Pharmacodynamics<unk>  acts as a σ1 receptor agonist, serotonin–norepinephrine reuptake inhibitor, and NMDA receptor antagonist, while<unk>  is an antiarrhythmic agent acting as a CYP2D6 inhibitor.<unk>  prevents the metabolism of<unk>  into its active metabolite dextrorphan, which is a much more potent NMDA receptor antagonist but much less potent serotonin reuptake inhibitor than<unk> . The mechanism of action of<unk>  in the treatment of PBA is unknown.
Dextromethorphan/quinidine
Fentanyl/fluanisone
Bupivacaine/meloxicam
Oxycodone/naloxone
Desloratadine/pseudoephedrine
Pseudoephedrine/loratadine
Phenylephrine/ketorolac
Buprenorphine/naloxone