Exclusion based on Minimum Non Zero Concentrations [Design Issues]

posted by drgunasakaran1  – 2012-12-11 06:53 (4939 d 19:02 ago) – Posting: # 9707
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Dear Mr Hiren,

❝ We are planning pivotal biostudy for one of the highly variable molecule (DR Formulation).


Are you dealing with Bisphophanates (Risendronate sodium 35 mg DR tablets)?

❝ 1) Inspite of >35 samples we got last point Cmax in 4 subjects in Reference arm


Check the literature of the drug, if the range of Tmax of your drug is very high and make sure that you didn't captured the sampling time points based on the Median Tmax rather than the Range.

❝ 2) After 3-4 zero concentrations in some subjects, we are getting Cmax immediately in next time point. This is similar to first point Cmax.


If the drug has rapid distribution phase simiar to Risedronate, you may get profile like this.

❝ 3) We got just 2 non zero concentrations in 4 subjects and 3 non zero concentrations in 3 subjects in Reference arm. Concentrations are rising and falling very sharply.


To avoid this, you should have very frequent sampling time points in the Tmax Range.

❝ Please guide on regulatory acceptability (particularly for USFDA) of such criterion.


In my personal opinion, regulatory may not accept this procedure.

Dr Gunasakaran Sambandan MD
Disclaimer: The replies/posts are my personal opinions, and they do not represent my company's views on the same. LinkedIn

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