<unk>  is a opioid antagonist that is FDA approved for the treatment of opioid-induced constipation (OIC) in adult patients with chronic non-cancer pain, including patients with chronic pain related to prior cancer or its treatment who do not require frequent (e.g., weekly) opioid dosage escalation.   Common adverse reactions include abdominal pain, diarrhea, nausea, and gastroenteritis.
Naldemedine
Avacopan
Clopenthixol
Levomepromazine
Dolastetron 
Dihydroergotamine 
Diisopromine
Methylergonovine 