PK-basics / terminology issues [Software]
Dear Vuvraj!
You can’t learn pharmacokinetics from a webforum. I would strongly suggest to read textbooks on PK, get some training in PK, or – as a starter – have a look at David Bourne's excellent ‘A First Course in Pharmacokinetics and Biopharmaceutics’. It doesn’t make sense to click through a piece of specialized software without knowledge of the basics behind. Sorry, there are no shortcuts.
Again, RTFM! For NCA formulas see
There’s no consensus on terminology in PK. This may sound strange more than 50 years after publication of the first textbook.1 That’s the reason many papers in the Journal of Pharmacokinetics and Pharmacodynamics still contain a section of abbreviations and definition of terms.
Vc is the Volume of the central compartment in a multi-compartment model used in textbooks e.g, Gibaldi/Perrier,2 Wagner,3 and more recently Gabrielsson/Weiner.4 WinNonlin uses the term V1 for the central and V2-3 for the first and second [sic] peripheral compartment(s). Unless your drug shows more than one segment in a semilog plot and you perform PK-modeling, you will not obtain Vc. Therefore in NCA you only get parameters based on the apparent elimination phase.
Even if Vc is used, the numbering of transfer rate constants still uses 1 for the central compartment:[2, p.49]
For PK formulas see
❝ I have got following parameters:
❝ Tmax, Cmax, AUC, Vz_Obs, Vz_Pred, Vss_Obs, Vss_Pred, CL_Obs, CL_Pred.
You can’t learn pharmacokinetics from a webforum. I would strongly suggest to read textbooks on PK, get some training in PK, or – as a starter – have a look at David Bourne's excellent ‘A First Course in Pharmacokinetics and Biopharmaceutics’. It doesn’t make sense to click through a piece of specialized software without knowledge of the basics behind. Sorry, there are no shortcuts.
Again, RTFM! For NCA formulas see
WinNonlin’s User's Guide > WinNonlin Model Libraries > Noncompartmental analysis > Plasma or serum data
.There’s no consensus on terminology in PK. This may sound strange more than 50 years after publication of the first textbook.1 That’s the reason many papers in the Journal of Pharmacokinetics and Pharmacodynamics still contain a section of abbreviations and definition of terms.

❝ [...] how to calculate Vc?
❝ Is Vc or Vz_obs same?
Vc is the Volume of the central compartment in a multi-compartment model used in textbooks e.g, Gibaldi/Perrier,2 Wagner,3 and more recently Gabrielsson/Weiner.4 WinNonlin uses the term V1 for the central and V2-3 for the first and second [sic] peripheral compartment(s). Unless your drug shows more than one segment in a semilog plot and you perform PK-modeling, you will not obtain Vc. Therefore in NCA you only get parameters based on the apparent elimination phase.
Even if Vc is used, the numbering of transfer rate constants still uses 1 for the central compartment:[2, p.49]
+-------------+ k12 +-------------+
| Central | ----→ | Peripheral |
| Compartment | ←---- | Compartment |
+-------------+ k21 +-------------+
|
| k10
↓
For PK formulas see
WinNonlin’s User’s Guide > WinNonlin Model Libraries > Pharmacokinetic models >
Model 2
(infusion, 1 compartment),Model 9
(infusion, 2 compartments),Model 19
(infusion, 3 compartments).
- References:
- Dost FH. Der Blutspiegel: Kinetik der Konzentrationsabläufe in der Kreislaufflüssigkeit. Leipzig: Thieme-Verlag; 1953 (in German).
- Gibaldi M, D Perrier D. Pharmacokinetics. New York: Marcel Dekker; 2nd ed. 1982 (reprint: New York: informa healthcare; 2007).
- Wagner JG. Pharmacokinetics for the Pharmaceutical Scientist. Lancaster: Technomic Publishing; 1993.
- Gabrielsson J, Weiner D. Pharmacokinetic & Pharmacodynamic Data Analysis: Concepts and Applications. Stockholm: Swedish Pharmaceutical Press; 4th edition 2006.
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Dif-tor heh smusma 🖖🏼 Довге життя Україна!
![[image]](https://static.bebac.at/pics/Blue_and_yellow_ribbon_UA.png)
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The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes
Complete thread:
- Bioequivalence study of Iron Sucrose Injection 20 mg/ml yuvrajkatkar 2009-09-15 14:04
- WinNonlin: RTFM ;-) Helmut 2009-09-17 15:06
- Bioequivalence study of Iron Sucrose Injection 20 mg/ml yuvrajkatkar 2009-09-18 08:37
- PK-basics / terminology issuesHelmut 2009-09-18 13:55
- Bioequivalence study of Iron Sucrose Injection 20 mg/ml yuvrajkatkar 2009-09-18 08:37
- WinNonlin: RTFM ;-) Helmut 2009-09-17 15:06