Polimery w medycynie最新文献

Free light chains accumulation is the reason of kidney injury in patients with multiple myeloma. The removal of free light chains can improve patients prognosis and survival, and in some cases allows for dialysotherapy discontinuation. Unfortunately, conventional dialysis is not effective enough in terms of free light chains removal. New high cut-off (HCO) techniques remove free light chains more effectively than conventional dialysis. In some cases, this technique may turn out better than hemodiafiltration. However, there are some differences between specific techniques in the removal of kappa and lambda light chains. Lambda light chains are better removed by polymethyl methacrylate membranes with a change of filter during dialysis. Kappa light chains are thoroughly removed by polymethyl methacrylate membranes and HCO (35,000 Da) polysulfone membranes. Unfortunately, it is very difficult to differentiate between the effect of HCO dialysis therapy and concomitant chemotherapy because some of the data is not fully conclusive. Using the proper technique for an individual patient may give optimally effective treatment results.

Background: Using positron annihilation lifetime spectroscopy (PALS), microstructural changes in commercial dental restorative composites under light-curing polymerization were identified as a modification in mixed positron/Ps trapping, where the decay of positronium (Ps; the bound state of positrons and electrons) is caused by free-volume holes mainly in the polymer matrix, and positron trapping is defined by interfacial free-volume holes in a mixed filler-polymer environment. In loosely packed composites with a filler content of <70-75%, this process was related to the conversion of Ps-to-positron trapping.

Objectives: To disclose such peculiarities in densely packed composites using the example of he commercially available acrylate-based composite ESTA-3® (ESTA Ltd., Kiev, Ukraine), which boasts a polymerization volumetric shrinkage of only 1.5%.

Material and methods: ESTA‑3® was used as a commercially available acrylate-based dental restorative composite. A fast-fast coincidence system of 230‑ps resolution based on 2 photomultiplier tubes coupled to a BaF2 detector and ORTEC® electronics was used to register lifetime spectra in normal-measurement statistics. The raw PAL spectra were treated using x3-x2-CDA (coupling decomposition algorithm).

Results: The annihilation process in the densely packed dental restorative composites (DRCs), as exemplified by the commercially available acrylate-based composite ESTA‑3®, is identified as mixed positron/ Ps trapping, where o-Ps decay is caused by free-volume holes in the polymer matrix and interfacial filler-polymer regions, and free positron annihilation is defined by free-volume holes between filler particles. The most adequate model-independent estimation of the polymerization volumetric shrinkage can be done using averaged positron annihilation lifetime. A meaningful description of the transformations in Psand positron-trapping sites under light curing can be developed on the basis of a semiempirical model exploring x3‑x2‑CDA. There is a strong monolithization of agglomerated filler nanoparticles in these composites, caused by the photo-induced disappearing of positron traps at the cost of Ps-decaying holes.

Conclusions: Governing the polymerization void-evolution process in densely packed DRC ESTA‑3® occurs mainly in the filler sub-system as positron-to-Ps trapping conversion, which is the reason for the low corresponding volumetric shrinkage.

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.