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RegisterReasons? [Study Assessment]
Hi Helmut
I have following thoughts w.r.t. to my points.
1. Change in subject will cause change in concentration. Even MVR of many regulatory and ISR also permits ~15% variation at Cmax point. The Cmax is generally variable than AUC. So if the ratio difference is +/- 15%, the discussion shall be of no point. But still may point out that there is difference.
2. BA method and same instrument needs to be mentioned. It could have impact.
» » 3. Same Internal standard batch? Change in internal standard changes height and thus ultimately concentration.
»
» Given, the IS response might be different. However, even if calibrators and QC samples are prepared with, say, an IS of just 50% of the declared content in one of the studies, the back-calculated concentrations should be similar and therefore, the T/R-ratios.
Although, it sounds odd, Even for NTI- with same CRO- Method-Instrument; I have witnessed change in concentration with just change in IS batch. It may have similar T/R but even there was difference in T/R.
I hope this may help.
Regards,
Dshah
I have following thoughts w.r.t. to my points.
1. Change in subject will cause change in concentration. Even MVR of many regulatory and ISR also permits ~15% variation at Cmax point. The Cmax is generally variable than AUC. So if the ratio difference is +/- 15%, the discussion shall be of no point. But still may point out that there is difference.
2. BA method and same instrument needs to be mentioned. It could have impact.
» » 3. Same Internal standard batch? Change in internal standard changes height and thus ultimately concentration.
»
» Given, the IS response might be different. However, even if calibrators and QC samples are prepared with, say, an IS of just 50% of the declared content in one of the studies, the back-calculated concentrations should be similar and therefore, the T/R-ratios.
Although, it sounds odd, Even for NTI- with same CRO- Method-Instrument; I have witnessed change in concentration with just change in IS batch. It may have similar T/R but even there was difference in T/R.
I hope this may help.
Regards,
Dshah
Complete thread:
- Significant difference in Cmax of Reference drug product Mehul Patel 2021-08-17 10:00 [Study Assessment]
![[Mix]](https://static.bebac.at/img/mix.png "open in Mix view")
- Significant difference in Cmax of Reference drug product Helmut 2021-08-17 11:57
- Significant difference in Cmax of Reference drug product Mehul Patel 2021-08-17 12:02
- Different products → different BA Helmut 2021-08-17 15:36
- Significant difference in Cmax of Reference drug product dshah 2021-08-21 10:48
- Reasons? Helmut 2021-08-21 21:43
- Reasons?dshah 2021-08-24 12:06
- Reasons? Helmut 2021-08-21 21:43
- Significant difference in Cmax of Reference drug product Mehul Patel 2021-08-17 12:02
- Significant difference in Cmax of Reference drug product Helmut 2021-08-17 11:57
Ing. Helmut Schütz