抄録
Experiments were made to clarify the relationship between surface view of powder particles of sulfonamide and their initial dissolution behavior, and the following results were obtained. 1) A particle surface appearance, in each particle size grade sieved from commercial sulfisomezole and sulfamethizole, and recrystallized sulfanilamide, was observed by scanning electron microscope and very fine particles adhering on the particle were found irrespective of particle size. Very fine adhering particles were scarcely found on the recrystallized particles. To remove the very fine adhering particles, these samples were treated with distilled water, 0.2% sodium lauryl sulfate solution, saturated solution of sulfonamide, or 0.2% sodium lauryl sulfate solution saturated with sulfonamide. Surface appearance of these treated samples revealed no adhering particle on the particles except for those treated with saturated solution of sulfonamide. Agglomerated ball-milled samples were composed of very fine particles of diameter ranging from 0.1 to 1 μm. 2) Examination of initial dissolution rates revealed that an increase of instantly dissolving parts with decrease in particle size was due to the very fine particles adhering on the particle, but, in spite of no adhering particles on the particle, the instantly dissolving parts also increased with decrease in particle size. This result supports the observation that surface free energy of powder particles may play an important part in the initial dissolution with decrease in particle size. The instantly dissolving parts of ball-milled sample increased greatly for each sulfonamide and it was around 25% of saturation.
