Therapeutic Drug Monitoring (TDM)

Therapeutic Drug Monitoring (TDM)

Therapeutic drug monitoring (TDM) is an area of clinical chemistry that specialises in measuring medication levels (concentrations) in patients, usually through blood samples but also through saliva samples. 

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Therapeutic Drug Monitoring (TDM)

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Using the TDM service

The assay service is routinely available Monday to Friday, 9am-5pm. For urgent assay requests, please contact the unit in advance. The unit will report on non urgent assay requests within 3 working days of receiving the sample in the laboratory, excluding weekends or bank holidays.

Sample type

The matrix of choice is serum or plasma, and although they can be used inter-changeably it is preferable to use one or the other. In most clinical settings the measurement of total serum concentrations will suffice and indeed most routine methods for measuring AEDs in sera do not discriminate between the component of drug that is free (unbound) and that that is bound to serum proteins.

A specialist AED Therapeutic Drug Monitoring (TDM) Service

Our Therapeutic Drug Monitoring (TDM) Unit will undertake the detailed pharmacokinetic investigation of individual patients with unusual clinical response to drugs during therapy or following overdose. Presently, it is the only AED TDM service in the UK which provides an analytical service for 24 AEDs currently licensed for clinical use and 2 pharmacologically active metabolites.

The Unit provides a specialist AED TDM service for in-patients and out-patients attending the National Hospital for Neurology and Neurosurgery (Queen Square), University College Hospitals NHS Trust and Epilepsy Society. Also, sample referrals are received from many NHS and private hospitals, institutions, forensic laboratories, private pathology laboratories and from veterinary practices throughout the UK. The service provision is cost effective and with rapid turnaround times.

What is Therapeutic Drug Monitoring (TDM)?

Therapeutic drug monitoring (TDM) is an area of clinical chemistry that specialises in measuring medication levels (concentrations) in patients, usually through blood samples but also through saliva samples. Because anti-epileptic drugs are among the types of drugs that can be easily under dosed or over dosed, they are particularly suitable for monitoring. The measured levels are used by the doctor to adjust each patient’s individual dosage and schedule to each patient’s individual therapeutic requirement. Thus, drug efficacy (the anti-epileptic effect of a drug) is kept to a maximum while the undesirable side effects are kept to a minimum.

Monitoring antiepileptic drugs

There are now 27 anti-epileptic drugs (AEDs) licensed for the management of patients with epilepsy in the UK. We offer a TDM service for 24 of these drugs and 2 pharmacologically active metabolites. During the past 10-20 years therapeutic monitoring of anti-epileptic drugs has served to substantially enhance the management of patients with epilepsy because drug administration (prescriptions) can be individualised.

Our Therapeutic Drug Monitoring Unit (TDM)

We provide a TDM assay service for AEDs and a pharmacokinetic consultation service (looking at how drugs distribute in the blood over time) to help individualise patient drug therapy. We carry out detailed pharmacokinetic investigation of individual patients who have experienced an unusual clinical response to drugs during therapy or following overdose.

We provide a specialist AED analytical service to the National Hospital for Neurology and Neurosurgery, University College Hospitals NHS Trust, and to many hospitals and organisation throughout the UK and from Europe.

How can the service be accessed?

Chalfont Centre switchboard number 01494 601 300
Email: TDM_Unit@epilepsysociety.org.uk
Main Laboratory 01494 601 424
Patient results and enquiries 01494 601 423
Consultant Clinical Scientist/Head of Unit Dr K Kipper 01494 601 355
Transformation Advisor Mr F McQueen 01494 601 355
Clinical Scientist Mr A. W. James 01494 601 424
Clinical Scientist Mr F. P. Quinlivan 01494 601 424
Quality & Administration Manager Mrs Kate Choinkowska 01494 601 490
Phlebotomy Services Mrs Julie Dick 01494 601 345
Phlebotomy Services Ms Jolanta Krysa 01494 601 345
Medical Director Professor J. W. Sander 01494 601 343