- Molecular NameAstemizole
- SynonymNA
- Weight458.581
- Drugbank_IDDB00637
- ACS_NO68844-77-9
- Show 2D model
- LogP (experiment)5.7
- LogP (predicted, AB/LogP v2.0)5.82
- pkaN/A
- LogD (pH=7, predicted)3.77
- Solubility (experiment)Insoluble
- LogS (predicted, ACD/Labs)(ph=7)-4.54
- LogSw (predicted, AB/LogsW2.0)0.0
- Sw (mg/ml) (predicted, ACD/Labs)0.0
- No.of HBond Donors1
- No.of HBond Acceptors5
- No.of Rotatable Bonds8
- TPSA42.32
- StatusFDA approved
- AdministrationN/A
- PharmacologyA second generation antihistamine drug which has a long duration of action.
- Absorption_value100.0
- Absorption (description)Astemizole is rapidly absorbed after oral administration.
- Caco_2N/A
- Bioavailability5.0
- Protein binding96.0
- Volume of distribution (VD)250 L/kg
- Blood/Plasma Partitioning ratio (D_blood)N/A
- MetabollsmThe drug undergoes extensive first-pass metabolism mediated by the cytochrome P450 enzyme system (mainly by isoenzyme CYP 3A4 and to a lesser extent by CYP2D6 and CYP2A6). Desmethylastemizole is the major metabolite and has histamine-H1 blocking activity. Other metabolites include norastemizole and 6-hydroxydesmethylastemizole.
- Half lifeAstemizole, 1 to 2 days; desmethylastemizole, 9 to 13 days. The half-life of the drug and metabolites may increase after long-term administration to 18 to 20 days.
- ExcretionThe metabolites are slowly excreted primarily in faeces via bile and undergo enterohepatic recycling. No unchanged drug has been detected and it is not known to accumulate once steady state levels have been reached.
- Urinary ExcretionN/A
- Clerance11 ml/min/kg.
- ToxicityElevated plasma-astemizole concentrations are associated with QT interval prolongation and serious cardiotoxicity. Arrhythmias, including torsade de pointes, have occurred rarely at doses as low as 20 to 30 mg daily.
- LD50 (rat)N/A
- LD50 (mouse)N/A