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41.
Sabiruddin Mirza Inna Miroshnyk Jyrki Heinämäki Osmo Antikainen Jukka Rantanen Pia Vuorela Heikki Vuorela Jouko Yliruusi 《AAPS PharmSciTech》2009,10(1):113-119
Crystal morphology engineering of a macrolide antibiotic, erythromycin A dihydrate, was investigated as a tool for tailoring
tabletting performance of pharmaceutical solids. Crystal habit modification was induced by using a common pharmaceutical excipient,
hydroxypropyl cellulose, as an additive during crystallization from solution. Observed morphology of the crystals was compared
with the predicted Bravais–Friedel–Donnay–Harker morphology. An analysis of the molecular arrangements along the three dominant
crystal faces [(002), (011), and (101)] was carried out using molecular simulation and thus the nature of the host–additive
interactions was deduced. The crystals with modified habit showed improved compaction properties as compared with those of
unmodified crystals. Overall, the results of this study proved that crystal morphology engineering is a valuable tool for
enhancing tabletting properties of active pharmaceutical ingredients and thus of utmost practical value. 相似文献
42.
Natalja Genina Heikki Räikkönen Jyrki Heinämäki Osmo Antikainen Simo Siiriä Peep Veski Jouko Yliruusi 《AAPS PharmSciTech》2009,10(1):282-288
The goal of the present study was to design a new technique to modify particle surface properties and, through that, to improve
flowability of poorly flowing drug thiamine hydrochloride and pharmaceutical sugar lactose monohydrate of two different grades.
The powdered particles were supplied by a vibratory feeder and exposed to an instantaneous effect of water mist generated
from an ultrasound nebulizer. The processed and original powders were evaluated with respect to morphology (scanning electron
microscopy, atomic force microscopy, and spatial filtering technique), flow, and solid state properties. It was found that
rapid exposition of pharmaceutical materials by water mist resulted in the improvement of powder technical properties. The
evident changes in flowability of coarser lactose were obviously due to smoothing of particle surface and decreasing in the
level of fines with very slight increment in particle size. The changes in thiamine powder flow were mainly due to narrowing
in particle size distribution where the tendency for better flow of finer lactose was related to surface and size modifications.
The aqueous mist application did not cause any alteration of the crystal structures of the studied materials. The proposed
water mist treatment technique appears to be a robust, rapid, and promising tool for the improvement of the technological
properties of pharmaceutical powders. 相似文献
43.
The purpose of this research was to develop a new method to predict the flow behavior of pharmaceutical powders using a multichamber
microscale fluid bed. Different amounts of poorly flowing paracetamol were added to various grades of microcrystalline celluloses
and silicified microcrystalline cellulose powders. Magnesium stearate was used as a lubricant. Experimental minimum fluidization
velocities (u
mf) were defined using 2 to 4 g (equal to 10 mL) of material (Video 1). The reference flowability of the powders was determined
using a specific flow meter. Also, the weight variation of the compressed powders, using a single-punch press, was measured.
When the amount of paracetamol in the excipients was increased, the experimentalu
mf increased and the fluidization behavior grew worse (Video 2). Principal component analysis (PCA) established that the pressure
difference over the bed as a function of fluidization velocity could be used to characterize the behavior of powders. The
increase in poor fluidization behavior of the powders was in accordance with the increasing amount of paracetamol and with
the increasing weight variation of the tablets. Furthermore, the angle of repose and the flow rate of silicified microcrystalline
cellulose powders were predicted using a partial least squares (PLS) model. The developed method to predict flowability is
a promising approach for use in the preformulation and formulation stages of new drug candidates, for example. 相似文献
44.
Short-term intragastric administration of selected polycyclic aromatic hydrocarbons (100 mg/kg daily for 4 days) to male Wistar rats resulted in marked changes in liver cytosolic aldehyde dehydrogenase activity. Non-carcinogenic anthracene, phenanthrene and chrysene produced a 2.5–3-fold increase in the activity assayed with propionaldehyde as substrate and NAD as coenzyme. Weakly carcinogenic 1,2-benzanthracene enhanced aldehyde dehydrogenase activity 9-fold and the potent carcinogens 3,4-benzpyrene and 3-methylcholanthrene 30-fold. With benzaldehyde as substrate and NADP as coenzyme the differences between the groups were even more pronounced. Somewhat similar but less manifest effects on aldehyde dehydrogenase activity were detected also in the liver microsomes and in the postmitochondrial fractions of the small intestinal mucosa. On the basis of their ability to induce aldehyde dehydrogenase activity the compounds could be divided into three groups. This classification was found to correlate well with the carcinogenic potency of the compounds. It appeared that the exposure to polycyclic aromatic hydrocarbons, especially the carcinogenic ones, was followed by synthesis of a new aldehyde dehydrogenase form. This new form was differentiated from the normally existing cytosolic aldehyde dehydrogenase by its ability to oxidize benzaldehyde in the presence of NADP. 相似文献
45.
Radiochemical assay of UDP glucuronyltransferase (p-nitrophenol) 总被引:1,自引:0,他引:1
46.
This study presents a new approach to model powder compression during tableting. The purpose of this study is to introduce
a new discrete element simulation model for particle–particle bond formation during tablet compression. This model served
as the basis for calculating tablet strength distribution during a compression cycle. Simulated results were compared with
real tablets compressed from microcrystalline cellulose/theophylline pellets with various compression forces. Simulated and
experimental compression forces increased similarly. Tablet-breaking forces increased with the calculated strengths obtained
from the simulations. The calculated bond strength distribution inside the tablets showed features similar to those of the
density and pressure distributions in the literature. However, the bond strength distributions at the center of the tablets
varied considerably between individual tablets. 相似文献
47.
