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CECIF ☆ Colombia, 2018-01-17 21:44 (2282 d 22:15 ago) Posting: # 18196 Views: 4,726 |
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Hello, I am trying to find the CVwithin of biperiden immediate release but I am struggling to find any literature on bioequivalence of biperiden. However, I found a cross-over study comparing pharmacokinetics of biperiden immediate release against extended release. Is it reasonable to assume the CVwithin of biperiden to be equal to the one on the study that I found? I mean, I think it will be smaller or equal at most, therefore if I assume it is the same for the sake of sample size calculation, I could be overestimating sample size, but I would not be sacrificing any statistical power, which is not statistically incorrect, right? Any help is welcome. many thanks |
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Helmut ★★★   Vienna, Austria, 2018-01-18 17:46 (2282 d 02:13 ago) @ CECIF Posting: # 18216 Views: 4,045 |
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Hi CECIF, ❝ […] I found a cross-over study comparing pharmacokinetics of biperiden immediate release against extended release. ❝ Is it reasonable to assume the CVwithin of biperiden to be equal to the one on the study that I found? Difficult to say. Can you give the reference? ❝ I mean, I think it will be smaller or equal at most, therefore if I assume it is the same for the sake of sample size calculation, I could be overestimating sample size, but I would not be sacrificing any statistical power, which is not statistically incorrect, right? Maybe. Maybe not. Even if sampling times were properly chosen in the study you found, the variability of Cmax of the MR product might be lower than the one of the IR product – simply because MR profiles are “flatter”. What we get in a 2×2×2 crossover study is the pooled variability (from the unknown swR and swT). Given that, it might well be that the CVw of IR is higher than the one you extracted from the literature. I suggest to perform a pilot study, a Two-Stage Design, or – if you want to go directly to the pivotal study – allow for a safety margin. — Dif-tor heh smusma 🖖🏼 Довге життя Україна! ![[image]](https://static.bebac.at/pics/Blue_and_yellow_ribbon_UA.png) Helmut Schütz ![[image]](https://static.bebac.at/img/CC by.png) The quality of responses received is directly proportional to the quality of the question asked. 🚮 Science Quotes |
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ElMaestro ★★★ Denmark, 2018-01-18 18:03 (2282 d 01:56 ago) @ Helmut Posting: # 18217 Views: 3,918 |
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Hi Hötzi, ❝ I suggest to perform a pilot study, a Two-Stage Design, or – if you want to go directly to the pivotal study – allow for a safety margin. The generic way: Contact 37 different CRO's for a quotation for Biperiden IR filmcoated tablets, tell them you expect a T/R ratio of 106% or whatever on basis of dissolution studies and you hope for 80% power. Some of them will respond back with a quotation involving a specific sample size, so you ask naïvely where that comes from. Then they will say that in the previous study they conducted on Biperiden IR the CV was so-and-so with this or that design "but please keep this information confidential". And voila, you have totally wasted a lot of time for employees in a boatload of companies but you got the type of information you were looking for. — Pass or fail! ElMaestro |
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jag009 ★★★ NJ, 2018-01-21 04:32 (2279 d 15:27 ago) @ ElMaestro Posting: # 18236 Views: 3,732 |
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Hi ElMaestro Yup, it worked for me many times. J |
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Yura ★ Belarus, 2018-01-19 11:05 (2281 d 08:54 ago) @ Helmut Posting: # 18221 Views: 3,872 |
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Hi Helmut If in carrying out a two-stage design in the first stage with N = 20 subjects bioequivalence is shown, what should be done with the second stage?  Best regards |
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Helmut ★★★ Vienna, Austria, 2018-01-19 13:21 (2281 d 06:38 ago) @ Yura Posting: # 18224 Views: 3,917 |
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Hi Yura, ❝ If in carrying out a two-stage design in the first stage with N = 20 subjects bioequivalence is shown, what should be done with the second stage? Open a bottle of champagne, since there is no need for a second stage (see the left branches of the flowcharts in this post). BTW, all of my TSDs passed in the 1st.  AFAIK, only the Indonesian agency requires a “second stage” in such a case for reasons I fail to comprehend. Think about a fixed-sample study which passed BE: would anybody ask for another one? IIRC, ElMaestro wrote a paper* about it (I’m traveling and can’t check). Edit:
— Dif-tor heh smusma 🖖🏼 Довге життя Україна! Helmut Schütz The quality of responses received is directly proportional to the quality of the question asked. 🚮 Science Quotes |
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Yura ★ Belarus, 2018-01-19 14:21 (2281 d 05:38 ago) @ Helmut Posting: # 18227 Views: 3,937 |
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Hi Helmut,  |
Ing. Helmut Schütz