Drug Interaction Report

GENERALLY AVOID: Salicylates may interfere with the renal elimination of methotrexate and may displace it from binding sites. The pharmacologic effect and toxicity of methotrexate may be increased. Patients receiving high-dose methotrexate are at a greater risk of developing toxicity.

MANAGEMENT: If these agents must be used concomitantly, caution should be exercised and the patient should be monitored closely for signs and symptoms of bone marrow suppression and nephrotoxicity. Patients should be advised to report possible symptoms of toxicity including nausea, vomiting, diarrhea, stomatitis, sore throat, chills, fever, rash, unusual bruising or bleeding, jaundice, dark urine, swelling of the extremities, or shortness of breath to their physician. Patients should also be counseled to avoid any other over-the-counter salicylate products.

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MONITOR: Concomitant administration of cyclosporine and methotrexate may be associated with an increased risk of toxicity. In rheumatoid arthritis patients (n=20), the concentrations of methotrexate were increased by 30% and concentrations of the 7-hydroxy metabolite decreased by 80%. There was no significant change in cyclosporine concentrations (n=6). The mechanism is unknown.

MANAGEMENT: Close monitoring of cyclosporine and methotrexate concentrations, renal function, and liver enzymes is recommended during concurrent therapy. Dosage adjustments may be necessary. Patients should be advised to report any nausea, vomiting, mouth sores, diarrhea, abdominal pain, dizziness, fatigue, or headache.

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MONITOR: Nonsteroidal anti-inflammatory drugs (NSAIDs) may potentiate the nephrotoxic effects of cyclosporine, especially if dehydration is present. The exact mechanism is unknown but is apparently unrelated to plasma cyclosporine levels. The interaction has been reported with diclofenac and sulindac. Data for other NSAIDs are not available, but a similar effect may be expected based on their common pharmacologic action.

MANAGEMENT: Renal function should be closely monitored in patients receiving concomitant therapy with cyclosporine and NSAIDs.

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MONITOR: Limited data suggest that consumption of greater than 180 mg/day of caffeine may interfere with the efficacy of methotrexate (MTX) in patients with rheumatoid arthritis. The exact mechanism of interaction is unknown but may be related to the antagonistic effect of caffeine on adenosine receptors, as anti-inflammatory properties of MTX is thought to result from the accumulation of adenosine. In a study of 39 patients treated with MTX 7.5 mg/week (without folate supplementation) for 3 months, patients with high caffeine intake (more than 180 mg/day) experienced significantly less improvement in morning stiffness and joint pain from baseline than patients with low caffeine intake (less than 120 mg/day). There were no significant differences between the responses of patients with moderate caffeine intake (120 to 180 mg/day) and those of the other 2 groups. In an interview of 91 patients treated with MTX, 26% of patients who discontinued the drug were regular coffee drinkers compared to only 2% of those still receiving the drug. Because treatment failure was the reason for MTX discontinuation in 80% of patients who discontinued, the investigators suggested that caffeine may have interfered with MTX efficacy.

MANAGEMENT: Until further information is available, the potential for interaction should be considered in patients who consume substantial amounts of caffeine and caffeine-containing foods and are prescribed methotrexate for rheumatoid arthritis. It may be appropriate to limit caffeine intake if an interaction is suspected in cases of treatment failure.

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GENERALLY AVOID: Administration with grapefruit juice (compared to water or orange juice) has been shown to increase blood concentrations of cyclosporine with a relatively high degree of interpatient variability. The mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits.

GENERALLY AVOID: Administration with red wine or purple grape juice may decrease blood concentrations of cyclosporine. In 12 healthy volunteers, 12 ounces total of a merlot consumed 15 minutes prior to and during cyclosporine administration (single 8 mg/kg dose of Sandimmune) decreased cyclosporine peak blood concentration (Cmax) and systemic exposure (AUC) by 38% and 30%, respectively, compared to water. The time to reach peak concentration (Tmax) doubled, and oral clearance increased 50%. Similarly, one study were 12 healthy patients were administered purple grape juice and a single dose of cyclosporine showed a 30% and a 36% decrease in cyclosporine systemic exposure (AUC) and peak blood concentration (Cmax), respectively. The exact mechanism of interaction is unknown but may involve decreased cyclosporine absorption.

