the lowest concentration of drug in the blood after a dose of that drug (that is, before the level begins to increase again as a result of administration of the next dose)

The minimum concentration of a drug in the body after dosing.

The minimum concentration that a compound achieves during a dosing interval. This value represents the lowest level of a given drug to which the virus is exposed to during the dosing period, and so it also represents the period in the dosing interval when the likelihood of viral breakthrough is greatest, if concentrations fall to subtherapeutic levels.

CMO Code of Federal Regulations, Title 21

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