I am not a medical professional but I know a fair bit of biochemistry. And a little bit about certain health stuff. I hope this does not come off as insulting or R00d.
With noted alcoholic Anna abusing IV spas, I have to ask- does that actually help at all?
Help with what being hungover? I've never tried it but theoretically absolutely especially if you get an IV treatment specifically designed to replace fluids and electrolytes like Ringer's lactate. Hangovers are basically about being really dehydrated. Which is why part of the way you can lessen their effects is drinking Gatorade before going to bed.
calling alcohol a diuretic. It suppresses vasopressin. Sounds simple.
It's more than that. Your body once you reach a certain BAV will just start pissing out Ethanol to get rid of it. It's not a lot either which means if you go crazy and have like 10+ drinks your body is going to be pissing away a substantial amount of water.
I have never heard of spironolactone causing something like this, probably because you only take it when you need it and it just fixes or ameliorates the problem unless you OD on it. But caffeine, though the amount in soda is pretty low, absolutely will dehydrate you pretty easy. Warehouse workers have to be told not to drink Energy drinks or they could actually factually pass out. It happens semi-frequently I'd bet, but I don't feel like digging through OSHA to figure out how often it happens.
pumping your blood with a lipid targeting solvent that easily passes through the blood brain barrier?
OK OK so Ethyl alcohol is actually a pretty polar solvent. The rules for solvents can be pretty nonintuitive, but it is not incorrect to think that there is a big spectrum where you have something like water on one end and then something like Hexane or oil on the other. Ethyl Alcohol is kind of a little bit of a bridge but it is a shitty bridge if you have something like most lipids. Surfactants like soap are generally much better at that kind of thing. Iirc lipids are either something like fatty acids or steroids(4+ring connected together).
nociception normally, but does that really mean it can't hurt? Isn't the pain from bumping your funny bone or looking at bright lights coming from nerves that also don't normally sense pain?
I think I understand the question you are trying to ask so let me answer that and a couple other things and hopefully untangle some stuff.
The Pain from alcohol is just dehydration plain and simple. Btw it is really really fucking bad for you to be dehydrated which is why it hurts. Your brains swims in this nice soft cushion of Cerebral Spinal fluid which is mostly just water and electrolytes. Which is why you have a big headache when you are dehydrated. Dehydration is one of those things that can very easily kill you and so if you are sick or injured and dehydrated that is one of your biggest concerns.
Though worth noting it is not any kind of sensor nerves in your actual brain that making it hurt. It is the nerves in your head sending a signal to your spine which sends the signal to your brain.
Basically all the nerves in your body actually go to your spine first before going to your brain to be processed. So basically any kind of sensor neuron is going to be connected to your spine not your brain. But not your nose FOR SOME FUCKING REASON. But the process is still basically the same iirc. The signal gets sent to your spine which might do something with it reflexes or otherwise then gets send to your brain and interpreted and depending on how your body interprets it then it might become pain.
As far as how Alcohol affects the neurons in your brain and your nervous system in general. It acts as a depressant which is to say it increases the threshold at which neurons fire. This depresses your nervous system in that big major systems are less likely to fire or less likely to fire as strongly. The systems that tend to cause things like pain and anxiety tend to be stronger than the systems that do other things so alcohol feeds good even though it is a depressant. Forgive me if my neurosciences is a bit off its way outside my wheelhouse so I have to use what I know about electronics and comp sci to get a grasp on it.
I hope you got some question answered and some knowledge and enjoyment out of my massive autistic post.