Accumulating evidence for a drug-drug interaction between methotrexate and proton pump inhibitors.

BACKGROUND: A number of medications are known to interact with methotrexate through various mechanisms. The aim of this article is to apprise practitioners of a new labeling change based on the accumulating evidence for a possible drug-drug interaction between methotrexate (primarily at high doses) and proton pump inhibitors (PPIs). METHODS: The U.S. Food and Drug Administration (FDA) Adverse Event Reporting System (AERS) database of spontaneous adverse event reports and the published literature were searched for cases reporting an interaction between methotrexate and PPIs. RESULTS: A search of the AERS database and existing literature found several individual case reports of drug-drug interactions and three additional supportive studies that suggest potential underlying mechanisms for the interaction. CONCLUSION: There is evidence to suggest that concomitant use of methotrexate (primarily at high doses) with PPIs such as omeprazole, esomeprazole, and pantoprazole may decrease methotrexate clearance, leading to elevated serum levels of methotrexate and/or its metabolite hydroxymethotrexate, possibly leading to methotrexate toxicities. In several case reports, no methotrexate toxicity was found when a histamine H2 blocker was substituted for a PPI. Based on the reviewed data, the FDA updated the methotrexate label to include the possible drug-drug interaction between high-dose methotrexate and PPIs. Physicians should be alerted to this potential drug-drug interaction in patients receiving concomitant high-dose methotrexate and PPIs.

Progressive multifocal leukoencephalopathy associated with efalizumab use in psoriasis patients.

BACKGROUND: Progressive multifocal leukoencephalopathy (PML), a rare, potentially fatal demyelinating disease, affects primarily immunocompromised individuals. The Food and Drug Administration (FDA) received reports of PML associated with efalizumab (Raptiva), a biologic agent approved for psoriasis. In July 2009, efalizumab was voluntarily withdrawn from the US market because of the risk of PML. OBJECTIVE: To describe 3 cases of PML in psoriasis patients treated with efalizumab. METHODS: The FDA's Adverse Event Reporting System (AERS) database was searched for post-marketing reports of PML associated with biologic agents that are FDA approved for psoriasis (adalimumab, alefacept, efalizumab, etanercept, infliximab) from market approval to January 30, 2009. RESULTS: Twelve cases suggestive of PML were identified: adalimumab (1), efalizumab (4), etanercept (3), and infliximab (4). Efalizumab was the only drug with cases reporting PML in the setting of psoriasis. All cases of PML in efalizumab-treated patients presented 3 years or more after treatment initiation and resulted in death. Cases of PML in patients treated with adalimumab, etanercept, or infliximab occurred in patients treated for conditions other than psoriasis and were confounded by the use of other immunosuppressive therapies or were not confirmed PML cases. LIMITATIONS: AERS data are limited because of an underreporting of spontaneous post-marketing adverse events and variable quality and quantity of information provided. CONCLUSIONS: These cases suggest that prolonged efalizumab therapy is a risk factor for PML. Although the cases reported treatment for longer than 3 years, a specific treatment duration that does not place patients at risk for PML has not been defined.

Allergic reaction to platinum in silicone breast implants.

Platinum is used as a catalyst in the manufacture of silicone breast implants. Because platinum is recognized as a potent sensitizer in certain circumstances, some have expressed concern that women with silicone breast implants are exposed to platinum, which is causing allergic reactions. We searched the literature for information on the level of platinum in breast implants and reports of sensitization that clearly related to platinum in women with breast implants. We found no published report with convincing evidence that platinum causes allergic reactions in women with breast implants or that women with breast implants are any more likely to have allergic reactions than women without breast implants.