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11 záznamů v Medvik Filtry

Článek online

Model-Based Evaluation of Drying Kinetics and Solvent Diffusion in Pharmaceutical Thin Film Coatings

Navrátil, Ondřej
Autor Navrátil, Ondřej ORCID Department of Chemical Engineering, University of Chemistry and Technology Prague, Technicka 3, 166 28, Prague 6, Czech Republic
Kolář, Jiří
Autor Kolář, Jiří ORCID Department of Chemical Engineering, University of Chemistry and Technology Prague, Technicka 3, 166 28, Prague 6, Czech Republic
Zadražil, Aleš
Autor Zadražil, Aleš ORCID Department of Chemical Engineering, University of Chemistry and Technology Prague, Technicka 3, 166 28, Prague 6, Czech Republic
Štěpánek, František
Autor Štěpánek, František ORCID Department of Chemical Engineering, University of Chemistry and Technology Prague, Technicka 3, 166 28, Prague 6, Czech Republic. Frantisek.Stepanek@vscht.cz

Pharmaceutical research. 2022 ; 39 (9) : 2017-2031. [pub] 20220805

Pharm Res
ISSN 1573-904X
Medvik
Zdroj

PURPOSE: Fluid-bed coating processes make it possible to manufacture pharmaceutical products with tuneable properties. The choice of polymer type and coating thickness provides control over the drug release characteristics, and multi-layer pellet coatings can combine several active ingredients or achieve tailored drug release profiles. However, the fluid-bed coating is a parametrically sensitive process due to the simultaneous occurrence of polymer solution spraying and solvent evaporation. Designing a robust fluid-bed coating process requires the knowledge of thin film drying kinetics, which in turn critically depends on an accurate description of concentration-dependent solvent diffusion in the polymer. METHODS: This work presents a mathematical model of thin film drying as an enabling tool for fluid-bed process design. A custom-built benchtop drying cell able to record and evaluate the drying kinetics of a chosen polymeric excipient has been constructed, validated, and used for data collection. RESULTS: A semi-empirical mathematical model combining heat transfer, mass transfer, and film thickness evolution was formulated and used for estimating the solvent diffusion coefficient and solvent distribution in the polymer layer. The combined experimental and computational methodology was then used for analysing the drying kinetics of common polymeric excipients: poly(vinylpyrrolidone) and two grades of hydroxypropyl methylcellulose. CONCLUSIONS: The experimental setup together with the mathematical model represents a valuable tool for predictive modeling of pharmaceutical coating processes.

Článek

Antibiotic depot system with radiofrequency controlled drug release

Colloids and surfaces. B, Biointerfaces. 2022 ; 217 (-) : 112618. [pub] 20220607

Colloids surf., B Biointerfaces
ISSN 1873-4367
Medvik
Zdroj

Drug depot systems have traditionally relied on the spontaneous dissolution and diffusion of drugs or prodrugs from a reservoir with constant exposure to the surrounding physiological fluids. While this is appropriate for clinical scenarios that require constant plasma concentration of the drug over time, there are also situations where multiple bursts of the drug at well-defined time intervals are preferred. This work presents a drug depot system that enables repeated on-demand release of antibiotics in precise doses, controlled by an external radiofrequency magnetic field. The remotely controlled depot system consists of composite microcapsules with a core-shell structure. The core contains micronized drug particles embedded in a low-melting hydrophobic matrix. The shell is formed by a hydrogel with immobilised magnetic nanoparticles that facilitate local heat dissipation after exposure to a radiofrequency magnetic field. When the melting point of the core material is locally exceeded, the embedded drug particles are mobilised and their surface is exposed to the external aqueous phase. It is shown that drug release can be controlled in an on/off manner by a chosen sequence and duration of radiofrequency pulses. The capacity of the depot system is shown to be significantly higher than that of purely diffusion-controlled systems containing a pre-dissolved drug. The functionality of the depot system is demonstrated in vitro for the specific case of norfloxacin acting on E. coli.

Článek online

Nádory páteřního kanálu
[Tumours of the spinal canal]

Onkologie (Olomouc, Print). 2021 ; 15 (5) : 243-246. [pub] 20211011

ISSN 1802-4475
Medvik
Zdroj

Nádory páteřního kanálu tvoří přibližně 15 % všech nádorů CNS. Tvoří poměrně heterogenní skupinu nádorů podle tkáně, ze které vyrůstají. Dále se rozdělují podle lokalizace na extradurální, intradurální extramedulární a intramedulární nádory a z hlediska šíření na primární nádory páteřního kanálu a nádory metastatické. Léčba primárních nádorů je na prvním místě chirurgická. Cílem je úplné odstranění nádorů nebo alespoň dostatečná dekomprese neurálních struktur, v některých případech i pro uplatnění adjuvantní radioterapie nebo chemoterapie. Rozvoj mikrochirurgické operační techniky a peroperační neurofyziologické monitorace umožňuje tohoto cíle dosáhnout ve vysokém procentu případů.

