• Overview

Therapeutic drug monitoring are blood tests to measure the concentration of certain medications in your blood.

You might need therapeutic drug monitoring if you are prescribed medication that is easily under or over dosed. Drugs that might cause significant side effects may also be monitored. In addition, some drugs need to be monitored because the amount of drug prescribed does not correlate well with the amount that reaches the blood.

To monitor toxic effects of some medications tests such as urea and electrolytes, creatinine and liver function tests are carried out at prescribed intervals to check kidney and liver function. Monitoring can help identify decreases in the efficiency and functioning of the body in processing and eliminating the drugs.

The timing of blood collection is an important part of therapeutic drug monitoring. When you take a dose of medication, the amount in the blood rises for a period of time, peaks, and then begins to fall; usually reaching its lowest level (trough) just before the next dose. To be effective, peak levels should be below toxic concentrations and trough levels should remain in the therapeutic range.

Examples of drugs that may be monitored are:

WarfarinAnticoagulant (anti blood clotting) therapy
LithiumAnti-depression therapy
AzathioprineImmune system suppressant
MethotrexateImmune system suppressant
MyocrisinImmune system suppressant
RoaccutaneUsed to treat acne or rosacea
HRT Profile

Hormone replacement therapy monitoring

Cardiff and Vale Hospitals

The Vale Hospital, Hensol Castle Park, Vale of Glamorgan, CF72 8JX

Cardiff Bay Hospital, Dunleavy Drive, Cardiff, CF11 0SN

02920 836700
Switchboard 02920 836 700
Enquiries and Bookings 02920 836714
Radiology 02920 836731
Physiotherapy 01443 449269

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