摘要:

AbstractPredicting crystal shape is important in crystallization processes. In this paper, we have modelled the crystal morphology of the non‐steroidal anti‐inflammatory drugS‐(+)‐ibuprofen, and investigated the effect of hexane solvent on crystal morphology.Crystals ofS‐(+)‐ibuprofen exhibit a polar morphology, and rapid growth elongates the crystals along the polarbaxis. The attachment energy model successfully predicts the appearance of all faces observed in a hexane‐grown crystal, in approximately the same order of morphological importance, except for {īīī}. The appearance of {īīī} in the observed morphology can be accounted for by assuming that hexane‐adsorption onto {īīī} faces slows their growth rate sufficiently to increase their morphological importance. This seems reasonable, given the largely non‐polar nature of the faces, and can be reproduced in the model by decreasing the attachment energy of {īīī} to simulate reduced growth rate.The results suggest that using hexane as the recrystallizing solvent does modify the morphology ofS‐(+)‐ibuprofen, although the modifications are relatively minor. Hexane does not dramatically affect the gross external crystal shape, and this is in marked contrast

ISSN:1460-8081    

DOI:10.1111/j.2042-7158.1996.tb00584.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractPrediction of precipitation of insoluble calcium phosphate salts in 3‐in‐1 total nutrient admixtures (TNAs) is desirable because the cloudiness of such preparations prevents easy visual detection of precipitates.The precipitation of calcium phosphate in 3‐in‐1 TNAs was studied by determining the apparent solubility product (Ksp′) of calcium phosphate in the admixture. The Ksp′ was found to be a function of the admixture composition. For a specific admixture, the Ksp′ is independent of the initial calcium and phosphate salt concentrations and their molar ratio. For the same admixture formulation, the use of calcium gluconate yielded Ksp′ at least twice that obtained using calcium acetate.The application of Ksp′ is straightforward in predicting the precipitation of calcium phosphate. The control of the concentration of calcium and phosphate salts added to 3‐in‐1 TNAs at a level below the Ksp′ eliminates the potential problem of calcium

ISSN:1460-8081    

DOI:10.1111/j.2042-7158.1996.tb00585.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe aim of the present study was to investigate how the dissolution kinetic parameters were influenced by the changes in the physical properties of magnesium oxide, the starting material of granulation.Granulation was carried out in a laboratory fluidized‐bed system using oil‐in‐water (o/w) emulsion as a granulation liquid. Pretreatment (modification of the physical properties of the granulation base material) was needed to avoid the adhesion of magnesium oxide to the wall of the plastic fluidization column. The constant pH method was used for the in‐vitro dissolution study. Weibull distribution was applied to characterize the dissolution rate of magnesium oxide.The pretreatment, and consequently, the changes in the physical properties of the starting material, granulated under the same conditions, significantly affected the dissolution kinetic parameters of the Weibull e

ISSN:1460-8081    

DOI:10.1111/j.2042-7158.1996.tb00586.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractBiodegradable microspheres of polylactide have been prepared for the controlled release of model proteins. Studies have shown that release from these microspheres is dependent on properties of the polymer and the protein encapsulated. The combination of two proteins will have an effect on the characteristics of the particles produced and the release profiles obtained.Using a solvent evaporation technique, low molecular weight poly(L)lactide microspheres were produced, loaded with different ratios of a number of model proteins. The effects on loading efficiency, particle size, surface charges and release were examined.The results suggest that the outcome of the presence of carrier proteins, and co‐encapsulated adjuvants on the properties of the microspheres produced must be studied for each combination employe

ISSN:1460-8081    

DOI:10.1111/j.2042-7158.1996.tb00587.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe aim of this study was to investigate the effect of pH on the partition coefficient of enkephalins, and to examine how this influences their ability to permeate corneal membranes. The partition coefficient, P, betweenn‐octanol and water of (d‐Met2‐Pro5) enkephalin (Penta) and its derivative (d‐Met2‐Pro5)tetra‐O‐acetylgalacotosylenkephalinamide (P‐gal) at different pH values was determined by HPLC analysis of each phase. P‐gal was more lipophilic than the parent compound Penta. The effect of pH on the ionization and passive transport through rabbit corneas of [14C‐tyrosine]Penta and [14C‐tyrosine]P‐gal was also investigated. Penta has three pKavalues, 3·57, 6·86 and 9·84. P‐gal has two pKavalues, 7·30 and 10·01.Autoradiophotography was used to detect the permeation and distribution of the two compounds in the corneal membrane at very low concentrations and at different pH values. At pH 7·6, P‐gal penetrated while Penta did not. After adjusting the pH to 5, both Penta and P‐gal pe

