Desoxyn and Tolerance

[nleksan]

SWIM is prescribed 4 5mg Desoxyn tablets a day (total of 20mg orally/day) and has been taking them for 6 months, and before that was taking 15-25mg dextroamphetamine daily for 6 months. For 5 years prior he was on a mix of Adderall (racemic amphetamine) and Concerta/Ritalin (methylphenidate).

SWIM is wondering how much this has upped his tolerance should he ever decide to use methamphetamine recreationally. This is purely a hypothetical question as he does not wish to decrease the medication's effectiveness for it's prescribed purpose. But, curiosity being what it is, SWIM wonders what the doses would be for various other MOAs considering he has somewhat of a tolerance.

Specifically:
Insufflated -
Smoked -
Intravenous -

Thanks in advance for your opinions.