Generally, the risk of B12 toxicity or overdose is only low, but keep in mind that vitamin B12 shots may probably give other side effects
The accumulation of amphetamines effectively reverses the transporter carrier mechanisms, leading to a massive, non-exocytotic efflux of vesicular dopamine out into the cytosol, where it is subsequently transported into the synaptic cleft (Wimalasena 2011)(see Figure 2 Mechanism B)
The Thermo Scientific LipidSearch software (version 5.0) was used to compile the list of identified lipids (precursor tolerance 3 ppm, product tolerance 5.0 ppm, product threshold-1.0)
doi: 10.1007/978-3-030-55035-6_5
Here are the two books
That single distinction, the receptor each one targets, explains almost everything else about how these three peptides behave in published studies