<unk> (injection) is a analgesic that is FDA approved for the treatment of moderate to severe pain. It is also indicated for preoperative medication, for support of anesthesia.   Common adverse reactions include pruritus, hypotension, abdominal pain, constipation , nausea, vomiting, xerostomia, confusion, dizziness, headache, somnolence, dyspnea, hypoxia, fatigue, fever.
Oxymorphone 
Hydromorphone 
Butorphanol 
Morphine 
Nalorphine
Normorphine
Oxycodone
Dihydrocodeine