Someone here said oxymorphone lol. While undoubtedly probably the most euphoric substance listed here it is definitely NOT underrated as everyone knows of how great it is. Methadone can be underrated, IV of pure methadone in adequate dosage I've found to produce a rush almost identical to heroin. So much so I was flabbergasted as I didn't expect any sort of rush whatsoever. Now the dosage was 50mg+ if I remember correctly, so a small 10mg dose won’t have that effect but if you got a multi cc size syringe and pure clean methadone then yes IV can be amazing. Tho I think it’s something that should only be tried occasionally.
As for my personal most underrated drugs I'll list gabapentin/pregabalin as the most underrated. I prefer pregabalin as it doesn't require the staggered dosing of gabapentin and all that which makes for simpler usage. The reason it’s so amazon is that it seems to work in every situation. It works as a potentiator of opioids and other sedative, especially with opioids. It also gets rid of practically all withdrawal symptoms of both opioid and benzo withdrawal. In fact, I’ve noticed that if I took pregabalin one day to potentiate opioids it was quite common that on the next day I would simply forget to take my daily maintence opioid dose of methadone or whatever opioid I was using for maintenance. It's the oddest effect cause as any addict knows the thought of withdrawal coming on and having to take your daily maintence dose specifically methadone is not something you "just forget". That won't happen in a million years, yet it’s happened to me the day after taking pregabalin multiple times and other addicts I know have had the same weird effect. Somehow you just wake up feeling good and that good feeling just keeps the thought of taking methadone off your mind. You sort of lose track of time and before you know it you've gone a length of time without opioids where normally you’d already be horribly suffering. I found that about 24hrs after using dope is the point, I start feeling an ever increasing "need" for opioids. By 36hrs I'm sick, like badly sick, definitely at the point where my entire conscious and attention is solely focused on me withdrawing. Well after pregabalin I have made it to 36hrs and was not in WD. It'd be right around that time I’d start realizing that I’m feeling a little off and Holy Shit!!! I’ve gone 36hrs since I last used dope and I’m not dying!!?! AT that point if I use dope then that dope is given a secondhand potentiation for a 2nd day in a row by the pregabalin because that 36hr gap has lowered my tolerance somewhat and caused my blood levels of opioids to drop pretty low to where a smaller than usual dose hits harder than normal. Another benefit. If I don't have dope and instead take methadone and resume methadone maintenance then I start at a lower dose than normal and this allows me to perhaps slowly taper and reduce my opioid tolerance.
Using stimulants? Well, it’s useful here too in 2 different ways. It’s useful on the comedown from stimulants, but also while using stimulants it will level you out and counteract many of the "tweaked" out effects of too much stimulant use. So, it seems to combine greatly with practically every class of drug by either potentiating that drug, leveling the side effects from that drug, or helping you come down from that drug. The only substance class I can't personally talk about is mixing it with psychedelics or empathogens like mdma. I believe for the comedown it would go great for sure, and with empathogens specifically I can see a small dose of pregabalin going along nicely with the physical euphoria of mdma. I only think that mixing it with a psychedelic is the only situation where it wouldn’t improve the experience. I can see pregabalin's effects causing nausea and discomfort while tripping on serotogenic psychedelics, but for comedown definitely. Also, I guess I should mention dissociatives. I also have no experience with this combo tho I believe the effect would make the dissociative experience less pleasant once again due to the "spinning" and "drunken" effect gabagenics have I can see it exacerbate the spinning from dissociatives causing nausea, but who knows I haven't tried that combo. Also, I don't really see dissociatives as a class of substances that need any support for the "comedown" like stimulants of psychedelics do. So perhaps if anyone here has experience with such combos, they can comment to complete this gap of data here.
Anyways as you can see the gabagenics specifically gabapentin/pregabalin and I guess you can include methylpregabalin which in my opinion is identical to pregabalin except with a smaller dosage and slightly different duration and effects time curve. Also, other rare gabapentoids such as mirogabalin or atagabalin most likely have extremely similar effects. I believe this class of substances hold potential to produce many more analogues with slightly varying effects some of which may be superior in general others which may be superior when used for a specific reason such as opioid potentiator or stimulant comedown etc... Phenibut while technically belonging to a different class as a GABA b receptor agonist which is the same class as GHB, but it also at least partly has a mode of action that’s the same as gabapentoids may also find similar uses to pregabalin, tho by being a Gaba agonist it comes with a whole set of potential risks and dangers.
To conclude that’s my case for gabapentoids specifically gabapentin and pregabalin being the most underrated drugs. Used on their own they can be pleasant and enjoyable, but their true benefits shine when they are used in combination with other substances. One thing to remember about gabapentoids is that I've yet to encounter a class of substances that build up a tolerance as quickly as these drugs. A rule of thumb is that your tolerance will double each consecutive day of use. For example, while several places on the internet recommend between 300-600 as a good starting recreational dose of pregabalin I think that’s ridiculously too high. A novice taking 600mg for their first time will have a very unpleasant experience, and these drugs last a LONG time. I'm talking 10-12hrs of its main effects, and it’s very common to wake up the next day and still feel slight effects for most of that day. So, I personally start at 150-200mg as a dose. Then if on day 2 I wanna dose again I’ll have to double it or take about 300-400mg in order to have the same level and intensity of effects I had the day before. On day 3 that would increase to 600mg+. If you get to day 5 or 6, you'll no longer really be experiencing any of the recreational effects anymore, well only slightly no matter the dosage you take really. At that point you're only getting the medicinal benefits of the drug but not the recreational benefits. Now this is a rule of thumb and specific to me tho I’ve seen the same apply in others. Sometimes you can only increase the dose a little bit the 2nd day and the effects will still be at a level you want them tho slightly subdued and perhaps doing that you can stretch out how many days it'll remain effective. Tho generally this is a substance you only wanna take occasionally in order the benefit from its synergetic effects in combination with other drugs. There's really no reason to take it more than 2 days in a row (unless used to treat withdrawal). Usually, a week break is enough to fully reset your tolerance, then again if you used it multiple days in a row at high doses it may take much longer than a week.