Cumberland Pharmaceuticals Inc. said Thursday it is recalling six production lots of a drug used to treat overdoses of acetaminophen.The company said it is recalling the products because particulate matter was found in some vials. It said the source of the particulate matter came from the glass vial made by a former supplier. Cumberland said the recall is a precaution and there have been no observed side effects. The company said it switched to a new supplier in August 2009.Acetadote is an injectable drug that is approved to counteract the effects of an overdose of acetaminophen. Acetaminophen is a common ingredient in pain relievers, and the side effects of such an overdose can include liver damage and liver failure.Shares of Cumberland Pharmaceuticals fell 15 cents, or 2.5 percent, to $5.95 in after-hours trading.