Some active pharmaceutical ingredients, despite their desired therapeutic effects, have properties that make their use and the production of pharmaceutical dosage forms difficult. These include the active substance fenofibrate, which has poor solubility. One approach to improve solubility is to produce solid dispersions. These are made from the active substance and excipients, often using mesoporous materials whose specific structure and large surface area allow the active substance to be loaded into the pores. The efficacy of the constructed delivery system can be verified by a pharmacopoeial release test, which gives an indication of the proportion of the active substance that has been released and dissolved in the medium.
We have produced formulations with the active substance and the mesoporous excipient Syloid®244 FP in five different concentrations, in 10% increments. We wanted to determine how the proportion of the active ingredient in the dispersion affects the release in a suitable discriminatory medium. Solid dispersions were made under different conditions (organic solvent, temperature, pressure) and we also wanted to find out how these affect the proportion of active substance released. The best solid dispersion was selected and used for the production of tablets by means of a release test carried out at pH=1.2. The tablets were measured for strength, disintegration time and release test.
We found that the production of solid dispersions significantly improved the solubility of the active substance compared to physical mixtures or to the pure active substance. The results are related to the amorphous nature of the active substance in the solid dispersions, which was demonstrated by the absence of melting point when the samples were heated and the large specific surface area from which the active substance dissolves. We found that the efficiency of the dissolution enhancement also depends on the use of an organic solvent, as the active substance is more soluble in acetone compared to isopropanol. As a result, there was a higher efficiency of incorporation of the active substance into the pores of the Syloid and a higher percentage of the active substance dissolved in the case of using acetone to produce a solid dispersion. Finally, orodispersible tablets with an active ingredient content of 20% were produced, which disintegrated in less than 30 seconds and released 90% of the active ingredient in 120 minutes.
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