Eur J PediatrDOI 10.1007/s00431-009-0978-0
Clinical trial showing superiority of a coconut and anisespray over permethrin 0.43% lotion for head louseinfestation, ISRCTN96469780
Ian F. Burgess & Elizabeth R. Brunton &Nazma A. Burgess
Received: 16 February 2009 / Accepted: 23 March 2009# Springer-Verlag 2009
Abstract Permethrin is the most widely used pediculicide,
head louse infestation and is found in products from North
but evidence of resistance from several countries and
and South America, Asia, Australia, and most countries in
anecdotal reports from Germany suggest that permethrin
Europe. Several studies have now shown acquired resis-
lotion is now less effective. We designed a randomized,
tance to this insecticide in head lice, and in most cases, this
controlled, parallel group trial involving 100 participants
has been identified as being primarily mediated by a
with active head louse infestation to investigate the activity
recessive gene mutation known as “knockdown” resistance
of a coconut and anise spray and to see whether permethrin
(kdr) although this is not the only mechanism for
lotion is still effective, using two applications of product
resistance to these insecticides, which may also be degraded
9 days apart. The spray was significantly more successful
metabolically [, However, the impact of resistance is
(41/50, 82.0%) cures compared with permethrin (21/50,
variable depending upon the intensiveness of selection
42.0%; p<0.0001, difference 40.0%, 95% confidence
pressure through extensive and frequent use of pyrethroid
interval of 22.5% to 57.5%). Per-protocol success was
insecticides for treatment of infestation. Effectiveness of
83.3% and 44.7%, respectively. Thirty-three people
treatment is also influenced by the dosage form used for
reported irritant reactions following alcohol contact with
different products and whether active formulation exci-
excoriated skin. We concluded that, although permethrin
pients are present Consequently, some preparations
lotion is still effective for some people, the coconut and
with permethrin as the active ingredient may be more
anise spray can be a significantly more effective alternative
effective than others when used in the same community. It
is for this reason that 0.43% permethrin alcoholic lotion isone of the most used preparations in Germany because
Keywords Head lice . Permethrin . Essential oils .
alcohol is believed to enhance the penetration of insecti-
Coconut and anise spray has been shown to be effective
in killing laboratory reared lice and their eggs (E. Brunton,
unpublished data) and has been evaluated in two previousclinical investigations with good success rates
The insecticide permethrin is probably the most widely
However, the first study used a treatment regimen different
used active ingredient for treatments designed to eliminate
from the one currently used for the product in Europe andexperienced approximately 10% drop-out rate []. Theother evaluated only 12 subjects []. Overall, these studiesindicated that the product is likely to have a treatment
I. F. Burgess (*) : E. R. Brunton : N. A. BurgessMedical Entomology Centre,
success rate of around 90%, which would make it an
Insect Research & Development Limited,
acceptable alternative in areas where resistance is an issue
6 Quy Court, Colliers Lane, Stow-cum-Quy,
with conventional insecticides like permethrin.
We have conducted a randomized, assessor-blinded
e-mail: ian@insectresearch.comURL: www.insectresearch.com
(single-blinded) clinical trial to evaluate the efficacy of
coconut and anise spray in comparison with that of
pediculicide use, and success of previous treatments.
permethrin lotion and to compare the products for safety
Appointments were made for subsequent visits to the
participants in their homes for treatment and assessments. No payment was offered for participation. Anyone who hadlice but was ineligible to participate was offered treatment
using 4% dimeticone lotion as a standard of care treatmentand to prevent reinfestation of study participants.
This study was designed to compare the efficacy of acoconut and anise spray with 0.43% permethrin lotion with
Ethical approval for the study was granted by Leeds (West)
sufficient power to detect if the activity of either product
Research Ethics Committee (EudraCT 2007-006190-87). The
study was conducted in conformity with the principles of theDeclaration of Helsinki and of European Union Directive
2001/20/EC. Prior to giving consent, all participants statedthat they understood the purpose and requirements of the
Participants to this study were recruited by advertising in
investigation after having read the participation information
newspapers or parish magazines and from direct contact
booklet. Parents or guardians gave written consent for
with families who had participated in previous clinical
children younger than 16 years. Children also provided
studies and who had expressed a wish to be included in any
written or verbal assent, according to age, witnessed by the
future research. In each case, an information booklet was
delivered to the family, and an appointment was arrangedfor an investigator to visit. Potential participants were
screened for head lice using a standard detection comb usedin previous studies (“PDC”, KSL Consulting, Denmark).
