• Molecular NameCimetidine
  • SynonymCimetidine A/AB; Cimetidine Hcl
  • Weight252.346
  • Drugbank_IDDB00501
  • ACS_NO51481-61-9
  • Show 3D model
  • LogP (experiment)0.4
  • LogP (predicted, AB/LogP v2.0)0.52
  • pka6.8
  • LogD (pH=7, predicted)0.32
  • Solubility (experiment)11.5 mg/ml
  • LogS (predicted, ACD/Labs)(ph=7)-2.08
  • LogSw (predicted, AB/LogsW2.0)4.37
  • Sw (mg/ml) (predicted, ACD/Labs)0.57
  • No.of HBond Donors3
  • No.of HBond Acceptors6
  • No.of Rotatable Bonds8
  • TPSA114.19
  • StatusFDA approved
  • AdministrationOral, parenteral
  • PharmacologyA histamine H2-receptor antagonist that inhibits the production of acid in the stomach.
  • Absorption_value100.0
  • Absorption (description)Rapidly absorbed after oral administration.
  • Caco_2-5.89
  • Bioavailability84.0
  • Protein binding19.0
  • Volume of distribution (VD)1 L/kg
  • Blood/Plasma Partitioning ratio (D_blood)Plasma : whole blood ratio, about 1.0.
  • MetabollsmUnchanged cimetidine is the largest urinary component, followed by a polar conjugate tentatively identified as cimetidine N'-glucuronide, detected after oral administration with cimetidine. Smaller amounts of the oxidized metabolites, cimetidine sulphoxide and 5-hydroxymethylcimetidine, together with the hydrolysis products, cimetidine guanylurea and cimetidine guanidine, are also observed. Moreover, the N-demethylation metabolism pathway of cimetidine by rat liver microsomes (phenobarbital-induced rats) was supported by the identification of a new N-desmethylcimetidine metabolite. Major cimetidine S-oxygenase is the adult human liver FMO (form II), but cytochrome P450 are enabled in biotransformations too.
  • Half life2.0 h
  • ExcretionAbout 50 to 80% of an intravenous dose is excreted in the urine as unchanged drug in 24 h, together with about 10% as the sulfoxide metabolite and about 5% as the 5-hydroxymethyl derivative. Up to about 10% of the dose is eliminated in the faeces.
  • Urinary Excretion62
  • Clerance8.3 ml/min/kg; considerably reduced in elderly patients.
  • ToxicityCimetidine appears to be relatively non-toxic; recovery has occurred after ingestion of 24 g in one dose, and ingestion of 60 g during 5 days caused no untoward effects. During chronic therapy, toxic effects are reportedly associated with trough plasma concentrations greater than 1.3 mg/L.
  • LD50 (rat)N/A
  • LD50 (mouse)N/A