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FDA Safety Changes for DiaBeta and Chantix

Aug 23, 2009

The US Food and Drug Administration (FDA) has approved safety labeling revisions to warn of the risk for serious effects from Chantix and DiaBeta.

The FDA approved new safety labeling revisions due to the psychiatric 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.

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 (e.g., 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.