Title: Betazole
CAS Registry Number: 105-20-4
CAS Name: 1H-Pyrazole-3-ethanamine
Additional Names: 3-(2-aminoethyl)pyrazole; 3-(b-aminoethyl)pyrazole; ametazole; gastramine
Molecular Formula: C5H9N3
Molecular Weight: 111.15
Percent Composition: C 54.03%, H 8.16%, N 37.80%
Literature References: Prepd by the catalytic reduction of 3-pyrazoleacetaldehyde hydrazone: Jones, Mann, J. Am. Chem. Soc. 75, 4048 (1953); Jones, US 2785177 (1957 to Lilly).
Properties: Viscous liquid. bp0.5 118-123°.
Boiling point: bp0.5 118-123°
Derivative Type: Dihydrochloride
CAS Registry Number: 138-92-1
Trademarks: Histimin; Histalog (Lilly)
Molecular Formula: C5H9N3.2HCl
Molecular Weight: 184.07
Percent Composition: C 32.63%, H 6.02%, N 22.83%, Cl 38.52%
Properties: Crystals from ethanol, mp 224-226°. Sol in water. Practically insol in chloroform. Aq solns are acid to litmus.
Melting point: mp 224-226°
Therap-Cat: Diagnostic aid (gastric secretion stimulant).
Keywords: Diagnostic Aid.
Betel Bethanechol Chloride Bethanidine Betonicine Betoxycaine

Betazole structure.png
CAS number 105-20-4 YesY
PubChem 7741
ChemSpider 7455 YesY
UNII 1C065P542O YesY
ChEBI CHEBI:59170 YesY
ATC code V04CG02
Jmol-3D images Image 1
Molecular formula C5H9N3
Molar mass 111.15 g mol−1
ATC code


DrugBank DB00272
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Betazole is a histamine H2 receptor agonist. Also known as Ametazole. Betazole hydrochloride is known as gastramine and histalog.

It has been used as a gastric stimulant to test for maximal production of gastric secretion activity [1] The test can be used in diagnosis of diseases such as Zollinger-Ellison syndrome where there is excess acid production, in this case driven by over production of gastrin. The volume of acid secretion is measured following administration of betazole, diagnosis being secretion greater than 60% of the maximal acid secretion following betazole stimulation. This procedure can lead to complications and should be avoided in subjects with coronary artery disease [2] It is also used in diagnosis of gastritis in association with a test for secretin activity

Betazole is used as a stimulant in preference to histamine because of its specificity for the H2 receptor and its advantage of not generating the undesirable side effects that histamine would induce. It therefore does not require concomitant use of antihistaminic compounds to block the actions of histamine at other histamine receptor types.

Its action in stimulating histamine release can be of use when testing the effectiveness of H2 receptor blocking drugs such as Nizatidine.[3]