Studies of beneficial interactions between active medicaments and excipients in pharmaceutical formulations

A review of "up to date" research findings leading to new concepts of the pharmaceutical formulations and their interactions has been presented. The rational approaches to the excipients choice as well as to their interactions with medicaments have been shown as a basis for modern modelling of pharmaceutical formulations. The importance of complexation, hydrogen bonding, ion-dipole, dipole-dipole and van der Waals attractions as the tools which can modify the physicochemical, pharmacological or pharmacokinetical behaviour of the medicaments has been emphasised. In vivo studies (carried out in healthy human subjects-volunteers, in beagle dogs, in rats etc.) and in vitro studies (on excised human skin, hairless mouse skin etc.) as well as studies of chemical stability and bioavailability serve also as a proof of these interactions. Therefore, excipients are important components of pharmaceutical formulations and they can take an active part in the improvement of the characteristics of formulations (but they may also reduce the effectiveness of some preparations). In this context, the so called active and inactive ingredients in pharmaceutical formulations are inexact, old and "out-of date". Their further use is only conventional. In conclusion, among the various modern techniques applied the combination of infrared spectroscopy and X-ray diffraction has been estimated as the most successful in proving the interactions between drugs and excipients. Finally, pharmaceutical formulations and their interactions have constituted a diverse and rapidly expanding held of Pharmacy (Pharmaceutical Technology, Pharmaceutical Industry and Pharmaceutical Sciences) which covers a wide range of numerical topics within an unified framework. (C) 1999 Elsevier Science B.V. All rights reserved.