Solubilization of timolol maleate in reversed micellar systems -: Measurement of particle size using SAXS and PCS

Small angle X-ray scattering (SAXS) and photon correlation spectroscopy (PCS) are two methods to measure par-tide sizes in the order of 10 nm magnitude, which can be used to characterize reversed micellar systems, in this case reverse micelles consisting of lecithin and isopropyl myristate (IPM). In this study these micelles an loaded with different concentrations of the amphiphilic anti-glaucoma drug timolol maleate (TM). The PCS results are consistent with those yielded by SAXS, showing a decrease of particle size with higher TM concentration. In addition, SAXS is capable to give information about the particle shape. This kind of evaluation yields an ellipsoidal shape for micelles with low drug loads, which transform into nearly spherical micelles at higher drug concentrations. (C) 2000 Elsevier Science B.V. All rights reserved.