Inhibitors of Anionic Tubular Secretion:
Comment:
In patients receiving antineoplastic doses of methotrexate, ciprofloxacin and co-trimoxazole have been associated with methotrexate toxicity such as bone marrow suppression and GI toxicity. A causal relationship is not well established, but the severity of the reactions dictates caution. The risk with low-dose methotrexate (e.g., for arthritis) is probably much lower, but one should still be alert for evidence of methotrexate toxicity. Probenecid can increase methotrexate levels by 2-3-fold. The effect of quinolones other than ciprofloxacin on methotrexate is not established, but be alert for evidence of methotrexate toxicity. Pralatrexate concentrations are increased by probenecid; caution with other inhibitors of renal clearance is warranted.
Class 2: Use Only if Benefit Felt to Outweigh Risk