Determination of serum tolbutamide by gas chromatography

Simmons, D.L.; Ranz, R.J.; Picotte, P.

doi:10.1016/s0021-9673(01)91894-1

Cited by 32 publications

(6 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It was concluded that a polymorphic transition had taken place from atype of original form to another crystal form. Based on the reports of Simmons 14) and Kimura,15) the newly prepared crystal form in SFD products was identified as b-type crystalline. In addition, the diffraction peaks decreased as the amount of HPMC in the composite particles increased.…”

Section: Effect Of Solution Concentration On Specific Surface Areamentioning

confidence: 99%

Particle Characterization of Poorly Water-Soluble Drugs Using a Spray Freeze Drying Technique

Kondo

Niwa

Okamoto

et al. 2009

CHEMICAL & PHARMACEUTICAL BULLETIN

View full text Add to dashboard Cite

657Many newly developing compounds have been dropped out during the early stages of drug development process because of poorly water-soluble property. Poorly water-soluble drugs often demonstrate the low bioavailability when administered orally due to the low dissolution and absorption rate in the gastrointestinal tract. Therefore, improvement of the solubility of poorly water-soluble compounds is an important mission in drug development.Increasing the solubility and dissolution rate of poorly water-soluble drugs is a significant challenge to pharmaceutical scientists. Technologies that have been commonly used to achieve this task include mechanical milling, 1) coprecipitation, 2,3) spray-drying, 4) the complex formation with watersoluble excipients, 5) and freeze-drying. 6) Spray drying has also been widely used as a technique to improve water solubility. However, it is not always appropriate for thermolabile compounds because the spray-drying process requires elevated temperatures. Although lyophilization or freeze-drying is a promising technique to produce pharmaceutical powders with improved solubility, the freezing rate is so slow that this technique is often difficult to apply in the pharmaceutical industry.Spray freezing into liquid nitrogen (SFL) is a novel cryogenic atomization technology, developed by Williams et al. [7][8][9][10][11] in which either an aqueous or an aqueous-organic cosolvent solution containing an active pharmaceutical ingredient (API) and a pharmaceutical excipient is atomized directly into cryogenic liquid nitrogen. This method via atomization resulted in production of fine particles with a significant large specific surface area, with high yields, and has also been found to prevent interparticle aggregation. In addition, when insulin was atomized by this method, it was possible to obtain lower crystallinity while preventing protein aggregation.In our previous work, 12) the solid dispersions were prepared by rapidly cooling of melt drugs in ice or in liquid nitrogen, and it was found that liquid nitrogen was appropriate as a cryogenic source to prepare particle-shaped solid dispersion with amorphous drug. Based on these previous results, we devised new atomization with quick freezing drying (a novel spray freeze drying: SFD) process which combined the spray dryer with the freeze drying equipment. This SFD method is spraying the drug solution over the surface of liquid nitrogen using the nozzle of the spray drier unlike the SFL method. Mumenthaler and Leuenberger 13) use the spray dryer as well as us, however, the freezing temperature makes it freeze at Ϫ70-Ϫ90°C, comparatively high temperature.The objective of this study was to utilize SFD technology for the preparation of composite particles containing a watersoluble polymer and a poorly water-soluble drug. In addition, the particles obtained by SFD were physicochemically characterized in the viewpoint of solubility improvement. ExperimentalMaterials Tolbutamide (TBM), which was commercially purchased from Wako Pure Chemical Indust...

show abstract

Section: Effect Of Solution Concentration On Specific Surface Areamentioning

confidence: 99%

Particle Characterization of Poorly Water-Soluble Drugs Using a Spray Freeze Drying Technique

Kondo

Niwa

Okamoto

et al. 2009

CHEMICAL & PHARMACEUTICAL BULLETIN

View full text Add to dashboard Cite

show abstract

“…Pharmaceutical Application of PolymorphismPolymorphism and Tableting Behavior of PowdersSimmons et al (85) reported that tolbutamide exists as Forms A and B, and they evaluated their respective tableting behavior. A preliminary evaluation on a rotary press revealed that Form B was responsible for both powder bridging in the hopper and extensive capping problems during tableting.…”

Section: Single-entity Crystalline Solids-polymorphsmentioning

confidence: 99%

Characterization of Habits and Crystalline Modification of Solids and Their Pharmaceutical Applications

Haleblian¹

1975

Journal of Pharmaceutical Sciences

449

202

View full text Add to dashboard Cite

“…However, most of the problems encountered with metastable forms are related to their physical and chemical instabilities. For example, tolbutamide exists as forms A and B; during tableting, the plate-like form B causes powder bridging in the hopper and capping problems, whereas, form A does not have such problems (Simmons, 1972). Lactose, a commonly used tablet diluent, exists as monohydrate and anhydrous crystals with different mechanical behavior (Wong, 1988 (Haleblian, 1975 Brecevic and Sketic (1986).…”

mentioning

confidence: 99%

The kinetics of solvent-mediated phase transformations

1985

Proc. R. Soc. Lond. A

334

210

View full text Add to dashboard Cite

A number of mineralogical and synthetic precipitates undergo solid to solid phase changes via a solution phase. A review of the literature reveals a lack of both experimental data and a framework for its interpretation. A model is developed, for the case of a polymorphic phase transformation, which involves the dissolution of the metastable phase and growth of nuclei of the stable phase. The concepts of dissolution and growth time scales have been introduced and it is shown that their sum is the time required for the disappearance of the metastable phase. Mechanistic insight is best obtained by measurement of the supersaturation profile rather than conversion data. It is shown that such profiles are dominated by the plateau supersaturation, which is the point at which dissolution and growth are balanced. Its value is determined by the relative surface areas of the phases and their kinetic constants. The model has been successfully used to simulate available kinetic data for the α → β polymorphic transformation in copper phthalocyanine.

show abstract

Determination of serum tolbutamide by gas chromatography

Cited by 32 publications

References 2 publications

Particle Characterization of Poorly Water-Soluble Drugs Using a Spray Freeze Drying Technique

Particle Characterization of Poorly Water-Soluble Drugs Using a Spray Freeze Drying Technique

Characterization of Habits and Crystalline Modification of Solids and Their Pharmaceutical Applications

The kinetics of solvent-mediated phase transformations

Contact Info

Product

Resources

About