Green’s Dictionary of Slang

1. money.

1959

E. De Roo Young Wolves 118: How come you gotta say ‘money’? Can’tcha be modern and say ‘vitamins’ or ‘bread’ or somethin’ like that?

2. (drugs) any drugs available in pill or capsule form.

1980

E. Folb Runnin’ Down Some Lines 169: Both barbiturates and amphetamines were referred to as [...] vitamins.