Dear Group Members,Back to the Top
I have a very basic query in p'kintics.
In US FDA guidelines for BA/BE studies, it is mentioned that blood
should be collected for at least 3 terminal half-lives.
Also, they recommeded a washout period of at least 5 terminal
elimination half lives.
I want to know from the experts like you that what is the difference
between plasma half-life, terminal half-life (Many times in PDR only
plasma or elimination half life is mentioned).
Thanks in advance,
Dear Shrikrishna,Back to the Top
Plasma half life is a time measurement which starts when the drug
reaches equilibrium (equilidrium=fully absorbed= when equal amounts of
drug are in circulation and at point of administration)
Elimination half life is when plasma levels fall to half what they were
at equilibrium due to drug being metabolized and eliminated.
It is usually the elimination half life that is used to determine
dosing schedule to decide when it is safe to put patients on a new drug
etc. Generally 5 x the elimination half life = time at which the drug
is completely (97%) eliminated from the body (assuming that the drug
was given in a single original dose)
Hope this will help
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