Therapeutic drug Monitoring. What is therapeutic drug monitoring (TDM)? Individualization of drug doses by maintaining plasma/blood drug concentrations within a target range---- therapeutic range therapeutic window.
Individualization of drug doses by maintaining plasma/blood drug concentrations within a target range---- therapeutic range
Takes care of inter-individual variability.
Therapeutic failure results when either the concentration is too low, ineffective therapy, or is too high, producing unacceptable toxicity. Between these limits of concentration lies a region associated with therapeutic success – regarded as a Therapeutic window.
Drug concentration (log scale)
Drug concentration (log Scale)
Plasma/ serum; cyclosporin- whole blood.
Timing: least variable point in dosing interval– predose/trough concentration.
Wait for steady state to be achieved---at least 5 half-lives. Exceptions are there! Drugs with long half-life.
HPLC, GLC, Immunoassays- sensitivity, specificity.
Free drug vs total drug concentration.
Importance of plasma protein binding.
Remember that only total drug concentration is measured but only the free drug is active!
Drug Therapeutic range (mg/L)
Sodium valproate 50-100
Gentamicin peak>5, trough<2
Amikacin peak>15, trough<5
Vancomycin peak20-40, trough<10
ESTIMATE INITIAL DOSE
REFINE DOSE ESTIMATE