AUCall OR AUClast???

Dear All, [left]We use WinNonlin software for BE calculation which gives AUCall and AUClast parameters. Can anybody tell me, Between AUClast and AUCall which value is truelly determine the AUCt ? We specifically work on Extended release drug for US market. In Clinical trials, Most of the time last concentration values comes as BLQ so we replace BLQ by zero. So AUCall value adds the extra area from Clast to zero in AUC calculation. Is it feasible to consider AUCall as an AUCt parameter? I am Confused.[/left] Thanks in Advance. Regards, Tushar

Dear Tushar - I would report AUClast since as this is the parameter that is explicitly defined in text books etc. AUC[sub]tz[/sub] = AUC up to the last validated measurable plasma concentration Csub[/sub]. AUCall takes AUClast and adds a ‘triangle’ to the next sampled point and I would consider it a secondary parameter, particularly if you have an otherwise well defined profile and can extrapolate to AUCinf with confidence. Simon.

Dear Tushar, please avoid AUCall – it’s Pharsight’s invention. You will not find it in any textbook on PK. Regulatory authorities worldwide require AUC[sub]t[/sub] (=AUClast) and AUC[sub]∞[/sub] (=AUCinf). If you go with AUCinf, I would recommend to use AUCinfpred instead of AUCinfobs. For some background see this thread at the BEBA-Forum.

Dear Sdavis, Thank you very much for your prompt and quick reply. Confusion is sorted out. Dear Helmut, Many thanks for your reply as well as the link which you have provided. It gives perfect idea about this issue and Excellently explained with graphical examples. Many Thanks Once Again, Regards, Tushar