Coconut and anise spray (Paranix spray/Lyclear Spray-
The level of infestation was graded on an analog scale
Away, Omega Pharma NV, Nazareth, Belgium; fractionated
(heavy infestation is equal to more than one louse found
coconut oil (caprylic capric triglyceride), propan-1-ol, anise
with a single stroke of the comb, medium infestation is
oil (from star anise), and ylang-ylang flower oil, the
equal to one louse found with the first stroke of the comb,
proportions of which are proprietary information) was
and light infestation is equal to one louse found after
supplied in 60-ml plastic bottles with a finger pump spray
several strokes of the comb). In practice, most people with
head. The permethrin lotion was supplied as 100-ml glass
heavy infestation had at least 25 lice of all stages, and some
bottles with a sprinkler opening containing an alcohol
were estimated to have in excess of 500 mobile lice of all
solution with 430 mg per 100 ml (0.43% w/v) permethrin
development stages present, as well as viable eggs.
(permethrin, ethanol, propan-2-ol, water, propylene glycol,
Those people with lice who conformed to the study
and sodium dihydrogen phosphate; InfectoPedicul lotion,
eligibility requirements were conducted through a standard
InfectoPharm GmbH, Heppenheim, Germany).
informed consent and assent procedure. All family mem-
In order to ensure a correct treatment, each of the
bers over the age of 2 years who had lice and were
products was applied in exact conformity with the
otherwise eligible could be enrolled.
instructions for use supplied in the package. The coconut
All participants agreed to be available for the 14-day
and anise spray was applied to dry hair over its full length
duration of the study prior to enrolment. Anyone who had a
until wetted. When the permethrin lotion was applied, the
known sensitivity to any component of the products; had
hair was first shampoo-washed and then towel-dried, after
used hair bleach, permanent colorants, permanent waves, or
which, the lotion was applied drop by drop until all the hair
undergone treatment with trimethoprim or co-trimoxazole
was soaked with the fluid to the point of running off. In
within the past 4 weeks; or who had used a pediculicide
each case, the investigators spread the fluid through the hair
within the previous 2 weeks was excluded. Also excluded
using their fingers to ensure thorough coverage.
was anyone with a secondary scalp infection (impetigo),
The coconut and anise spray was left in place for 15 min
with a chronic scalp condition (e.g., psoriasis), was
before washing out using shampoo and water. The
pregnant or nursing, had participated in a clinical trial
permethrin lotion was left for 45 min, after that period, it
within the previous 4 weeks, or had previously participated
was removed by rinsing with water alone. The washing
process was performed by carers who were advised of the
After consent was taken, baseline demographic data
time to remove the product, which in many cases, while the
were collected on gender, age, hair characteristics, previous
investigator was still present. They were also advised not to
divulge the identity of the treatment to investigators
to investigators in batches of ten. A duplicate set was
conducting assessments in order to maintain blinding.
prepared in case an emergency code break was required. As
Those participants, treated using the permethrin lotion,
each participant was enrolled, the investigators selected the
were also asked not to shampoo their hair for 3 days.
next available numbered envelope available to them from the
For both products, a second treatment was applied 9 days
allocation. Randomization was by individual, so, when more
later. Participants were advised not to use nit combs or other
than one member of a family was enrolled, it was possible for
pediculicide preparations during the course of the study.
them to receive different treatments.
