Ephedrine is the principal active ingredient in the herb
ephedra or ma huang.
It is similar in form to the appetite control drug
phenylpropanolamine (now banned in the U.S.),
also known as norephedrine, meaning
ephedrine whose methyl group has been replaced by a
It is also similar to the
controlled stimulant amphetamine, which is norephedrine
with the hydroxyl group replaced by a hydrogen.
Pseudoephedrine is an isomer of ephedrine, with the
hydroxyl group on the other side of the molecule.
Ephedra is used in diet products as an appetite depressant and
stimulant, and in sports drinks to mask fatigue.
It is also used as a bronchial stimulator, and to relieve symtoms
of the common cold.
Ephedrine enhances the release of the hormone norepinephrine in the body,
and also binds to the same receptors as that hormone,
causing excess calories to be converted to heat instead of
being stored as fat. It also raises blood pressure. Epinephrine
and norepinephrine are also known as adrenaline and noradrenaline.
Ephedrine thus acts to stimulate an "adrenaline rush".
aspirin can increase
the effects of ephedrine. Norepinephrine works in part by
increasing the levels of cyclic AMP in cells. Caffeine inhibits
the enzyme that breaks down cyclic AMP. Together, ephedrine
makes more cyclic AMP, and caffeine prevents it from breaking
down. Aspirin inhibits the receptors that turn off release
of norepinephrine. So ephedrine releases norepinephrine, and
aspirin prevents the release from being turned off.
Ephedrine by itself has been shown to be ineffective as a weight
loss treatment. Ephedrine combined with either caffeine or
aspirin was effective. The effect appears to be caused by a
reduction in appetite, and preventing the metabolic rate decrease
usually associated with a reduced calorie diet.
Due to its effect as a stimulant on the heart and central
nervous system, ephedrine can cause heart problems, stroke,
and other medical complications (including death),
and there is pressure to
regulate it or ban it in the U.S., as was done with its
By Simon Quellen Field