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Posted by valerioreggi on 26 Sep 2011 at 15:25 GMT


The report on the progress made to find a convenient route for preparing industrial-scale quantities of levo-praziquantel is an interesting academic exercise which in isolation appears to be a significant step forward for schistosomiasis treatment. However the concept of development of this isomer seems to disregard the context in which schistosomiasis control takes place and, in particular, it omits to mention the following points:

- there are insufficient quantities of quality-assured praziquantel to treat those who should receive it; as a result, over half of all people in sub Saharan Africa at risk have never been treated, and regular treatment reaches less than 20% of those who should receive the drug according to WHA resolution 54.19 of 2001”

- affected populations would not be able to pay for praziquantel even if enough quantities were available today; this no-market situation makes most manufacturers uninterested in producing praziquantel; it is unlikely that the situation would be different if a convenient route to produce levo-praziquantel existed;

- most praziquantel currently made available to populations in need is either donated by Merck-Serono, procured through privately donated funds or more recently funded directly by a two governments (USA and UK); it is possible that an increase in the price of praziquantel would reduce these commitments.

It is within this context that the hypothetical advantages of levo-praziquantel and the small progress made during the past 10 years in developing viable economic and ecological ways for its production should be weighed. In addition, if and when such a new synthetic route becomes available, several years and important resources would be required to overcome non-clinical testing, clinical trials and other necessary regulatory steps before levo-praziquantel could be safely used in populations affected by schistosomiasis.

It is extremely important to ensure that any additional research effort should not divert much-needed resources from providing praziquantel - a safe medicine of proven efficacy - to populations in need. Finally, an amendment is needed to the Acknowledgements: racemic praziquantel was donated by Merck Serono S.A.; the World Health Organization's Department of Control of Neglected Tropical Diseases was simply a conduit.

Valerio Reggi, Denis Daumerie, Dirk Engels, Lorenzo Savioli - Department of Control of Neglected Tropical Diseases, WHO, Geneva, Switzerland
Alan Fenwick - School of Public Health, Imperial College, London, UK

No competing interests declared.