Method for Determining Dissolution Rates of Multiparticulate Systems

Phase Diagram and Dissolution-Rate Studies on Sulfathiazole-Urea Solid Dispersions

“…Dissolution Rates of Sulfathiazole in Solid Solutions---Although the solid solution approach has been advocated to obtain faster dissolution rates of poorly soluble drugs since 1965 (3), no in uitro dissolution-rate studies of the powder of a drug in a complete solid solution form have been reported so far. The DTA and X-ray diffraction methods were recently employed to disprove (22, 23) the previous studies on the existence of extensive solid solution formation in the chloramphenicol-urea (3, 24) and griseofulvin--succinic acid systems (25).…”

“…The enhancement of the absorption was attributed primarily to the achievement of crystal size reduction of sulfathiazole in the eutectic mixture. After reexamining the phase diagram reported by Sekiguchi and Obi (2), Goldberg et al (3) found that there existed a limited solid solution formation in both extremes of the phase diagram. Since, in a solid solution, the particle size of the solute will be reduced to its minimum state (i.e., at the molecular level), they proposed that the existence of the solid solutions, rather than the reduced crystal size in the eutectic mixture, was the primary factor in producing enhanced dissolution and GI absorption of sulfathiazole.…”

Pharmaceutical Sciences—1965

“…A novel method was developed for deterniining dissolution rates of multiparticulate systems (427). One cent (442) (447).…”

Determination of the Degree of Crystallinity in Solid-Solid Equilibria

“…In order to investigate this possibility and to determine the general applicability of the method, the sulfathiazole-urea system was chosen for further study. The phase diagram for this system as illustrated first by Sekiguchi (1) and as reproduced by Goldberg et al (3), is shown in Fig. 6.…”

“…The use of solid solutions' and eutectic mixtures to effect an increase in the dissolution rate of sparingly soluble drugs has been described (1)(2)(3)(4)(5). Systems which form eutectic mixtures and true solid solutions may be characterized by their phase diagrams which, in the temperature regions of solid-liquid equilibria, can usually be determined by conventional techniques of thermal analysis (6).…”