“Dextromethamphetamine” is the only real psychoactive isomer of meth so of course that’s what he has. That isn’t meths “intended” purpose. It was way back then. Now the only accepted medical need for it is ADHD and in extremely rare cases short term for obesity. Jesus Christ.
1 While dextromethamphetamine is what gets you high from meth by releasing dopamine to a lesser extent serotonin (which is why it's a functional drug) it's not true that is what he has. This is because when ephedrine and pseudoephedrine were heavily restricted groups started to use P2P as their replacement to manufacture meth which makes racemic meth and not d-meth like ephedrine and pseudoephedrine do.
Mexico's precursor chemical controls: Emergence of less potent types of methamphetamine in the United States
• With a P2P-associated change in isomers, methamphetamine potency should change as well. Mendelson et al. (2006) compared d-methamphetamine, l-methamphetamine, racemic methamphetamine and a placebo regarding ability to produce intoxication and a “high.” Twelve methamphetamine abusers received intravenous administrations of each in a 6-session, double-blind, balanced crossover design. Using a 100-point scale, the subjects assigned ratings for intoxication resulting in the following mean scores: d-methamphetamine: 46.0 (SD 35.3); l-methamphetamine: 30.3 (24.9); racemic methamphetamine: 24.7 (27.4); and placebo 1.7 (4.7). The mean scores for a “high” were d-methamphetamine: 46.5 (SD 35.0); l-methamphetamine: 31.0 (25.9), racemic methamphetamine: 25.4 (28.4); and placebo 1.5 (3.7).
• The ratings for d-methamphetamine were significantly higher than all other conditions, while the placebo's ratings were significantly lower than all other conditions. Racemic methamphetamine ratings were below those for l-methamphetamine, but the difference was not statistically significant. These findings indicate that l-methamphetamine and racemic methamphetamine both produce intoxication and a high, but neither is as potent as d-methamphetamine. They also indicate that although racemic methamphetamine includes the more potent d-methamphetamine, racemic methamphetamine's potency is no greater than that of l-methamphetamine, and possibly less"
https://www.sciencedirect.com/science/article/abs/pii/S0376871612003961
2 Using dextromethamphetamine as a functional drug to help people function better and longer at work/physical exercise was it's first large scale intended legal purpose. That's why it was used by countries during ww2 and given to their soldiers to help them function better just like amphetamine was used by the allies for the same purpose. It was also later used for fat loss, depression, and by people who wanted to improve their performance in sport. It was only when the racist war on drug's started and it got heavily restricted that it got mainly used for adhd