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 the treatment of 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 chronic pain, generalized pain disorders, leukemia, cancer, chronic pain, chemotherapy induced pain, epilepsy, migraine, neuropathic pain, post herpetic neuralgia, neuralgia, pain, drug addiction, detoxification of drugs, Alzheimer's disease, multiple sclerosis, multiple sclerosis, restless legs syndrome (RLS), cluster headache, depression, fibromyalgia, amyotrophic lateral sclerosis (ALS), convulsions, partial seizures, mood-stabilizing agent and bipolar disorder.