studies for their possible applications in food, cosmetics and pharmaceutical industry.

Results: Studies show that KG contains carbohydrates, while protein, fat, volatile oils, alkaloids and glycosides are absent. 1% aqueous solution of polysaccharide showed 25.58 × 103 kJ/kg activation energy and 1.39 Reynold's number. Viscosity average molecular weight of purified gum was found 1.73 × 105 D. Thermodynamic parameters, i.e., change in enthalpy ΔHv and change in enthalpy ΔHv, were found to be 12.26 × 103 kJ/mol and 24.47 kJ/mol, respectively. Mathematical approach also determined the rod shaped conformation of KG in aqueous solution. IR spectroscopic study shows the presence of free (COO-) and esterified (COO-R) carboxylic acid, ether (C-O stretching), galacturonic acid and mannose in polysaccharide 1H NMR study predicts presence of tetrahydropyran hydrogen in molecule. Furthermore, KG was also characterized as a suspending agent using paracetamol as a model drug. Flow rate, pH, particle size and settling behavior of suspensions were evaluated. Initial particle size of dispersed phase particles does not change significantly after 45 days.

Conclusions: From the findings of the research it can be concluded that KG can be used as an excipient in cosmaceuticals and pharmaceuticals and its characteristic rheological behavior may attract rheologists.

Background: Nevirapine, an antiviral drug, is a potent reverse transcriptase inhibitor (NNRTI). It is used in combination with nucleoside analogues for treatment of HIV type-1 (HIV-1) infection and AIDS. Nevirapine is a BCS class II drug which shows dissolution rate limited absorption.

Objectives: The aim of the present research was to provide a fast dissolving solid dispersion of nevirapine.

Material and methods: The solubility of nevirapine was initially determined individually in four hydrotropic agents - namely urea, lactose, citric acid and mannitol - at a concentration of 10, 20, 30 and 40% w/v solutions using purified water as a solvent. The highest solubility was obtained in the 40% citric acid solution. Then different combinations of 2 and 3 hydrotropic agents in different ratios were used to determine solubility, so that the total concentration of hydrotropic agents was always 40%.

Results: The highest solubility was obtained in a solution of lactose and citric acid at the optimum ratio of 15:25. This optimized combination was utilized in preparing solid dispersions by a common solvent technique using distilled water as a solvent. The solid dispersions were evaluated for XRD, DSC and FTIR to show no drug-hydrotrope interaction.

Conclusions: It was concluded that the concept of mixed hydrotropic solid dispersion is a safe, novel and cost-effective technique for enhancing the bioavailability of poorly water-soluble drugs by dissolving the drug in a nonionized form. The enhancement in solubility of nevirapine using hydrotropy is a clear indication of its potential to be used in the future for other poorly water-soluble drugs in which low bioavailability is a major concern.

Background: Breakthrough resolutions in current biopolymer engineering rely on reliable diagnostics of atomic-deficient spaces over the finest sub-nanometer length scales. One such diagnostic is positron annihilation lifetime spectroscopy, which probes space-time continuum relationships for the interaction between electrons and their antiparticle (positrons) in structural entities like free-volume defects, vacancies, vacancy-like clusters, interfacial voids and pores, etc.

Objectives: This paper is intended to highlight the possibilities of positron annihilation lifetime spectroscopy as an informative instrumentation tool to parameterize free-volume evolution in light-cured dimethacrylate dental restorative composites exemplified by Charisma® (Heraeus Kulzer GmbH, Hanau, Germany) and Dipol® (Oksomat-AN Ltd, Kyiv, Ukraine).

Material and methods: The subjects of the study were the commercially available dimethacrylate-type dental restorative composites Charisma® and Dipol®. The analysis used a fast-fast coincidence system of 230 ps resolution based on 2 photomultiplier tubes coupled to BaF2 scintillator detectors and ORTEC® (ORTEC, Oak Ridge, USA) electronics to register lifetime spectra in normal-measurement statistics evolving ~1 million coincidences.

Results: The annihilation process in both composites is identified as mixed positron-Ps (positronium) trapping, where ortho-Ps decaying is caused entirely by free-volume holes in the polymer matrix, and the 2nd component is defined mainly by interfacial free-volume holes between filler nanoparticles and the surrounding polymer. The most appropriate model-independent estimation of photopolymerization volumetric shrinkage in dental restorative composites can be done using averaged positron annihilation lifetime. Partiallyconstrained x4-term analysis of lifetime spectra is less efficient, giving greater scatter of variance with an additional artifact of fixed shortest lifetime allowing unresolved mixing in the 2nd component. A meaningful phenomenological description of transformations in Ps and positron-trapping sites under light curing, which occurs more efficiently in Charisma® than in Dipol® nanocomposites, can be developed at the basis of a semi-empirical model exploring a x3-x2-coupling decomposition algorithm.

Conclusions: A deep understanding of void-evolution processes in dimethacrylate dental composites employing positron annihilation lifetime spectroscopy makes it possible to diagnose, characterize and engineer novel biomaterials for advanced use in medical practice.

Background: The use of mucoadhesive natural polymers in designing mucoadhesive patch systems has received much attention.

Objectives: The study involved the development and evaluation of buccal patches of atenolol using fenugreek (Trigonella foenum-graecum L.) seed mucilage with hydroxylpropyl methyl cellulose (HPMC K4M) and a backing membrane (ethyl cellulose 5% w/v).

Material and methods: These atenolol-releasing buccal patches were prepared using a solvent casting technique. The buccal patches prepared were evaluated for average weight, thickness, drug content, folding endurance and moisture content. Ex vivo mucoadhesive strength, force of adhesion and bonding strength were determined using porcine buccal mucosa. The mucosal permeation of atenolol through the porcine buccal mucosa was carried out using a Franz diffusion cell in phosphate buffer saline, pH 6.8. These buccal patches were also characterized by SEM and FTIR spectroscopy.

Results: The average weight, thickness, drug content, folding endurance and moisture content of these atenolol-releasing buccal patches were found satisfactory for all the patches. Amongst all, the F-4 buccal patch showed maximum mucoadhesive strength (31.12 ±1.86 g), force of adhesion (30.53 × 10-2 N) and bond strength (1748.89 N/m2). Ex vivo atenolol permeation from the buccal patches showed drug permeation across the excised porcine buccal mucosa over 12 h. The F-4 buccal patch showed maximum permeation flux (29.12 μg/cm2/h).

Conclusions: The developed atenolol-releasing buccal patches can be beneficial over the conventional drug delivery systems to decrease the dosing frequency and enhance patient compliance.