Application of treatment could not be blinded due to the
different physical and chemical natures of the study treatments. This study was therefore single-blinded with post-treatment
The primary outcome measure for the study was elimina-
assessments performed by different investigators unaware of
tion of infestation, i.e., no lice present, using two
which treatment products had been used (assessor blinded).
applications of the product. Previous studies have shownthat it is possible to effect a cure using this treatment
regimen but, because the background prevalence of lice inthe population is currently high , ], it is possible for
Statistical analyses were performed by an independent
participants to be reinfested after the second treatment. To
statistical consultant. Fisher exact tests were used for
address this problem, an algorithm used in past studies able
presence/absence variables. Differences in success rates
to distinguish moderate levels of reinfestation from cases of
were measured by the 95% confidence interval (CI)
treatment failure , was applied to this study also.
calculated using a normal approximation to the binomial
Post-treatment assessments were conducted by dry
distribution. Quantitative variables were compared by using
detection combing using the “PDC” comb on days 2, 7,
an unpaired t test or the Mann–Whitney U test.
11, and 14 after the day of first treatment. The aim of theseassessments was to determine whether any lice were stillpresent, and if any were found, they were collected in the
case record and examined by microscope to determine thedevelopment stage and, if appropriate, the gender. Day 14
assessment was considered the most important, so, a morethorough combing examination was made on this day. A
This study was performed between March and July 2008 in
successful treatment was achieved if no lice were found on
the counties of Cambridgeshire and Suffolk, UK. During
days 11 and 14, following the second application of
this time, 139 people from 49 households were screened for
treatment. Outcomes of treatment were therefore catego-
head louse infestation, and a further 117 household
rized as cure, reinfestation following cure, or treatment
members either declined screening or were unavailable.
Our aim was to eliminate lice from each household tominimize the risk of reinfestation, so, any person who had
head lice but was ineligible to join the study was offered astandard of care treatment (Hedrin® 4% lotion) for self-
A total sample size of 100 participants (50 in each of the
administration. The most common household sizes were six
treatment groups) was considered sufficient to detect a
(23 participants) or four (20 participants). From those found
difference of 35% between groups in the success rate at
infested, consent to participate was obtained for 85 children
14 days, with 90% power and 95% confidence. This 35%
and 15 adults between the ages of two and 49, median
difference represented the difference between a 35% success
10 years. Most participants (78) lived in households with
rate in one product group and a 70% rate in the other group.
more than one family member participating in the study, ten
The actual sample size required was 47 per group, so,
families having two participants in the study, 12 families
recruitment of 50 per group made allowance for dropout.
three participants, two families four, and one family eachhaving five and seven participants.
The study group was divided equally between the two
treatments (50 per group), and 96 participants completed
Treatment allocation was in balanced blocks of ten derived
the study (Fig. ). Two dropped out from the permethrin
lotion group, requesting a rescue treatment following day 6
, seed 2348, 19 March 2008). Allocation at the point of
assessment on ground of lack of efficacy. One participant
delivery was made from instruction sheets enclosed in
from the same family was lost to follow-up from the
opaque, sealed, sequentially numbered envelopes distributed
coconut and anise spray group, and one child from the
spray group was excluded from per-protocol analysis
was achieved by 21/50 (42.0%) of the participants in the
because the wrong second treatment was applied. Data
permethrin lotion group and by 41/50 (82.0%) of the
from these participants were included in the intention to
participants in the coconut and anise spray group. In both
treat analyses. All other participants had complete data sets
groups, all outcomes were counted as cures (no lice
with two treatments 9 days apart and follow-up checks on
following the second treatment), with only one case of
reinfestation in each. The difference in rate of successbetween the two treatments was estimated as 40.0% (95%
CI of 22.5% to 57.5%) which meant that the coconut andanise spray was highly significantly (p<0.001) more
Table shows that there were no differences between the
effective than permethrin lotion in the population tested.
groups in respect of age; gender (in both groups, the
Elimination of protocol violators from the analysis gave
majority were female); hair length, thickness, dryness/
per-protocol success rates of 44.7% for the permethrin
oiliness, or degree of curl; intensity of infestation; or
lotion group and 83.3% for the coconut and anise spray
previous experience using head louse products. There was
group, a difference of 39.6%, which was also highly
also no difference with regard to medical history.
