Extraction of Free Drug from Nanoparticle Formulation in Biological Matrix

High extraction efficiency

There is currently no consistent, robust method for separating free and nanoparticle-bound drug from a biological matrix. This method of free drug extraction is urgently needed in order to predict in vivo stability and determine bio-available, free drug profile in pharmacokinetic samples. These methods could aid in the design of nanoformulations with better controlled release properties, as well as aid in safety assessment and estimation of a clinical starting dose. This study utilizes a Dispersive Pipette XTRaction technology for INTip? solid phase extraction of free doxetaxel (DTX) and paclitaxel (PTX) from two nanoformulations. DTX was extracted from a nanoliposomal formulation (Azaya Therapeutics) and PTX was extracted from an albumin nanoparticle formulation (Abraxane?, Abraxis BioSiences, Inc.), both in 25% rat plasma. Extracted drug was analyzed by a validated HPLC method and extraction efficiency was consistently 70% for both drugs. Consistent with the pharmacokinetic data for these formulations, neither formulation was found to be stable, with drug readily extracted from the nanoformulation containing biological matrix. Chemical analysis of nanoliposomal cholesterol and albumin nanoparticle protein in the extraction flow through suggested that the nanoformulations themselves were not extracted. Further size analysis by dynamic light scattering of the flow through from saline extracted samples demonstrated that the nanoliposome size was unaffected by the sample extraction procedure, while the albumin nanoparticle was disrupted. The data supports further investigation of this method for extraction of free drug from biological matrix.