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HV ☆ India, 2010-04-14 20:37 (5914 d 01:24 ago) Posting: # 5136 Views: 3,880 |
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Dear all, There are a few narrow therapeutic index drugs with prolonged elimination half-life e.g. warfarin, tacrolimus, etc. These are the drugs for which usually tightended interval (90-111.11% for EU and 90-112% for HPFB) is applicable for AUC. Is it possible to apply truncated approach (sampling till 72 hrs) for these molecules? Thanks, Heema Valera |
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Helmut ★★★   Vienna, Austria, 2010-04-14 20:48 (5914 d 01:14 ago) @ HV Posting: # 5137 Views: 3,192 |
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Dear Heema, Why do you think that it is not possible? — 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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HV ☆ India, 2010-04-14 21:19 (5914 d 00:43 ago) @ Helmut Posting: # 5139 Views: 3,149 |
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❝ Why do you think that it is not possible? Dear Helmut, thanks for prompt response! i think so, because overall extent of absorption is of importance for such NTIs. And the truncated approach repesents only a fraction of total extent. Will you please share your thoughts on application of truncted area (AUC72) for NTIs as well? Thanks, Heema |
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Helmut ★★★ Vienna, Austria, 2010-04-14 21:38 (5914 d 00:24 ago) @ HV Posting: # 5141 Views: 3,139 |
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Dear Heema, ❝ [...] overall extent of absorption is of importance for such NTIs. No, in BE we are interested in the difference of absorption between formulations. Elimination is specific for the drug. After 2-4× tmax the AUC-ratio does not change any more, only variability increases (just saw Kamal Midha walking 'round the corner  ). In other words AUC72(T)/AUC72(R) ~ AUC504(T)/AUC504(R) ~ AUCinf(T)/AUCinf(R), but AUC's CVintra,72<CVintra,504<CVintra,inf. Please search the forum for examples and references.Above said is only true for immediate relase formulations (elimination = slowest phase). For some MR formulations (CR, but not DR) the slowest phase is absorption - the one we are interested in: in such a case truncation does not make sense. Luckily there are only a few stupid controlled release formulations of drug with a long half-life on the market. — 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 |
Ing. Helmut Schütz