Cmin Explained
Cmin is a term used in pharmacokinetics for the minimum blood plasma concentration reached by a drug during a dosing interval, which is the time interval between administration of two doses. This definition is slightly different from Ctrough, the concentration immediately prior to administration of the next dose.[1] Cmin is the opposite of Cmax, the maximum concentration that the drug reaches. Cmin must be above certain thresholds, such as the minimum inhibitory concentration (MIC), to achieve a therapeutic effect.[2]
In most cases Cmin is directly measurable. At steady state the minimum plasma concentration can also be calculated using the following equation:[3]
= Salt factor
=
Bioavailability
= Dose
=
Elimination rate constant
=
Absorption rate constant
=
Volume of distribution
= Dosing interval
Cmin is also an important parameter in bioavailability and bioequivalence studies, it is part of the pharmacokinetic information recommended for submission of investigational new drug applications.[4]
Notes and References
- Book: Weimann . H. J. . Cawello . W. . Brett . M. . Zimmermann . H. . Pabst . G. . Sierakowski . B. . Giesche . R. . Baumann . A. . 1999 . Parameters for Compartment Free Pharmacokinetics: Standardisation of Study Design, Data Analysis and Reporting . Drug concentrations and directly derived parameters . Shaker-Verlag . 9783826547676 . 44511664 . Aachen, Germany . 25–40. (pages 31–34 in 2003 edition)
- Dalton . Bruce R. . March 2023 . What Is the Best Vancomycin Therapeutic Drug Monitoring Parameter to Assess Efficacy? A Critical Review of Experimental Data and Assessment of the Need for Individual Patient Minimum Inhibitory Concentration Value . Microorganisms . en . 11 . 3 . 567 . 10.3390/microorganisms11030567 . 36985141 . 10051726 . 2076-2607 . free .
- http://www.pharmpress.com/files/docs/clinical_pharmacokinetics_samplechapter.pdf
- https://www.fda.gov/downloads/Drugs/.../Guidances/ucm070124.pdf
