Can Therapeutic Drug Monitoring with Monotherapy Achieve Similar Results as Combination Therapy for IBD?

A recent retrospective study (S Lega et al. Inflamm Bowel Dis 2019; 25: 134-41) suggests that proactive therapeutic drug monitoring (pTDM) with infliximab (IFX) helps achieve similar outcomes as combination therapy (with immunomodulator) in patients with inflammatory bowel disease.

Before reviewing the key findings, it is important to emphasize a few crucial limitations/methods:

  • The study enrolled 83 patients; only 16 received were in the monotherapy pTDM group.
  • This was a retrospective study
  • The authors utilized TDM at week 10.  If the IFX level was <20 mcg/mL, the dose and frequency of infliximab were both adjusted. If the level was between 20 & 25, either the frequency was adjusted or no adjustment, and if the level was >25, then no adjustment in dosing was performed.

Key findings:

  • The frequency of infliximab discontinuation with mono therapy in those with pTDM was lower than in those with ‘standard of care’ TDM (P=0.04) but did not differ from patients receiving combination therapy
  • Overall 9 of the 83 patients (11%) discontinued IFX during the 1-year study

In the discussion, the authors suggest that week 14 TDM may be suboptimal as this is the first time patients have an 8-week interval.

My take: The jury is out with regard to whether pTDM can negate the need for combination therapy  –a prospective trial is needed; however, the idea of getting TDM a bit earlier is intriguing, particularly as it has been shown that a high percentage of pediatric patients are receiving an insufficient dose of infliximab (Is Standard Infliximab Dose Tool Low in Pediatrics?)

Key words: 10 weeks, therapeutic drug monitoring, infliximab, trough

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Disclaimer: These blog posts are for educational purposes only. Specific dosing of medications/diets (along with potential adverse effects) should be confirmed by prescribing physician/nutritionist.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition.

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