drying time
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Cíl: Cílem studie je vyhodnotit opakovatelnost měření neinvazivního break-up time (NIBUT) keratografem při jeho stanovení z jednoho, dvou či třech dílčích měření a doporučit pro praxi vhodnou metodiku. Dalším cílem je ověřit, zda opakovaná měření neovlivňují měřenou hodnotu. Materiál a metodika: Do studie bylo zařazeno 38 zdravých dobrovolníků (30 žen a 8 mužů) ve věku od 19 do 50 let, u každého bylo měřeno vždy jen jedno oko. Studie byla koncipována jako prospektivní. Po 15minutové adaptaci na podmínky vyšetřovny podstoupil každý účastník dvě série měření NIBUT (test, retest) na keratografu OCULUS 3. Minimální časový odstup obou sérií byl 10 minut, každá série obsahovala tři dílčí měření v odstupu přibližně 3 minuty. Výsledný NIBUT byl v každé sérii stanoven (A) jako první hodnota v dané sérii, (B) jako průměr prvních dvou nebo (C) všech tří měření v dané sérii. Opakovatelnost byla hodnocena Bland-Altmanovou analýzou a vyjádřena koeficientem opakovatelnosti. Sledován byl vždy pouze čas prvního roztržení slzného filmu. Výsledky: Statistická analýza neprokázala statisticky signifikantní rozdíly jak mezi dílčími měřeními NIBUT v jednotlivých sérií (p = 0,92, p = 0,81), tak při porovnání všech šesti měření (p = 0,95). Průměrné hodnoty dílčích měření se pohybovaly od 13,6 s do 14,4 s. Pro postupy A, B a C byly zjištěny koeficienty opakovatelnosti (po řadě) 15,0 s, 12,1 s a 10,0 s. Doplňující analýza pro 12 očí s nízkým NIBUT (< 10 s) prokázala statisticky signifikantně lepší opakovatelnost v této skupině, a to s koeficienty 7,0 s (metodika A), 6,0 s (B) a 4,6 s (C) . Závěr: Stanovení NIBUT ze tří po sobě jdoucích měření (s dostatečným, ideálně několikaminutovým odstupem) významně zlepšuje opakovatelnost. Přitom takto opakovaná měření NIBUT nemají významný vliv na měřenou hodnotu. Uvedenou metodiku měření NIBUT na keratografu lze doporučit pro použití v praxi.
Aim: The primary aim of this study is to evaluate the repeatability of noninvasive break-up time (NIBUT) measurement by keratograph when it is determined from one, two or three partial measurements, and to recommend a suitable methodology for practice. Another goal is to verify that repeated measurements do not affect the measured value. Material and Methods: Thirty-eight healthy volunteers (30 women and 8 men) aged between 19 and 50 years old were included in the study, in which only one eye of each volunteer was measured. The study was designed as a prospective one. Each subject adapted to the local conditions of the laboratory for 15 minutes and subsequently underwent two series of NIBUT measurements (test, retest) on an OCULUS 3 Keratograph. The minimum time interval between the two series was 10 minutes, in which each series contained three partial measurements approximately 3 three measurements in the given series. Repeatability was assessed by a Bland-Altman analysis and expressed as a repeatability coefficient. In every case, only the time of the first break-up of the tear film was monitored. Results: The statistical analysis did not show statistically significant differences both between partial measurements of NIBUT in the individual series (p = 0.92, p = 0.81) and when comparing all six measurements (p = 0.95). The mean values of the partial measurements ranged from 13.6 s to 14.4 s. The repeatability coefficients were found to be 15.0 s, 12.1 s and 10.0 s for methodologies A, B and C, respectively. A supplementary analysis for 12 eyes with low NIBUT (< 10 s) showed statistically significantly better repeatability in this group, with coefficients of 7.0 s (methodology A), 6.0 s (B) and 4.6 s (C). Conclusion: Determination of NIBUT from three consecutive measurements (with a sufficient interval of ideally a few minutes) significantly improves repeatability. Such repeated NIBUT measurements do not have a significant effect on the measured value. The mentioned methodology for measuring NIBUT on a keratograph can be recommended for use in practice.
- Klíčová slova
- slzný film, break-up time test, opakovatelnost měření, keratograf OCULUS 3,
- MeSH
- diagnostické techniky oftalmologické * klasifikace přístrojové vybavení MeSH
- prospektivní studie MeSH
- rohovka diagnostické zobrazování fyziologie patologie MeSH
- syndromy suchého oka * diagnostické zobrazování diagnóza MeSH
- Publikační typ
- práce podpořená grantem MeSH
Spray drying is commonly used for producing amorphous solid dispersions to improve drug solubility. The development of such formulations typically relies on comprehensive excipient and composition screening, which requires the preparation of many spray-dried powder samples. This is both labour-intensive and time-consuming when carried out manually. In the present work, the formulation screening task was automated by coupling a laboratory spray dryer operated in a semi-continuous mode with custom-made add-ons, allowing for rapid, computer-controlled production of formulation samples with systematically varying composition. The practical use of the spray drying robot in formulation development was demonstrated on a case study of poorly water-soluble model drugs simvastatin and ezetimibe. Six different polymers and several drug:polymer ratios were screened for the enhancement of dissolution properties. From a pool of 28 spray-dried samples, ternary compositions containing Eudragit L100-55 were identified as the most suitable ones for further processing and characterisation. The ability to populate the formulation design space rapidly and automatically made it possible to construct maps of physico-chemical properties such as glass transition temperature or dissolution rate. The spray drying robot thus enables the acceleration of early formulation development and a deeper understanding of composition-property relationships for multi-component spray dried powders.
