Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.
Hydralazine is a vasodilator: it relaxes the muscle in the walls of small arteries, so they widen and blood pressure falls. It is used for high blood pressure, including in pregnancy, and together with isosorbide dinitrate for heart failure. It is sold as Apresoline, among other names.
Hydralazine is inactivated in the liver by the enzyme NAT2 (N-acetyltransferase 2). About half of people of European ancestry are slow acetylators, with two low-activity NAT2 copies; they keep higher levels of hydralazine, and long-term use in them is linked to a higher chance of a lupus-like reaction. CPIC has published a guideline on NAT2 and hydralazine, and the US FDA lists an effect on drug levels. Almost all the studies on this page concern NAT2.
Clinical guidelines that name a gene for Hydralazine. They sort people into groups by the gene copies they carry.
US FDA: NAT2. Poor Metabolizer. 2013.
Every published finding on gene variants and Hydralazine. Upload your DNA file to see which of these rows apply to you.
PharmGKB weighs all studies of a variant and rates how strong the evidence is, from 1A (strongest) to 4.
NAT2 NAT2*4, NAT2*5, NAT2*6, NAT2*7, NAT2*16: Level 3. Metabolism/PK. 16.
NAT2 NAT2*6, NAT2*7, NAT2*14, NAT2*16: Level 3. Toxicity: Hypertension. 6.
NAT2 NAT2*1, NAT2*4, NAT2*6, NAT2*7, NAT2*14, NAT2*16: Level 3. Efficacy: Hypertension. 5.
Studies of how quickly the body processes this medication.
Studies of how well it worked in people carrying a variant.
Studies of how much of the drug people needed or tolerated.
Study findings and evidence levels: PharmGKB (CC BY-SA 4.0). Guidelines: CPIC and DPWG, as bundled in PharmCAT. Most studies were done mainly in people of European ancestry.
More drugs from the same category
Not a prescribing recommendation. This page is educational information about pharmacogenomic research and clinical guidelines - it is not medical or dosing advice, and not a prediction of how any medication will work for you. Never start, stop, or change a medication or dose based on it; talk to your doctor or pharmacist, who can order clinical-grade testing if appropriate.
Content updated September 2026.
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