Pfizer has initiated a voluntary recall of a specific lot of its anxiety drug Xanax after stability testing yielded an out of specification result for an assay at the 46-month stability testing time point.

The affected Xanax (alprazolam) lot was shipped to pharmaceutical distributor Besse Medical between August 2011 and March 2012. The recall was deemed Class 2 by the FDA.

Pfizer has advised Besse to stop distributing the product and quarantine it immediately. It also requested that Besse forward a copy of the request to other wholesalers or retailers to which the drug was distributed.

Pfizer says the affected lot is not likely to cause adverse health consequences.