Cmin

Cmin is a term used in pharmacokinetics for the minimum blood plasma concentration reached by a drug during 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][2] 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.

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
k: elimination constant
ka: absorption 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

  1. HJ Weimann (2003). "Drug concentrations and directly derived parameters". In W Cawello (ed.). Parameters for Compartment-Free Pharmacokinetics. Aachen: Shaker-Verlag. pp. 31–4.
  2. AGAH working group Pharmacokinetics, 2004.
  3. http://www.pharmpress.com/files/docs/clinical_pharmacokinetics_samplechapter.pdf
  4. https://www.fda.gov/downloads/Drugs/.../Guidances/ucm070124.pdf


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