Homatropine

Homatropine
Clinical data
AHFS/Drugs.com	Monograph
MedlinePlus	a601006
ATC code	S01FA05 (WHO) ;
Legal status
Legal status	In general: ℞ (Prescription only);
Identifiers
	IUPAC name (N-Methyl-8-azabicyclo[3.2.1]oct-3-yl) 2-hydroxy-2-phenylacetate;
CAS Number	87-00-3 ;
PubChem CID	6321423;
DrugBank	DB00725 ;
ChemSpider	16498795 ;
UNII	8QS6WCL55Z;
ChEMBL	ChEMBL1233442 ;
CompTox Dashboard (EPA)	DTXSID6044014 ;
ECHA InfoCard	100.001.561
Chemical and physical data
Formula	C16H21NO3
Molar mass	275.348 g·mol−1
3D model (JSmol)	Interactive image;
	SMILES CN3[C@H]1CC[C@@H]3C[C@@H](C1)OC(=O)C(O)c2ccccc2;
	InChI InChI=1S/C16H21NO3/c1-17-12-7-8-13(17)10-14(9-12)20-16(19)15(18)11-5-3-2-4-6-11/h2-6,12-15,18H,7-10H2,1H3/t12-,13+,14+,15? ; Key:ZTVIKZXZYLEVOL-MCOXGKPRSA-N ;
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Homatropine (Equipin, Isopto Homatropine) is an anticholinergic medication that is an antagonist at muscarinic acetylcholine receptors and thus the parasympathetic nervous system. It is used in eye drops as a cycloplegic (to temporarily paralyze accommodation), and as a mydriatic (to dilate the pupil).

The related chemical compound homatropine methylbromide (methylhomatropine) is a different medication. Homatropine is less potent than atropine and has a shorter duration of action. It is available as the hydrobromide salt. Homatropine is also given as an atropine substitute,^[1] given to reverse the muscarinic and CNS effects associated with indirect cholinomimetic (anti-AChase) administration.

Homatropine hydrobromide is on the World Health Organization's List of Essential Medicines.^[2]

It is an antagonist of all five muscarinic acetylcholine receptors.^[3]

^ Scharer LL, Burhenne HJ (April 1964). "Megacolon associated with administration of an anticholinergic drug in a patient with ulcerative colitis". The American Journal of Digestive Diseases. 9 (4): 268–274. doi:10.1007/bf02232133. PMID 14142388. S2CID 19169565.
^ World Health Organization (2023). The selection and use of essential medicines 2023: web annex A: World Health Organization model list of essential medicines: 23rd list (2023). Geneva: World Health Organization. hdl:10665/371090. WHO/MHP/HPS/EML/2023.02.
^ Lavrador M, Cabral AC, Veríssimo MT, Fernandez-Llimos F, Figueiredo IV, Castel-Branco MM (January 2023). "A Universal Pharmacological-Based List of Drugs with Anticholinergic Activity". Pharmaceutics. 15 (1): 230. doi:10.3390/pharmaceutics15010230. PMC 9863833. PMID 36678858.

[1] Scharer LL, Burhenne HJ (April 1964). "Megacolon associated with administration of an anticholinergic drug in a patient with ulcerative colitis". The American Journal of Digestive Diseases. 9 (4): 268–274. doi:10.1007/bf02232133. PMID 14142388. S2CID 19169565.

[WHO23rd-2] World Health Organization (2023). The selection and use of essential medicines 2023: web annex A: World Health Organization model list of essential medicines: 23rd list (2023). Geneva: World Health Organization. hdl:10665/371090. WHO/MHP/HPS/EML/2023.02.

[LavradorCabralVeríssimo2023-3] Lavrador M, Cabral AC, Veríssimo MT, Fernandez-Llimos F, Figueiredo IV, Castel-Branco MM (January 2023). "A Universal Pharmacological-Based List of Drugs with Anticholinergic Activity". Pharmaceutics. 15 (1): 230. doi:10.3390/pharmaceutics15010230. PMC 9863833. PMID 36678858.

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