INTRODUCTION, INDICATION AND PROTOCOL FOR TDM

CLINICAL PHARMACOKINETICS & PHARMACOTHERAPEUTIC DRUG MONITORING

UNIT-4

Therapeutic Drug monitoring: 

Introduction to TDM (Therapeutic drug monitoring) &

Indications for TDM, Protocol for TDM.

 

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Therapeutic drug monitoring (TDM) is the clinical practice of measuring

specific drugs at designated intervals to maintain a constant concentration in a

patient's bloodstream, thereby optimizing individual dosage regimens.

It is used mainly for monitoring drugs with narrow therapeutic range, drugs

with marked pharmacokinetic variability, medications for which target

concentrations are difficult to monitor, and drugs known to cause therapeutic

and adverse effects.

 The process of TDM is predicated on the assumption that there is a

definable relationship between dose and plasma or blood drug

concentration, and between concentration and therapeutic effects.

 TDM begins when the drug is first prescribed, it involves determining an

initial dosage regimen appropriate for the clinical condition and such

patient characteristics (age, weight, organ function, and concomitant drug

therapy)

 Interpreting concentration measurement involves factors like sampling

time in relation to drug dose, dosage history, patient response and the

desired target.

 The goal of TDM is to use appropriate concentrations of difficult to

manage medications to optimize clinical outcomes in patients in various

clinical situations.

 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. (or)

 TDM refers to the individualization of drug dosage by maintaining

plasma or blood drug concentrations within a targeted therapeutic range

or window.

 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.

 TDM involves measuring drug concentrations in various biological fluids

and interpreting these concentrations in terms of relevant clinical

parameters.

 Clinical pharmacists and pharmacologists use pharmacokinetic principles

to assess these interpretations.

OBJECTIVES:

• To attain rapid and safe concentration of drug in plasma within the

desired therapeutic range in order to provide the safest approach to

optimal drug therapy.

• To coordinate clinical pharmacology, pathology, chemistry, toxicology,

analytical chemistry and medicine.

• To remove empirical trial and error approach.

PURPOSE OF TDM

 Performing TDM requires a multidisciplinary approach.

 Accurate and clinically meaningful drug concentrations are attainable

only by complete collaboration by a TDM team, typically comprised of

scientists, clinicians, nurses, and pharmacists.

 Excellent communication among team members is necessary to ensure

that best practices in TDM are achieved .

 The indications for drug monitoring have widened to include efficacy,

compliance, drug-drug interactions, toxicity avoidance, and therapy

cessation monitoring.

 Measuring plasma concentrations may be helpful, however, as a low

measurement reflects either poor recent compliance.

 Poor compliance is implicated if the patient is prescribed a dose that is

unlikely to be associated with a measured low concentration or if a

previous measurement suggested that the plasma concentration should be

higher for the given dose.

INTRODUCTION, INDICATION AND PROTOCOL FOR TDM