Novel organogels for topical delivery of naproxen: design, physicochemical characteristics and in vitro drug permeation

Taking into account possible irritation of the skin upon contact with naproxen (NPX) crystals and lower bioavailability after administration of the suspended or ionized drug, the aim of the work was to design and characterize novel and easy-to-formulate gels with the entirely dissolved drug in the acidic form. The formulations contained ethanol, SynperonicTMPE/L 62 and Arlasolve (R) DMI or Transcutol (R). Carbopol (R) 940 was used as the thickener. The properties of organogels were compared with six market products. The rheological measurements included steady flow experiments and oscillatory analysis. The texture profile analysis was conducted to calculate the mechanistic parameters. The in vitro permeation studies were performed on SOTAX CE 7 smart apparatus with the application of Strat-M artificial membranes. The obtained organogels fulfilled the requirements for topical products in terms of consistency, uniformity, stability, drug dissolution and permeation. The permeation studies revealed distinct differences among the commercial hydrogels according to permeation coefficients (k(P)), drug flux (J(ss)) and average cumulative amount of NPX per area after 12h (Q(12h)). The presented work clearly shows that the organogels can be proposed as an alternative for commercial products where NPX occurs in the form of crystals.