Dear colleagues,

In the context of phase I trials, I am trying to find clear guidance regarding the minimum acceptable interval between participation in two clinical trials of an IMP, for either healthy volunteers OR patients.

The 2012 ABPI guidelines contain the following wording:

"In general, subjects should not receive an IMP systemically less than three months after the previous one. However, on occasions a shorter interval may be justified, especially when using well-characterised, marketed drugs with a short half-life and little risk of carryover effects."

However I have seen protocols that require longer intervals (4 months) where the first trial is of a new chemical entity, however I cannot ascertain if this is convention or based on specific guidance.

The ABPI wording above suggest that, for example, bioequivalence studies for established products with shorter half lives, would not require a three interval, but 30 days might be acceptable assuming the half live was relative short (e.g. <24 hours).

Any thoughts/experience/comments most welcome.

Thanks in advance.