This might help, upon looking up the two substanses both Phentermine, and Amphetermine here's what I got...
Amphetamines release stores of norepinephrine and dopamine from nerve endings by converting the respective molecular transporters into open channels. Amphetamine also releases stores of serotonin from synaptic vesicles. Like methylphenidate (Ritalin) amphetamines also prevent the monoamine transporters for dopamine and norepinephrine from recycling them (called reuptake inhibition) which leads to increased amounts of dopamine and norepinephrine in synaptic clefts.
These combined effects rapidly increases the concentrations of the respective neurotransmitters in the synaptic cleft, which promotes nerve impulse transmission in neurons that have those receptors.
Phentermine, as many other prescription drugs, works with neurotransmitters in the brain. It is a centrally-acting stimulant chemically related to the amphetamines. It stimulates neuron bundles to release a particular group of neurotransmitters known as catecholamines; these include dopamine, epinephrine (also known as adrenalin), and norepinephrine (noradrenaline). This is the same mechanism of action as other stimulant appetite suppresants such as sibutramine, diethylpropion, and dextroamphetamine.
So my guess is that after all that use of Phentermine, you've had those chemicles dumped into your blood steam, like Amphetamin's Phen works on the nuro transmetors of the brain, with out the Phen in your system, you can go into a state of Anphetamin Psycoses...or depression, because of the lake of dopemine...
hope this helped...
