Penicillin, Procaine
4-Thia-1-azabicyclo(3.2.0)heptane-2-carboxylic acid, 3,3-dimethyl-7-oxo-6-((phenylacetyl)amino)- (2S-(2alpha,5alpha,6beta))-, compd. with 2-(diethylamino)ethyl 4-aminobenzoate (1:1), monohydrate