Development of drug adsorbates onto soluble inorganic silicate glass surface: example with acetaminophen.

A ternary melt-derived inorganic glass system (Igl) of composition corresponding to 62SiO(2), 35Na(2)O, 3Al(2)O(3 )(wt.%) has been formulated and studied as a drug carrier. The [Al(2)O(3)/Na(2)O] ratio is less than one and the aluminium ion is a network former that retards the glass dissolution. The processing conditions lead to a brittle, easily grinding, amorphous product. The Igl structure was proven by IR-spectroscopy, energy-dispersive spectrometry, X-ray diffraction, scanning electron microscopy. A very important fact established is that the Igl corrosion (dissolution) is pH-dependent. Inorganic glass system was transformed into model acetaminophen (APH) adsorbate (APH/Igla 1:1(w/w)) with mild experimental conditions and evaluated as a drug carrier. No interactions between Igl and APH during the processing were proven. Besides, APH settles onto the glass surface as crystalline phase. A lower extent of corrosion, apparent solubility and delayed in vitro APH release from the adsorbate in water and artificial gastric juice in comparison to the samples untreated drug and APH/Iglm physical mixture were established. It is hypothesized that the glass decomposition products, formed into contact with a solvent, initiate interactions with APH at the glass/solution interface. Similar behaviour of the Igl and its drug adsorbates could be expected in gastro-intestinal tract.