An<unk>  (or opioid receptor<unk>  is a drug which has mixed agonist and antagonist actions at different opioid receptors and thus cannot clearly be described as either an opioid agonist or antagonist. An example of an<unk>  is buprenorphine, which is a partial agonist of the μ-opioid receptor and an antagonist of the κ-opioid receptor.
Opioid modulator
Opioid antagonist
Endocannabinoid enhancer
Atypical antidepressant
Norepinephrine reuptake inhibitor
Glycine reuptake inhibitor
Dopamine reuptake inhibitor
Mood stabilizer