Potential application of surfactant systems in formulation of dosage forms with slightly soluble substances

In order to achieve fast release of ibuprofen, slightly soluble model substance (0.52104 mol/l), surfactant systems for oral use with different PEG-40 hydrogenated castor oil (C)/diethylene glycol monoethyl ether (T) ratios were investigated. Comparison between dissolution profiles for ibuprofen from formulated systems and from two commercial products, film tablets and soft capsules, is presented in this paper. Photon correlation spectroscopy has shown that after high dilution with water, surfactant systems were able to form micellar solutions. The size of micelles varies from 14.8 ± 0,075 nm to 16.2 ± 0,021 nm with increasing C/T ratio from 1:2 to 2:1. Although with increasing content of PEG-40 hydrogenated castor oil larger micelles have formed, lower values of polydispersity index indicated that more homogeneous distribution of micelles size was gained. Conductometric analysis has demonstrated that system composing of C/T ratio 2:1, has shown most pronounced interaction between droplets, which can be seen as high rise of electrical conductivity with increasing water content (% (wwater/wtotal)) in the sample. No significant difference in percolation threshold between formulations with different C/T ratios was observed. Different surfactant systems were adsorbed on magnesium aluminometasilicate, as adsorbent with high specific active surface (≈300 m2/g), in order to investigate potential influence of adsorbent on ibuprofen dissolution rate. Formulated systems, with or without adsorbent were filled in hard gelatin capsules. The dissolution profiles of ibuprofen from different formulations were obtained in 30 minutes by dissolution apparatus with rotating baskets and compared with dissolution profiles of ibuprofen from commercial products. For formulations without adsorbent faster release of ibuprofen in first minutes of dissolution test, showed formulations with C/T ratio 2:1 and 1:1. Magnesium aluminometasilicate, as adsorbent with high specific surface area, significantly improved release rate of ibuprofen from formulation with C/T ratio 2:1, but, for formulation with C/T ratio 1:1, significantly lower release of ibuprofen was observed. Formulations with other C/T ratios in terms of fast ibuprofen release did not give satisfying results. Obtained results show that in comparison to dissolution profile of ibuprofen from commercial products proper C/T ratio as well as magnesium aluminometasilicate, as adsorbent with high specific surface area, can significantly increase release of ibuprofen.