Summary

Levofloxacin may increase methotrexate blood levels by reducing its kidney clearance, potentially leading to enhanced methotrexate toxicity. This interaction requires careful monitoring and possible dose adjustments when these medications are used together.

Introduction

Levofloxacin is a fluoroquinolone antibiotic commonly prescribed for bacterial infections including pneumonia, urinary tract infections, and skin infections. Methotrexate is an antimetabolite medication used as chemotherapy for various cancers and as an immunosuppressant for autoimmune conditions like rheumatoid arthritis and psoriasis. Both drugs are frequently prescribed, making awareness of their potential interaction clinically important.

Mechanism of Interaction

The interaction occurs primarily through competition for renal tubular secretion pathways. Levofloxacin can inhibit the active transport of methotrexate in the kidneys, specifically affecting organic anion transporters (OATs) that are responsible for methotrexate elimination. This competition reduces methotrexate clearance from the body, leading to increased plasma concentrations and prolonged exposure to the drug.

Risks and Symptoms

The primary risk is methotrexate toxicity, which can manifest as severe bone marrow suppression, gastrointestinal toxicity (nausea, vomiting, diarrhea, mucositis), hepatotoxicity, and nephrotoxicity. Patients may experience increased risk of infection due to immunosuppression, bleeding due to thrombocytopenia, and severe anemia. In extreme cases, this interaction can be life-threatening, particularly in patients receiving high-dose methotrexate or those with pre-existing kidney impairment.

Management and Precautions

Close monitoring is essential when these drugs are co-administered. Monitor complete blood count, liver function tests, and kidney function more frequently than usual. Consider reducing methotrexate dose or extending dosing intervals. Ensure adequate hydration and consider leucovorin rescue if high-dose methotrexate is used. Alternative antibiotics should be considered when possible. If concurrent use is necessary, monitor methotrexate levels if available and watch for early signs of toxicity including mouth sores, unusual bleeding, or signs of infection.

Levofloxacin interactions with food and lifestyle

Levofloxacin should be taken with caution regarding dairy products and mineral supplements. Calcium, magnesium, aluminum, iron, and zinc can significantly reduce levofloxacin absorption when taken together. Take levofloxacin at least 2 hours before or 2 hours after consuming dairy products, antacids, or mineral supplements. Avoid excessive caffeine intake as levofloxacin may increase caffeine effects, potentially causing nervousness, rapid heartbeat, or sleep disturbances. Limit sun exposure and use sunscreen, as levofloxacin increases photosensitivity and risk of severe sunburn. Alcohol does not have a direct interaction with levofloxacin but should be limited during infection treatment to support immune system recovery.

Methotrexate interactions with food and lifestyle

Alcohol consumption should be avoided or strictly limited while taking methotrexate due to increased risk of liver toxicity and hepatotoxicity. Both methotrexate and alcohol can cause liver damage, and their combination significantly increases this risk. Patients should also maintain adequate hydration and avoid excessive sun exposure, as methotrexate can increase photosensitivity. Folic acid supplementation is commonly recommended to reduce certain side effects, though this should be discussed with a healthcare provider as timing and dosing are important.