Influence of penetration enhancers on topical delivery of 5-aminolevulinic acid from bioadhesive patches
Article first published online: 10 JUN 2010
© 2010 The Authors Journal compilation © 2010 Royal Pharmaceutical Society of Great Britain
Journal of Pharmacy and Pharmacology
Special Issue: Recent advances in transdermal drug delivery
Volume 62, Issue 6, pages 685–695, June 2010
How to Cite
Morrow, D. I.J., McCarron, P. A., Woolfson, A. D., Juzenas, P., Juzeniene, A., Iani, V., Moan, J. and Donnelly, R. F. (2010), Influence of penetration enhancers on topical delivery of 5-aminolevulinic acid from bioadhesive patches. Journal of Pharmacy and Pharmacology, 62: 685–695. doi: 10.1211/jpp.62.06.0004
- Issue published online: 10 JUN 2010
- Article first published online: 10 JUN 2010
- Received August 28, 2009Accepted December 16, 2009
- 5-aminolevulinic acid;
- bioadhesive patch;
- permeation enhancers;
- topical drug delivery
Objectives The inclusion of chemical penetration enhancers in a novel patch-based system for the delivery of 5-aminolevulinic acid (ALA) was examined in vitro and in vivo. Poor penetration of ALA has been implicated as the primary factor for low response rates achieved with topical ALA-based photodynamic therapy of thicker neoplastic lesions, such as nodular basal cell carcinomas.
Methods Several chemical permeation enhancers (dimethylsulfoxide, Labrafac CC, Labrafac PG and Labrafil M1944CS) were incorporated into bioadhesive patches tailored to deliver 19 mg ALA/cm2.
Key findings In-vitro depth penetration studies into excised porcine skin showed that high concentrations of ALA (>9 μmol/cm3) could be delivered to a depth of 1.875 mm. However, inclusion of permeation enhancers did not significantly increase ALA delivery, relative to the control (P > 0.05). In-vivo studies were in strong agreement with in-vitro results, with formulations containing chemical enhancers showing no improvement in delivery compared with the control.
Conclusions The patches designed in this work are suited to defineable ALA delivery without the need to immobilise patients for up to 6 h, as is common with the cream-under-occlusion approach. Overall, permeation enhancers were not found to markedly enhance the topical delivery of ALA. However, chemical penetration enhancers may have a greater effect on the delivery of more lipophilic ALA prodrugs, which are thought to primarily permeate the stratum corneum via the intercellular pathway.