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Dear All
We are planning to conduct three- way, three-period crossover
bioequivalence study so for that I want to know whether the washout
period should be kept uniform for all periods and if it is not
uniform can it affect the pharmacokinetics of drug. Please clarify
for the same .
Vishal P Borikar
Glenmark Research Centre
Clinical Research Dept.
Turbhe,Navi Mumbai-400 705
Ph:022 56100560/61 Ext No.212
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Dear Vishal,
Washout period is very critical in crossover studies , there should be
adequate washouts given between the each period to avoid carryover
effect
from one priod to another. If it is not adequate it may lead to predose
concentartion appearnace and period and sequence effect. For a three
way
crossover it is advisbale to keep the washout period equal.It can vary
between the periods but in any case it should not be less than the
minimum
washout period.
Regards
Manoj Kumar Vishwakarma
Group- Leader
Biopharmaceutics
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Dear Vishal
I believe it will depend on the type of active. If there will be a
carry over effect such as liver enzyme inductions, you need to give a
period that is long enough for the enzyme to go back to the base
line. Also, the elimination t1/2, you do not need to have one wash-
out period shorter than the other if the short period is not long
enough to give the base line. I would keep it uniform and long
enough for the above reasons
Regards
Nabil
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Dear Vishal
I do agree with Manoj's opinion. If you have any problem in
scheduling three periods, then you keep at least 10 half-lifes as
washout period, so that you can avoid carryover effect. But it is
always better to keep same washout between periods.
Regards
D Mallikarjuna Rao
Principal Scientist-Clinical Development
Discovery Research
Dr. Reddy's Laboratories Ltd.
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