Theophylline

Therapeutic drug monitoring (TDM) is testing that measures the amount of certain medicines in your blood. It checks whether the amount of medicine you take is safe and effective.

Therapeutic drug monitoring (TDM) helps determine the best dosages if you're taking certain hard-to-dose medicines. Many medicines that require TDM are ones that you might take for a long time. While you are taking the medicines, you may have changes that could affect the medicine levels in your blood.