When you take speed you should now that in fact appart from tge cut that is usually caffeine the loe percetage of amphetamine is actually a 50:50 ratio dextroamphetamine:levoamphetamine. If talking about the pharmacology of the dextroamphetamine we are talking about a highly dopaminergic also noradrenergic and slightly serotonergic so you get a clean high with no anxiety and CNS stimulation motivation and focus but when talking about levoamphetamine we are talking about a compound that is bassically less dopaminergic so less focus, motivation... less CNS stimulation. However is more noradrenergic so it stimulates the peripheral nervous system causing more of a fight or flight effect, when talking about serotonin is what really changes between dextro and levo enantiomers. While dextroamphetamine is slightly serotonergic on the contrary levoamphetamine have 0 sertoninn activity.

Due to the slightly longer levoamphetamine half life that means that dextroamphetamine is the compound that wears out first, so when time passes and they start to were off the levoamphetamine ratio ends up higher thsn the dextro one due to the levo been longer. That means that serotonin release drops to near 0 or 0, dopamine drops slightly and norepinephrine in fact increases.

That drop in serotonin increase in norepinephrine the metabolization from the CYP26 that causes the oxidation of amphetamine into 4-hydroxyamphetamine that is almost only know for the norepinephrine release us what ends up causing that during the comedown of amphetamine you might experience extreme anxiety with large doses. Think about how would you feel if serotonin that is the only monoamine that causes relaxation droping while norepinephrine increasing that actually causes the fight or flight response, you would definetely feel anxious. Because your body enters in a very similar reaction as if you had to run from a bear that was hidden in the forest and os running towards you.

And that's bassically why I think that speed causes such levels of anxietywhile wearing of.

So bassically if you take a large dose of racemic amphetamine have benzos or any other sedative like gabapentanoids or antipsychotics on hand if you don't want to experience the horrible comedown anxiety