Performance evaluation of PAMAM dendrimer based simvastatin formulations

The purpose of this investigation was to evaluate the performance of poly (amidoamine) (PAMAM) dendrimers, with three different surface groups, to be used as drug carriers. Drug-dendrimers complexes were investigated for solubility studies, dissolution studies, in vitro drug release studies, and for stability studies. The solubility enhancement was found maximum with PEGylated dendrimers (33 times) followed by amine (23 times) and hydroxyl (17.5 times) dendrimers. The solubility profile of simvastatin-dendrimer complex showed a linear correlation (Higuchi A(L)-type diagram) between solubility and dendrimers concentration. The formation of the complexes between drug molecules and dendrimers were characterized by the FTIR spectra of these complexes, showing the appearance of the bond formed between the functional groups of the drug (OH and COOH) and dendrimers (NH2 and OH). The drug-dendrimer complexes displayed the controlled release action during in vitro release studies. Pure simvastatin (SMV) was released in 5 h whereas the PEGylated dendrimers-SMV complexes released the drug up to 5 days. The non-PEGylated formulations released the drug up to 24 h. Formulations with amine and PEGylated dendrimers were subjected to accelerated stability studies. Formulations with amine dendrimers were found to be most stable in dark, low temperature (0 degrees C) whereas the dark, RT was most suitable storage conditions for formulation with PEGylated dendrimers. (C) 2010 Elsevier B.V. All rights reserved.