The main outcome analysis was the comparison of rates of
In both treatment groups, some lice were found after the
cure or reinfestation after cure in the total population of 100
first application of treatment. However, the numbers of lice
participants analyzed. According to these criteria, success
on each day and the range of developmental stages
recovered at each of the assessments were generally greater
lotion (p<0.05), which indicates that it was more effective
in the permethrin lotion treated group compared with the
to prevent louse eggs from hatching than the permethrin
coconut and anise spray treated group (Table Examina-
lotion. This means that for both treatments, the second
tion for the presence of live lice on days 2 and 7, which is
application is generally necessary for elimination of
related to immediate activity of the treatments and to the
infestation because some louse eggs may not be adequately
ability of the treatments to inhibit louse eggs from hatching,
coated with product during the treatment process. However,
found that 35 (70%) of the participants in the permethrin
16 (32%) of those treated using permethrin lotion showed
lotion group and 26 (52%) of the participants in the coconut
all developmental stages of lice on one or both assessment
and anise group had lice at one or more developmental
days following the first treatment, compared with just two
stages on either of these two days. In most cases, these lice
(4%) of those treated with the spray, indicating that the
were newly emerged nymphs. In the group treated using the
efficacy of the permethrin product was significantly lower
coconut and anise spray, the number of people with lice
(p<0.01) and possibly affected by resistance to the
approximately doubled between days 2 and 7 due to
hatching of eggs, although the actual number of young
All participants treated using permethrin lotion reported
nymphs found on participants treated using the spray was
not shampooing hair until at least 3 days after treatment. Of
significantly lower than on those treated using permethrin
these, 27/50 (54%) had not shampooed their hair by day 6
Table 2 Presence of lice on days 2, 7, 11, and 14
Number of participants with lice (number of participants [mean number of lice, range])
Lice at any stage 1st stage nymphs 2nd stage nymphs 3rd stage nymphs Adult males
examination. In the per-protocol group, a non-significant
trend was found in which those who delayed shampoo useuntil day 6 (9/25=36%) were less likely to be cured than
There were 55 adverse events reported, and 37 participants
those who shampooed between days 3 and 6 (12/23=52%).
reported one or more adverse events, 20 in the permethrin
The quantity of treatment applied varied with the thickness
lotion group, and 17 in the coconut and anise spray group.
(density) and length of the hair on each participant, longer
Of these, 44 adverse events were recorded in 33 partic-
and/or thicker hair requiring more product than shorter and/or
ipants in relationship to study treatment. The remainder
finer hair. If required, a second bottle of product was available
(11 events) were related to concomitant illness or minor
for use on long or thick hair in order to ensure adequate
accidents. In the permethrin lotion group, 12 of the 50
coverage, but in practice, this was found to be unnecessary.
participants analyzed had a single adverse event, six had
Weighing of the bottles before and after treatment
two adverse events, one had three adverse events, and one
allowed an estimation of the quantity of product applied
had four events (20 participants experiencing an adverse
at each treatment. Generally, approximately twice as much
event and 31 adverse events in total). In the coconut and
permethrin lotion was used as coconut and anise spray.
anise spray group, 12 of the 50 participants had one adverse
Mean estimates of permethrin lotion used were 46 g (range
event, three had two adverse events, and two had three
from 13.8 to 85.1) for the first application and 44 g (range
adverse events (17 participants with an adverse event and
from 6.7 to 84.2) for the second application. Quantities of
coconut and anise spray used were 30.6 g (range from 8.9
Adverse events related to treatment were mostly
to 49.5) for the first application and 25.7 g (range from 6.8
stinging or burning sensations on the scalp or neck or
to 49.7) for the second application.
both during and after treatment. Most of these events were
The two products were comparable in their ease of
apparently related to intensity of infestation and the
application and of spreading the preparations through the
number of bite reactions on the scalp. However, it was
hair. However, there were some significant differences
clear that the cause of the adverse events in each case was
between the products with regard to the feeling of the
the level of alcohol in the products, with a possible effect
product on the hair and scalp. The coconut and anise spray
from essential oil in the spray, these components being
was more likely to feel itchy or warm rather than cool (p<
likely irritants to broken or excoriated skin. Such events
0.01). The odor of the spray was considered strong
were more or less evenly distributed between the two
compared with that of the lotion (p<0.001) but was
acceptable for both products, and the spray was considered
No subject had a serious adverse event, and there was no
more difficult to wash out, mainly because the hair was
evidence of any difference between groups in respect of
greasier after use (p<0.001). Nevertheless, a majority of
frequency, outcome, action taken, relationship to study
participants said they would prefer to use the spray again
treatment, relationship to concomitant illness or drug, or
compared with the lotion (86% vs 58%, p<0.004).
