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Table 3 Overview of all available studies on erythrocyte MTX-PG concentrations and pharmacokinetics in patients with IBD

From: Subcutaneous administration, higher age and lower renal function are associated with erythrocyte methotrexate accumulation in Crohn’s disease: a cross-sectional study

Article

Population

Methotrexate

Method

Pharmacokinetic results

First author, year, journal

N

From

Age (y)†

CD (%)

Active disease (%)

Oral (%)

Dose (mg/wk)

Co-therapy (%)

Study dsesign

Method of MTX-PG measurement

 

Morrow, 2021, Pharmaceuticals17

&

Shakhnovich, 2019, [A] Gastroenterology25

21

USA

5–21

90

48

86

5–25†

IFX (100)

Cross-sectional

HPLC–MS/MS

of

MTX-PG1-6

Relationship of dose and MTX-PGtotal (ρ = 0.56) and MTX-PG(3–5) (ρ = 0.51)

No relationship of IFX concentration and MTX-PGtotal or MTX-PG3-5

No relationship of route of administration and MTX-PG concentration§

Fischer, 2017, Clinical Pharmacology and Drug Development18

&

Shivi, 2014, [A] Inflammatory bowel disease26

12

USA

30–68

100

42

17

25; at least 12 weeks

Steroid (25)

Cross-sectional

HPLC–MS/MS

of

MTX-PG1-5

Interpatient variation of 28-fold for

MTX-PGtotal

Fong, 2014, [A] Journal of Crohn’s and Colitis19

21

UK

22–59

76

57

90

17 ± 1ǂ

IFX (57)

ADA (14)

Retrospective cohort

HPLC of MTX-PG1-5

A linear relationship between dose of MTX and PG1–5 was observed (ρ = n/a)

Brooks, 2007, Therapeutic Drug Monitoring20

18

NZ

24–80

72

37

78

15–25†; at least 12 weeks

Steroid (39)

Cross-sectional

HPLC –UV (day 0, 14 and 28)

of

MTX-PG1-5

Dose-dependent increase of MTX-PG4 and MTX-PG(4,5) and MTX-PG (3,4,5) (ρ = n/a)

No relationship between MTX-PGn and eGFR

Egan, 1999, Alimentary Pharmacology and Therapeutics21

30

USA

21–71

53

n/a

0

15 (60%)

25 (40%)

Steroid

(100)

Prospective cohort of 16 weeks

Competitive protein binding assay

of

MTX-PGtotal

Significant increase of MTX-PGtotal after dose escalation

  1. [A] = abstract only. ADA = adalimumab. CD = Crohn’s disease. IFX = infliximab. mg/wk = milligram per week. MTX-PG = methotrexate polyglutamate. N = number of patients included. NZ = New Zealand. UK = United Kingdom. USA = United States of America. † = minimum – maximum. ǂ = mean ± standard deviation. § = information derived by contact author