A few years ago, in autumn 2017 or thereabouts (feels like a decade ago, because that's what it's like when you're a mentally-ill stimulant user in your 20s), around when I was first seriously offered a (dextro)amphetamine script of some variety by my psych to treat my severely disabling lethargic/fatigued TRD, I asked a naive, sincere question around Druggit in various subs (can't recall which ones atm): given that Vyvanse is a prodrug for dextroamphetamine and purports, is advertised to be long-acting and therapeutically last "all day" (that's how I remember Vyvanse being marketed in the early days--it was heavily implied that it was a "one and done" formulation), what are the subjective, qualitative differences between Vyvanse and Dexedrine Spansules/dextroamphetamine ER, all other things being equal, and accounting for dosage (applying the conversion)?

I thought this was going to be a simple, straightforward question I only didn't know the answer to because I was a newbie, lack of experience, just beginning to make a lane change into the fast lane. But to my puzzlement, nobody gave me a straightforward answer. It seemed like one of those things where nobody knows and yet pride dictated that nobody wanted to admit that they didn't have a clue. People avoided, ducked/dodged the question. Posted tweaky rants about other stimulants and formulations that were of only tangential relevance at best in the comments, hijacking the threads. Told me I should be on some other totally different formulation. Commented incoherent gibberish. Finally fed up and sleep-deprived after an all-nighter, I got into it with one guy setting off an epic chain of absurd banter, a good-old-fashioned "flame war" that IIRC turned weirdly sexual at one point. It was ridiculous and I still giggle about it to this day. But all BS aside, I now have enough experience with both dextroamphetamine ER (a generic of spansules, but a high-quality generic) and Vyvanse to make a direct comparison. Past me from 2017 and anyone else curious, here's your answer (and stop pretend flame-flirting with that guy and go to sleep!):

Vyvanse lasts about twice to 2.5 times as long as an IR Adderall (and presumably IR dex, may be able to confirm that in the future) and is lovely in its own right but does not live up to its advertised/marketing promises of "lasting all day", and due to its idiosyncratic biological "release" prodrug mechanism, it isn't truly an "extended release" formulation per se. Amphetamine in any formulation and through any RoA is extraordinarily sensitive to urine pH, dietary intake variables, etc., but all other things being equal, if "left to its own devices" with minimal intake of foods/beverages that decrease urine pH, and perhaps intake of foods/beverages that increase urine pH to boost/extend it etc., it lasts about 6-7 hours max--and on hour 6-7, it's going to be rapidly ebbing away. Dex spansules, by contrast, again if taken under optimal conditions and "left to their own devices" (minimal eating of urine-acidifying foods, taken after a night of adequate sleep with no/minimal/reset tolerance on an empty stomach slightly pH-decreased, etc., etc.), can last up to approximately twice that long.

Duration-wise, spansules deliver. This is therapeutically positive for controlling symptoms and/or staying speedy (in the fast lane over longer distances, to belabor the metaphor) throughout the waking day, but it can be problematic when it comes to insomnia. Booster-dosing with Vyvanse is tricky and inadvisable. Booster-dosing with spansules is damn near impossible if you want to sleep that night. You can take a 30 or 40 mg Vyvanse between 10--11:30pm and be asleep by 6 or 7 (if you take Vitamin C, drink decaf green tea, etc. as you're winding down). You can not take a spansule in that timeframe and be asleep by early morning. So plan accordingly.

Spansules are smoother throughout their duration of action, and the stimulating action/"high" if you will comes in gentle waves of a sort. They both kick in in roughly around the same time after dosing, but while Vyvanse has a more gradual onset, once it has fully kicked in, you subjectively get all of it, the peak feeling, which "hits harder" and kicks you in the face at higher doses. It continues at that level for a few hours and gradually yet rapidly diminishes to the comedown. No "waves" where you can feel phases of it subtly kicking in hours later to sustain continuity of blood dextroamph level as with spansules (which makes sense given the physical spansule design, with beads going off at staggered times). It kicks in, you get it, you have it until you don't, that's it.

That's the strange thing about Vyvanse--the best analogy is that there's a gradual gradient on- and off-ramp, but you're forcefully "pushed" quickly up and down them despite the gradual nature. Dex spansules, on the other hand, while the on and off ramps' "gradients" feel very similar in "gradient", which is also a gradual, not steep one--subjectively, the come-up and come-down feel more gradual because you're not moving up or down them as quickly, though you do get on the on-ramp from the level floor a little faster. But once you're on, subjectively you feel the gradual nature of the gradient because you're not being shoved up it by someone jogging behind you. That's an elaborate, weird metaphor but it's the best way I can describe this and compare the two.

Because dex spansules act in perfectly-overlapping/synchronized phases to maintain the ER mechanism, "extend the release", they're less emotionally-numbing (which can be a good or a bad thing depending upon the reasons you take them), frankly less tweaky, and you don't get "stuck" nearly as strongly--task-switching is actually possible! (Who'da thought?) In general, you feel less "drugged" on them, hence the smoother aspect, because of those slight variations/dips in blood dextroamphetamine level throughout the day they allow you to have. This is also counterintuitive--but that's, in the case of spansules, or at least it seems to be, a good thing. Having a consistently high blood amph level isn't better functionally-speaking. Spansules maintain sufficient amphetamine level in the bloodstream so you don't come down/crash between the bead-release phases, but those little dips remind you you're human. It's easier to eat. To interact with other people. To remember there's a world outside of your own solipsistic little inner fantasy world/mind awash in chemicals. To plan and execute different tasks rather than be buffeted by your speedy flighty whims and then inextricably beholden to them for the next several hours. This is where spansules really shine over Vyvanse, IMHO. Now, it's not like how people describe low-dose Desoxyn where you don't even feel like you're on an amphetamine at all, but it's a lot closer to that "natural, non-drugged" feeling than Vyvanse is. Like with Addy, with Vyvanse you're on frickin' speed and there's no escaping that. Either you can't feel it, only get negative side effects at too-low dosages, or you're speeding hard at sufficient dosages. There's a wider window of happy middle ground with spansules.