The tumours of the spinal canal form about 15% of the central nervous system tumours. They form rather heterogenous group of tumours based on the tissue they arise from. Based on their localization, they are divided to extradural, intradural extramedullar and intramedullar tumours. Furthermore, we distinguish the primary tumours and the metastatic tumours. The primary tumours are treated mainly by surgical treatment. The main goal is the total removal of the tumour or at least the sufficient decompression of the neural structures. In addition, there is a time window to apply adjuvant radiotherapy or chemotherapy in respect to the histopathology. The development of the microsurgical operative technique and intraoperative neurophysiological monitoring helps to achieve this goal in the majority of cases.

Článek online

Current Treatment of Anterior Communicating Artery Aneurysms: Single Center Study

Brain sciences. 2020 ; 10 (8) : . [pub] 20200731

Brain Sci
ISSN 2076-3425
Medvik
Zdroj

INTRODUCTION: Anterior communicating artery aneurysms (ACoAAs) are the most frequent intracranial aneurysms treated at neurosurgical departments with a vascular program. MATERIAL AND METHODS: We reviewed patients with ACoAAs in a single institution over ten years (2008-2017). The focus was on the final outcome; complications, age, and clinical condition with respect to modalities were analyzed. RESULTS: A total of 198 patients treated during this period was included in the study: 176 patients had a ruptured ACoAA and 22 had an unruptured ACoAA. Then, 127 (71%) were treated surgically and 51 (29%) by endovascular means. Out of the whole series, a good recovery occurred in 123 patients (62%), moderate disability in 11 (5.5%), severe disability in 19 (10%), vegetative state in 11 (5.5%), and death in 34 (17%). In the 157 patients (72.5%) with a subarachnoid hemorrhage (SAH), both modalities had a favorable outcome: 27.5% had an unfavorable outcome, 12% had complications in surgery versus 17.6% during endovascular treatment. No statistical difference in outcome, complications, and age was noted between modalities. Surgical treatment was more frequently adopted for patients in a better clinical condition (p ≤ 0.05). CONCLUSION: More than two thirds of the patients (72.5%) reached a favorable outcome. There was no difference in age between the treatment modalities. Risks of complications are present and specific for both modalities.

Publikační typ
časopisecké články MeSH

Článek online

Middle cerebral artery aneurysms with intracerebral hematoma-the impact of side and volume on final outcome

Acta neurochirurgica. 2017 ; 159 (3) : 543-547. [pub] 20170109

Acta Neurochir
ISSN 0942-0940
Medvik
Zdroj

BACKGROUND: Middle cerebral artery aneurysms (MCA aneurysms) belong to the most frequent type of intracranial aneurysms forming an intracerebral hematoma. The consequences of the hematoma-the laterality, the impact of ICH volume and size of the aneurysm with the final outcome of these patients had not been studied in detail in this location, and we focused on the analysis of these factors. METHODS: Patients with MCA aneurysms and associated intracerebral hematomas with a volume ≥10 ml were studied; these were treated from January 2006 to December 2015. During this period, more than 700 patients with spontaneous subarachnoid hemorrhage were admitted to the Department of Neurosurgery, University Hospital Brno. The data were collected from the subarachnoid hemorrhage database of the unit and from the local hospital registry. All consecutive patients at the treating center were involved in this retrospective study. We collected clinical data such as age, gender, aneurysm location, preoperative hematoma size, Hunt-Hess grade and type of surgical procedures. We focused on the analysis of the final outcome [Glasgow Outcome Scale (GOS) score] in relation to ICH volume, side of bleeding and finally the relationship between aneurysm size and the volume of ICH. RESULTS: Fifty-eight patients with an MCA aneurysm and ICH were included; the mean age of this series was 59.4 years. Thirty-six patients (62%) had clinical status Hunt-Hess 4-5 on admission. The mean size of the intracerebral hematoma was 47.1 ml (10-133 ml). Most frequently, in 30 patients (52%), the hematoma had bled into the temporal lobe. Fifty three patients were operated on, and 5 were treated conservatively because of their poor condition. Twenty-three patients (40%) had a favorable Glasgow Outcome Scale score, and 35 (60%) had an unfavorable outcome including 20 patients (35%) who died. Of the 53 patients operated on, 20 (38%) underwent decompressive hemicraniectomy (DHC). Patients with an unfavorable outcome had significantly larger hematomas with a median size of 54 ml, whereas those with a favorable outcome had a median size of 26 ml (p = 0.0022). Larger hematomas were found on the right side. The cutoff volume for an unfavorable outcome in ICH was 25 ml. The outcomes were not related to the side of the ICH (p = 0.42), and the aneurysm size did not predetermine the ICH volume (p = 0.3159). CONCLUSION: Our study confirms the benefit of the active treatment of patients with MCA aneurysms and associated ICH. A significant proportion of these patients achieves a favorable outcome. No association between the side of bleeding and outcome was demonstrated. Hematomas larger than 25 ml have a greater tendency to lead to an unfavorable outcome. The treatment decision-making process should not differ for either side.