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Methotrexate and nonsteroidal antiinflammatory drug interactions
1Department of Pharmacy, University Medical Center, Jacksonville, FL.
Objective:
To determine if the coadministration of methotrexate (MTX) and nonsteroidal antiinflammatory drugs (NSAIDs) results in a clinically significant drug interaction.
Data Sources:
A case report of hematologic toxicity following the administration of MTX and flurbiprofen at our institution is presented. Six previously published case reports and five pharmacokinetic studies regarding MTX and NSAID interactions are available to assist in the evaluation of this potential interaction.
Data Synthesis:
Cases of various clinical manifestations during concomitant MTX and NSAID administration, including acute renal failure and pancytopenia, have been reported. The exact mechanism of the interaction has not been fully elucidated. Suggested theories to explain the mechanism of MTX toxicity include reduction in MTX clearance secondary to renal capillary constriction induced by NSAIDs, displacement of MTX or its metabolite from plasma proteins, competition between MTX and NSAIDs for renal tubular excretion, or impairment of hepatic metabolism of MTX by NSAIDs. Studies comparing MTX pharmacokinetics with or without concurrent NSAID therapy have not shown statistical differences in the parameters evaluated. However, one study did demonstrate differences in the pharmacokinetics of 7-hydroxy-methotrexate, the active metabolite of MTX, when MTX was administered with aspirin.
Conclusions:
Although a clinically significant interaction does not occur in all patients, numerous case reports are available that demonstrate possible problems following the coadministration of MTX and NSAIDs. To date, the specific circumstances during which the reaction may occur have not been well defined.
Insights
Coadministration of methotrexate (MTX) and nonsteroidal anti-inflammatory drugs (NSAIDs) can lead to serious adverse events like renal failure and pancytopenia. While not all patients experience this drug interaction, the exact circumstances remain unclear.
Area of Science:
- Pharmacology
- Toxicology
- Drug Interactions
Background:
- Investigating the potential for clinically significant drug interactions between methotrexate (MTX) and nonsteroidal anti-inflammatory drugs (NSAIDs).
- Evaluating a case of hematologic toxicity from concurrent MTX and flurbiprofen administration.
Observation:
- Review of published case reports detailing adverse events such as acute renal failure and pancytopenia during combined MTX and NSAID use.
- Analysis of pharmacokinetic studies examining MTX and NSAID interactions.
Findings:
- Potential mechanisms include reduced MTX clearance, protein displacement, competition for renal excretion, or impaired hepatic metabolism.
- Pharmacokinetic studies generally show no statistically significant differences, though one noted altered metabolite levels with aspirin.
- Numerous case reports indicate potential problems, but specific triggers for this drug interaction are not well-defined.
Implications:
- Clinically significant interactions between MTX and NSAIDs are possible, though not universal.
- Further research is needed to define the precise conditions under which these adverse events occur.
- Caution is advised when coadministering MTX and NSAIDs due to potential severe toxicities.