Polimery w medycynie最新文献

Background: Tinidazole (TNZ) is an anti-parasite drug used in the treatment of a variety of amebic and parasitic infections. It has low solubility in aqueous media and is categorized under Class II of the Biopharmaceutical Classification System.

Objectives: The aim of this research was to study the potential for enhancing the solubility of TNZ using carboxylic acid co-crystals.

Material and methods: The solubility of TNZ was determined individually using 6 carboxylic acids for forming co-crystals at a 1:1 stoichiometric ratio. Three carboxylic acids - namely tartaric acid (TA), oxalic acid (OA) and glutaric acid (GA) - resulted in the formation of co-crystals with enhanced solubility. An equilibrium solubility study of TNZ co-crystals at 1:1.5 and 1:2 stoichiometric ratios was also carried out. The co-crystals which developed were evaluated using X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC) to study the drug-co-crystal former interactions.

Results: The solubility of TNZ in distilled water was found to be 0.014 mg/mL. The highest enhancement ratio was obtained with TNZ and TA at a ratio of 1:1. Differential scanning calorimetry thermograms suggested that the drug and carboxylic acids had undergone interactions such as hydrogen bonding. The XRD and DSC results confirmed the formation of co-crystals.

Conclusions: It was concluded that the results of enhanced solubility of TNZ using co-crystals is a clear indication of the potential for co-crystals to be used in the future for other poorly water-soluble drugs, considering that co-crystals are a safe and cost-effective approach.

Among patients and health professionals who are exposed to ionizing radiation during diagnostic and therapeutic procedures, refractive errors are common and soft contact lenses are widely used to correct them. Changes in the inner structure of contact lens may influence the safety of its usage through modification of its water content or oxygen accessibility to cornea. Therefore, analysis of impact of external factors, therein ionizing radiation used in medicine, on contact lenses parameters is necessary, particularly to compare the presence of free volume gaps in the structure of the polymer soft contact lenses. Possible change in dimensions or quantity of free volume gaps in the structure of the material caused by the exposure to ionizing radiation may have negative influence on oxygen permeability. To prevent such process, different means could be used, i.a., positron annihilation lifetime spectroscopy (PALS), Raman spectroscopy and mid-infrared spectroscopy (MIR). Use of contact lenses which reduce transport of oxygen to cornea increases the risk of corneal hypoxia - one of the possible complications of using contact lenses. Research on effects of different types of ionizing radiation (X-ray, gamma, beta) on materials used in production of contact lenses is vital because of the connection of this issue with the safety of contact lenses wearers. Such research can also shed light on the problem of safe use of contact lenses by persons exposed to ionizing radiation.

In recent years, starch has become a new potential biomaterial for pharmaceutical applications. This biopolymer has unique physicochemical and functional characteristics, as well as various advantages such as low price, relative ease of isolation in pure form from the plant source, non-toxicity, biodegradability, good biocompatibility, and interaction with living cells. Starch is currently used in pharmacy as a binder, disintegrating agent, film-forming material, raw material for production of microspheres and nanoparticles, and a component of drug delivery systems. Porous starch, which can be obtained with physical, chemical and enzymatic methods of modification, has a large specific surface area thanks to the presence of pores and channels. It has excellent adsorption capacity and can be used to enhance the dissolution rate of poorly soluble drugs or as shell material to improve the stability and water-solubility of compounds. As a component of drug delivery systems, porous starch has another advantage: it is biodegradable, so there is no need to remove it from the body after the release of the active agent.

Quadriceps tendon rupture is a severe and demanding problem in knee surgery, especially when it is recurrent and when elderly patients are involved. It can have a devastating impact when it is a complication following knee arthroplasty. There are many procedures for dealing with this problem, but none of them offer reliable results. The most popular methods of treatment are traditional transosseous sutures and suture anchors, often in combination with semitendinosus augmentation. In cases of osteoporotic bone or hamstring insufficiency, these solutions are not appropriate. One way to manage quadriceps tendon rupture is to use polyethylene terephthalate tape (poly tape) as scaffolding for tissue ingrowth. Because of its structure, poly tape provides adequate strength and allows early mobilization. Besides being durable, multifilament high tenacity polyethylene terephthalate is flexible. Poly tape augmentation is particularly recommended in the following cases: recurrent rupture of the quadriceps tendon; extensor apparatus damage following total knee arthroplasty (TKA); delayed diagnosis of quadriceps tendon rupture; and in elderly patients (with weak bones and poor ligament quality). The surgical technique is simple and the procedure has a low complication rate. There have been many studies confirming the security of polyethylene terephthalate use in the human body. There is also a great deal of evidence concerning tissue ingrowth in the mesh structure of poly tape. Allergic reactions and inflammatory responses are rare.

Background: The effects of external factors such as X-ray irradiation on the structure and physical properties of contact lenses are very important for both the patients using contact lenses and medical personnel.

Objectives: The aim of the study was to investigate the effect of X-rays on the structure of Narafilcon A silicone-hydrogel contact lenses.

Material and methods: In order to study the structural changes caused by X-rays in Narafilcon A polymer contact lenses, the following spectroscopy methods were used: positron annihilation lifetime spectroscopy (PALS), Fourier transform middle infrared spectroscopy (FTIR) and Raman spectroscopy (RS). Irradiation of the investigated sample was carried out using an Elekta Synergy accelerator. The contact lenses were irradiated with the following total doses of X-rays: 0.05 Gy, 0.5 Gy, 0.8 Gy, and 1.0 Gy.

Results: The PALS measurements showed that X-ray irradiation caused slight changes in the size of the free volume and the fractional free volume in the structure of the polymer contact lenses examined. However, the FTIR and RS measurements showed that X-rays did not break the monomer bonds in the polymeric structure of the sample.

Conclusions: The changes revealed by the PALS method may be related to possible displacement of monomer chains, resulting in changes in the dimensions and numbers of free volumes. The finding that X-ray radiation does not affect or damage polymer bonds can in the future contribute to the use of X-ray and gamma radiation to sterilize contact lenses.

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.