HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: ptj.20080043v1 88/10/1177    most recent Submit a response Alert me when this article is cited Alert me when Rapid Responses are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Google Scholar Articles by Sylvestre, J.-P. Articles by Delgado-Charro, M B. PubMed PubMed Citation Articles by Sylvestre, J.-P. Articles by Delgado-Charro, M B.

In Vitro Optimization of Dexamethasone Phosphate Delivery by Iontophoresis

JP Sylvestre, PhD, is Postdoctoral Researcher, Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, United Kingdom
RH Guy, PhD, is Professor, Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, BA2 7AY, United Kingdom
MB Delgado-Charro, PhD, is Lecturer in Pharmaceutical Sciences, Department of Pharmacy and Pharmacology, University of Bath

Address all correspondence to Dr Guy at: r.h.guy{at}bath.ac.uk

Background and Purpose: This study was designed to evaluate the effects of competing ions and electroosmosis on the transdermal iontophoresis of dexamethasone phosphate (Dex-Phos) and to identify the optimal conditions for its delivery.

Methods: The experiments were performed using pig skin, in side-by-side diffusion cells (0.78 cm²), passing a constant current of 0.3 mA via Ag-AgCl electrodes. Dex-Phos transport was quantified for donor solutions (anodal and cathodal) containing different drug concentrations, with and without background electrolyte. Electrotransport of co-ion, citrate, and counterions Na⁺ and K⁺ also was quantified. The contribution of electroosmosis was evaluated by measuring the transport of the neutral marker (mannitol).

Results: Electromigration was the dominant mechanism of drug iontophoresis, and reduction in electroosmotic flow directed against the cathodic delivery of Dex-Phos did not improve drug delivery. The Dex-Phos flux from the cathode was found to be optimal (transport number of 0.012) when background electrolyte was excluded from the formulation. In this case, transport of the drug is limited principally by the competition with counterions (mainly Na⁺ with a transport number of 0.8) and the mobility of the drug in the membrane.

Discussion and Conclusion: Dex-Phos must be delivered from the cathode and formulated rationally, excluding mobile co-anions, to achieve optimal iontophoretic delivery.

This article has been cited by other articles:

				F. B Underwood Invited Commentary Physical Therapy, October 1, 2008; 88(10): 1185 - 1187. [Full Text] [PDF]