Polimery w medycynie最新文献

Background: Eprosartan mesylate is a poorly water-soluble drug. It does not dissolve well in the aqueous gastrointestinal fluid, which means it is not absorbed well via the oral route, because a drug can cross cell membranes when it is dissolved in the gastrointestinal fluid.

Objectives: The purpose of this research was to enhance the aqueous solubility and dissolution rate of eprosartan mesylate using the solid dispersion technique. Enhancing the solubility and dissolution leads to better absorption via the oral route.

Material and methods: A number of eprosartan mesylate-laden polymeric solid dispersions were prepared with hydroxypropyl methylcellulose (HPMC) and polysorbate 80 by means of the solvent evaporation technique. The impact of the weight ratios of the constituents on the solubility and dissolution rate was studied in comparison with the plain drug. The formulation presenting the optimal solubility and dissolution underwent the solid-state characterization using X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR).

Results: Both polysorbate 80 and HPMC positively affected the solubility and dissolution of eprosartan mesylate.

Conclusions: In particular, a ternary solid dispersion consisting of eprosartan mesylate, HPMC and polysorbate 80 at a weight ratio of 1:4.2:0.3 showed the highest solubility (36.39 ± 3.95 mg/mL) and dissolution (86.19 ±4.09% in 10 min). Moreover, the drug was present in the amorphous form in the solid dispersion with no covalent drug-excipient interactions.

Background: Poly-γ‑glutamic acid (γ‑PGA) provides an environmentally friendly alternative to plastic materials which have widely polluted the environment.

Objectives: The microbial production of γ‑PGA, an amino acid biopolymer with glutamic acid subunits, was investigated using renewable agricultural residues in an attempt to find cheaper substitutes for conventional synthetic media components.

Material and methods: Bacteria which produce γ‑PGA were isolated through depolymerizing Coix lacryma-jobi, a cellulosic grass, and the effects of various carbon and nitrogen sources, temperature, inoculant load, incubation period, and pH on γ‑PGA yield were determined after submerged fermentation. Bacterial growth was measured turbidimetrically at 550 nm. The γ‑PGA produced was characterized using Fourier transform infrared (FT-IR) spectroscopy and the polymer shape was determined using scanning electron microscopy (SEM).

Results: The best γ‑PGA producer was molecularly identified as Bacillus toyonensis As8. The conditions which produced the highest γ‑PGA yield were glucose, ammonium sulfate, 25°C, a pH of 5.5, and an incubation period of 48 h. This bacterium yielded the most γ‑PGA (26.45 g/L) on cassava peels, while other agro-wastes (corn cob, sorghum leaves, Coix noir leaves, and rice bran) also supported bacterial growth with lower γ‑PGA yields than conventional carbon sources. The wrinkled γ‑PGA had absorbance peaks of hydroxyl, amide, carbonyl, and amine groups comparable with the ranges of those found in commercial γ‑PGA.

Conclusions: The use of agricultural by-products as fermentation substrates increased γ‑PGA yield and may therefore be used as substitute components in γ‑PGA production.

Background: Cellulose microcrystalline (MCC), hydroxypropyl methylcellulose (HPMC) and croscarmellose sodium are cellulose derivatives which are widely used in pharmaceutical technology. Although they are inert pharmaceutical ingredients, they can influence the release profile of an active substance from the dosage form depending on their distribution, type and quantity used in the formulation.

Objectives: The aim of the present investigation was to examine the effect of chosen cellulose derivatives on the physical and analytical attributes of a drug product containing an active substance of Biopharmaceutics Classification System (BCS) class II.

Material and methods: The tablets were prepared using the wet granulation technology. The batches differed in the amount and grade of HPMC, the type of MCC and the distribution of croscarmellose sodium. The granule properties as well as physical (tablet hardness, disintegration time, friability) and analytical (dissolution profile in different media) attributes of the tablets were examined.

Results: The flow characteristics were satisfying in the case of all prepared batches. However, the differences in flow properties were visible, especially in the cases where MCC of coarser particles was replaced with MCC of finer particles. The type of MCC used in the product formula also had a significant influence on the drug product dissolution profile. The batches in which MCC of finer particles was used had substantially better results, regardless of HPMC viscosity type and the distribution of croscarmellose sodium between the inner and outer phase. What is more, the differences in the results between batches of different MCC types were especially visible in dissolution conditions, i.e., 0.1N hydrochloric acid (HCl).

Conclusions: By choosing the right type, quantity and distribution of cellulose derivatives, it was possible to obtain the optimal formula of the drug product similar to in-vitro conditions to the reference drug. Out of all the tested excipients, the type of cellulose microcrystalline was found to have the most critical influence on both physical and analytical properties of the pharmaceutical formulation.

Polymorphism of pharmaceutical substances has a significant impact on their physicochemical properties, durability, bioavailability and consequently on their pharmacological activity. Solid dosage forms may exist in both crystalline and amorphous forms. Amorphous varieties are characterized by higher solubility and dissolution rates, while crystalline forms show greater purity and storage stability. The choice between the crystalline or amorphous form of a drug is extremely important to ensure effective and safe pharmacotherapy. Statins - the most commonly used group of drugs in the treatment of lipid disorders - are an example of drugs that occur in many crystalline and amorphous forms. Statins belong to class II in the biopharmaceutical classification system (BCS), which means that they are poorly soluble, but permeate biological membranes well. The bioavailability of statins shows considerable variation, which is associated with the first-pass effect in the liver and the accumulation of the drug in the hepatocytes. The improvement of bioavailability after oral administration of poorly soluble medicinal substances remains one of the most challenging aspects of the drug development process. A specific polymorphic form is obtained by applying appropriate conditions during the process of its preparation under industrial conditions, including the use of a suitable solvent, a specific temperature or rate of crystallization. The article provides a comprehensive update on the current knowledge of the influence of polymorphic form on statin solubility and bioavailability. Research is still being carried out to obtain new polymorphic varieties of statins that are characterized by better physicochemical and pharmacokinetic parameters.

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.