does the aripiprazole label call for half the dose with a strong cyp2d6 inhibitor like bupropion?
“air-pipersol's drug label recommends reducing its dose by half when coprescribed with a strong 2D6 inhibitor like bupropion.”
a host, a psychiatry resident said on PsychEd: Educational Psychiatry Podcast, 2026-09-01, at 16:37. hear it in context → the speaker cited: the aripiprazole drug label.
the episode: PsychEd Shorts 16: CYP Metabolism (at 16:37). we link the show's own page; we do not re-host audio.
first, the part that holds
the speaker has the label right. the current aripiprazole prescribing information tells prescribers to "administer half of usual dose" when aripiprazole is taken with a strong CYP2D6 inhibitor, and FDA's own reference table lists bupropion as a strong CYP2D6 inhibitor.
what we found when we went and looked
we read the current aripiprazole prescribing information on DailyMed (revised 1/2025). Its dose-adjustment table, repeated in the drug-interaction section, says: "Strong CYP2D6 (e.g., quinidine, fluoxetine, paroxetine) or CYP3A4 inhibitors (e.g., itraconazole, clarithromycin) | Administer half of usual dose." the label's examples don't include bupropion, but FDA's table of clinical CYP inhibitors puts bupropion in the strong CYP2D6 inhibitor category, and the bupropion label reports that bupropion raised desipramine exposure (AUC) about 5-fold. the speaker didn't mention one exception, and it matters: the same label says that when aripiprazole is used as an add-on treatment for major depressive disorder, it "should be administered without dosage adjustment." that is the setting where aripiprazole and bupropion most often end up together.
assertion by assertion
| assertion | verdict | what the record says |
|---|---|---|
| the aripiprazole label recommends halving the dose when it is co-prescribed with a strong CYP2D6 inhibitor | confirmed | the label's dose-adjustment table and its drug-interaction table both say "administer half of usual dose" for strong CYP2D6 inhibitors (examples given: quinidine, fluoxetine, paroxetine). we read the reference-listed-drug label revised 1/2025. generic labels follow the same text, but we didn't read each one. [1] |
| bupropion is a strong CYP2D6 inhibitor | confirmed | FDA's table of clinical CYP inhibitors classifies bupropion as a strong CYP2D6 inhibitor, along with paroxetine, quinidine, terbinafine and fluoxetine. the bupropion label says bupropion and its metabolites inhibit CYP2D6 and reports a roughly 5-fold rise in desipramine AUC. FDA uses this table to classify drugs for labeling. it is not a measurement of aripiprazole levels taken with bupropion. [2][3] |
| the aripiprazole label itself names bupropion as an example | misattributed | the speaker's wording could be heard this way. the aripiprazole label doesn't mention bupropion. its examples are quinidine, fluoxetine and paroxetine, so bupropion falls under the rule only through FDA's separate classification. the speaker's wording ('a strong 2D6 inhibitor like bupropion') is consistent with that classification, so we don't count this against the claim. [1][2] |
| the halving applies whenever the two drugs are combined, including add-on treatment for depression | false | the label makes an exception: "When adjunctive [aripiprazole] is administered to patients with major depressive disorder, [aripiprazole] should be administered without dosage adjustment as specified in Dosage and Administration (2.3)." the add-on depression dosing already starts low, at 2 to 5 mg/day within a range of 2 to 15 mg/day. the speaker didn't say this. a listener could easily assume it. [1] |
| half is the only adjustment the label gives for CYP2D6 interactions | undersold | the label goes further than halving. it calls for a quarter of the usual dose with strong CYP2D6 and CYP3A4 inhibitors together, and a quarter for known CYP2D6 poor metabolizers who also take a strong CYP3A4 inhibitor. it also calls for half the dose in known CYP2D6 poor metabolizers, and for a return to the original dose once the inhibitor is stopped. [1] |
both directions
for the speaker: the label's wording matches the speaker's paraphrase almost exactly, and it appears twice: once in the dose-adjustment table and once in the drug-interaction table. FDA's inhibitor table lists bupropion as a strong CYP2D6 inhibitor, and the bupropion label states that bupropion inhibits CYP2D6. it names antipsychotics (haloperidol, risperidone, thioridazine) as substrates whose dose may need to come down and reports a roughly 5-fold rise in desipramine exposure. calling bupropion "a strong 2D6 inhibitor" is FDA's own classification.
against: the label exempts add-on treatment for major depressive disorder from the adjustment. that is the main setting where aripiprazole is combined with an antidepressant such as bupropion, and there the label says to give aripiprazole "without dosage adjustment." stated with no exception, the rule fits schizophrenia, bipolar and other non-adjunctive uses but misdescribes the depression add-on case. the aripiprazole label also never names bupropion, so applying the rule to bupropion depends on FDA's separate classification table.
what this cannot say
we read one label version: the reference-listed-drug prescribing information on DailyMed, revised 1/2025. we didn't check every generic, the long-acting injectable labels or the label versions in force in other countries. we heard only the quoted sentence from the episode, so we can't tell whether the speaker was discussing the depression add-on case or another use. FDA's table assigns bupropion its category from probe-substrate studies such as the desipramine study in the bupropion label. it doesn't measure how much aripiprazole levels rise with bupropion, and we didn't look for pharmacokinetic studies of that pair. this is a check of what the label says. it isn't dosing advice.
sources, each one fetched and read
- aripiprazole prescribing information (reference listed drug), revised 1/2025, DailyMed, U.S. National Library of Medicine, setid c040bd1d-45b7-49f2-93ea-aed7220b30ac What we read there: Table 1: "Strong CYP2D6 (e.g., quinidine, fluoxetine, paroxetine) or CYP3A4 inhibitors (e.g., itraconazole, clarithromycin) | Administer half of usual dose"; "When adjunctive [aripiprazole] is administered to patients with major depressive disorder, [aripiprazole] should be administered without dosage adjustment as specified in Dosage and Administration (2.3)." strong CYP2D6 and CYP3A4 inhibitors together: "Administer a quarter of usual dose." Fetched 2026-10-13 (HTTP 200). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=c040bd1d-45b7-49f2-93ea-aed7220b30ac
- U.S. Food and Drug Administration, For healthcare professionals: FDA's examples of drugs that interact with CYP enzymes and transporter systems, Table 1 (clinical inhibitors) What we read there: lists bupropion, fluoxetine, paroxetine, quinidine and terbinafine as strong CYP2D6 inhibitors. Fetched 2026-10-13 (HTTP 200). https://www.fda.gov/drugs/drug-interactions-labeling/healthcare-professionals-fdas-examples-drugs-interact-cyp-enzymes-and-transporter-systems
- bupropion hydrochloride extended-release tablets prescribing information, revised 11/2025, DailyMed, U.S. National Library of Medicine, setid a435da9d-f6e8-4ddc-897d-8cd2bf777b21 What we read there: "Bupropion and its metabolites (erythrohydrobupropion, threohydrobupropion, hydroxybupropion) are CYP2D6 inhibitors"; names antipsychotics (e.g., haloperidol, risperidone, thioridazine) among CYP2D6 substrates; bupropion "increased the Cmax, AUC, and T½ of desipramine by an average of approximately 2-, 5-, and 2-fold, respectively." Fetched 2026-10-13 (HTTP 200). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=a435da9d-f6e8-4ddc-897d-8cd2bf777b21
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