my husband suffers from chronic back pain due to an accident 4 1/2 years ago. he fractured l4 and now contends with arachnodities (sp.?) in stage 2. he was originally on vicoden but had some liver enzyme side effects and was switched to oxycontin. since taking this drug, i have noticed a personality change (very irritable and very difficult to live with) is this a side effect? and is there alternative paid meds that he could use to give him the same or more relief but without the irratibility?