Gelatin - Mineral interaction:
ii) Film studies-
Cooper et al (1972) reported that an interaction between gelatin and dyes in the gelatin films could be studied by examining the shifts in λ max in thevisible range and for changes in the amide I (1625 cm –1) and amide II (1520 cm –
1 ) bands of the protein in the IR spectrum. IR spectra of gelatin films containing RO (at all the concentrations attempted) , copper sulphate and potassium iodide showed disappearance of both these peaks indicating gelatin – mineral interaction. The dissolution data of the above stored films also indicated protracted disintegration. The IR spectra of the films containing manganese sulphate, magnesium oxide, dicalcium phosphate and zinc sulphate did not indicate interaction. The dissolution data (except in case of manganese sulphate) also supports this observation. It was observed that the rate of interaction accelerated due to-
- Increased humidity and (ii) presence of RO/ FF (except in case of manganese sulphate where iron salts showed a protective influence)
- Liquid phase interactions
- Changes in pH and viscosity.
The soluble salts used indicated acidic salts (copper sulphate and manganese sulphate) and basic (potassium iodide) while the insoluble salts included alkaline earth metal salts (magnesium oxide and dicalcium phosphate) and iron salts (RO/ FF). In case of acidic and basic salts, any interaction between gelatin and the action would bring forth changes in the pH. The decrease in pH with stored gelatin solutions containing copper sulphate and an increase in pH with those containing potassium iodide support interaction. The interaction possibly even increased the viscosity of the samples as observed from the viscosity data.
Insignificant change in the pH indicated lower degree of interaction (as also observed from atomic absorption spectral data given under formulation studies). Also, the insignificant changes in viscosity value supports this
The minerals employed in sot gelatin hematinic capsules show migration into the gelatin shell due to the higher water and humectants content of soft gelatin capsules shell than the hard gelatin shell which subsequently end up in interaction between the gelatin and the captions resulting in protracted disintegration or rupture. These interactions in the capsules could lead to noncompliance with the official disintegration tests standards. However, the effect of this interaction on the bioavailability of the content has not been reported so far.