Methamphetamine produces similar effects to the central nervous system as other stimulants, but with fewer peripheral effects. Methamphetamine’s lipophilicity (ability to dissolve in fat/lipids) allows it to cross the blood brain barrier much quicker than other stimulants.
The main active ingredient or metabolite of methamphetamine in the body is amphetamine, but there are other metabolites that are also released, including 4-hydroxymethamphetamine (pholedrine), norephedrine and 4-hydroxynorephedrine.
Methamphetamine acts on a range of neurotransmitter systems in the brain; serotonin, noradrenaline and dopamine. It acts by inhibiting their re-uptake in a very similar way to MDMA. Components of a neuron work to remove a neurotransmitter once they have been used by the neuron, and methamphetamine reduces their function, so causes an increase in the levels of these neurotransmitters. It also increases the activity of the dopamine-synthesising enzyme tyrosine hydroxylase, which in turn produces more dopamine.