Which drugs to monitor:
(1) drugs with narrow therapeutic index
(2) drugs with significant dose-related toxic effects
(3) drugs that are critical to the patient
What to monitor:
(1) parent drug and/or active metabolites
(2) potentially toxic metabolites
Which patients to monitor:
(1) Those with a disease or drug affecting drug absorption or distribution
(2) Those with a disease or drug affecting drug elimination (such as renal insufficiency).
(3) Those who do not respond as expected to a given dose.
|
Situation
|
When to Monitor
|
|
looking for dose-related toxicity
|
peak level
|
|
looking for accumulation during intermittent dosing
|
just before next dose
|
|
looking for accumulation during a continuous infusion
|
anytime
|
For drugs that slowly distribute to their receptors, such as digoxin, blood samples may not reflect tissue/receptor levels until late in the distribution phase, when plasma levels are equivalent to tissue levels.
