<unk> (inhalation) is an opioid analgesic that is FDA approved for the treatment of pain.   Common adverse reactions include nausea, vomiting, dizziness, insomnia, sedation, somnolence, and nasal congestion.
Butorphanol 
Normorphine
Levorphanol
Morphine 
Hydromorphone 
Oxymorphone 
Nalorphine
Dihydrocodeine