ISSN:1460-8081    

DOI:10.1111/j.2042-7158.1996.tb00588.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractLiquorice has long been used in the treatment of peptic ulcer. In this study the protective effects of liquorice and two of its derivatives, deglycyrrhinized liquorice (DGL) and high‐glycyrrhinized liquorice (HGL), against gastric experimental lesions induced by piroxicam and mefenamic acid were examined in rats. Three different granulation methods were used to coat piroxicam and mefenamic acid powders by liquorice, DGL or HGL, in order to study whether the granulation process had any effect on extent of lesions.The results were analysed by ulcer index and it was seen that coating piroxicam and mefenamic acid with liquorice and its derivatives reduced the number and size of ulcers, decreasing the ulcer index from 2·1 to 0·6 (P<0·01) and from 1·93 to 0·86 (P0·01) for piroxicam and mefenamic acid, respectively, and the incidence from 90 to 46·7% and from 96·5 to 53·3% for piroxicam and mefenamic acid, respectively.HPLC determination of plasma concentrations showed that coating of piroxicam and mefenamic acid by liquorice and its derivatives did not reduce their oral absorption; the decrease in the ulcerogenicity of coated granules cannot be attributed to a decrease of absorption resulting from the coating. It was also concluded that different granulation processes had no significant effect on the activity of th

ISSN:1460-8081    

DOI:10.1111/j.2042-7158.1996.tb00589.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractImplantation of biomaterials or surface‐modified capsules such as drug‐delivery systems into the body induces various cellular responses around the implanted sites. The interaction between various cells and biomaterials has been investigated by analysing cell growth rates, cell morphologies and various cellular responses such as protein secretion. The RNA in‐situ hybridization technique was originally developed to measure gene expressions in multicellular organisms such as tissue sections. We have modified and applied this procedure for in‐vitro cultured cells to evaluate the biocompatibility of biomaterials.As a model study, we have shown that cellular responses to surface‐modified materials, such as collagen‐type‐I‐treated materials with or without a cytokine, can be evaluated by this RNA in‐situ hybridization technique. This work suggested that the expression of a marker gene (T gene) was regulated by several parameters, including modifications of cell‐culture substrate surfaces and the presence of soluble proteins (cytokines) in the culture medium.These results suggest that cellular responses to biomaterials with or without cytokines can be examined by parameters obtained by RNA in

ISSN:1460-8081    

DOI:10.1111/j.2042-7158.1996.tb00590.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe purpose of this work was to study the role of nitric oxide (NO) synthesis in the antinociceptive effect of paracetamol, indomethacin and diclofenac in the rat.Although all three drugs induced a significant antinociceptive effect, the mechanism of action did not appear to be the same.NG‐Nitro‐l‐arginine (L‐NAME), an inhibitor of nitric oxide synthesis, did not significantly modify the effects of paracetamol and indomethacin, whereas it reduced the effect of diclofenac. The effect of L‐NAME on diclofenac‐induced antinociception was partially reversed byl‐arginine.Results suggest differences in the mechanism of action of non‐steroidal anti‐inflammatory drugs, thel‐arginine‐NO‐cyclic GMP pathway being involved in the antinociceptive effect of some, but not of all t

ISSN:1460-8081    

DOI:10.1111/j.2042-7158.1996.tb00591.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractLittle is known about the pharmacokinetics and pharmacodynamics of magnolol despite numerous pharmacological investigations. Hence the present study which aimed to examine the pharmacokinetics of magnolol after its oral administration in rats, and to determine its pharmacodynamic properties with regard to its effect on locomotor activity.The absorption half‐life, the elimination half‐life, the time of maximum concentration and the maximum concentration were found to be 0·63 h, 2·33 h, 1·12 h and 0·16 μg mL−1, respectively. Oral bioavailability was about 4·9%. Oral administration of higher doses of magnolol (20, 50 and 100 mg kg−1), but not lower doses (5 or 10 mg kg−1), significantly suppressed the locomotor activity of the animal.A first order one‐compartment model was proposed after oral administration of magnolol (20 mg kg−1). For reduction of locomotor activity, the minimum effective oral dose was 20 mg kg−1, with a minimum effective plasma concent

ISSN:1460-8081    

DOI:10.1111/j.2042-7158.1996.tb00592.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe aim of the present study was to describe the pharmacokinetics of transplacental passage of flunitrazepam compared with antipyrine as a marker.Placental transfer of both drugs was studied using the rat term placental perfusion system. Flunitrazepam showed considerably rapid passage across the placenta. Both the first‐order transfer constant (ktr= 0·171 min−1) and the first‐order equilibration constant (keq= 0·061 min−1) tended to be higher than those of antipyrine (ktr= 0·046 min−1, keq= 0·020 min−1). On the other hand, there was a significant difference between flunitrazepam and antipyrine in the foetal concentrations reached at equilibrium (Ceqm= 640·113 and 1541·136 ng mL−1, respectively) and in the foetomaternal concentration ratio at equilibrium (FMCReq= 0·324 and 0·991, respectively).This indicates that flunitrazepam reaches lower concentrations in the foetal compartment and therefore it might be a relatively safe drug when used during pregnancy. Maternal plasma protein binding of both compounds was evaluated by equilibrium dialysis (flunitrazepam = 75·5%, antipyrine = 1·4%). The plasma protein binding could possibly be one of the most important factors

ISSN:1460-8081    

DOI:10.1111/j.2042-7158.1996.tb00593.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY