An investigation into the mechanisms of rapid release of standard extract from Ginkgo biloba leaf in polyethylene glycol 6000 solid dispersions.

The rapid-release mechanisms of standard extract from Ginkgo biloba leaf (EGb) in the polyethylene glycol (PEG) 6000 dispersions were investigated. The apparent equilibrium solubilities of the total flavone glycosides and the soluble solid materials of EGb increased linearly with the increasing concentrations of PEG 6000 solutions. In DSC curves, the peak, onset and endset temperatures of solid dispersions decreased with the increase of EGb weight percent. At the high drug loading, the initial dissolution rates of the total flavone glycosides of EGb had no significant change while the rates of PEG 6000 reduced with the drug concentration increase. The rates of PEG 6000 had no significant change as well as the rates of drug increased with the drug concentration increase at the low drug loading. The results indicated that there were apparent evidences for eutectic observation and soluble complex formation in the two-component solid dispersion of EGb and PEG 6000. The dispersions may belong to drug-controlled dissolution model at high drug loadings and carrier-controlled dissolution model at low drug loadings.