Anti-smoking drug Chantix has not been tied to psychiatric problems like depression and suicidal thoughts in two studies, federal health officials said Monday.
However, FDA officials said the findings from the federally-funded studies on Pfizer's anti-smoking drug are not yet definitive.
Since 2007, the FDA has been investigating reports of mood disorders and erratic behavior among Chantix patients, reports AP.
The agency said in a statement that two studies involving more than 26,000 patients did not show an increased rate of psychiatric hospitalizations among Chantix patients, compared with those using nicotine patches and smoking cessation treatments.
FDA regulators pointed out that the studies only recorded psychiatric problems that resulted in hospitalization, meaning many issues likely went unreported.
Additionally, the studies by the Department of Veterans Affairs and the Department of Defense were not large enough to detect very rare side effects.
Groups like the Federal Aviation Administration have already banned the drug for pilots and air traffic controllers due to side effects that could interfere with their work, AP reports.
The agency said it is continuing to study the problems and recommends patients consult their doctors if they experience side effects while using the drug.
