powder technology
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- MeSH
- celulosa MeSH
- farmaceutická technologie MeSH
- nosiče léků MeSH
- prášky, zásypy, pudry MeSH
- tablety MeSH
- Publikační typ
- přehledy MeSH
V návaznosti na statistické aspekty dávkování léčiv v náhodné práškové směsi jsou shrnuty vlastnostinenáhodných směsí mikronizovaných léčivých látek s pomocnými látkami řádově většíhorozměru částic. Literární přehled je zaměřen především k podmínkám vzniku interaktivním směsí,možnostem přesnějšího dávkování malých množství léčivých látek a omezení rizika oddělováníuspořádaných jednotek směsi (ordered unit). Z technologického hlediska jsou interaktivní směsiaktuální především pro přímé lisování tablet a dávkování mikronizovaného léčiva v práškovýchinhalátorech. Z teoretického hlediska jsou zajímavé poznatky o dočasném zvýšení rozpustnostiněkterých léčivých látek po vzniku amorfního povrchu při dlouhodobém míchání interaktivníchpráškových směsí.
Linking up with the statistical aspects of dosing the active ingredient in the randompowdermixture,the properties of non-random mixtures of micronized active ingredients with auxiliary substancesof the particle size larger by an order are summed up. The review of literature aims to report theconditions of the development of interactive mixtures, possible more precise dosing of small amountsof active ingredients, and limitation of the risk of ordered unit segregation. From the technologicalstandpoint, interactive mixtures are relevant primarily for direct compression of tablets and dosingof the micronized active ingredient in dry powder inhalers.From the theoretical standpoint, the dataconcerning a temporary increase in the solubility of some active ingredients after the developmentof an amorphous surface during long-term mixing of interactive powder mixtures are of interest.
Dry coating is often used technology for preparation of solid pharmaceutical forms. It brings more benefits than the typically used wet coating technology. The powder, which is used as coating material, can be used immediately, has less environmental impact and enhances mechanical and aesthetic properties of final pharmaceutical form. Many technologies have been developed, being generally classified into the following types: compression coating, hot-melt coating, supercritical fluid coating, plasticizer dry coating, electrostatic dry coating, photocurable dry coating and modified plasticizer-electrostatic-heat dry coating. This review summarizes basic principles of dry coating technologies, their benefits and disadvantages and provides a comparison of them.
Přesnost dávkování práškových léčiv v kusových lékových formách lze teoreticky předvídat pomocístatistických principů variability náhodných směsí, jejichž využití k tomuto účelu je tradičněsledováno. Kritický literární přehled uvedené problematiky je zaměřen především na náhodnémíchání práškových směsí, jejich homogenitu, objemové dávkování a využití korelogramu přisledování nenáhodných a segregovaných směsí. Poznatky jsou užitečné jak pro volbu vhodnéhorozměru částic, tak pro ověření vhodnosti použitých parametrů míchání a technologického zpracovánízískané směsi.
The precision of dosing of powder drugs in piece dosage forms can be theoretically forecast by meansof statistical principles of variability of random mixtures, the use of which for this purpose has beentraditionally examined. The present critical review of the literature of the subject is primarilyfocused on random mixing of powder mixtures, their homogenity, volume dosing, and the use ofa correlogram in the examination of nonrandom and segregated mixtures. The knowledge is usefulboth for the selection of a suitable particle size and for the verification of suitability of the employedparameters of mixing and the technological processing of the obtained mixture.
Rychlost sypání velikostních frakcí sorbitolu, kyseliny borité, citronanu draselného a citronanu sodného byla testována v rozmezí 0,0315 až 0,0800 cm. Modifikovaná rovnice sypání využívá sypné hustoty a středního rozměru částic jako nezávisle proměnných při odhadu rychlosti sypání. Pomocí středního rozměru částic lze vyjádřit efektivní průměr otvoru násypky, který zásadním způsobem ovlivňuje rychlost sypání. Použitelnost rovmce sypání je charakterizována průměrnou hodnotou rezidua odhadu 4,0 %.
The flow rate the sieve fractions of sorbitol, boric acid, potassium citrate and sodium citrate was tested within a range of 0.0315 to 0.0800 cm. The modified flow equation makes use of the poured density and the mean particle size as the independent variables in the estimation of the flow rate. By means of the mean particle size it is possible to express the effective diameter of the opening of the feed-hopper, which influences the flow rate in a principal manner. The usability of the flow equation is characterized by the mean value of the residue of estimation of 4 %.
- MeSH
- farmaceutická technologie MeSH
- prášky, zásypy, pudry aplikace a dávkování MeSH
- Publikační typ
- srovnávací studie MeSH
610 s.
The influence of the orifice height of a cylindrical, flat-bottomed hopper on the mass flow rate of the free-flowable size fractions of sodium chloride and boric acid was investigated. It was observed that a zone of sudden acceleration of the mass flow under gravity occurred when a critical orifice height had been achieved. Based on the results, an orifice diameter equal to 12 mm with a height of between 8-16 mm is recommended for the faster flow of sodium chloride while an orifice diameter equal to 8 mm with a height of less than 8mm is appropriate for the slower flow of boric acid. In summary, the orifice height should be taken into consideration as an important parameter of a cylindrical test hopper in order to obtain a reproducible and comparable mass flow as the single-point characteristic of powder flowability.
Indentation of a sphere into nonconsolidated powder excipients is a suitable complementary method for the evaluation of flow properties of the free-flowable noncohesive powders. To use the standard penetrometry method to indentation of nonconsolidated powder layer by a glass sphere of 16 mm in diameter, the suitable geometry of the measurement container is required to prevent undesirable moving in a direction opposite to that in which the indenting sphere moves. Thus, the powder indentation by a sphere seems to be similar to indentation by the Brinell hardness tester. In this work, the depth of indentation was measured for five pharmaceutical powder excipients: sodium chloride, sodium citrate, potassium citrate, sorbitol, and boric acid with the three size fractions in the range of 0.315-0.630 mm. To express powder flowability, the uniform mass and/or volume flow rate from the 10-mm cylindrical outlet of the cylindrical testing hopper was used. The relationships between the powder flow rate and its bulk density and/or the different characteristics of indentation were modeled by using linear regression. Out of the indentation characteristics, the mass of indentation calculated as the multiple of the volume of indentation and the powder bulk density could be recommended to estimate the powder mass flow rate due to the linear regression with the coefficient of determination equal to 0.973 and the accuracy of 4.3%. In conclusion, the indentation by the sphere could be recommended as a quick simple method for the comparison of flow properties of the nonconsolidated, noncohesive powder excipients.
Basic aspect of powder handling is powder flow which depends on mechanical properties of the solid material. This experimental work presents the results of flowability testing of the free-flowable particle size fraction of 0.0250-0.0315 cm of five powder excipients. The single-point determination of the mass flow rate from a cylindrical, flat-bottomed hopper was primarily influenced by the diameter of a circular orifice. The significant effect of the orifice height was also noted. Increasing the orifice height, the flow under gravity is directed resulting in the sudden acceleration of the flow rate. The critical zone relates to the orifice diameter. The multi-point determination of flowability employed the actual parameters of the flow equation which allows the prediction of the mass flow rate. The precision of the prediction was the basic criterion in optimization of the orifice geometry. Based on the results, the orifice height of 1.6 cm can be recommended for the correction of faster powder flow. For the slower powder flow, an orifice height of 0.2 cm can be used alternatively. In conclusion, the information about the orifice height used should be referred to whenever test the powder flowability and compare the results.
