Guidelines for clinical trials proposed

A recent paper in the International Journal of Dermatology has proposed guidelines and protocols for clinical trials of pediculicides.

The paper, authored by Barker et al., and published in the July 2012 edition of the journal, offers the possibility of standardising techniques for testing the efficacy of anti-lice treatments.

The authors note that, in the absence of an accepted international standard, protocols for clinical trials currently vary widely. Forty-six pediculosis-related clinical trials have been registered since 2004. Some of the issues with current variation in determining pediculosis activity are discussed here.

The paper offers recommendations for protocols of one-, two- and three-stage anti-lice treatments. These follow the pattern of treatment, assessment by visual examination and/or combing and re-treatment as necessary.

They note that there is no agreement on the ideal gap between treatments, and leave this up to the investigators to decide. Most data on the subject of lice hatching times indicate that the interval should be between 7 and 10 days, but this varies depending on temperature, amount of hair on the head and even whether the eggs have already been treated with a pediculicide.

The paper further covers recommendations for the experience of the assessors conducting the examinations, method of dry- or wet-combing and comb type.

They recommend that the assessor should be blinded, as far as possible, from knowing which treatment they are examining, and that studies should be conducted using a comparator pediculicide.

Regarding the outcome of treatment, they recommend that efficacy of treatment should be expressed as a 'louse-free rate', and that this is only properly established via combing: "Visual inspection alone...is insufficient to declare a subject as 'louse-free." They propose a louse-free rate of 90 ± 3% to be the standard for judging whether a product is efficacious.

This paper does not cover protocols for in vitro and ex vivo assessments, which also suffer from a lack of protocol standardisation, but will be of relevance to those designing future Phase III pediculicide trials.