Mechanochemically induced disordered structures of vincamine: The different mediation of two cross-linked polymers

The aims of this research were to prepare highly bioavailable binary cogrounds (vincamine-AcDiSol® or PVP-Cl) by means of a mechanochemical process and to study the mediation of each polymer in the induction of physical transformations of the drug.From a set of fifteen cogrounds for each crosslinked polymer, two samples were selected in each group on the basis of the AUC of in vitro dissolution profiles with the help of a statistical comparison. The chosen samples were analysed by means of TEM, XRPD, Raman-spectroscopy/imaging, SSNMR, also including the study of 1H spin-lattice relaxation times. The research encompassed in vivo oral absorption studies in rats, pharmacokinetic analysis and physical stability studies during 1 year. An intimate drug-polymer mixing was found in the coground samples with domain average dimensions smaller than 100 Å; this reflected in a remarkable enhancement of the in vitro and in vivo bioavailability. Different disordered states were detected in the coground samples as a function of cogrinding time and the type and amount of polymer used.Though both crosslinked polymers produced a remarkable enhancement of the oral bioavailability, coground systems based on AcDiSol® are preferable in terms of pharmacokinetic performance and physical stability.

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