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Criteria for World Health Organization (WHO) recommended drugs

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  • Elie Hassenfeld
    We re finalizing intervention reports for Carter Center programs and one thing we haven t found discussed consistently in the DCP (Disease Control Priorities
    Message 1 of 1 , Feb 12, 2009
      We're finalizing intervention reports for Carter Center programs and one thing we haven't found discussed consistently in the DCP (Disease Control Priorities Project) is the clinical evidence of effectiveness for drugs (i.e. that a given drug has a *medical* impact on the condition it treats). For example, in the case of albendazole to treat soil-transmitted helminths (worms), the studies we've seen cited discuss weight gains adn cognitive performance but not infection rates directly. I went looking for a comprehensive source that presents the criteria the WHO uses to approve drugs.

      Bottom line: I didn't find anything we can point to as *the source* that WHO recommended drugs work medically. For each drug though, WHO cites its source. In the case of albendazole, it's Cochrane reviews. I haven't checked others to see how they'll play out but would guess it'll be similar.

      • There is a WHO Model List of Essential Medicines (Children: http://www.who.int/childmedicines/publications/EMLc%20(2).pdf; Adults: http://www.who.int/medicines/publications/08_ENGLISH_indexFINAL_EML15.pdf). The report says, "The core list presents a list of minimum medicine needs for a basic health care system, listing the most efficacious, safe and cost‐effective medicines for priority conditions." (Children, Pg 1) But, it never says anything about the criteria used to evaluate "efficacious." Poking around on the WHO Medicines site (where I found this list), I didn't find anything either.
        • This report includes albendazole. It's marked for review:. "Review evidence of efficacy and safety of use of anthelminth/antifilarial/antischistosomal and antitrematode medicines in children below the specified age in current licences." (Chidlren, Pg 5) But, that seems to only be for children under the age of 24m.
      • WHO has a report on the necessary guidelines for a good clinical trial and how to evalaute drug effectiveness: http://www.who.int/medicinedocs/en/d/Jwhozip13e/1.html. It's not clear that this ties back to recommended drugs. Maybe it does; I didn't find it.
      • The WHO has an Essential Medicines Library, where you can search for a specific drug and see how, when, why it was included: http://www.who.int/emlib/. Here's the search for albendazole: http://www.who.int/emlib/MedicineDisplay.aspx?Language=EN&MedIDName=10%40albendazole. It was initially included for a reason unrelated to STHs, though it's currently used for STHs. This page seems like the best aggregate source we'll find. The page lists references to papers at the bottom.
        • Ref 1: http://www.who.int/medicinedocs/en/d/Js4953e/5.2.html#Js4953e.5.2: Seems like only evidence is nutritional outcomes (though the fact that they cite cognitive outcomes is weird/worrisome given that we don't think anyone's (Miguel/Kremer or Cochrane) really claiming that effect: "A review of available data on health benefits of treating soil-transmitted helminth infections in these young children concluded that treatment reduced the likelihood of growth stunting and favourably influenced nutritional and cognitive outcomes. The conference also reviewed human and animal toxicological data and concluded that in children as young as 12 months there are no reasons for exclusion from treatment with albendazole or mebendazole according to existing literature and company drug information (1). Hence, a recommendation was made that children from one year old onwards should be included in systematic deworming programmes."
        • Ref 2: http://www.who.int/wormcontrol/documents/en/pvc_20024full.pdf: Major review of whether some drugs can be given to children under age of 24m. Gets into nitty gritty medical details -- "Albendazole binds to intracellular tubulin, selectively affecting helminths and inhibiting essential absorptive functions in the organism." I can't figure out if section 6.2 on Pg 16 is telling me that it's effective or not. It does say, "Unmetabolized ALB [albendazole] is directly effective against intestinal
          nematodes in the alimentary tract." (Pg 24 -- there's no ref her, but there were paper refs back in section 6.2, so maybe those are the studies) Pg 27 reports on 8 studies in Africa of albendazole in children under 24m and the results. It's a little confusing. Sometimes it talks about another drug (mebendazole) and sometimes it talks about impact when combined with iron supplements. Finally, it says that it resulted in "reduction in parasite prevalence and/or intensity after treatment;" but also that "Most of the studies that have been done involved small sample sizes and in some cases parasitological data, including measures of intensity of infection, were lacking."
        • Ref 3 and 4: Cochrane papers we've read (one for albendazole for LF and one is the earlier version of the paper Ron read for STH)
        • Ref 5: cite with no link or seemingly unrealted to albendazole for STHs
        • Ref 6: WHO guidelines paper thing from 1990: http://whqlibdoc.who.int/trs/WHO_TRS_796.pdf. Page 11 does say, "Only those drugs should be selected for which sound and accurate data on efficacy and safety are available from clinical studies."
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