FDA Safety Changes: Chantix, DiaBeta, Aralen

Yael Waknine

August 19, 2009

This activity is part of an ongoing CME/CE initiative to provide information on label changes reported by the FDA. Activities of this nature will be posted on Medscape on a weekly basis.

August 19, 2009 — The US Food and Drug Administration (FDA) has approved safety labeling revisions to warn of the risk for serious neuropsychiatric effects in patients taking varenicline as an aid to smoking cessation; drug interactions that may potentiate the hypoglycemic effects of glyburide in patients with type 2 diabetes mellitus; and the risk for serious adverse events in breast-feeding infants whose mothers are receiving chloroquine phosphate antimalarial therapy.

Varenicline (Chantix) Linked to Risk for Serious Neuropsychiatric Events

On July 1, the FDA approved safety labeling revisions for varenicline tartrate tablets (Chantix, Pfizer, Inc) that include a black-box warning regarding the risk for serious neuropsychiatric events.

The warning was based on postmarketing reports of changes in mood (including depression and mania), psychosis, hallucinations, paranoia, delusions, homicidal ideation, hostility, agitation, anxiety, and panic, as well as suicidal ideation, suicide attempt, and completed suicide. These events have occurred in patients with and without preexisting psychiatric disease.

Although some neuropsychiatric symptoms may have occurred in association with nicotine withdrawal, they were also reported in patients who had not yet discontinued smoking. The majority of cases occurred during treatment, but some also were reported after withdrawal of varenicline therapy.

Because varenicline may cause worsening of current psychiatric illness (even if it is under control) and cause recurrence of prior illness, patients should inform their healthcare provider of any such illness before initiating varenicline therapy. The FDA notes that patients with serious psychiatric illnesses (eg, schizophrenia, bipolar disorder, and major depressive episodes) were excluded from clinical trials of varenicline, and the drug's safety in this population has not been established.

Patients and their families/caregivers should be alert to changes in mood or behavior during treatment with varenicline; these changes should be immediately reported to a healthcare provider. Although discontinuation of therapy is likely to result in symptom resolution, some patients may require ongoing monitoring and supportive care.

The FDA also warned that motor vehicle crashes, near-miss accidents, and other unintentional injuries have occurred in patients taking varenicline. In some cases, patients reported somnolence, dizziness, loss of consciousness, or difficulty concentrating, potentially resulting in impairment. Patients should be cautious when driving, operating heavy machinery, or engaging in other potentially hazardous activities until they know how varenicline will affect them.

The agency notes that although the risks of varenicline therapy should be considered for patients seeking treatment, smoking cessation is linked to significant and immediate health benefits; use of varenicline has been shown to increase the likelihood of smoking abstinence by as long as 1 year relative to placebo.

Glyburide (DiaBeta) Drug Interactions May Cause Hypoglycemia

On July 9, the FDA approved revisions to the safety labeling for glyburide tablets (DiaBeta, sanofi-aventis US) to warn of drug interactions.

The hypoglycemic action of sulfonylureas, including glyburide, may be potentiated by certain drugs. Agents previously listed by the FDA have included nonsteroidal anti-inflammatory drugs, clarithromycin, and other drugs that are highly protein bound, such as salicylates, sulfonamides, chloramphenicol, coumarins, probenecid, monoamine oxidase inhibitors, and β-adrenergic blocking agents.

The agency now warns that disopyramide, fluoxetine, and quinolones also potentiate the effects of sulfonylureas. Patients receiving these drugs in conjunction with glyburide should be closely observed for signs of hypoglycemia and for loss of glycemic control when the drugs are withdrawn.

Glyburide is indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus.

 Chloroquine (Aralen) Maternal Therapy Poses Risk to Nursing Infants

On June 12, the FDA approved safety labeling revisions for chloroquine phosphate tablets (Aralen, sanofi-aventis US) to warn of the potential for serious adverse events in nursing infants.

According to the FDA, a decision should be made whether to discontinue therapy or stop nursing, taking into account the potential clinical benefit of the drug to the mother.

In a study of 11 lactating mothers, the maximum daily dose of the drug received by the breast-feeding infant was about 0.7% of the maternal start dose (600 mg base) in malaria chemotherapy. Separate chemoprophylaxis for the infant is required.

Chloroquine is indicated for the suppressive treatment of malaria and for acute attacks of malaria caused by Plasmodium vivax, Plasmodium malariae, Plasmodium ovale, and susceptible strains of Plasmodium falciparum. The drug is also indicated in the treatment of extraintestinal amebiasis.

Chantix Prescribing Information

Diabeta Prescribing Information

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