Therapeutic Drug Monitoring is a measurement of specific drug concentration levels at timed intervals in patients, usually through blood/serum samples, and is necessary where control of drug concentrations is required to achieve optimum treatment for the patient, or where there is a narrow range between the therapeutic and toxic levels.

The AXIO Proficiency Testing Therapeutic Drugs Monitoring Scheme (TDM) provides independent performance assessment for the routine quantification of a wide range of anti-epileptic and other therapeutic drugs.

The operation of this scheme is supported by an Advisory Group consisting of members of professional bodies, scheme participants, and others experienced in the field. The scheme reports on the performance of UK participants (who have clinical responsibilities) to the National Quality Assurance Advisory Panels for Chemical Pathology.