Effective insect repellent formulation in both surfactantless and classical microemulsions with a long-lasting protection for human beings

Chem Biodivers. 2009 Jun;6(6):934-47. doi: 10.1002/cbdv.200800225.


The aim of this work is to develop a new generation of repellent products with a long-lasting protection based on a natural component, para-menthane-3,8-diol (PMD). The active is first rendered soluble in a surfactantless microemulsion (H(2)O/(i)PrOH/PMD) and then in classical microemulsions. The presence of self-associated nanostructures is detected by dynamic light scattering (DLS). A synergetic system of surfactants (Cremophor) RH40 and Texapon N70) is used. Additionally, 2-ethylhexane-1,3-diol and ethyl (-)-(S)-lactate are incorporated. The final product contains, as main components, 46% of H(2)O, 25% of (i)PrOH, 20% of non-H(2)O-soluble PMD, and only 4% of surfactants. Investigations of lasting protection on human volunteers are carried out using a cage test bioassay protocol and Aedes aegypti mosquitoes. A complete protection of 315 min is found on the test persons using the surfactantless microemulsion. An extension is observed with the final formulation to reach a mean of complete protection of 385 min. This study demonstrates that alternative formulations using a natural active instead of synthetic chemicals like N,N-diethyl-m-methylbenzamide (DEET) can be efficient for human protection against mosquitoes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aedes / drug effects
  • Animals
  • Chemistry, Pharmaceutical
  • Cyclohexane Monoterpenes
  • Emulsions
  • Humans
  • Insect Repellents / chemistry*
  • Insect Repellents / pharmacology
  • Menthol / analogs & derivatives*
  • Menthol / chemistry
  • Menthol / pharmacology
  • Surface-Active Agents / chemistry*
  • Time Factors


  • Cyclohexane Monoterpenes
  • Emulsions
  • Insect Repellents
  • Surface-Active Agents
  • Menthol
  • terpin