What kind of pill is white, oblong and has 10/325 on one side and M523 on the other?

An oval white pill with the imprint 10/325 on the front, and M523 on the back of it is 325mg/10mg of Acetaminophen and oxycodone hydrochloride (made by Mallinckrodt Pharmaceuticals).

Acetaminophen and oxycodone hydrochloride is a narcotic analgesic combination that is used to treat chronic pain, and pain. Abuse of this drug may lead to psychological or physical dependence.

This prescription-only medication may pose a risk to an unborn fetus, and should be used only under a doctor's supervision.

In Canada, the patent for “Controlled release oxycodone compositions” has expired, meaning that generic forms of the drug are likely to become available shortly in the country.

Saturday, December 08 2012
Source: http://www.drugs.com/imprints/10-325-m523-6767.html