Table 1.

Pharmacodynamic and pharmacokinetic properties

Class	Dextromethorphan: NMDA receptor antagonist & sigma-1 receptor agonist Bupropion: dopamine and norepinephrine reuptake inhibitor and CYP2D6 inhibitor
Formulation	45 mg dextromethorphan/105 mg bupropion ER tablets
Route	Oral
Metabolism	Dextromethorphan: CYP2D6 de-methylation
	Bupropion: CYP2B6 hydroxylation and reduction
Half-life	Dextromethorphan/bupropion: 22 hours
Steady state	8 days
Elimination	Dextromethorphan:
	CYP2D6 extensive metabolizers: 37−52% urine, 2% unchanged
	CYP2D6 poor metabolizers: 45−83% urine, 26% unchanged
	Bupropion: 87% urine, 10% feces, 0.5% unchanged
Drug interactions	MAOIs, serotonergic agents, dopaminergic agents, strong CYP2D6 inhibitors, strong CYP2B6 inducers, agents metabolized by CYP2D6, agents which lower seizure threshold, digoxin, alcohol

NMDA, N-methyl D-aspartate; ER, extended release; MAOIs, monoamine oxidase inhibitors.