Interfacial behaviour of pharmaceutical excipients

Since drug release from dosage forms has importance for absorption from the gastrointestinal system, physicochemical characterisation of pharmaceutical systems is essential during the development of an optimal formulation with high efficacy and quality. Interfacial parameters of several pharmaceutical excipients were studied regarding their possible modifying effect on drug release from the dosage form. Measured data on water adsorption, wetting contact angle, and surface tension of pharmaceutical systems were evaluated to characterise the interfacial behaviour during the dissolution of the active ingredient. The results demonstrated that the drug liberation process markedly depends on the wettability of the dosage form. The action of added excipients was investigated by applying the Weibull distribution as a mathematical model for dissolution kinetics and using a two-factor, three-level factorial experimental design to evaluate the effect of critical phenomena, such as water uptake and surface tension.



The physical characteristics of the formulated samples of drugs are useful to predict the drug release, liberation, and dissolution conditions. The characteristics of sam- plus simulating the dosage forms are important for proper evaluation of the results. The study of the interfacial behaviour of formulated samples results in good prediction possibilities for the practice of pharmaceutical technology.

The results verify that to achieve higher bioavailability, formulating a solid dispersion from a poorly water soluble drug, or applying surfactants in the dosage form, would be the solution for the solubility difficulties.


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Book: Progress in Colloid and Polymer Science