03-09-2012, 10:18 AM
THERAPEUTIC DRUG MONITORING
THERAPEUTIC DRUG MONITORING.pptx (Size: 515.86 KB / Downloads: 104)
DEFINITION
Therapeutic drug monitoring (TDM) is generally defined as the clinical laboratory measurement of a chemical parameter that, with appropriate medical interpretation, will directly influence drug prescribing procedures by combining knowledge of pharmaceutics, pharmacokinetics, and pharmacodynamics, TDM enables the assessment of the efficacy and safety of a particular medication in a variety of clinical settings.
The goal of this process is to individualize therapeutic regimens for optimal patient benefit.
CRITERIA IN WHICH TDM IS USEFULL
Certain drugs have a narrow therapeutic range
In concentrations above the upper limit of the range, the drug can be toxic.
In concentrations below the lower limit of the range, the drug can be ineffective.
Not all patients have the same response at similar doses.
TDM IS UNNECESSARY WHEN
1) Clinical outcome is unrelated either to dose or to plasma concentration.
2) dosage need not be individualized.
3) the pharmacological effects can be clinically quantified.
4) when concentration effect relationship remains unestablished.
5) drugs with wide therapeutic range such as beta blockers and calcium channel blockers.
INDICATIONS FOR TDM
Drug efficacy difficult to establish clinically (Phenytoin).
Suspected toxicity
Inadequate therapeutic response
Compliance concerns
Dosage change
Change in patient’s clinical state
Change in co-medications
Manifestations of toxicity and disease state are similar
INTERPRETIVE CRITERIA
Measuring the blood concentration of certain therapeutic drugs is only one aspect of effective TDM monitoring.
True TDM testing takes into consideration all the factors that can affect results, as well as all the factors that can affect interpretation, as described below:
APPLICABILITY OF TR:
Therapeutic ranges are recommendations derived by observing the clinical reactions of a small group of patients taking the drug.
ANTIEPILEPTICS
This class of drugs, also known as anticonvulsants, is most often prescribed for the management of epilepsy, though it may also be prescribed for other indications such as tic douloureux, myotonia, bipolar effective disorder, prophylaxis of certain varieties of migraine and of cardiac dysrhythmia.
CLINICAL SIGNIFICANCE
TDM data provides the clinician with greater insight into the factors determining the patients response to drug therapy.
For example when a patient fails to respond to a usual therapeutic dose,measurement of plasma level can help to distinguish a noncompliant patient and a patient who is a true non-responder.
TDM also provides useful information regarding individual variations in drug utilization patterns and alteration in drug utilization as a consequence of altered physiological state or disease process.