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]

S = Salt factor
F = Bioavailability
D = Dose
ke = Elimination rate constant
ka = Absorption rate constant
Vd = Volume of distribution
τ = 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]

References

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  1. ^ Weimann, H. J.; Cawello, W.; Brett, M.; Zimmermann, H.; Pabst, G.; Sierakowski, B.; Giesche, R.; Baumann, A. (1999). "Drug concentrations and directly derived parameters". Parameters for Compartment Free Pharmacokinetics: Standardisation of Study Design, Data Analysis and Reporting. Aachen, Germany: Shaker-Verlag. pp. 25–40. ISBN 9783826547676. OCLC 44511664. (pages 31–34 in 2003 edition)
  2. ^ 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. 11 (3): 567. doi:10.3390/microorganisms11030567. ISSN 2076-2607. PMC 10051726. PMID 36985141.
  3. ^ http://www.pharmpress.com/files/docs/clinical_pharmacokinetics_samplechapter.pdf Archived 29 March 2018 at the Wayback Machine [bare URL PDF]
  4. ^ https://www.fda.gov/downloads/Drugs/.../Guidances/ucm070124.pdf [bare URL PDF]