Prohormone & Supplement Ingredients:

Methyl-synephrine

Synephrine is an adrenergic agonist that has gained popularity as being an ephedrine alternative. It's found in many species of plants, however the main source today for synephrine is citrus aurantium, aka "bitter orange". Once ephedra was banned, many supplement companies switched to synephrine or methyl-synephrine for their fat loss products.

Methyl-synephrine is often compared to octopamine and suggested to primarily activate beta-3 receptors. Some data suggests the increase in thermogenic activity caused by synephrine may not equate to clinically significant weight loss over time, however methyl-synephrine would likely have a more pronounced effect.

Physiological effects
A study using a bitter orange extract standardized for 27 mg synephrine failed to induce any changes in hemodynamics. Conversely, in another study using twice the amount, significant effects were observed for heart rate, systolic pressure, and diastolic pressures, in which all values increased. This would indicate that the minimum threshold dose to elicit adrenergic activity to be somewhere between 27 mg and 54 mg for adult males.

Although synephrine has demonstrated an ability to induce lipolysis (fat burning) by activating beta-3 receptors en vitro, its efficiency in doing so en vivo is greatly limited because of its inherent affinity for alpha receptors. The dose required to sufficiently trigger lipolysis within adipocytes would be intolerable due to its effects on hemodynamics.

The primary difference between synephrine and methylsynephrine is the addition of a methyl group on the alpha carbon. This has extensive pharmacodynamic implications as it increases the affinity of the compound for beta-receptors.

Methylsynephrine has been used clinically for orthostatic hypotension due to its effects on stroke volume, ejection fraction, and cardiac index. It has been used in doses of up to 120mg in healthy adults with no adverse effects. Even at this dose, diastolic pressure decreased, which is evidence for very little alpha-adrenergic activity.

Furthermore, it had no effect on heart rate or mean arterial pressure. Some of methylsynephrines therapeutic efficacy is mediated by acting as a norepinephrine-releasing agent, and also by inhibiting its uptake. The majority of methylsynephrines pharmacological appeal resides in its ability to activate beta receptors, which is exemplified through its effects on the heart and haemodynamics. This also implies significant beta-3 activity and an ability to induce lipolysis which is consistent with some of its marketing claims.

Another deviation from synephrine is methylsynephrines limited propensity to activate alpha-2 receptors on platelets. This would avoid the complications of intravascular clotting, which has resulted in myocardial infarction mortality associated with synephrine, although allow for the possibility of cerebral hemorrhage.

Methyl-synephrine is a unique compound which has not been used frequently in clinical practice. Due to its ephedrine-like pharmacology and its (surprisingly) clean safety record, it will likely become a more common ingredient in fat loss supplements in the future. It is currently uncontrolled in the United States.
Supplements with this ingredient:
None (for now)

Links to additional information on Methyl-synephrine
lets talk about methyl synephrine (Added on 12/6/2012)
methylsynephrine (Added on 12/6/2012)

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