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Tushar.g ☆ India, 2010-05-20 08:54 (5872 d 08:45 ago) Posting: # 5355 Views: 9,568 |
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Dear All, I am new in this field and want to learn IVIVC concept using R package. My query is regarding computation of absorption constant, elimination and volume and distribution. In R, we need to specify the values of absorption constant, elimination and volume of distribution. Can anybody tell me, based on what conditions we have to select these 3 values? Actually, I have one pilot 2-way crossover bio-study data of ER oral formulation with 6 subjects which shows bioequivalence result (ratio & C.I. are between 80% to 125%) but when I input these data and its dissolution into R software to check IVIVC and its prediction error. It shows prediction error 37% and 41% for Cmax and AUC respectively. which is quite doubtful. Thanks in advance. Regards, Tushar |
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yjlee168 ★★★   Kaohsiung, Taiwan, 2010-05-20 09:35 (5872 d 08:05 ago) (edited on 2010-05-20 23:16) @ Tushar.g Posting: # 5356 Views: 8,416 |
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Dear Tushar, I suppose you're using ivivc for R. ❝ values of absorption constant, elimination and volume of distribution. ❝ Can anybody tell me, based on what conditions we have to select these 3 values? The elimination rate constant (kel)and Vd can be obtained from literature or any IV, solution, IR dosage form study. I don't think that it requries you to enter absorption rate constant. ❝ Actually, I have one pilot 2-way crossover bio-study data of ER oral formulation with 6 subjects which shows bioequivalence result (ratio & With 6 subjects in one pilot to show bioequivalence? Wow! ❝ C.I. are between 80% to 125%) but when I input these data and its dissolution into R software to check IVIVC and its prediction error. It shows prediction error 37% and 41% for Cmax and AUC respectively. which is quite doubtful. Supposed you have done everything correctly, it is not so surprised at all. It implies that you have a poor ivivc model, although you have proved that THIS formulation is bioequivalent to its brand product. Please note that iviivc for R uses internal validation right now. For external validation, you have to calculate yourself with a spreadhseet (like ms-excel or oo-calc). Or the PK model of your study drug is more complicated, such as more than one-compartment linear or nonlinear PK model. If this is the case, it limits the use of ivivc for R. Here is a nice post for ivivc reference by Helmut. — All the best, -- Yung-jin Lee bear v2.9.6:- created by Hsin-ya Lee & Yung-jin Lee Kaohsiung, Taiwan https://www.pkpd168.com/bear Download link (updated) -> here |
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Gajanan ● 2011-01-31 08:53 (5616 d 07:46 ago) @ yjlee168 Posting: # 6518 Views: 7,915 |
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I am trying to establish an IVIVC with R. In the IVIVC menu, I selected PK paremeters from literature and opted to enter PK parameters from references (option 2).In the data editor, I enetered, Ke and Vd values for 3 subjects and saved them. In step 3 (in vitro dissolution data and in vivo absorption data, I selected option 1, Input edit raw data from keyboard.Then I entered observed concentration and fraction dissolved data for 3 different PH and 3 formulations for 12 time points. In step 4, develop an IVIVC model: Model dependent method, I selected model dependent method, Which takes me to step 4, where an IVIVC model is developed. I have selected 1 compartment model Wagner Nelson method. I have entered dose value of extended release forms. Then the software asks me to 'Enter PK parameter data file name'. At this step I dont know what I am supposed to know. I am new to IVIVC and request help on this |
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yjlee168 ★★★ Kaohsiung, Taiwan, 2011-01-31 09:19 (5616 d 07:21 ago) (edited on 2011-01-31 10:12) @ Gajanan Posting: # 6519 Views: 7,851 |
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Dear Gajanan, ❝ [cut here..] ❝ references (option 2). In the data editor, I enetered, Ke and Vd values for 3 subjects and saved them. In step 3 (in vitro dissolution data and in vivo O.k., remember the file name that you used to save your Ke and Vd at this step. ❝ value of extended release forms. Then the software asks me to 'Enter PK parameter data file name'. ❝ At this step I dont know what I am supposed to know. Enter the same file name (no file extension, please) that you just entered above. It should work. Sorry about this. I will fix this later. — All the best, -- Yung-jin Lee bear v2.9.6:- created by Hsin-ya Lee & Yung-jin Lee Kaohsiung, Taiwan https://www.pkpd168.com/bear Download link (updated) -> here |
Ing. Helmut Schütz