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I would like to know how to fix time points in BE study when
comparing an Immediate release (given as BID) formulation with that
of Sustained release formulation? How to calculate the Cmax for IR
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Good question. I can, however, help in the first part based on my
experience in TID (IR) v/s OD (ER) formulation.
1. Look at the Tmax, Cmax and half life of the molecule (IR). Place
the timepoints more frequently near the near each Tmax. E.g., if the
Tmax is 3 hours, then for the IR formulation in BD dose pattern, keep
the sample timepoints more frequent around 3 hr and 15 hr post dose
(you must consult your biostatistician as well!). Look for the food
effect when doing fed study. e.g., in case food prolongs tmax, then
you may want take more "frequent samples" after the Tmax timepoint.
2. Try to adjust the dinner timing 30 mins prior to the second (BD)
dose in case you are planning a fed study.
3. The sampling timepoints of IR drug will differ with ER drug hence
you must train your staff, esp phlebotomists well!
4. Since there will be more timepoints, keep in mind the total amount
of blood to be withdrawn. Check your standard practices on how much
maximum blood you can withdraw. In case the blood loss is over 350ml
in the entire study, for subject safety reasons, choose a population
having a healthy haemoglobin level (you may have to tweak your
Let me know if you have anymore questions. All the best!
Dr. Gagandeep Singh
Head, Clinical Research
BioArc (Alembic Ltd) India
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