Pharmacist-Driven Therapeutic Infliximab Monitoring at the Point of Care Using Rapidly Assessed Drug Levels in Patients with Inflammatory Bowel Disease : Therapeutic Drug Monitoring

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Original Article

Pharmacist-Driven Therapeutic Infliximab Monitoring at the Point of Care Using Rapidly Assessed Drug Levels in Patients with Inflammatory Bowel Disease

Rentsch, Clarissa A. MClinPharm*,†; Ward, Mark G. MD*; Luber, Raphael P. MD*; Taylor, Kirstin M. MD*; Gibson, David J. MD*; Headon, Belinda RN*; Rosella, Ourania BSc(Hons)*; Su, Heidi Y. MD*; Friedman, Antony B. MD*; Dooley, Michael BPharm, PhD‡; Sparrow, Miles P. MD*; Gibson, Peter R. MD*

Author Information

*Department of Gastroenterology Alfred Health and Central Clinical School, Monash University. Ms. Rentsch is now with the Department of Gastroenterology, Royal Melbourne Hospital, Melbourne;

†Department of Pharmacy, Alfred Health; and

‡Faculty of Pharmacy and Pharmaceutical Sciences, Monash University, Melbourne, Australia.

Correspondence: Peter R. Gibson, MD, Department of Gastroenterology, Alfred Hospital, 99 Commercial Rd, Melbourne, VIC 3004, Australia (e-mail: [email protected]).

Supported by an Alfred Research Trusts small project grant. Bühlmann Laboratories AG provided the assays and the associated equipment.

C. A. Rentsch: Concept, design, implementation, analysis, writing, and editing of the manuscript. M. G. Ward: Design, analysis, and editing of the manuscript. R. P. Luber: implementation, editing. K. M. Taylor: design, implementation, and editing of the manuscript. D. J. Gibson: analysis and editing of the manuscript. B. Headon: implementation, editing. O. Rosella: analysis and editing of the manuscript. H. Y. Su: implementation and editing of the manuscript. A. T. Friedman: Design, analysis, editing. M. Dooley: design and editing of the manuscript. M. P. Sparrow: design, implementation, and editing of the manuscript. P. R. Gibson: Concept, design, writing, and editing of the manuscript.

C. A. Rentsch has received speaking honoraria from Takeda. M. G. Ward has received speaking honoraria from Janssen, AbbVie, Ferring, Takeda, MSD, and Shire; has received educational grants or research support from MSD, Ferring, and AbbVie; and owns shares in Atmo Biosciences. R. P. Luber has received educational grants from Ferring, Pfizer, and Vifor Pharma. H. J. Su has received speaking honoraria from Janssen. A. B. Friedman received speaking honoraria from Janssen, AbbVie, Ferring, Takeda, and Shire. He has received educational grants and research support from AbbVie, Ferring, Pfizer, Takeda, Orphan, and Janssen. M. P. Sparrow has received educational grants or research support from Ferring, Orphan, and Gilead; speaker fees from Janssen, Abbvie, Ferring, Takeda, Pfizer, and Shire; and has served on advisory boards for Janssen, Takeda, Pfizer, Celgene, Abbvie, MSD, and Emerge Health. P. R. Gibson has served as a consultant or advisory board member for Anatara, Atmo Biosciences, Immunic Therapeutics, Novozymes, Falk Pharma, and Takeda; has received research grants for investigator-driven studies; and owns shares in Atmo Biosciences. The remaining authors declare no conflict of interest.

The protocol was approved by the Alfred Health Ethics Committee (53/16) and complied with the Declaration of Helsinki 1975 as revised in 1996.

Therapeutic Drug Monitoring 45(3):p 383-391, June 2023. | DOI: 10.1097/FTD.0000000000001044

Abstract

Background: 

Therapeutic monitoring of infliximab is limited by the time lag between drug-level measurement and dose adjustment, along with the cost of dose escalation. Strategies for dose reduction in stable patients on maintenance infliximab at supratherapeutic levels are uncertain. This study determined the feasibility of a pharmacist-driven strategy for immediate dose adjustment using a sliding scale at the point of care in stable patients with inflammatory bowel disease on maintenance therapy.

Methods: 

Adult patients with stable disease undergoing maintenance therapy with infliximab infusions, 5 mg/kg every 8 weeks, were prospectively studied. Trough drug levels were assessed by a rapid assay (and later by ELISA) at all infusions for up to 12 months with immediate but quantitatively small dose adjustment according to a sliding scale targeting a therapeutic range of 3–7 mcg/mL. Disease activity was assessed both clinically and biochemically.

Results: 

The rapid assay and ELISA detected similar infliximab levels, and the strategy added approximately 30 minutes to the duration of infusion events. Only 20% of 48 patients (77% with Crohn disease) had baseline trough infliximab concentrations within the therapeutic range. This value increased 3-fold after 24 and 48 weeks of interventions. One in 2 patients had baseline supratherapeutic levels, and most were brought into the therapeutic range without a discernible impact on disease activity by 1 dose adjustment, but 2 or 3 adjustments were generally needed for 29% of patients with subtherapeutic levels. Overall, drug costs were reduced by 4%.

Conclusions: 

Immediate dose adjustment after infliximab rapid assay performed by a pharmacist using a sliding scale is a feasible strategy. Supratherapeutic infliximab levels can be safely and quickly brought into the therapeutic range using small dose adjustments without affecting disease activity, offsetting (at least partly) costs associated with dose escalation.

Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.

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