Hedrin lotion (4% dimeticone in a silicone solvent)

Hedrin lotion (4% dimeticone in a silicone solvent)

• is a topical treatment for head lice
• is a colourless and odourless liquid - it has a slightly oily texture - that is applied to the hair
• it is left to dry and washed off after at least 8 hours
• it is important that the scalp and all the hair are wetted with the fluid (including the full length of long hair)
• two applications of treatment, 7 days apart, are recommended - this is in order to kill nymphal lice emerging from eggs which might not have been killed by the first application
• mode of action
  • the dimeticone in its silicone solvent is believed to immobilse the lice once they become covered in the preparation. As the solvent evaporates the lice are then left coated by a layer of dimeticone - it is believed that the lice die by reverse osmotic effects caused by a disruption of their ability to manage internal water
  • no evidence that lice can become resistant to dimeticone
• a review concluded that ".. it seems reasonable to regard dimeticone as a first-line alternative to malathion, permethrin or phenothrin, particularly for parents or patients who do not wish to use conventional insecticides..."

Reference:

1. Drug and Therapeutics Bulletin (2007); 45(7):52-5.