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Pronunciationhoe mat' roe peen[1]
Trade namesEquipin, Isopto Homatropine
Other namesHomatropine hydrobromide
  • (N-Methyl-8-azabicyclo[3.2.1]oct-3-yl) 2-hydroxy-2-phenylacetate
Clinical data
Drug classAnticholinergic[2]
Main usesDilate the pupil[2]
Side effectsIncreased eye pressure, stinging, sensitivity to light, dry mouth[2]
Duration of actionUp to 4 days[2]
External links
Legal status
  • Rx only, not FDA approved, only sold in UK
Chemical and physical data
Molar mass275.348 g·mol−1
3D model (JSmol)
  • CN3[C@H]1CC[C@@H]3C[C@@H](C1)OC(=O)C(O)c2ccccc2
  • 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? checkY

Homatropine, sold under the brand name Homatropaire among others, is a medication used to dilate the pupil as part of an eye exam or to help with the pain of anterior uveitis.[3][2] It is used as an eye drop.[3] Effects begin within 10 minutes and may last for up to 4 days.[2]

Common side effects include increased eye pressure, stinging, sensitivity to light, and dry mouth.[2] Other side effects may include delirium or agitation.[2] It is an anticholinergic.[2]

Homatropine was first made in 1883 or 1884.[4][5] It is available as a generic medication.[1] It is on the World Health Organization's List of Essential Medicines as an alternative to atropine.[6] In the United States a 5 ml bottle costs about 40 USD as of 2021.[7] It is made from atropine.[1]

Medical uses

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 given to reverse the muscarinic and CNS effects associated with indirect cholinomimetic (anti-AChase) administration.

It has also been combined with opioids in an attempt to decrease the risk of misuse.[1]

The related chemical compound homatropine methylbromide (methylhomatropine) is a different medication.

Side effects



  1. 1.0 1.1 1.2 1.3 "Atropine". LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. National Institute of Diabetes and Digestive and Kidney Diseases. 2012. Archived from the original on 6 May 2021. Retrieved 10 December 2021.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 "Homatropine Monograph for Professionals". Drugs.com. Archived from the original on 29 September 2021. Retrieved 10 December 2021.
  3. 3.0 3.1 BNF 81: March-September 2021. BMJ Group and the Pharmaceutical Press. 2021. p. 1211. ISBN 978-0857114105.
  4. Foley, Paul Bernard (2003). Beans, Roots and Leaves: A History of the Chemical Therapy of Parkinsonism. Tectum Verlag DE. p. 167. ISBN 978-3-8288-8496-0. Archived from the original on 2021-12-11. Retrieved 2021-12-10.
  5. Sneader, Walter (23 June 2005). Drug Discovery: A History. John Wiley & Sons. p. 121. ISBN 978-0-471-89979-2. Archived from the original on 11 December 2021. Retrieved 10 December 2021.
  6. World Health Organization (2021). World Health Organization model list of essential medicines: 22nd list (2021). Geneva: World Health Organization. hdl:10665/345533. WHO/MHP/HPS/EML/2021.02.
  7. "Homatropine ophthalmic Prices, Coupons & Patient Assistance Programs". Drugs.com. Archived from the original on 29 December 2018. Retrieved 10 December 2021.

External links