Clinical data
Trade namesEpontol
AHFS/Drugs.comInternational Drug Names
ATC code
  • Propyl {4-[2-(diethylamino)-2-oxoethoxy]-3-methoxyphenyl}acetate
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.014.384 Edit this at Wikidata
Chemical and physical data
Molar mass337.416 g·mol−1
3D model (JSmol)
  • O=C(OCCC)Cc1cc(OC)c(OCC(=O)N(CC)CC)cc1
  • InChI=1S/C18H27NO5/c1-5-10-23-18(21)12-14-8-9-15(16(11-14)22-4)24-13-17(20)19(6-2)7-3/h8-9,11H,5-7,10,12-13H2,1-4H3 checkY
 ☒NcheckY (what is this?)  (verify)

Propanidid is an ultra short-acting phenylacetate general anesthetic. It was originally introduced by Bayer in 1963[1] but anaphylactic reactions caused it to be withdrawn shortly afterwards.

Even though Cremophor EL has been shown to cause anaphylactic reactions in humans in several cases (both when given intravenously and orally), it is still debated whether propanidid itself may have contributed to the reactions.

It has been argued that the toxic effects or reactions to propanidid (and Althesin) were due to the drugs themselves.[2] Several cases of negative reactions have been recorded for different drugs using Cremophor EL as solubilizer, suggesting that the negative reactions were mainly caused by Cremophor and not by the drug substances themselves.


  1. ^ US patent 3086978, Hiltmann, R.; Wollweber, H.; Hoffmeister, F.; Wirth, W., "3-Methoxy-4-Carbamidomethoxy-Phenylacetic Acid Esters", issued 1963-04-23, assigned to Bayer 
  2. ^ Clarke, R. S.; Dundee, J. W.; Carson, I. W. (1973). "A New Steroid Anaesthetic - Althesin". Proceedings of the Royal Society of Medicine. 66 (10): 1027–1030. doi:10.1177/003591577306601023. PMC 1645602. PMID 4148526.