| Abstract [eng] |
During the development of pharmaceutical forms, the focus is often on assessing the quality of an already modelled pharmaceutical form. Microemulsion systems that do not meet the quality requirements may affect the stability, solubility, and release of the active substance from the pharmaceutical form. In order to model microemulsions that meet the quality requirements, it is important to select suitable excipients and to evaluate the influence of individual excipients on microemulsion systems. According to the importance of such a study, the object of the study was selected modelled microemulsions with different excipients and microemulsions with resveratrol. The results of the studies showed that a larger area of the modelled microemulsions in pseudo-trinary phase diagrams were formed with the cosurfactant polyglyceryl-6-isostearate than with the cosurfactant ethanol. Microemulsions with synthetic oils form a larger area than the microemulsions with natural oils in the pseudo-trinary phase diagrams. Mean droplet size of microemulsions with the cosurfactant polyglyceryl-6-isostearate ranged from 57.61 to 107.3 nm., polydispersity values were from 0.330 to 0.519, viscosity values varied between 41.4 and 83.4 mPa·s, pH values were from 7.16 to 7.33 and electrical conductivity varied between 58 and 145 μS/cm. Mean droplet size of microemulsions with the cosurfactant ethanol ranged from 28.06 to 73.58 nm, polydispersity values were from 0.280 to 0.647, viscosity values varied between 4.5 to 25.7 mPa·s, pH values were from 5.44 to 5.85 and electrical conductivity varied between 6.6 and 10 μS/cm. Mean droplet size increased by 0.3–110 % after resveratrol incorporation into microemulsions, respectively. Lower viscosity and electrical conductivity of microemulsions were determined (p < 0.05). Resveratrol release studies in vitro have confirmed that a higher amount of resveratrol, regardless of the oil phase and selected cosurfactant, was released from microemulsions at surfactant and cosurfactant ratio 9:1. Microemulsions that were modelled with cosurfactant polyglyceryl-6-isostearate the highest amount of resveratrol was released when the lipophilic phase was isopropyl myristate (57.41 %) and from modelled microemulsion with cosurfactant ethanol – with ethyl oleate (67.59 %). Based on the results of the study, it can be concluded that different excipients that have been used in modeling microemulsions had an influence on microemulsions forming area in pseudo-trinary phase diagrams. Different selected excipients (cosurfactants and oils) influenced the physicochemical parameters of microemulsions. Changes of higher mean droplet size, lower electrical conductivity and viscosity were determined when resveratrol was incorporated into microemulsions. In vitro studies confirmed that modelled microemulsions are capable of releasing the active substance and are suitable carriers for resveratrol incorporation. |
