Ok so here is the deal modern APs are considered dirty drugs which means they bind to a lot of stuff it's roughly twenty different receptors. The really important one in terms of blocking hallucinations is the d2 dopamine receptor...this not only blocks dopamine activity but it also prevents any dopamine related decrease in the glutamate receptor/ion channel NMDA....both of these paths are involved in hallucination and it's sort of a circular loop because NMDA can feed back to induce dopamine secretion. That's the key part. The modern drugs also have some activity on serotonin which is supposed to mitigate some of the extrapyrimidal side effects or EPS and potentially alter mood as well since these are the targets of antidepressants. Finally another key factor in both weight gain and sleepiness is how much they bind to the histamine receptor. All of the antipsychotics are derived from antihistamines....so it's kinda like taking Benadryl which is often used as a sleep aid. Basically all the binding intensities for these different receptors vary among the different APs and a good pdoc can prescribe you a pill that's different than what your on based on your complaint about the first one.

Now onto metformin...it's considered helpful for weight loss even with APs it's often called excercise in a bottle. What it does is activate a protein called AMPK in the periphery....AMPK is a cellular energy sensor. Ironically AMPK in the brain and in the periphery act different. When AMPK gets phosphorylated in the brain it actually makes you want to eat because it registers as low energy but it's he opposite in the skeletal muscles....it helps melt away stored energy like fat. APs the ones with weight gain actually activate AMPK in the brain which makes you want to eat but metformin does activate in the brain only skeletal muscles...it's does have side effects like diarrhea in some people so it may or may not be worth it but a recent study suggested people lost 6kg which is what 12 pounds?

Anyway yes I gained weight on risperidone. 10 pounds...that was an awful med but it stabilized me then I switched to abilify to reverse the prolactin effects...but yeah risperidone I once ate a cupcake only to realize it was stale...then even knowing it was stale I ate a second one...why? Basically my brain truly felt I was starving...