Tolazoline

Tolazoline is a non-selective competitive α-adrenergic receptor antagonist.^[1] It is a vasodilator that is used to treat spasms of peripheral blood vessels (as in acrocyanosis). It has also been used (in conjunction with sodium nitroprusside) successfully as an antidote to reverse the severe peripheral vasoconstriction which can occur as a result of overdose with certain 5-HT_2A receptor agonist drugs such as 25I-NBOMe,^[2] DOB, and Bromodragonfly.^[3][4]

Tolazoline

Clinical data
AHFS/Drugs.com	International Drug Names
Routes of administration	Intravenous
ATC code	C04AB02 (WHO) M02AX02 (WHO) QV03AB94 (WHO)
Identifiers
IUPAC name 2-Benzyl-4,5-dihydro-1H-imidazole
CAS Number	59-98-3 Y
PubChem CID	5504
IUPHAR/BPS	7310
DrugBank	DB00797 Y
ChemSpider	5303 Y
UNII	CHH9H12AQ3
KEGG	D08614 Y
ChEBI	CHEBI:28502 Y
ChEMBL	ChEMBL770 Y
CompTox Dashboard (EPA)	DTXSID3023683
ECHA InfoCard	100.000.408
Chemical and physical data
Formula	C10H12N2
Molar mass	160.220 g·mol−1
3D model (JSmol)	Interactive image
SMILES N\1=C(\NCC/1)Cc2ccccc2
InChI InChI=1S/C10H12N2/c1-2-4-9(5-3-1)8-10-11-6-7-12-10/h1-5H,6-8H2,(H,11,12) Y Key:JIVZKJJQOZQXQB-UHFFFAOYSA-N Y
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History

Tolazoline was first used in the 1980s as an alternative reversal agent for xylazine.^[5]

Pharmacology

Tolazoline binds to the a₂ adrenergic receptor at a ratio of 4:1, the lowest of all a₂ adrenergic receptor antagonists. Tolazoline activates the imidazoline receptor.^[5]

IV tolazoline has slow elimination and a large distribution in the horse.^[6][5]