MONITOR: Food has been found to have variable effects on the absorption of cyclosporine. There have been reports of impaired, unchanged, and enhanced absorption during administration with meals relative to the fasting state. The mechanisms are unclear. Some investigators found an association with the fat content of food. In one study, increased fat intake resulted in significantly increased cyclosporine bioavailability and clearance. However, the AUC and pharmacodynamics of cyclosporine were not significantly affected, thus clinical relevance of these findings may be minimal.

MANAGEMENT: Patients receiving cyclosporine therapy should be advised to either refrain from or avoid fluctuations in the consumption of grapefruits and grapefruit juice. Until more data are available, the consumption of red wine or purple grape juice should preferably be avoided or limited. All oral formulations of cyclosporine should be administered on a consistent schedule with regard to time of day and relation to meals so as to avoid large fluctuations in plasma drug levels.

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GENERALLY AVOID: Coadministration of methotrexate with other agents known to induce hepatotoxicity may potentiate the risk of liver injury. Methotrexate, especially at higher dosages or during prolonged treatment, has been associated with severe hepatotoxicity including acute hepatitis, chronic fibrosis, cirrhosis, and fatal liver failure.

MANAGEMENT: The risk of hepatic injury should be considered when methotrexate is used with other potentially hepatotoxic agents (e.g., acetaminophen; alcohol; androgens and anabolic steroids; antituberculous agents; azole antifungal agents; ACE inhibitors; cyclosporine (high dosages); disulfiram; endothelin receptor antagonists; interferons; ketolide and macrolide antibiotics; kinase inhibitors; minocycline; nonsteroidal anti-inflammatory agents; nucleoside reverse transcriptase inhibitors; proteasome inhibitors; retinoids; sulfonamides; tamoxifen; thiazolidinediones; tolvaptan; vincristine; zileuton; anticonvulsants such as carbamazepine, hydantoins, felbamate, and valproic acid; lipid-lowering medications such as fenofibrate, lomitapide, mipomersen, niacin, and statins; herbals and nutritional supplements such as black cohosh, chaparral, comfrey, DHEA, kava, pennyroyal oil, and red yeast rice). Baseline and periodic monitoring of hepatic function is recommended, while liver biopsy may be warranted during long-term use of methotrexate. Patients should be advised to seek medical attention if they experience potential signs and symptoms of hepatotoxicity such as fever, rash, itching, anorexia, nausea, vomiting, fatigue, right upper quadrant pain, dark urine, pale stools, and jaundice.

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GENERALLY AVOID: The concurrent use of aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) and ethanol may lead to gastrointestinal (GI) blood loss. The mechanism may be due to a combined local effect as well as inhibition of prostaglandins leading to decreased integrity of the GI lining.

MANAGEMENT: Patients should be counseled on this potential interaction and advised to refrain from alcohol consumption while taking aspirin or NSAIDs.

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MONITOR: Limited data suggest that consumption of greater than 180 mg/day of caffeine may interfere with the efficacy of methotrexate (MTX) in patients with rheumatoid arthritis. The exact mechanism of interaction is unknown but may be related to the antagonistic effect of caffeine on adenosine receptors, as anti-inflammatory properties of MTX is thought to result from the accumulation of adenosine. In a study of 39 patients treated with MTX 7.5 mg/week (without folate supplementation) for 3 months, patients with high caffeine intake (more than 180 mg/day) experienced significantly less improvement in morning stiffness and joint pain from baseline than patients with low caffeine intake (less than 120 mg/day). There were no significant differences between the responses of patients with moderate caffeine intake (120 to 180 mg/day) and those of the other 2 groups. In an interview of 91 patients treated with MTX, 26% of patients who discontinued the drug were regular coffee drinkers compared to only 2% of those still receiving the drug. Because treatment failure was the reason for MTX discontinuation in 80% of patients who discontinued, the investigators suggested that caffeine may have interfered with MTX efficacy.

MANAGEMENT: Until further information is available, the potential for interaction should be considered in patients who consume substantial amounts of caffeine and caffeine-containing foods and are prescribed methotrexate for rheumatoid arthritis. It may be appropriate to limit caffeine intake if an interaction is suspected in cases of treatment failure.

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One study has reported that coadministration of caffeine and aspirin lead to a 25% increase in the rate of appearance and 17% increase in maximum concentration of salicylate in the plasma. A significantly higher area under the plasma concentration time curve of salicylate was also reported when both drugs were administered together. The exact mechanism of this interaction has not been specified. Physicians and patients should be aware that coadministration of aspirin and caffeine may lead to higher salicylate levels faster.

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