from Wikipedia, the free encyclopedia
Structural formula
Structural formula of the synephrine enantiomers
( R ) -Synephrine (top) and ( S ) -Synephrine (bottom)
Non-proprietary name Oxedrine
other names
  • 1- (4-hydroxyphenyl) -2-methylaminoethanol
  • 4- (1-Hydroxy-2-methylaminoethyl) phenol
Molecular formula C 9 H 13 NO 2
External identifiers / databases
CAS number 94-07-5 [( RS ) synephrine]
EC number 202-300-9
ECHA InfoCard 100.002.092
PubChem 7172
ChemSpider 6904
DrugBank DB09203
Wikidata Q421351
Drug information
ATC code
Drug class

Sympathomimetic , antihypotonic

Mechanism of action

α 1 -adrenoceptor - agonist

Molar mass 167.21 g · mol -1
Physical state


Melting point

184-185 ° C

pK s value


safety instructions
Please note the exemption from the labeling requirement for drugs, medical devices, cosmetics, food and animal feed
GHS labeling of hazardous substances
07 - Warning


H and P phrases H: 315-319-335
P: 261-305 + 351 + 338
Toxicological data

270 mg kg −1 ( LD 50mouseiv )

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Synephrine is an alkaloid found in bitter orange . As phenylethylamine - derivative is chemically and pharmacologically to the ephedrine related.

Synephrine is used as a metabolism-stimulating and performance-enhancing agent. In connection with naringin and hesperidin , the metabolism-stimulating effect is improved - without known significant negative impairments such as B. Increase in heart rate and blood pressure. If taken at the same time as caffeine , the effects can be mutually reinforcing - but in particular the potential to increase heart rate and blood pressure.

Bitter orange extract preparations are said to help weight loss due to the synephrine content (“ fat burner ”), but the effectiveness is controversial. In the USA, synephrine is increasingly being used as a replacement for ephedrine , which is now available there on a prescription .

Synephrine was patented by Boehringer Ingelheim in 1931 and is used (mostly in the form of tartrate ) as a sympathomimetic . It can be used orally and intravenously to treat low blood pressure ("circulatory weakness"), i.e. as an antihypotonic, and locally (eye drops) to reduce the swelling of the conjunctiva, but no longer has any particular therapeutic significance.

Risk assessment

For some products that are currently available on the market, due to the dosage level and the combination with caffeine, there are sufficient suspicions that these preparations do not meet the requirements of Art. 14 of Regulation (EC) 178/2002 and are therefore not classified as safe are. Here it is taken into account that the target group of the preparation are people who are already exposed to increased cardiovascular stress due to physical exertion, which may be even higher in the case of overweight .

Trade names

Sympatol ® ( A , excluding trade), Dacryoboraline ® ( F , excluding trade)

Individual evidence

  1. a b c Entry on synephrine in the ChemIDplus database of the United States National Library of Medicine (NLM) .
  2. a b Data sheet (±) -Synephrine from Sigma-Aldrich , accessed on April 23, 2011 ( PDF ).
  3. Sidney J. Stohs, Harry G. Preuss, Mohd Shara: A review of the human clinical studies involving Citrus aurantium (bitter orange) extract and its primary protoalkaloid p-synephrine . In: International Journal of Medical Sciences . tape 9 , no. 7 , January 1, 2012, p. 527-538 , doi : 10.7150 / ijms.4446 , PMC 3444973 (free full text).
  4. Sidney J. Stohs, Harry G. Preuss, Samuel C. Keith, Patti L. Keith, Howard Miller: Effects of p-synephrine alone and in combination with selected bioflavonoids on resting metabolism, blood pressure, heart rate and self-reported mood changes . In: International Journal of Medical Sciences . tape 8 , no. 4 , April 28, 2011, p. 295-301 , PMC 3085176 (free full text).
  5. Gilbert R. Kaats, Howard Miller, Harry G. Preuss, Sidney J. Stohs: A 60day double-blind, placebo-controlled safety study involving Citrus aurantium (bitter orange) extract . In: Food and Chemical Toxicology: An International Journal Published for the British Industrial Biological Research Association . tape 55 , May 1, 2013, p. 358-362 , doi : 10.1016 / j.fct.2013.01.013 , PMID 23354394 .
  6. Avoxa & # 150; Mediengruppe Deutscher Apotheker GmbH: Pharmaceutical newspaper online: Synephrine: Dangerous effects on the heart and circulation. Retrieved January 26, 2017 .
  7. a b Health assessment of sports products and slimming products containing synephrine and caffeine (PDF; 196 kB) Opinion No. 004/2013 of the Federal Institute for Risk Assessment (BfR) dated November 16, 2012
  8. Entry on Synephrine. In: Römpp Online . Georg Thieme Verlag, accessed on June 16, 2014.