U n i v e r s i t y o f S t r a t h c l y d e , Glasgow, S c o t l a n d . ABSTRACT S p i r o n o l a c t o n e was o b t a i n e d i n t h r e e polymorphic and f i v e s o l v a t e d c r y s t a l l i n e forms which d i f f e r e d i n i n i t i a l d i s s o l u t i o n r a t e i n water by a b o u t a f a c t o r o f 1 2 , t h e most r a p i d l y d i s s o l v i n g form a c h i e v i n g c o n c e n t r a t i o n s a b o u t twice t h e e q u i l i b r i u m s o l u b i l i t y ; on p r o l o n g e d c o n t a c t w i t h water t r a n s f o r m a t i o n t o an h y d r a t e d phase o c c u r r e d . I t is s u g g e s t e d t h a

Hib meningitis in Central Manila is common. The incidence is particularly high in children <6 months old. Adverse neurologic outcomes and a high case fatality rate in children younger than 1 year suggest that a vaccination program would be useful.

Using infrared spectroscopy, X-ray diffractometry, differential thermal analysis, scanning electron microscopy, solubility and dissolution rate measurements, it was demonstrated that the comminution of digoxin results in the appearance of an amorphous phase. The examination of spironolactone and 17 beta-oestradiol by infrared spectroscopy and differential thermal analysis showed that these compounds also undergo changes in their crystallinity on grinding. Since the dissolution characteristics of poorly soluble drugs may be complex functions of surface area and crystallinity, it is concluded that the most pertinent method for standardizing a sample of a polymorphic drug of low solubility is by means of a powder dissolution test, as the results embrace the influences of particle size, aggregation and polymorphism.

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