Biomedical subjects

A R Ebian

Publications and source records attributed to A R Ebian.

10 recordsLinked to original sources

PubMed1986

Solubilization of water by hydrotropic salts.

The effect of some electrolytes, nonelectrolytes, surfactants, and hydrotropic salts on the solubility of water in 1-butanol and 1-hexanol was investigated. While sodium chloride and sodium acetate decrease the solubility of water in 1-butanol, urea has no significant effect. The ionic surfactants, sodium lauryl sulfate and cetrimide, cause an initial decrease in the solubility of water in 1-butanol followed by an increase at high surfactant concentrations. The nonionic surfactant, polysorbate 20, does not show the initial decrease in water solubility. On the other hand, the hydrotropic salts, sodium benzoate, sodium salicylate, and sodium gentisate, are shown to be the best water solubilizers in 1-butanol. Sodium salicylate showed the maximum solubilizing power. The effect of sodium benzoate, sodium salicylate, and sodium lauryl sulfate on the solubility of water in 1-hexanol was also investigated. Similar results were obtained.

Chemical Phenomena↗

PubMed1986

A study of some factors affecting the dissolution rate enhancement of sulfamethoxazole by crystallization in aqueous surfactant solutions.

Effects of crystallization of poorly water soluble sulfamethoxazole in aqueous surfactants solutions on its in vitro dissolution rates were investigated. Marked enhancement was observed. Infrared spectra studies on the prepared crystals indicated polymorphic changes. Some factors affecting the dissolution rate enhancement of crystals prepared in the presence of surfactant namely, the type of the dissolution apparatus, the method of preparation, the type of surfactant, the concentration of surfactant, and washing and soaking of the crystals, were studied. The results of the different effects and possible mechanisms involved are discussed.

Chemistry, Pharmaceutical↗

PubMed1975

Succinylsulfathiazole crystal forms. II: Effect of additives on kinetics of interconversion.

The effect of various additives on the rate of transformation of the metastable anhydrous succinylsulfathiazole Form I to the water-stable dihydrate Form II in aqueous suspensions was studied. Some structurally related compounds, viscosity-imparting agents, surfactants, and coloring agents were used as possible transformation retardants. The effect of including seeds of Form II in the presence and absence of additives is also discussed. Some additives, e.g., methylcellulose and phthalysulfathiazole, showed significant transformation-retarding effects. Other additives, e.g., sulfanilamide and glycerin, increased the rate of transformation. Coloring agents had only slight effects. Utilization of the results in the formulation of physically stable aqueous suspensions of succinylsulfathiazole is discussed.

Chemical Phenomena↗

PubMed1975

Succinylsulfathiazole crystal forms. III: Crystal growth studies.

Crystal growth accompanying the transformation of succinylsulfathiazole crystal forms in aqueous suspensions was studied using a projecting microscope. The effects of increase of temperature, agitation, inclusion of seeds of Form II (the water-stable dihydrate), sulfathiazole, methylcellulose, and polysorbate 80 on the particle-size distribution of anhydrous succinylsulfathiazole Form I were examined. Rates of crystal growth, calculated as increase of diameter per unit time, were given under different experimental conditions. Increase of temperature, agitation, and seeding with nuclei of Form II had significant growth-accelerating effects. Sulfathiazole and polysorbate 80 had growth-retarding effects. Methylcellulose inhibited the crystal growth of Form I for over a year. Aqueous suspensions of Form II did not show any change in particle-size distribution. The crystal growth was shown to be a direct consequence of the transformation of the crystal form. Physical conditions and additives which had accelerating or retarding effects on the rate of succinylsulfathiazole in aqueous suspensions.

Chemical Phenomena↗

PubMed1975

The effect of crystal forms of some barbiturates on their pharmaceutical properties. Part 1: Phenobarbitone.

Up to 13 polymorphic forms of phenobarbitone have been reported in the literature. By melting the commercial sample and cooling under specified controlled conditions, three polymorphic forms II, II, XII, and a mixed form of II and III were obtained. The interconversion of the different forms was studied by special procedures including suspension in water, heating, and heavy dry grinding. The hydrated form XIII and a new hydrated one, designated XIV, were produced by suspending different other forms in water. Heating was found to affect transformation from any form to form I. IR spectroscopy and hot stage microscopy were used for the identification of the different polymorphic forms. Initial dissolution rate studies were carried out on only five forms. The dissolution rate constants were in the following decreasing order: II greater than III greater than I greater than XIV greater than XIII. Form II was found to dissolve at a rate constant about twice that of both hydrated forms.

Chemical Phenomena↗

PubMed1974