About Therapeutic Drug Management

Therapeutic drug monitoring is a branch of clinical chemistry designed for measuring drug levels in the blood. It is a drug management tool that assists the clinician in individualizing drug dosage for optimal effect to achieve clinical efficacy and minimize toxicity. Assessment of a patientís predisposition to therapy is another drug management tool.

Therapeutic drug management has progressed beyond the population approach and now targets concentrations for the individual patient. To personalize drug therapy, therapeutic drug monitoring can be applied independently or in conjunction with genetic and/or other molecular tests. Genetic/molecular testing predicts responsiveness to therapy and profiles resistance and susceptibility of infectious agents, but it does not ensure a desired drug level.

Therapeutic drug monitoring in combination with genetic, molecular or biomarker testing is a powerful approach. It matches individuals with optimal drugs and personalizes the management of therapy with optimal dosing.

The goals of therapeutic drug management are to:

  • Select an appropriate drug
  • Define an individual therapeutic range, the range of drug concentrations associated with the best achievable response in a given person

    Reference Range versus Individual Therapeutic Range

    The reference range is based on population studies. It is the range of drug concentrations quoted by a laboratory that specifies a lower limit (below which a therapeutic response is unlikely) and an upper limit (above which toxicity is likely). These limits are guidelines for the general popluation. The reference range may be called therapeutic when effective. However, some people will derive optimal benefits at concentrations outside the reference range, and others can have toxic effects at concentrations within it.

    An individiual therapeutic range is unique and based on a patient’s personal response to a drug. It is the range of drug concentrations that produce an optimal response in a particular patient. Because this range varies among individuals, clinicians can use TDM to determine it empirically. For many, but not all patients, the individual therapeutic range will lie within, or close to, the reference range.

  • Measure the actual drug level that corresponds to a specific dose
  • Achieve and maintain optimal dosing for safe and effective therapy

When managing drug dosing, One Size Does Not Fit All