It is the most direct approach to assess the pk of drug in the body
PLASMA perfuses all the tissues of the body, including the cellular elements in the blood
Small molecules in the blood are carried thru the plasma
Changes in the drug concentration in plasma will reflect changes in tissue drug concentrations.
Measuring the plasma drug level is a responsive method of monitoring the course of therapy.
bound and unbound.
A drug's efficiency may be affected by the degree to which it binds to the proteins within blood plasma.
The less bound a drug is, the more efficiently it can traverse cell membranes or diffuse.
1 Compliance monitoring
2 Individualizing therapy – during early therapy and during dosage changes
3 Diagnosing under-treatment
4 Avoiding toxicity
5 Monitoring and detecting drug interactions
6 Guiding withdrawal of therapy
- allow for the adjustment of the drug dosage
- to individualize and optimize therapeutic drug regimens.
- When there is alterations in physiologic functions, monitoring may provide a guide to the progress of the disease state
- enable the investigator to modify the drug dosage accordingly.