Treatment of head louse infestation with 4% dimeticone lotion:
randomised controlled equivalence trial
Ian F Burgess, Christine M Brown, Peter N Lee
Objective To evaluate the efficacy and safety of 4% dimeticone
lotion for treatment of head louse infestation.
Design Randomisedcontrolled equivalence trial.
Setting Community, with home visits.
Participants 214 young people aged 4 to 18 years and 39
adults with active head louse infestation.
Interventions Two applications seven days apart of either 4.0%
dimeticone lotion, applied for eight hours or overnight, or 0.5%
phenothrin liquid, applied for 12 hours or overnight.
Outcome measures Cure of infestation (noevidence of head
lice after second treatment) or reinfestation after cure.
Results Cure or reinfestation after cure occurred in 89 of 127
(70%) participants treated with dimeticone and 94 of 125 (75%)
treated with phenothrin (difference − 5%, 95% confidence
interval − 16% to 6%). Per protocol analysis showed that 84 of
121 (69%) participants were cured with dimeticone and 90 of
116 (78%) werecured with phenothrin. Irritant reactions
occurred significantly less with dimeticone (3/127, 2%) than
with phenothrin (11/125, 9%; difference − 6%, − 12% to − 1%).
Per protocol this was 3 of 121 (3%) participants treated with
dimeticone and 10 of 116 (9%) treated with phenothrin
(difference − 6%, − 12% to − 0.3%).
Conclusion Dimeticone lotion cures head louse infestation.
Dimeticone seemsless irritant than existing treatments and has
a physical action on lice that should not be affected by
resistance to neurotoxic insecticides.
Recently, most Western countries have encouraged physical
methods to treat head louse infestation, either alone or as a component of conventional insecticidal treatments.1 2 The commonest method used in the United Kingdom is wet combingwith
conditioner, known as “bug busting” (Community Hygiene Concern, London). Existing evidence suggests that this method is of
low effectiveness,3–5 which, combined with treatment failure
attributed to insecticide resistance, has resulted in an increased
prevalence of lice in most communities since 1995.6–8
Dimeticone lotion is a new product, with no conventional
insecticide activity. Itcontains 4% long chain linear silicone
(dimeticone) in a volatile silicone base (cyclomethicone). Both
compounds are used extensively in cosmetics and toiletries, and
a shorter chain dimeticone is used as an anti-flatulent for infant
colic. Dimeticone is a clear, odourless fluid, which is applied in
the same way as other lotions for head lice infestation, by coating
the scalp and full length ofthe hair. The product dries by evaporation of the cyclomethicone solvent. We selected application for
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eight hours or overnight on the basis of a phase II clinical study
that compared two 20 minute treatments a week apart with two
treatments for eight hours or overnight. In 40 randomised
participants (35 children), the 20 minute regimen cured 12 of 20
(60%) and theeight hours or overnight treatment cured 18 of 20
(90%), giving a difference of − 30% (95% confidence interval
− 55% to − 5%).
We compared the efficacy of two applications seven days
apart of either 4.0% dimeticone lotion or 0.5% d-phenothrin liquid. Phenothrin is currently the most widely used pediculicide in
the United Kingdom, and we selected the liquid because its
physical form anddosage is most similar to that of dimeticone
lotion (it is applied for 12 hours or overnight) and it is safe for
people with asthma.
Participants and methods
We recruited participants by advertising through local newspapers and radio. Those families who telephoned the study coordinator received an information booklet by post. Those who
wished to enrol telephoned the study coordinator to...