It isn't exactly obscure, but my doctor changed my prescription to 120 15mg Dexedrine spansules instead of 120 10mg spansules. 60mg a day is the highest recommended dose of extended release dextroamphetamine.
Dexedrine Spansule (Dextroamphetamine) 15mg capsule - Family Fare Pharmacy
Dexedrine vs. Adderall: Comparing ADHD medications