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FDA Safety Changes: Tysabri and Soma
The US Food and Drug Administration (FDA) has approved safety labeling revisions to advise that natalizumab intravenous infusion is linked to a risk for progressive multifocal leukoencephalopathy and is therefore only available through a restricted distribution program; carisoprodol is linked to a risk for allergic and idiosyncratic reactions.
Carisoprodol (Soma) Linked to Risk for Idiosyncratic and Allergic Reactions
On June 8, the FDA approved safety labeling revisions for carisoprodol 350-mg tablets (Soma, made by MedPointe Pharmaceuticals, Inc) to advise of the risks for allergic and idiosyncratic reactions associated with its use.
The FDA warned that the first dose of carisoprodol has been followed very rarely by idiosyncratic symptoms that appear within minutes or hours, including extreme weakness, transient quadriplegia, dizziness, ataxia, temporary loss of vision, diplopia, mydriasis, dysarthria, agitation, euphoria, confusion, and disorientation. Although these effects usually subside over the course of the next several hours, supportive and symptomatic therapy (including hospitalization) may be necessary.
In addition, allergic reactions have been reported to occur between the first and fourth doses in carisoprodol-naive patients with cross-reaction to meprobamate, a carisoprodol metabolite. Symptoms have included skin rash, erythema multiforme, pruritus, eosinophilia, and fixed drug eruption; severe reactions have manifested as asthmatic episodes, fever, weakness, dizziness, angioneurotic edema, smarting eyes, hypotension, and anaphylactoid shock.
Carisoprodol should be discontinued in patients with allergic or idiosyncratic reactions, and appropriate therapy symptomatic therapy initiated. This may include use of epinephrine, antihistamines, and (in severe cases) corticosteroids.
The FDA notes that use of carisoprodol is contraindicated in patients with acute intermittent porphyria and those who are allergic to or who have had idiosyncratic reactions to carisoprodol or meprobamate-related compounds.
Because of its potential for sedative effects, carisoprodol should be used with caution in patients using alcohol, other central nervous system depressants, or psychotropic drugs; concomitant use of carisoprodol and meprobamate is not advised.
Carisoprodol is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions; its safety and efficacy in patients aged 12 years and younger have not been established. Carisoprodol should be used with caution in addiction-prone individuals.
Meprobamate is indicated for the management of anxiety disorders or for the short-term relief of anxiety symptoms.