Binary Micellar Solutions of Poly(Ethylene Oxide)-Poly(Styrene Oxide) Copolymers with Pluronic® P123: Drug Solubilisation and Cytotoxicity Studies

The non-commercial copolymers E45S8, E45S17 and their mixtures with Pluronic (R) P123 (E21P67E21) were studied as carriers of the model drug griseofulvin. Critical micelle concentration (cmc) (dye solubilisation method), drug solubilisation capacity (S-cp and S-h) determined by ultraviolet-visible (UV-Vis) spectroscopy and H-1 nuclear magnetic resonance (H-1 NMR) and cytotoxicity (LDH activity in human neutrophils) were studied. E45S17 1.0 wt.% dispersions presented colloidal aggregates limiting its S-cp in comparison to E45S8, but in 0.1 wt.% solutions this phenomenon seemed to be absent and E45S17 presented a higher S-cp. The mixtures that showed the best S-cp results contained 50% of P123 and presented low cmc. An evaluation of literature data suggested a minimum E-m content of 62% in EmSn copolymers below which the increase of S-n length does not lead to an increase of S-h. The results suggested no toxicity of the copolymers on human neutrophils, supporting the use of P123 and poly(styrene oxide) containing copolymers as drug carriers.