A clue about ethidium toxicity

Undergrad via methods%40net.bio.net (by sylvain.bauer from laposte.net)
Sun Jun 17 07:21:40 EST 2007


As you know ethidium (aka homidium) is also used as trypanocide in cattle,
sheep, goat ect... No ADI (admitted daily intake) are available for ethidium
however there is one for isometamidium which is a closely related to
homidium and also intercalate in DNA. Also it was found that isometamidium
is transform in homidium in the body (less thant
1%)(http://www.inchem.org/documents/jecfa/jecmono/v31je10.htm).


The ADI of isometamidium is 0-100 microgramme/kg
(http://66.102.9.104/search?q=cache:7ct_Z9QkXWwJ:www.ipfsaph.org/cds_static/en/jecfa_veterinary_drug_residue_isometamidium_en_cthttpwwwfaoorgaosipfsaphinformat
ionsourcejecfa_JECFAEVAL57.html+isometamidium+who+adi&hl=en&ct=clnk&cd=1&gl=uk).


"
An ADI of 0-100 µg per kg of body-weight was established for
isometamidium based on the non-toxic dose level of 50 mg/kg bw/day
in the 13-week rat study and a safety factor of 500. The Committee
chose this safety factor because of the marginal pharmacological
effects seen at the lowest dose in the rat study and the limited
extent of the data available, although it recognized that neither
the drug nor its metabolites were bioavailable when given by the
oral route."


So if isomethidium give rise to 0.1% of homidium, the proportionnal ADI of
homidium could be : 0.1 microgramme par kg so 6 microgramme for a 60 kg
person. 

In this study, it is shown that isometamidium have a strongest toxic effect
than homidium: http://www.inchem.org/documents/jecfa/jecmono/v25je10.htm  
    

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