Cytochrome P450 1A2
CYP1A2 is the liver enzyme that clears caffeine, clozapine, and a handful of other drugs. Its activity is shaped by both genetics and lifestyle (smoking speeds it up, certain foods slow it down), but the underlying gene still sets your baseline. About 40 percent of people carry a variant that classifies them as rapid metabolizers; the rest process caffeine at an average or slower rate.[1]
Gene2Rx reports your CYP1A2 genotype across 3 named star alleles, built from 2 variants curated by PharmVar.
Star alleles (like *1, *2, *4) are standardized names for distinct versions of a pharmacogene. *1 is the reference; higher numbers identify variants discovered later that change the enzyme's activity.
You inherit one allele from each parent, so your genotype is a pair (e.g. *1/*4). The pair determines your predicted phenotype — for example, whether you metabolize a drug at a normal, decreased, or no-function rate.
PharmVar is the international registry that defines and curates these allele names. Gene2Rx tests the variants required to call every CYP1A2 allele in the PharmVar catalog.
Gene2Rx covers 1 medication with published pharmacogenetic guidance for CYP1A2, drawn from CPIC and FDA sources. Each drug links to its full pharmacogenetics page.
These branded medications include at least one active ingredient whose metabolism or action involves CYP1A2. Each links to its full pharmacogenetic breakdown.
This page lists drugs affected by CYP1A2. A Gene2Rx report tells you which metabolizer group you fall into, and what that means for every medication on this list.
Get your report Look up a medicationInformational only, not medical advice. The presence of a CYP1A2 pharmacogenetic guideline does not mean every patient needs to change their dose. Never start, stop, or change a medication without talking to your prescribing clinician.