Abstract | OBJECTIVE: METHODS: Human RFC-(over)expressing CEM cells of T cell origin were used to analyze the effect of SSZ on the RFC-mediated cellular uptake of radiolabeled MTX and the natural folate leucovorin. Moreover, both cells with and those without acquired resistance to SSZ were used to assess the antiproliferative effects of MTX in combination with SSZ. RESULTS: Transport kinetic analyses revealed that SSZ was a potent noncompetitive inhibitor of RFC-mediated cellular uptake of MTX and leucovorin, with mean +/- SD K(i) (50% inhibitory concentration) values of 36 +/- 6 microM and 74 +/- 7 microM, respectively. Consistent with the inhibitory interaction of SSZ with RFC, a marked loss of MTX efficacy was observed when MTX was coadministered with SSZ: up to 3.5-fold for CEM cells in the presence of 0.25 mM of SSZ, and >400-fold for SSZ-resistant cells in the presence of 2.5 mM of SSZ. Importantly, along with diminished efficacy of MTX, evidence for cellular folate depletion was obtained by the demonstration of an SSZ dose-dependent decrease in leucovorin accumulation. CONCLUSION: At clinically relevant plasma concentrations, interactions of SSZ with RFC provide a biochemical rationale for 2 important clinical observations: 1) the onset of (sub)clinical folate deficiency during SSZ treatment, and 2) the lack of additivity/synergism of the combination of SSZ and MTX when these disease-modifying antirheumatic drugs are administered simultaneously. Thus, when considering use of these drugs in combination therapies, the present results provide a rationale both for the use of folate supplementation and for spacing administration of these drugs over time.
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Authors | Gerrit Jansen, Joost van der Heijden, Ruud Oerlemans, Willem F Lems, Ilan Ifergan, Rik J Scheper, Yehuda G Assaraf, Ben A C Dijkmans |
Journal | Arthritis and rheumatism
(Arthritis Rheum)
Vol. 50
Issue 7
Pg. 2130-9
(Jul 2004)
ISSN: 0004-3591 [Print] United States |
PMID | 15248210
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- ATP Binding Cassette Transporter, Subfamily B, Member 1
- Antirheumatic Agents
- Membrane Transport Modulators
- Membrane Transport Proteins
- Reduced Folate Carrier Protein
- SLC19A1 protein, human
- Sulfasalazine
- Folic Acid
- Leucovorin
- Methotrexate
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Topics |
- ATP Binding Cassette Transporter, Subfamily B, Member 1
(metabolism)
- Antirheumatic Agents
(administration & dosage, pharmacokinetics, pharmacology, therapeutic use)
- Arthritis, Rheumatoid
(drug therapy)
- Biological Transport
(drug effects)
- Cell Line
- Dose-Response Relationship, Drug
- Drug Interactions
- Drug Resistance
- Drug Therapy, Combination
- Folic Acid
(metabolism)
- Humans
- Leucovorin
(pharmacokinetics)
- Membrane Transport Modulators
- Membrane Transport Proteins
(antagonists & inhibitors, metabolism)
- Methotrexate
(pharmacokinetics, therapeutic use)
- Reduced Folate Carrier Protein
- Sulfasalazine
(administration & dosage, pharmacology, therapeutic use)
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