Synephrine
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| CompTox Dashboard (EPA) | |
| ECHA InfoCard | 100.002.092 |
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| Formula | C9H13NO2 |
| Molar mass | 167.205 g/mol g·mol−1 |
Synephrine (or oxedrine) is a drug commonly used for weight loss. While its effectiveness is widely debated, synephrine has gained significant popularity as an alternative to ephedrine, a related substance which has been made illegal or restricted in many countries due to health risks and its use as a precursor in the illicit manufacturing of methamphetamine. Products containing bitter orange or synephrine are suspected of causing adverse cardiovascular reactions [1]. Synephrine is derived primarily from the fruit of Citrus aurantium, a relatively small citrus tree, of which several of its more common names include Bitter Orange, Sour Orange, and Zhi shi. Dietary supplements generally supply single oral doses of 3–30 mg, while as a pharmaceutical agent it is given orally or by parenteral injection in 20–100 mg doses as a vasoconstrictor to hypotensive patients.[2]
Claims
- Burns fat
- Increases energy
- Increases metabolism
- Promotes weight loss
- Increases body heat
Synephrine and neosynephrine
There has been some confusion surrounding synephrine and phenylephrine (neosynephrine), one of its positional isomers. The chemicals are similar in structure; the only difference is the location of the aromatic hydroxyl group. In synephrine, the hydroxyl is at the para position, whereas in neosynephrine it is at the meta position. Each compound has differing biological properties.
- Phenylephrine acts primarily on alpha1 adrenergic receptors, so it has mainly vasoconstricting actions.
- Synephrine's pharmacology has not been thoroughly studied. Some comparisons with octopamine have been performed.[3] There is some evidence that it may act at β3 adrenergic receptors.[4]
Associated risks
Many diet products such as "Stacker 2", "Xenadrine-EFX", etc contain a "stack" of synephrine along with caffeine, sometimes with an NSAID. Some reports have indicated that such diet pills cause numerous harmful effects. The Mayo Clinic published a report that suggested a link between Stacker 2 pills and increased risk of ischemic stroke, increased blood pressure, and myocardial infarction (heart attack).
Synephrine can also cause arrhythmias [5]. It is similar to ephedrine [5] and can therefore show similar symptoms (see ephedrine adverse effects).
Following the presentation of a healthy young man with a myocardial infarction, a case study and subsequent literature review found that the makers of "nutritional supplements" who replaced ephedrine with its analogs p-synephrine and/or p-octopamine from "bitter orange" had in effect simply found a loophole in the FDA's April 2004 regulation banning ephedra in those supplements by substituting a similar substance the regulation did not address, while permitting them to label the products as "ephedra-free".[6]
References
- ^
Jordan S, Murty M, Pilon K (2004). "Products containing bitter orange or synephrine: suspected cardiovascular adverse reactions". Canadian Medical Association Journal. 171 (8): 993–4. PMID 15497209.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ Baselt RC (2008). Disposition of Toxic Drugs and Chemicals in Man (8th ed.). Foster City, California: Biomedical Publications. pp. 1471–2. ISBN 9780962652370.
- ^ Brown CM, McGrath JC, Midgley JM; et al. (1988). "Activities of octopamine and synephrine stereoisomers on alpha-adrenoceptors". Br. J. Pharmacol. 93 (2): 417–29. PMC 1853804. PMID 2833972.
{{cite journal}}: Explicit use of et al. in:|author=(help); Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ Carpéné C, Galitzky J, Fontana E, Atgié C, Lafontan M, Berlan M (1999). "Selective activation of beta3-adrenoceptors by octopamine: comparative studies in mammalian fat cells". Naunyn Schmiedebergs Arch. Pharmacol. 359 (4): 310–21. doi:10.1007/PL00005357. PMID 10344530.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ a b Livsmedelsverket (Swedish FDA)
- ^ Thomas JE, Munir JA, McIntyre PZ, Ferguson MA (2009). "STEMI in a 24-year-old man after use of a synephrine-containing dietary supplement : a case report and review of the literature". Tex Heart Inst J. 36 (6): 586–90. PMC 2801940. PMID 20069086.
{{cite journal}}: CS1 maint: multiple names: authors list (link)