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jag009 ★★★ NJ, 2014-09-16 18:42 (3889 d 00:22 ago) Posting: # 13525 Views: 7,206 |
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Hi all, Question, maybe elementary but need some hints... What factors can lead to a long Tmax like 7-8 hours? Lets say the drug 1) is BCS Class 1, 2) dissolution is completed within 1 hour (NLT 80% in 30 mins)? 1) Site specific/region specific absorption such as drug absorption does not take place until the lower part of the small intestine? 3) Saturable carrier transport? 2) Highly protein bound properties? Thanks John |
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luvblooms ★★ India, 2014-09-18 09:02 (3887 d 10:02 ago) @ jag009 Posting: # 13534 Views: 5,965 |
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Hey John Some questions First ❝ What factors can lead to a long Tmax like 7-8 hours? Lets say the drug 1) is BCS Class 1, 2) dissolution is completed within 1 hour (NLT 80% in 30 mins)? ❝ 1) Site specific/region specific absorption such as drug absorption does not take place until the lower part of the small intestine? (Or the absorption happens across the GIT with higher absorption in certain sections rich) ❝ 3) Saturable carrier transport? (What if the carrier is not ditibuted through out GIT?? ) ❝ 2) Highly protein bound properties? Would like to add some more a) Cmax build up by hepatic recirculation (typical example Ezetemibe and Raloxifene) d) Tissue distribution (If I am right Amlodipine is the typical example of this case  ) I had a couple of papers related to some specific highly soluble drugs with longer Tmax. Give me a couple of days I would try to find them out. — ~A happy Soul~ |
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jag009 ★★★ NJ, 2014-09-19 19:09 (3885 d 23:54 ago) @ luvblooms Posting: # 13544 Views: 5,904 |
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Thanks Bloom, ❝ Would like to add some more ❝ a) Cmax build up by hepatic recirculation (typical example Ezetemibe and Raloxifene) ❝ ❝ d) Tissue distribution (If I am right Amlodipine is the typical example of this case ❝ ❝ I had a couple of papers related to some specific highly soluble drugs with longer Tmax. Give me a couple of days I would try to find them out. One more: drugs with long half life will show increased Tmax. John |
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luvblooms ★★ India, 2014-09-21 07:29 (3884 d 11:35 ago) @ jag009 Posting: # 13551 Views: 5,884 |
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Hey John, ❝ One more: drugs with long half life will show increased Tmax. Would differ on this one cos it is not always true. Remember Tacrolimus Thalf ~48hrs but tmax~2 hrs Similar story for Ibandronate, Risedronate etc where thalf >48hrs but tmax<2hrs. — ~A happy Soul~ |
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nobody nothing 2014-09-21 18:58 (3884 d 00:05 ago) @ luvblooms Posting: # 13552 Views: 5,760 |
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❝ ❝ One more: drugs with long half life will show increased Tmax. Actually, I don't see the mechanism for that, rapid absorption might occur, no matter what the terminal elimination looks like. If you have flip-flop kinetics, it's a different story... — Kindest regards, nobody |
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Croosov ☆ Germany, 2014-09-24 20:24 (3880 d 22:39 ago) @ luvblooms Posting: # 13568 Views: 5,811 |
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If it is a study under steady state conditions a possible late tmax could be found because the subject took the drug too early, before the last pk blood sample was drawn... Anyway, is it allowed to exclude this datapoints from analysis? |
Ing. Helmut Schütz