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 , the concentration immediately prior to administration of the next dose. is the opposite of , the maximum concentration that the drug reaches. must be above certain thresholds, such as the minimum inhibitory concentration (MIC), to achieve a therapeutic effect.

In most cases is directly measurable. At steady state the minimum plasma concentration can also be calculated using the following equation: C_{min} = \frac{SFDk_a}{V_d(k_a-k_e)} \times \left( \frac{e^{-k_e\tau}}{1-e^{-k_e\tau}}-\frac{e^{-k_a\tau}}{1-e^{-k_a\tau}} \right) = Salt factor = Bioavailability = Dose = Elimination rate constant = Absorption rate constant = Volume of distribution = Dosing interval