Types of medicine
What Is a CYP3A Inhibitor? Drug Interactions Explained
CYP3A Inhibitor · say it: sip-THREE-ay in-HIB-ih-terAlso written: CYP3A4 inhibitor, strong CYP3A inhibitor, moderate CYP3A inhibitor
Short answer
A CYP3A inhibitor is a medicine or food that slows the liver enzyme CYP3A, which can make other medicines build up in the body.
What it means
CYP3A is a group of enzymes, mainly in the liver and gut, that break down many medicines. A CYP3A inhibitor is something that slows these enzymes down. When that happens, other medicines that rely on CYP3A to be cleared can build up to higher levels than intended. Examples of inhibitors include some antifungals, some macrolide antibiotics, some HIV medicines and grapefruit juice.
Labels mention CYP3A inhibitors in the 'Drug interactions' section. They may be described as 'strong' or 'moderate', depending on how much they slow the enzyme. The label may say to avoid the combination, change the dose or watch for side effects. This is why pharmacists ask about all your medicines and supplements.
A CYP3A inhibitor is the opposite of a CYP3A inducer, which speeds the enzyme up and can make other medicines less effective.
Where you may see it
- The 'Drug interactions' section of medicine labels
- Leaflets under 'Other medicines and this medicine'
- Pharmacist interaction checks
📄 How it looks on a report
Avoid concomitant use with strong CYP3A inhibitors. If unavoidable, reduce the dose.
🙅 What it does not mean
- Being on a list of interacting medicines does not mean you can never take them together; sometimes a dose change is enough.
- It is not only prescription medicines; grapefruit juice and some herbal products can matter.
- An interaction warning does not mean either medicine is unsafe on its own.
🗒️ Questions to ask your doctor
💊 Medicines whose labels mention “CYP3A Inhibitor”
Plain-English explanations of each medicine, from its official FDA label.
- Alprazolam
a benzodiazepine, a type of central nervous system medicine
- Apixaban
A factor Xa inhibitor, a blood thinner medicine (anticoagulant)
- Rivaroxaban
a factor Xa inhibitor, a type of blood thinner (anticoagulant)
- Simvastatin
a cholesterol-lowering medicine of the HMG-CoA reductase inhibitor type (often called a statin)
- Tamsulosin
An alpha-blocker medicine. The label calls it an alpha 1 adrenoceptor antagonist that acts on the prostate. The FDA class is not listed.
🔗 Read more from trusted sources
- “CYP3A Inhibitor” on MedlinePlus ↗
US National Library of Medicine
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General information about a medical word, not advice about your own results. Ask the clinician who ordered the test what it means for you.