The invention relates to the compounds of formula I or its pharmaceutical acceptable salts, as well as polymorphs, solvates, enantiomers, stereoisomers and hydrates thereof. The pharmaceutical compositions comprising an effective amount of compounds of formula I and methods for treating or preventing moderate to severe pain, may be formulated for oral, buccal, rectal, topical, transdermal, transmucosal, intravenous, parenteral administration, syrup, or injection. Such compositions may be used to treatment of muscle pain, spasticity, neuropathic pain, fibromyalgia, post-operative pain, muscle spasticity, headache, chronic pain, sub-chronic pain and local pain.
