title: Solubilization of the novel anionic amphiphilic photosensitizer TPCS 2a by nonionic Pluronic block copolymers.
abstract: The influence of four nonionic Pluronic block copolymers (L44, F68, P123 and F127) on the solubilization and aggregation of the novel anionic amphiphilic photosensitizer TPCS(2a), intended for use in the technology of photochemical internalization (PCI), was evaluated in aqueous media as part of pharmaceutical preformulation studies. The evaluation was performed by use of UV-Vis spectroscopy for diluted samples of TPCS(2a) (3×10(-6)M), and capillary viscosimetry, freezing point depression measurements and atomic force microscopy (AFM) at pharmaceutical relevant concentrations (2; 10 or 30 mg/ml TPCS(2a)). The critical micelle concentration (CMC) of the Pluronics in presence of TPCS(2a) was determined spectrophotometrically. The Pluronic block copolymers solubilized the photosensitizer above CMC at ambient temperature by formation of vehicle-drug complexes apparently organized in networks of varying viscosity and morphology, which were sensitive towards the addition of neutral and charged excipients.
authors.affiliation: University of Oslo, School of Pharmacy, Department of Pharmacy, Division Pharmaceutics, Norway. marianne.lilletvedt@farmasi.uio.no
authors.forename: M
authors.initials: M
authors.lastname: Lilletvedt
authors.forename: G
authors.initials: G
authors.lastname: Smistad
authors.forename: H H
authors.initials: HH
authors.lastname: Tønnesen
authors.forename: A
authors.initials: A
authors.lastname: Høgset
authors.forename: S
authors.initials: S
authors.lastname: Kristensen
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D005079:Excipients / Q000737:chemistry; D006801:Humans; D008823:Micelles; D018625:Microscopy, Atomic Force; D010316:Particle Size; D017319:Photosensitizing Agents / Q000737:chemistry*; D020442:Poloxamer / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry*; D012995:Solubility; D013056:Spectrophotometry, Ultraviolet; D013501:Surface-Active Agents / Q000737:chemistry; D013696:Temperature; D014783:Viscosity
chemical_list: D000903:Antibiotics, Antineoplastic; D005079:Excipients; D008823:Micelles; D017319:Photosensitizing Agents; D011166:Porphyrins; D013501:Surface-Active Agents; C559366:meso-tetraphenyl chlorin disulphonate; D020442:Poloxamer