E: [Pharmwaste] Measuring the amount of pharms reaching
jumullot at aol.com
jumullot at aol.com
Tue Feb 27 12:45:54 EST 2007
Dear Ann,
I full agree with your interpretation about metabolism in humans and I confirm that a basic data like the percentage of intact drug excreted in urine is not always easy to find (and I don't sepak about feces), even in specialized pharmaceutical bibliography (if you're interested I compiled this information for frequent antibiotics, frequent antineploastics and top 10 drugs in my local hospitrals for each anatomical class).
Just a precision about what you explain : metabolites in urine (that do not appear in % of intact drug) ar often conjugates (glucurono and/or sulfo conjugates and others) and the experience of oestrogens by example but also data about some drugs tends to demonstrate that these conjugates gave back the intact drug in sewage under the influence of physicochemical conditions and/or microbial activity. That is to say that event if you find a small percentage of "intact" drug in urine you can habve large amounts in sewage after few hours of degradation (it complicates the model, isn't it?). A good example about that is acetaminophen : few % of intact drug in urine but major metabolites are conjugates that turn back into acetaminophen in sewage.
The morale of this story from my point of view is that you should study all phamacokinetic data about a drug to have an idea of the percentage of "intact" ("native" intact or "transformed" intact) that could reach the wastewater ... and remember that there is a lot of interindividual variability !
Best regards,
Jean Ulrich MULLOT
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