Tolterodine Tartrate Loaded Cationic Elastic Liposomes for Transdermal Delivery: In Vitro, Ex Vivo, and In Vivo Evaluations.

Objective: Tolterodine tartrate (TOTA) is a first-line therapy to treat overactive urinary bladder (OAB). Oral delivery causes high hepatic clearance, xerostomia, headache, constipation, and blurred vision. We addressed Hansen solubility parameter (HSP) and Design Expert oriented optimized cationic elastic liposomes for transdermal application.

Methods: The experimental solubility was conducted in HSPiP predicted excipients to tailor formulations using surfactants, stearylamine, ethanol, and phosphatidylcholine (PC). These were evaluated for formulation characteristics. The optimized OTEL1 and OTEL1-G (gel) were compared against the drug solution (DS) and liposomes. In vitro and ex vivo studies were accomplished to investigate the insights into the mechanistic understanding of TOTA release and permeation ability. Finally, confocal laser scanning microscopy (CLSM) supported ex vivo results.

Results: HSP values of TOTA were closely related to tween-80, stearylamine, and human's skin. The size (153 nm), %EE (87.6%), and PDI (0.25) values of OTEL1 were in good agreement to the predicted values (161 nm, 80.4%, and 0.31) with high desirability (0.963). Spherical and smooth OTEL1 (including OTEL1-G and liposomes) vesicles followed non-Fickian drug release as compared to DS (Fickian) as evidence with n > 0.5 (Korsmeyer and Peppas coefficient). OTEL1 (containing lipid and surfactant as 90 mg and 13.8 mg, respectively) exhibited 2.6 and 1.8-folds higher permeation flux than DS and liposomes, respectively. Biocompatible cationic OTEL1 was safe and non-hemolytic.

Conclusions: OTEL1 was promised as a lead vesicular approach and an alternative to conventional oral therapy to treat OAB in children and advanced age patients.