0
Yes, theophylline and caffeine (and the closely related theobromine) are drugs. Relatively mild ones, but they do act as stimulants.
theophylline
Aminophylline dose * 0.8 = Theophylline dose
Herbert Weinfeld has written:
'A study of metabolism of caffeine and theophylline' -- subject(s): Caffeine, Theophylline, Metabolism
shunga