Zusammenfassung In vorliegender Arbeit wurde vornehmlich versucht, die Permeabilität der Epidermisprotoplasten vonRhoeo discolor für Ammoniak und. Essigsäure quantitativ zu bestimmen. Die Bestimmung geschah in erster Linie auf Grund von Beobachtungen über die Deplasmolysegeschwindigkeit dieser Protoplasten in Lösungen von Ammoniumazetat, wobei vorausgesetzt wurde, daß praktisch allein die hydrolytisch abgespaltenen Essigsäure- und Ammoniakmoleküle durch das Plasma permeieren.Für die Permeationskonstante der Essigsäure ergaben sich bei Benutzung derselben Maßeinheiten wie in den Arbeiten von Poijärvi und Bärlund Werte zwischen 20 und 60, für diejenige des Ammoniaks solche zwischen 200 und 2000. In nur vorläufig orientierenden Versuchen wurde außerdem gefunden, daß die Permeationskonstante der Milchsäure etwa von der Größenordnung 2 und die der Buttersäure etwa von der Größenordnung 200 ist. Alle diese Werte gelten allein für die undissoziierten Säurenbzw. Basenmoleküle.Der von uns für Ammoniak gefundene Wert ist weit größer als der entsprechende Wert von Poijärvi. Der Unterschied dürfte u. a. darauf zurückzuführen sein, daß die von uns bestimmte Konstante sich hauptsächlich nur auf die Permeation durch den Protoplasmaschlauch bezieht, während der Vorgang, dessen Geschwindigkeit in den Versuchen von Poijärvi gemessen wurde, sich aus mehreren Einzelprozessen zusammensetzt, unter denen die Permeation durch das Plasma nur einer ist.Da einer exakten Bestimmung von Permeationskonstanten leicht permeierender Basen sehr große Schwierigkeiten entgegenstehen, bedürfen die bisher erhaltenen diesbezüglichen Werte einer gründlichen Nachprüfung. 相似文献
48.
Korkeala Hannu Sorvettula Olli Mäki-Petäys Osmo Hirn Jorma 《Acta veterinaria Scandinavica》1982,23(3):407-415
The different agar diffusion methods were compared using antibiotic and sulphonamide-impregnated filter-paper discs and the kidneys of healthy and emergency-slaughtered pigs and cows after slaughter. No method used seemed to be sensitive to all antimicrobial drugs preimpregnated onto discs. Tetracycline yielded a greater zone of inhibition at pH 6 than at pH 8 and aminoglycosides, erythromycin, polymyxin B and lin cornycin at pH 8 than at pH 6. It therefore seems necessary to use different pHs (6 and 8). The addition of trimethoprim to the medium is necessary for the detection of sulphonamides. Bacillus subtilis BGA used as the test organism was more sensitive to sulphonamides on the “Test agar for the inhibitor test” containing trimethoprim than on the “Iso-Sensitest agar” also containing trimethoprim. The addition of trimethoprim to “Test agar for the inhibitor test” is recommended at pH 8 but not at pH 6 because false-positive cases (with inhibition zones > 2 mm) were observed at pH 6 with trimethoprim on the kidneys of healthy pigs. 相似文献
49.
Blood parasites and male fitness in the pied flycatcher 总被引:2,自引:0,他引:2
In vertebrates the effect of parasites on host ecology has almost been ignored. Recently the view that well-adapted parasites
do not harm their hosts has been challenged and there is growing evidence that parasites do have a present-day effect on a
great variety of host fitness components. The pied flycatcher is a small migratory passcrine bird. Any decrease in condition
caused by disease should affect its ability to cope with physical demands of migration. Here we examine whether blood parasites
have any effect on male arrival time. Males infected with Trypanosoma arrived on average 2 days later than males with no Trypanosoma infection. Infected males also had shorted tails and tended to have shorter wings. By contrast, there was no difference in
male arrival time between males infected with Haemoproteus and healthy males. It seems that Trypanosoma infection lowered male condition and consequently the ability to moult and migrate. The difference in length of feathers
may have generated the difference in arrival times. Early arrival is highly important for males, since only the first males
become polygynous and breeding prospects deteriorate rapidly with any delay in egg laying. Estimated reduction in breeding
success for infected males was about 20%. 相似文献
50.
Polyterritoriality, the occupation of two spatially separateterritories by male birds, has been suggested to enable malesto conceal their pairing status. The idea that males deceivefemales has recently been questioned with arguments that femaleswould easily be able to detect polyterritorial males and thatthey mate in the second territories because better breedingoptions are not available close by. We arranged for pied flycatcher(ficedula hypoleuca) females a choice between neighboring unmatedand already-mated males. Females were unable to discriminateagainst already-mated males, even though their breeding successthereby would have been increased. These results allow rejectionof any polygyny models that assume females use male pairingstatus as a criterion for mate choice. Females would reducethe probability of mating polygynously by choosing dull, yearlingmales with high song rate, even though in most cases it is difficultto differentiate already-mated and unmated males. In fact, femalesdid not prefer colorful males, opposing a general pattern foundin other bird species. However, females did not specificallyprefer dull males nor did they respond to slight differencesin song rates. The seemingly nonadaptive, imperfect female behaviorsuggests that the evolution of female selectivity is constrained,allowing deception by males to be successful in the evolutionaryarms race between the sexes. [Behav Ecol 1990,-1:171177] 相似文献