Improved stability and release control of levodopa and metaraminol using ion-exchange fibers and transdermal iontophoresis

T Kankkunen, I Huupponen, K Lahtinen… - European journal of …, 2002 - Elsevier
T Kankkunen, I Huupponen, K Lahtinen, M Sundell, K Ekman, K Kontturi, J Hirvonen
European journal of pharmaceutical sciences, 2002Elsevier
Achievement of controlled drug delivery and stability of drugs during storage is a problem
also in transdermal drug delivery. The objective of this study was to determine, whether an
easily oxidized drug, levodopa, could be stabilized during storage using pH-adjustment and
ion-exchange fibers. Controlled transdermal delivery of the zwitterionic levodopa was
attempted by iontophoresis and ion-exchange fiber. Ion-exchange kinetics and transdermal
permeation of a cationic (presumably more stable) model drug, metaraminol, were …
Achievement of controlled drug delivery and stability of drugs during storage is a problem also in transdermal drug delivery. The objective of this study was to determine, whether an easily oxidized drug, levodopa, could be stabilized during storage using pH-adjustment and ion-exchange fibers. Controlled transdermal delivery of the zwitterionic levodopa was attempted by iontophoresis and ion-exchange fiber. Ion-exchange kinetics and transdermal permeation of a cationic (presumably more stable) model drug, metaraminol, were compared to the corresponding data of levodopa. Levodopa was rapidly oxidized in the presence of water, especially at basic pH-values. At acidic pH-values the stability was improved significantly. Ion-exchange group and the pH had a clear effect on the release of both the levodopa and metaraminol from the ion-exchange fiber. The adsorption/release kinetics of metaraminol were more easily controllable than the corresponding rate and extent of levodopa adsorption/release. Iontophoretic enhancement of drug permeation across the skin was clearly more significant with the positively charged metaraminol than with the zwitterionic levodopa. Ion-exchange fibers provide a promising alternative to control drug delivery and to store drugs that are degraded easily.
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