Minimum blood plasma concentration of a drug during the time between two doses
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]