Aerosol based detectors for the investigation of phospholipid hydrolysis in a pharmaceutical suspension formulation.

A high performance liquid chromatography (HPLC) method was developed to quantify free fatty acids (FFA) in a pharmaceutical suspension formulated with phospholipids as stabilizing agents. Specifically, a suspension of crystalline itraconazole microparticles stabilized with Lipoid E80 was used as a model system to study the physicochemical stability of an aqueous, phospholipid-based suspension for injection. The hydrolysis of the phospholipids during storage at elevated temperatures (40 degrees C) necessitated the development of a suitable HPLC method for the determination of free fatty acid content in the suspension samples. HPLC methods using two types of aerosol detectors were investigated for the above purpose. Reversed-phase separation coupled with either an evaporative light scattering detector (ELSD) or a Corona(Plus) charged aerosol detector (CAD) was used. A comparison of the methods indicated that the CAD method provided better sensitivity, precision, recovery, and linearity for the parameters evaluated. As a result, this method was chosen for the stability study of itraconazole suspension and has been incorporated in subsequent formulation studies.