• Molecular NameHydralazine
  • SynonymHydralazine hydrochloride
  • Weight160.18
  • Drugbank_IDDB01275
  • ACS_NO86-54-4
  • Show 3D model
  • LogP (experiment)1.0
  • LogP (predicted, AB/LogP v2.0)1.16
  • pka0.5, 7.1
  • LogD (pH=7, predicted)0.65
  • Solubility (experiment)Soluble
  • LogS (predicted, ACD/Labs)(ph=7)-0.94
  • LogSw (predicted, AB/LogsW2.0)0.54
  • Sw (mg/ml) (predicted, ACD/Labs)17.36
  • No.of HBond Donors3
  • No.of HBond Acceptors4
  • No.of Rotatable Bonds1
  • TPSA63.83
  • StatusFDA approved
  • AdministrationOral, intravenous
  • PharmacologyA direct-acting smooth muscle relaxant used to treat hypertension by acting as a vasodilator primarily in arteries and arterioles. By relaxing vascular smooth muscle, vasodilators act to decrease peripheral resistance, thereby lowering blood pressure.
  • Absorption_value100.0
  • Absorption (description)Readily absorbed after oral administration.
  • Caco_2N/A
  • Bioavailability23.0
  • Protein binding87.0
  • Volume of distribution (VD)3 to 8 L/kg
  • Blood/Plasma Partitioning ratio (D_blood)N/A
  • MetabollsmIt undergoes first-pass acetylation, the extent of which is genetically determined. The major metabolites are: 3-methyl-1,2,4-triazolo[3,4-a]phthalazine (MTP—the acetylation product); hydralazine pyruvic acid hydrazone (HPH) which is the major plasma metabolite; 4-(2-acetylhydrazino)phthalazin-1-one (N-AcHPZ) which is the major urinary metabolite; 3-hydroxymethyl-1,2,4-triazolo[3,4-a]phthalazine (3-OHMTP).
  • Half lifehydralazine 0.4~2 h, HPH about 4 h, MTP about 1.5~2 h
  • ExcretionAbout 65% of a dose is excreted in the urine in 24 h. In rapid acetylators, about 30% is excreted as N-AcHPZ and 10 to 30% as conjugated 3-OHMTP; in slow acetylators, about 15 to 20% is excreted as N-AcHPZ and up to 10% as conjugated 3-OHMTP. Other metabolites include phthalazin-1-one (PZ), 1,2,4-triazolo[3,4-a]phthalazine (TP), 9-hydroxy-MTP, phthalazine, tetrazolo[5,1-a]phthalazine and hydrazones of hydralazine formed with acetone and α-ketoglutaric acid. About 10% of a dose is eliminated in the faeces.
  • Urinary ExcretionN/A
  • CleranceN/A
  • ToxicityThe most common adverse events reported in clinical trial studies are headache, anorexia, nausea, vomiting, diarrhea, palpitations, tachycardia, angina pectoris.
  • LD50 (rat)N/A
  • LD50 (mouse)N/A