Synephrine (or oxedrine) is a drug aimed at encouraging fat 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 concerns about potential problems with heart disease risk[1] and its use in methamphetamine manufacture. 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.
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, while 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.[2] There is some evidence that it may act at β3.[3]
Associated risks
Many diet products such as Stacker 2 contain synephrine along with caffeine. 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 cardiac infarcts.