In a (sizable, maybe it's a huge coconut shell) nutshell, there's the core of the differences between Vyvanse and dextroamphetamine spansules. The latter, on balance, are far superior in nearly every way when the doses are truly equal or near-equal. The main problem is that they can work too well--last far too long (it can be useful/nice knowing that with Vyvanse there's a firmly-defined 6-7 hour max duration limit), and if you're sensitive to amphetamine or likely to be anxious (if the dose is too high for your tolerance at the time, or you have something else in your system that will interact with/amplify it, etc.), spansules will affect you worse, quicker. Spansules are more sensitive, naturally, to gastrointestinal pH and that's a potential downside depending upon diet/lifestyle. Apathy with Vyvanse was actually a plus for me, but for most people I can't imagine it would be, but anyway if you want to blot out the world and feel emotionally armored and apathetic without totally frying yourself and still staying within the bounds of oral pharmaceutical amphetamines, Vyvanse works well for that. Vyvanse also can work well, might be better for intense and moderately long work/study sessions/stretches where you just need to buckle down, hone in on one thing and get it done, but for daily functionality, spansules are IMHO a better way to go.

So there you go. Despite the second-person perspective of much of this post that may imply otherwise, caveat that of course YMMV and this is all simply what I've garnered from my personal experience and knowledge/conjecture about why these two formulations work the way they do based upon their different designs (physical ER mechanism versus biological/prodrug). I have to say, everything else accounted for, I'm doing a lot better on spansules (technically dex ER) versus a second daily dose of Vyvanse or even a "booster dose" of IR Adderall (which is tasty and nice to have around for other RoAs (snorting/plugging/sublingual/buccal), but yeesh can that be hardon a girl's skin/overall physical appearance, and good luck quitting smoking on IR Addy), and I wonder what else I could've accomplished and how the last few years might've been different had I started with spansules instead of what soon became 70 mg Vyvanse in divided daily doses.

Now I'm also not totally disparaging Vyvanse here. It's kept me afloat for the past ~3 years and there's a lot I like about it, namely: I like that it is converted in the body to enantiopure dex (I really like my enantiopure stims). I like that the marketed/advertised "lower abuse potential" (BS or not in reality) might make certain stingy gatekeeping prescribers who operate on drug reputations rather than drug realities to Rx it where any other form of dex or Adderall/mixed salts might give them pause. I especially like that the government pays for it (in my state, at least--and that's why I continue to stay on it for at least one of my daily doses, as while generic spansules are affordable, I still have to pay out of pocket for those). ;-D

But at the same time, bluntly in the cold light of dawn (after an speeding all-nighter, haha), I'm glad we have it (another pharma amp formulation on the market is always welcome) but Vyvanse was in many ways a failed experiment in unprecedentedly ambitious amphetamine evergreening. The original company that did the R&D on it, it's said, was probably aiming for a CIII schedule classification which would make it eligible for refills and easier to prescribe more of, thus increasing profits. This obviously didn't pan out, and it really isn't "less abusable" unless RoA is the only definition of "abusability". It doesn't last nearly as long as Shire pinky-promises it does, requiring booster dosing for all-day symptom control, and something invented half a century before has nearly double its duration. It turns out that having a constant high blood level of dextroamphetamine for several hours isn't optimal for executive functioning--which is a major facet of the whole reason most people take this stuff in the first place, licitly or not. It's not easily soluble in water at all even though Shire insists it is. It doesn't even have the convenience of being completely insensitive to gastric pH--in theory it should be, but I swear that it's significantly less effective when administered with any food in the stomach, and an extra-acidic stomach really blunts/mutes it, maybe not to the extent that it would nullify an IR formulation of dex or Adderall, but yeah. Spansules were a brilliant, elegant invention. Having taken both, I can now say that from a purely consumer, efficacy perspective, that wheel didn't need to be reinvented--spansules didn't need to be fixed as they weren't broken. Sometimes what's tried and true works best, and this is just as true in the drug realm as it is with, say, home appliances and newfangled kitchen gadgets. Dexedrine spansules, and really dextroamphetamine period in all its forms, are greatly under-prescribed due to outdated stigma that doesn't make sense in a world where pharma amphetamines are again ubiquitous.

In conclusion (really more of a coda), to hell with people who don't answer simple, sincere, ingenuously asked questions on Reddit and instead give the asker shit rather than stop bloviating for a moment to admit they don't know, to hell with pharmaceutical companies that advertise disingenuously and perennially evergreen amphetamines in a plethora of ways to squeeze every possible dime of profit out of a century-old substance that everyone who needs it to cope should be able have cheap and easy access to the best forms of in this dystopian hellscape, and to hell with getting "stuck" and having your productivity go down the drain via an inability to task-switch--am I right? ;-) Spansules are stellar. Fellow pillheads out there, (deftly) ask your prescriber, local "ADHD" dealer kid or clandestine Mexican mail-order pharmacist about dextroamphetamine ER/spansules today!