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Proactive Therapeutic Drug Monitoring -Different Time Points

September 7, 2019 9:00 am

Yesterday’s post outlined expert recommendations for proactive therapeutic drug monitoring (pTDM). Today’s post reviews a study (NV Casteele et al. Clin Gastroenterol Hepatol 2019; 17: 1814-21) which identifies optimal levels at earlier time points. The authors note that “higher infliximab (IFX) concentrations during induction therapy are correlated with long-term relapse-free and colectomy-free survival.”

The authors analyzed data from 484 patients with active ulcerative colitis (UC) from two double-blind, placebo-controlled, parallel group studies: ACT-1 and ACT-2.

Key findings:

IFX levels ≥18.6 mcg/mL at week 2, ≥10.6 mcg/mL at week 6, and ≥34.9 mcg/mL at week 8 were associated with Mayo endoscopic scores (MES) of ≤1 at week 8.
IFX level of ≥5.1 mcg/mL at week 14 was associated with MES of ≤1 at week 30
IFX level of ≥6.7 mcg/mL at week 14 was associated with MES of 0 at week 30

My take: In pediatric patients receiving monotherapy with an anti-TNF agent, checking earlier levels (week 6, week 8, or week 10) may help avoid low troughs which are associated with a higher likelihood of treatment failure. This study provides guidance on target levels at earlier time points.

Related blog posts:

Briefly Noted: Induction Infliximab Levels Infliximab level ≥18 mcg/mL at week 6 was strongly associated with clinical and biologic response as well as achieving an infliximab level ≥5 mcg/mL at week 14 (AUC 0.85).
Is Standard Infliximab Dose Too Low in Pediatrics?
Combination Therapy Study Points to Central Role of Adequate Drug Levels
Can Therapeutic Drug Monitoring with Monotherapy Achieve Similar Results as Combination Therapy for IBD? | gutsandgrowth 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.
Don’t be Fooled About Withdrawing Immunomodulator Cotherapy -Look Past the Headline

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.