Therapeutic Drug Monitoring in IBD

• Used to check drug concentrations and assess for anti-drug antibodies

• Can help to determine type of failure based on drug and anti-drug antibody levels

• Three types of drug failure

  • mechanistic

  • Non-immune PK failure

  • Immune mediated PK failure

Why TDM in IBD?

Drug level

• Ideally, a trough concentration

• Can be measured during induction or maintenance therapy

Anti-drug antibody level

• Antibodies formed to the biologic itself

• Low-titer or high-titer quantification

Measured together!

We monitor for

• Mechanistic failure

• Non-immune PK failure or Immune mediated PK failure

Types of DRUG FAILURE: Primary nonresponse is ____ while secondary nonresponse is _______

Increase dose or decrease frequency

If a patient with CD/UC has no response to Anti-TNF therapy, and has LOW drug concentration and NO Anti-drug antibody concentration, you should: 

Switch to another anti-TNF therapy

If a patient with CD/UC has no response to Anti-TNF therapy, and has LOW/NORMAL drug concentration and HIGH Anti-drug antibody concentration, you should: 

Switch Drug class

If a patient with CD/UC has no response to Anti-TNF therapy, and has NORMAL drug concentration and NO Anti-drug antibody concentration, you should: