One topic which I have been keenly interested in is microdosing. What is it?
Simply stated, microdosing is a technique whereby experimental compounds are administered to humans in very small doses (typically 1/100th of a therapeutic dose). The drug's pharmacokinetics are characterized through the use of very sensitive detection techniques.
Why is this interesting? Prior to microdosing approaches, pharmacokinetic characterizations were always performed in animals (typically rats, but dogs and sometimes monkeys may be used). Other techniques may be used (e.g., liver microsomes) to supplement these data. The bottom line is that even with all of these data, candidates may still fail in Phase I clinical trials due to pharmacokinetic issues such as poor oral absorption.
Microdosing enables companies to characterize directly human pharmacokinetics. This enables companies to reduce their dependence on animal data which can be misleading. Plus, you are looking at "real" human data. Via microdosing, you have an excellent estimate of bioavailability, half life, clearance, etc., etc. Now there are many instances where pharmacokinetic characteristics are dose dependent. But, even in those cases, microdosing gets you much closer to an intelligent go/no decision versus purely animal and in vitro studies.
A few good introductions to this approach are here, here, here, and here.
The US FDA has recently issued guidelines on the use of microdosing techniques, and major pharmaceutical companies are all over this already. I'm curious to see if the major CROs are offering this as a service.
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