Transdermal patches for site-specific delivery of anastrozole: In vitro and local tissue disposition evaluation

Anastrozole is a potent aromatase inhibitor and there is a need for an alternative to the oral method of administration to target cancer tissues. The purpose of the current study was to prepare a drug-in-adhesive transdermal patch for anastrozole and evaluate this for the site-specific delivery of anastrozole. Different adhesive matrixes, permeation enhancers and amounts of anastrozole were investigated for promoting the passage of anastrozole through the skin of rats in vitro. The best in vitro skin permeation profile was obtained with the formulation containing DURO-TAK 87-4098, IPM 8% and anastrozole 8%. For local tissue disposition studies, the anastrozole patch was applied to mouse abdominal skin, and blood, skin, and muscle samples were taken at different times after removing the residual adhesive from the skin. High accumulation of the drug in the skin and muscle tissue beneath the patch application site was observed in mice compared with that after oral administration. These findings show that anastrozole transdermal patches are an appropriate delivery system for application to the breast tumor region for site-specific drug delivery to obtain a high local drug concentration.