Does CPIC say which drug to use instead when a patient is a poor metabolizer?

Usually not. Across 33 CPIC drug-gene pairs in psychiatry and cardiology, CPIC names a specific alternative agent for 1 (clopidogrel). Elsewhere it states a constraint — for example "consider a clinically appropriate alternative antidepressant not predominantly metabolized by CYP2D6" — and leaves the choice of agent to the prescriber, because that choice depends on indication, comorbidity and interaction history.

What should be used instead of clopidogrel in a CYP2C19 poor metabolizer?

CPIC’s answer depends on the indication. For acute coronary syndrome or percutaneous coronary intervention, CPIC recommends avoiding clopidogrel and using prasugrel or ticagrelor at standard dose if there is no contraindication (Strong). For neurovascular indications CPIC recommends avoiding clopidogrel and considering an alternative P2Y12 inhibitor, without naming prasugrel or ticagrelor (Moderate). The three indication-specific recommendations are not interchangeable.

Does a CPIC evidence level mean there is a prescribing recommendation?

No. CPIC assigns an evidence level to more drug-gene pairs than it publishes prescribing recommendations for. Of the pairs in scope here, 22 carry a CPIC level but have no phenotype recommendation table — including warfarin, where CPIC publishes a dosing algorithm instead. A level is a statement about evidence, not an instruction.

PGx Decision Aid: CPIC Guidance for Psychiatry and Cardiology

CPIC usually tells you what to avoid, not what to use instead. Across 33 drug-gene pairs in psychiatry and cardiology, CPIC names a specific alternative agent for 1 (clopidogrel). Everywhere else it states a constraint and leaves the choice of agent to the prescriber. CPIC data as of 2026-10-01.

Key takeaways

33 drug-gene pairs with a published CPIC recommendation — 22 psychiatry, 11 cardiology.
342 distinct phenotype recommendations, because CPIC stratifies some drugs by indication and some by a second gene.
Clopidogrel has three indication-specific recommendations that are not interchangeable: CPIC names prasugrel and ticagrelor for ACS/PCI, and withholds those names for neurovascular indications.
22 pairs carry a CPIC evidence level but no prescribing recommendation. A level is a statement about evidence, not an instruction.
Recommendation text below is reproduced verbatim from CPIC and is not paraphrased.

Graded by CPIC, with no recommendation table

Drug	Gene	CPIC level	Why not shown
acenocoumarol	CYP2C9	B	CPIC grades this pair at level B but publishes no phenotype recommendation table for it.
labetalol	CYP2D6	B/C	CPIC grades this pair at level B/C but publishes no phenotype recommendation table for it.
lofexidine	CYP2D6	B/C	CPIC grades this pair at level B/C but publishes no phenotype recommendation table for it.
warfarin	CYP2C9	A	CPIC recommends a published pharmacogenetic dosing algorithm rather than a phenotype-keyed recommendation. Rendering a card would misrepresent the guideline.
risperidone	CYP2D6	B	CPIC grades this pair at level B but publishes no phenotype recommendation table for it.
amoxapine	CYP2D6	B/C	CPIC grades this pair at level B/C but publishes no phenotype recommendation table for it.
amphetamine	CYP2D6	B/C	CPIC grades this pair at level B/C but publishes no phenotype recommendation table for it.
clobazam	CYP2C19	B/C	CPIC grades this pair at level B/C but publishes no phenotype recommendation table for it.
clozapine	CYP2D6	B/C	CPIC grades this pair at level B/C but publishes no phenotype recommendation table for it.
donepezil	CYP2D6	B/C	CPIC grades this pair at level B/C but publishes no phenotype recommendation table for it.
flecainide	CYP2D6	B/C	CPIC grades this pair at level B/C but publishes no phenotype recommendation table for it.
haloperidol	CYP2D6	B/C	CPIC grades this pair at level B/C but publishes no phenotype recommendation table for it.
mirtazapine	CYP2D6	B/C	CPIC grades this pair at level B/C but publishes no phenotype recommendation table for it.
perphenazine	CYP2D6	B/C	CPIC grades this pair at level B/C but publishes no phenotype recommendation table for it.
protriptyline	CYP2D6	B/C	CPIC grades this pair at level B/C but publishes no phenotype recommendation table for it.
thioridazine	CYP2D6	B/C	CPIC grades this pair at level B/C but publishes no phenotype recommendation table for it.
timolol	CYP2D6	B/C	CPIC grades this pair at level B/C but publishes no phenotype recommendation table for it.
zuclopenthixol	CYP2D6	B/C	CPIC grades this pair at level B/C but publishes no phenotype recommendation table for it.
pimozide	CYP2D6	A/B	CPIC grades this pair at level A/B but publishes no phenotype recommendation table for it.
aripiprazole	CYP2D6	B	CPIC grades this pair at level B but publishes no phenotype recommendation table for it.
diazepam	CYP2C19	B/C	CPIC grades this pair at level B/C but publishes no phenotype recommendation table for it.
propafenone	CYP2D6	B/C	CPIC grades this pair at level B/C but publishes no phenotype recommendation table for it.

Recommendations are republished from the Clinical Pharmacogenetics Implementation Consortium (CPIC), licensed CC BY-SA 4.0. ReachMD is not the author of any clinical recommendation shown here. Candidate agent lists marked “derived from CPIC data” are computed by ReachMD from CPIC's own therapeutic classes and drug-gene pair table under CPIC's stated constraint, and reviewed by a clinical pharmacist. They are not exhaustive, not ranked, and not a formulary. Absence of CPIC guidance for a gene is not evidence that an agent is unaffected by it.

This page does not interpret genotypes and gives no patient-specific dosing advice.

CPIC · ClinPGx

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