Because it's been life-changing for me, and countless others? It's not just time release; that's the old school drugs like Concerta.
The chief problem I have with all stimulants is too fast of an impulse response. It comes on too fast, crashes too fast. For me, for instant release drugs, I experience the following half-lives:
- methylphenidate: 60-90m
- amphetamine salts/dexedrine: 3-4h
- caffeine: 3h
- modafinil: 6-8h
Once a drug reaches about 1.5 HLs (about one Tau/time constant, conveniently), I start fading hard. There is a hysteresis effect: peaking/crashing/re-dosing is not the same as plateauing at some in-between value. Once my brain checks out, that's kind of it for the day.
So what Concerta, Adderall XR, and similar do for me, is give me what feels like two randomly spaced doses of instant release over a 4-6h window. This is unpredictable and thrashes my mental state. It peaks too high and crashes too low. The companies market these drugs based on averaging the plasma profiles of individuals to show a nice smooth curve, but I dug into the literature and this is NOT what you see on an individual level, at all. Concerta just doesn't do it for me.
Vyvanse is way smoother. The plasma peak is already low-pass filtered by the pharmacokinetics of hydrolysis of the lysdexamphetamine. As a result, my subjective experience is basically a 6h plateau. I split my dose to basically get a nice, actually smooth profile over 8-12h with a gentle taper instead of a crash. That also means lower peak plasma conc, and peak plasma is the greatest risk factor in neurotoxicity.
If you actually dig into the literature on neurotoxicity of amphetamines, you basically don't see any until you start getting to the equivalent of 50-100mg IR, and even then it's basically within the noise floor until you get to hundreds of mg per day.
The chief problem I have with all stimulants is too fast of an impulse response. It comes on too fast, crashes too fast. For me, for instant release drugs, I experience the following half-lives:
- methylphenidate: 60-90m
- amphetamine salts/dexedrine: 3-4h
- caffeine: 3h
- modafinil: 6-8h
Once a drug reaches about 1.5 HLs (about one Tau/time constant, conveniently), I start fading hard. There is a hysteresis effect: peaking/crashing/re-dosing is not the same as plateauing at some in-between value. Once my brain checks out, that's kind of it for the day.
So what Concerta, Adderall XR, and similar do for me, is give me what feels like two randomly spaced doses of instant release over a 4-6h window. This is unpredictable and thrashes my mental state. It peaks too high and crashes too low. The companies market these drugs based on averaging the plasma profiles of individuals to show a nice smooth curve, but I dug into the literature and this is NOT what you see on an individual level, at all. Concerta just doesn't do it for me.
Vyvanse is way smoother. The plasma peak is already low-pass filtered by the pharmacokinetics of hydrolysis of the lysdexamphetamine. As a result, my subjective experience is basically a 6h plateau. I split my dose to basically get a nice, actually smooth profile over 8-12h with a gentle taper instead of a crash. That also means lower peak plasma conc, and peak plasma is the greatest risk factor in neurotoxicity.
If you actually dig into the literature on neurotoxicity of amphetamines, you basically don't see any until you start getting to the equivalent of 50-100mg IR, and even then it's basically within the noise floor until you get to hundreds of mg per day.