Here is a list of medical ingredients from a popular enrgy drink;
Paulliania cupana (guarana) seed extract standardized to %8 caffeine 94.6 mg
vitamin C (absorbic acid 113.5 mg
taurine 1892 mg
insitol 189.2 mg
creatine monohydrate or derivatives 47.3 mg
I-arginine 18.9 mg
grape seed extract 47.3 mg
vitamine B6 (pyridoxine hydrochloride) 3.8 mg
vitamine B12 (cyanocobalamin) 11.4 mcg
selenium (hydrolysed vegtebale Protine Chelate) 33.1 mg
caffine 143.8 mg
After this you can add any flavour or sweetner you like.
Let me know if you can duplicate this?