Reservoir Based Fentanyl Transdermal Drug Delivery Systems: Effect of Patch Age on Drug Release and Skin Permeation
To understand and evaluate the stability and skin permeation profiles of fentanyl reservoir systems as a function of patch age.
Drug release and skin permeation studies were performed using a modified USP apparatus 5 with a novel sample preparation technique.
The amount of fentanyl present in the EVA/adhesive layer (EAL) increased from about 17% of label claim (LC) at 5 months to 25% LC at 22 months. The increase in the drug concentration was mainly observed in the peripheral EAL. Simultaneously, the alcohol content of the patch decreased as a function of patch age. A significant effect of patch age on the drug content in the EAL and the drug release from the system was observed; however, skin permeation studies did not indicate an increase in drug delivery rate.
Novel sample preparation technique with USP Apparatus 5 allowed determination of in vitro skin permeation rates for fentanyl transdermal patches with different designs. Permeation rates with cadaver skin as substrate were found not to change with patch age despite changing drug concentration in the EAL.
KEY WORDSfentanyl reservoir systems skin permeation stability transdermal drug delivery
The authors would like to acknowledge John Black and Dr. Michael Trehy at the Division of Pharmaceutical Analysis, FDA for their help with the studies associated with this manuscript. The authors would also like to thank the scientists and regulatory and scientific personnel of the manufacturer of Duragesic fentanyl transdermal systems and Dr. Ravi Harapanhalli for their valuable comments and suggestions.
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