Opana is a narcotic drug that acts on the central nervous system and can lead to a physical dependence on the drug. This physical addiction is not the same as an addiction to illegal substances that have no medical purpose. You may build a tolerance to Opana which requires you to increase your dosage. If you suddenly stop taking the medication you may experience symptoms of withdrawal. This physical dependence can be monitored, and if you taper your dosage to discontinue treatment, withdrawal symptoms will not be so severe.