Please use this identifier to cite or link to this item: http://hdl.handle.net/1946/2345
Delivering drugs via the skin has many benefits. However, it is generally difficult to get drugs to cross the skin at a sufficient rate to deliver a therapeutic dose, even when the drug is potent. Therefore, numerous methods to enhance transdermal drug delivery have been developed and this area of research is increasingly expanding.
The main objective of this study was to examine the effects of a novel penetration enhancer in an ionic liquid (IL) form, composed of diisopropanolamine (DIPA) and isostearic acid (ISA), on skin permeation of two model drugs, ibuprofen (IBU) and lidocaine (LID). An in vitro skin permeation study was performed using Franz-type diffusion cells and the flux of drugs was examined across excised rat abdominal skin. HPLC was used as a method for measuring the permeated amount of drugs.
The results of this study indicate that the mixture of DIPA and ISA forms an ionic liquid which can be utilized as a penetration enhancer for transdermal drug delivery. Results from FT-IR analysis on the binary mixture of DIPA and ISA suggest that ion-pairing occurs between the two chemicals. Furthermore, a new lower melting point for the complex was established by DSC analysis. The IL-DIPA/ISA had very large enhancing effects on skin permeation of IBU in diethyl sebacate but resulted in decreased permeation for LID. Experiments with each of the IL components separately established that DIPA and ISA work together in a synergistic way. Furthermore, the enhancing effects of IL-DIPA/ISA were found out to be concentration and molar ratio dependent. The mechanism of penetration enhancement was studied by examining the relationship between all components. The results from a FT-IR and DSC analysis suggest that IBU and DIPA form an ion-pair which can render IBU more lipophilic and facilitate its penetration through the stratum corneum. ISA might make the transport easier by disrupting the lipid barrier of the SC. These findings may prove useful for transdermal drug delivery of weak acidic drugs with poor skin permeation.