<p>Patient with impaired resp function, severe bronchial asthma, convulsive disorders, acute alcoholism, delirium tremens, raised intracranial pressure, hypotension with hypovolaemia, cardiac arrhythmias, severe cor pulmonale, history of substance abuse, diseases of the biliary tract, pancreatitis, inflammatory bowel disorders, prostatic hypertrophy, adrenocortical insufficiency, toxic psychoses. Opioid dependent patients. Renal and hepatic impairment. Pregnancy and lactation.</p>