- MeSH
- polymery chemie MeSH
- příprava léků MeSH
- robotika * MeSH
- rozpustnost MeSH
- sprejové sušení * MeSH
- Publikační typ
- časopisecké články MeSH
The purpose of this study was to improve the survival of Bifidobacterium animalis subsp. lactis 10140 during freeze-drying process by microencapsulation, using a special pediatric prebiotics mixture (galactooligosaccharides and fructooligosaccharides). Probiotic microorganisms were encapsulated with a coat combination of prebiotics-calcium-alginate prior to freeze-drying. Both encapsulated and free cells were then freeze-dried in their optimized combinations of skim milk and prebiotics. Response surface methodology (RSM) was used to produce a coating combination as well as drying medium with the highest cell viability during freeze-drying. The optimum encapsulation composition was found to be 2.1 % Na-alginate, 2.9 % prebiotic, and 21.7 % glycerol. Maximum survival predicted by the model was 81.2 %. No significant (p > 0.05) difference between the predicted and experimental values verified the adequacy of final reduced models. The protection ability of encapsulation was then examined over 120 days of storage at 4 and 25 °C and exposure to a sequential model of infantile GIT conditions including both gastric conditions (pH 3.0 and 4.0, 90 min, 37 °C) and intestinal conditions (pH 7.5, 5 h, 37 °C). Significantly improved cell viability showed that microencapsulation of B. lactis 10140 with the prebiotics was successful in producing a stable symbiotic powdery nutraceutical.
- MeSH
- Bifidobacterium fyziologie účinky záření MeSH
- časové faktory MeSH
- gastrointestinální trakt mikrobiologie MeSH
- kojenec MeSH
- lidé MeSH
- lyofilizace * MeSH
- mikrobiální viabilita účinky záření MeSH
- náhražky mateřského mléka MeSH
- počet mikrobiálních kolonií MeSH
- příprava léků MeSH
- probiotika účinky záření MeSH
- skladování léků metody MeSH
- teplota MeSH
- Check Tag
- kojenec MeSH
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The paper discusses the real-time monitoring of the changing sample morphology during the entire lyophilization (freeze-drying) and vacuum-drying processes of model biopharmaceutical solutions by using an environmental scanning electron microscope (ESEM); the device's micromanipulators were used to study the interior of the samples in-situ without exposing the samples to atmospheric water vapor. The individual collapse temperatures (Tc) of the formulations, pure bovine serum albumin (BSA) and BSA/sucrose mixtures, ranged from -5 to -29 °C. We evaluated the impact of the freezing method (spontaneous freezing, controlled ice nucleation, and spray freezing) on the morphologies of the lyophiles at the constant drying temperature of -20 °C. The formulations with Tc above -20 °C resulted in the lyophiles' morphologies significantly dependent on the freezing method. We interpret the observations as an interplay of the freezing rates and directionalities, both of which markedly influence the morphologies of the frozen formulations, and, subsequently, the drying process and the mechanical stability of the freeze-dried cake. The formulation with Tc below -20 °C yielded a collapsed cake with features independent of the freezing method. The vacuum-drying produced a material with a smooth and pore-free surface, where deep cracks developed at the end of the process.
Bifidobacterium longum, one of the main microorganisms in the human gut, is used as an adjunct to lactic acid starter cultures or sold as a probiotic product. Therefore, Bifidobacterium longum cell suspensions get freeze-dried with protective additives to prevent activity losses. To date, investigations covering growth and inactivation kinetics of Bifidobacterium longum during the whole process (cultivation, drying, and storage) have been lacking. In this study, the effect of cultivation conditions and shelf temperature as well as the influence of protectants (maltodextrin, glucitol, trehalose) at various concentrations on cell survival during freeze-drying was assessed. Drying was followed by a storage at + 4 °C and + 20 °C for 70 days to evaluate inactivation kinetics. The impact of the different factors was assessed by measuring surival rate and residual moisture content at various points of time over the whole process. In parallel cell membrane integrity and glass transition were determined to reveal inactivation effects. Cultivation strategy had a strong influence on survival with a huge potential for process improvement. A pH of 6.0 at the growth optimum of the strain provides better conditions regarding cell survival after drying than free acidification (non-regulated pH conditions). During the drying step, membrane leakage due to the removal of water is the main reason for the inactivation in this process step. In this study, the highest survival of 49% was obtained with cells dried at + 35 °C shelf temperature with an addition of maltodextrin (75% bacterial dry matter, w/w). The results show that Bifidobacterium longum cells are mostly inactivated during drying, whereas storage conditions at + 4 °C with an addition of 75% BDM maltodextrin relative to bacterial dry mass prevent cell loss completely.
