Bupropion is a norepinephrine-dopamine reuptake inhibitor and nicotinic antagonist used for major depression, seasonal affective disorder, and smoking cessation (Zyban). Chemically unrelated to other antidepressants, it is a well-documented cause of amphetamine false positives on immunoassay, so a specific test matters for both adherence and interpretation.1
An unexpected amphetamine immunoassay positive in a patient on bupropion is often cross-reactivity, not stimulant use; confirming with LC-MS/MS avoids a wrong conclusion. Bupropion is measured through its active metabolite hydroxybupropion.2
LC-MS/MS measures hydroxybupropion, bupropion's active major metabolite, which confirms use.3 Because bupropion cross-reacts on amphetamine immunoassays, a specific test distinguishes bupropion from true amphetamine or methamphetamine exposure. CYP2B6 poor metabolizers or interacting drugs can produce atypical levels.
Confirms bupropion use. Hydroxybupropion indicates use within roughly 4 days.
Explains an amphetamine screen. Bupropion can cross-react on the amphetamine immunoassay.1
Metabolite is the marker. Testing targets hydroxybupropion, not the parent drug.
May indicate non-adherence. Absence in a prescribed patient can reflect missed doses or PRN use.
Altered metabolism. CYP2B6 variation or interactions can shift levels.
Timing and cutoff. Absence may reflect timing of last use or levels below the cutoff.
Bupropion analytes measured on definitive testing.
| Metabolite | Clinical Significance |
|---|---|
| Bupropion (parent) | NDRI; extensively metabolized; a small urinary fraction. |
| Hydroxybupropion | Active major metabolite (CYP2B6); the urine marker, half-life ~20 h. |