also required all parents/carers to comb the hair with a nitcomb to remove eggs and lice daily. Therefore, the level of
We have found that coconut oil and anise spray gave
intervention in those studies was greater than we employed,
superior efficacy for elimination of head louse infestation
yet the intention to treat cure rate for the Israeli study (60/70,
than 0.43% permethrin lotion, both products applied on two
85.7%) was not significantly different from our result using
only two applications 9 days apart. We cannot draw a
Coconut and anise spray is a class I medical device that
comparison with the Italian study because the combing
acts by coating lice in an oily film, obstructing the
component of treatment clearly contributed much of the
respiratory system in a similar way to several other medical
successful outcome as nearly all participants, including those
device products for control of head lice , However,
treated using a relatively weak comparator product, were
as the application time is relatively short, it is likely that
effectively cured by removal of all lice and eggshells before
triglycerides persisting on the hair and lice subsequent to
washing contribute to the efficacy. As the mode of action
Physiological resistance to insecticide-based products is
appears to be mainly due to the physical effects of coconut
now considered widespread in Europe and North America
oil coating the louse surface, it is not envisaged that lice
[, –and affects not only pyrethroid insecti-
may develop resistance to the product unlike pharmacolog-
cides like permethrin but also the organophosphate mala-
ically active insecticides like permethrin. Resistance to
thion , and previously used chemicals like the
permethrin has been shown to cause treatment failure in the
cyclodiene hexachlorocyclohexane (HCH or lindane). The
UK [We would therefore expect to encounter a
extent of this resistance varies not only with the country but
proportion of cases in every community with lice resistant
also with the region, district, town, or even street [, , ,
]. Consequently, there are no clear figures indicating the
In practice, we found approximately one third of our
proportion of cases in a population likely to experience
participants did not respond to treatment using permethrin
resistance, but resistance in some form has been found in
lotion, and that the alcohol in the lotion does not appear to
more than 80% of lice in some populations ], or to
contribute to the activity of the product to ensure its
influence the outcome of treatment in between 70% and
effectiveness in use. In contrast, the coconut and anise
90% of cases of infestation in affected areas. As a
spray was not only effective in most households, even
result, physically acting preparations like coconut and anise
where other family members treated using permethrin had
spray are now the treatment of choice for many consumers,
experienced treatment failure; it was also more cost
especially as they are not affected by resistance, and there is
effective. Based on the weights of product used in our
no recognized mechanism whereby lice might develop
study, we estimate that for an average application of 0.43%
tolerance of these materials. As a result, we believe that
permethrin lotion, the cost would be approximately €10.94
coconut and anise spray should remain a viable treatment
per application (€2.43 per cl). In contrast, the cost of an
option for most people well into the future.
average application of coconut and anise spray would beapproximately €9.64 (€3.32 per cl).
We were unable to detect any age-related trend for
Acknowledgements This study was supported financially by Omega
obtaining a successful treatment using either product, which
Pharma NV, Nazareth, Belgium, which played no active role in the
indicates that success, or lack of it, in eliminating lice was
design of the study, interpretation of the results, or the writing of themanuscript. We wish to thank Dr Marc Dams and Isabelle Dedeken for
not related to a likely increased risk of reinfestation in
administrative support. Thanks also to Laurence Noiroux of S-Clinica,
children as they played with their peers.
Brussels, Belgium for statistical analyses. Investigation team members
We found a higher incidence of “stinging at the site of
who contributed to the study but were not named as authors were Ian
application” adverse events to treatment in this study than
Jones, Audrey Pepperman, and Christine Sullivan. Medical supervisionfor clinical queries was provided by Dr Paul Silverston.
in our previous investigations [and this can only beattributed to alcohol components of treatment. However,none of the experiences lasted more than about 20 min and
ceased when the alcohol had evaporated. We did notobserve any subsequent Draize-type reactions. There are
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