- MeSH
- Bifidobacterium longum růst a vývoj MeSH
- buněčné kultury metody MeSH
- kinetika MeSH
- koncentrace vodíkových iontů MeSH
- kultivační média chemie MeSH
- lidé MeSH
- lyofilizace metody MeSH
- mikrobiální viabilita * MeSH
- polysacharidy MeSH
- probiotika MeSH
- sorbitol MeSH
- teplota MeSH
- trehalosa MeSH
- vysoušení metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The study evaluates the survivability and storage stability of seven Trichoderma strains belonging to the species: T. harzianum (1), T. atroviride (4), and T. virens (2) after the lyophilization of their solid state cultures on wheat straw. Biomass of Trichoderma strains was freeze-dried with and without the addition of maltodextrin. Furthermore, in order to determine the ability of tested Trichoderma strains to preserve selected technological features, the biosynthesis of extracellular hydrolases (cellulases, xylanases, and polygalacturonases) after a 3-month storage of lyophilizates was investigated. Strains of T. atroviride (except TRS40) and T. harzianum TRS85 showed the highest viability after lyophilization process (up to 100%). After 3 months of storage, T. atroviride TRS14 exhibited the highest stability (95.23%); however, the number of active conidia remained at high level of 106-107 cfu/g for all tested T. atroviride strains and T. harzianum TRS85. Interestingly, after a 3-month storage of lyophilized formulations, most of the tested Trichoderma strains exhibited higher cellulolytic and xylanolytic activities compared to the control, i.e., before freeze-drying process. The highest activities of these enzymes exhibited the following: T. atroviride TRS14-2.37 U/g and T. atroviride TRS25-21.47 U/g, respectively, whereas pectinolytic activity was weak for all tested strains, with the highest value of 0.64 U/g registered for T. virens TRS109.
The aim of this study was to prepare benzydamine hydrochloride loaded orodispersible films using modified semisolid extrusion 3D printing method. An innovative approach was developed where thin layer of drug loaded dispersion is printed and dried before printing of subsequent layers. Layer-by-layer drying as the in process step improves mechanical properties of films, uniformity of drug content and allows faster preparation of films in compounding settings due to shortening of drying time. Orodispersible films consisted of film forming maltodextrin, sorbitol as a plasticizer and hydroxyethylcellulose as a thickening agent. The height of the digital model showed excellent correlation with the disintegration time, weight, thickness and mechanical properties of prepared films. Drug content, predefined by volume of digital model and concentration of drug in print dispersion, showed excellent uniformity. The modified printing method shows great promise in a compounding production of personalized film dosage forms, and brings in possibilities such as one step preparation of films with compartmented drugs and incorporation of taste masking or release control layers.
A sensitive assay method was developed for a parallel, rapid and precise determination of dopamine and its metabolites, homovanillic acid, 3-methoxytyramine and 3,4-dihydroxyphenylacetic acid, from brain microdialysates. The method consisted of a pre-treatment step, freeze-drying (lyophilization), to concentrate dopamine and its metabolites from the microdialysates, and a detection step using liquid chromatography combined with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). In particular, the reaction monitoring mode was selected for its extremely high degree of selectivity and the stable-isotope-dilution assay for its high precision of quantification. The developed method was characterized by the following parameters: the precision of the developed method was determined as ≥88.6% for dopamine, ≥89.9% for homovanillic acid, ≥86.1% for 3-methoxytyramine and ≥88.1% for 3,4-dihydroxyphenylacetic acid; the mean accuracy was determined as ≥88.2% for dopamine, ≥88.3% for homovanillic acid, ≥85.9% for 3-methoxytyramine and ≥88.6% for 3,4-dihydroxyphenylacetic acid. The developed method was compared to (1) other combinations of pre-treatment methods (solid phase extraction and nitrogen stripping) with LC-MS and (2) another detection method, liquid chromatography, with electrochemical detection. The novel developed method using combination of lyophilization with LC-ESI-MS/MS was tested on real samples obtained from the nucleus accumbens of rat pups after an acute methamphetamine administration. It was proven that the developed assay could be applied to both a simultaneous analysis of all four substrates (dopamine, homovanillic acid, 3-methoxytyramine and 3,4-dihydroxyphenylacetic acid) in microdialysis samples acquired from the rat brain and the monitoring of their slight concentration changes on a picogram level over time following methamphetamine stimulus.
- MeSH
- chromatografie kapalinová metody MeSH
- dopamin analogy a deriváty analýza metabolismus MeSH
- krysa rodu rattus MeSH
- kyselina 3,4-dihydroxyfenyloctová analýza metabolismus MeSH
- kyselina homovanilová analýza metabolismus MeSH
- lineární modely MeSH
- lyofilizace MeSH
- methamfetamin aplikace a dávkování MeSH
- mikrodialýza MeSH
- nucleus accumbens chemie metabolismus MeSH
- potkani Wistar MeSH
- reprodukovatelnost výsledků MeSH
- senzitivita a specificita MeSH
- stabilita léku MeSH
- tandemová hmotnostní spektrometrie metody MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
