Quick Review Cards for Medical Laboratory Science

Therapeutic Drug Monitoring (TDM) Clinical Chemistry Review 115

TERM EXPLANATION

Minimum effective concentration (MEC) Lowest concentration of drug in blood that will produce desired effect

Minimum toxic concentration (MTC) Lowest concentration of drug in blood that will produce adverse response

Therapeutic index Ratio of MTC to MEC

Trough Lowest concentration of drug measured in blood. Reached just before next scheduled dose.

Shouldn’t fall below MEC

Peak Highest concentration of drug measured in blood. Drawn immediately on achievement of

steady state. Should not exceed MTC

Steady state Amount of drug absorbed & distributed = amount of drug metabolized & excreted. Usually

reached after 5–7 half-lives

Half-life Time required for concentration of drug to be ↓by half.

Pharmacokinetics Rates of absorption, distribution, biotransformation, & excretion

Most common methods: immunoassay, chromatography.