chak
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2007-12-26 16:30
(6760 d 21:18 ago)

Posting: # 1426
Views: 3,942
 

 clinically relevant Tmax in BE study [Regulatives / Guidelines]

Dear All,

As per ANVISA guideline, for the bioequivalence assessment the parameters Tmax must be considered if clinically relevant. Now what does clinically relevant means? How we can know that this is clinically relevant because generally BE studies are done on healthy subjects??
Hoping for a satisfactory answer.
regards
chak
Helmut
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2007-12-27 14:43
(6759 d 23:05 ago)

@ chak
Posting: # 1433
Views: 3,293
 

 clinically relevant Tmax in BE study

Dear chak!

❝ As per ANVISA guideline...


Not only per ANVISA, but according to many others as well (see the Guidance Collection)...

❝ ...Tmax must be considered if clinically relevant. Now what does clinically relevant means?


You should consult with a specialist in the therapeutic field. An example would be rapid-onset drugs, like analgetics.
If I’m suffering from a headache a difference of half an hour in tmax would be very important for me… :-D

❝ How we can know that this is clinically relevant because generally BE studies are done on healthy subjects??


I think that you are mixing two things up. Bioequivalence is a surrogate for clinical equivalence, i.e., we assume similarity in blood levels (pharmacokinetics) maps to similarity in the effect compartment (pharmacodynamics). This assumption is unquestioned, and has empirically been shown to be a valid one throughout the last 25+ years.

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chak
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2007-12-27 16:11
(6759 d 21:37 ago)

@ Helmut
Posting: # 1435
Views: 3,084
 

 clinically relevant Tmax in BE study

Dear helmut,

Thanks for the reply. But i want to clarify few more things. You have given the example of an analgesic. But if it is a CNS drug (e.g antidepressant, drug used in Alzheimer’s disease), which is required for longer period of time, how to conclude it is clinical relevant in BE studies?? please clarify.

regards
chak
Helmut
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2007-12-29 15:38
(6757 d 22:11 ago)

@ chak
Posting: # 1438
Views: 3,213
 

 clinically relevant Tmax in BE study

Dear chak!

❝ You have given the example of an analgesic.


This is one extreme where tmax obviously is of clinical relevance.

❝ But if it is a CNS drug (e.g antidepressant, drug used in Alzheimer’s disease), which is required for longer period of time, how to conclude it is clinical relevant in BE studies??


This is the other extreme where tmax is – also obviously – not important.
Generally only AUC and Cmax are the main metrics in BE assessment.
BTW, if both AUC and Cmax are within the acceptance range for BE, according to the principles of PK it’s quite unlikely that tmax will not be bioequivalent as well…
If in doubt:
  • have a look at published studies,
  • consult with a specialist in the clinical field,
  • go for a scientific advisory meeting with the regulatory body.

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