AAPS PharmSciTech

, Volume 14, Issue 1, pp 168–176 | Cite as

Development of W/O Microemulsion for Transdermal Delivery of Iodide Ions

  • Hao Lou
  • Ni Qiu
  • Catherine Crill
  • Richard Helms
  • Hassan Almoazen
Research Article


The objective of this study was to develop a water-in-oil (w/o) microemulsion which can be utilized as a transdermal delivery for iodide ions. Several w/o microemulsion formulations were prepared utilizing Span 20, ethanol, Capryol 90®, and water. The selected formulations had 5%, 10%, 15%, 20%, and a maximum of 23% w/w water content. Potassium iodide (KI) was incorporated in all formulations at 5% w/v. Physicochemical characterizations were conducted to evaluate the structure and stability. These studies included: mean droplet size, pH, viscosity, conductivity, and chemical stability tests. In vitro human skin permeation studies were conducted to evaluate the diffusion of the iodide ion through human skin. The w/o microemulsion formulations were stable and compatible with iodide ions with water content ranging from 5% to 23% w/w. The addition of KI influenced the physicochemical properties of microemulsion as compared to blank microemulsion formulations. In vitro human skin permeation studies indicated that selected formulations improved iodide ion diffusion significantly as compared to control (KI solution; P value < 0.05). Iodide ions were entrapped within the aqueous core of w/o microemulsion. Span 20, ethanol and Capryol 90 protected the iodide ions against oxidation and formed a stable microemulsion. It is worth to note that according to Hofmeister series, iodide ions tend to lower the interfacial tension between water and oil and consequently enhance overall stability. This work illustrates that microemulsion system can be utilized as a vehicle for the transdermal administration of iodide.


iodide microemulsion skin permeation transdermal 



The authors cordially thank M. Liu for the professional assistance.


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Copyright information

© American Association of Pharmaceutical Scientists 2012

Authors and Affiliations

  • Hao Lou
    • 1
  • Ni Qiu
    • 2
  • Catherine Crill
    • 3
  • Richard Helms
    • 3
  • Hassan Almoazen
    • 1
  1. 1.Department of Pharmaceutical SciencesUniversity of Tennessee Health Science CenterMemphisUSA
  2. 2.Department of PharmacologyGuangzhou Medical UniversityGuangzhouChina
  3. 3.Department of Clinical PharmacyUniversity of Tennessee Health Science CenterMemphisUSA

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