White, fine crystals or powder; odorless;
relatively stable to air and light; solutions dextroro-
tatory. Sparingly soluble in water; slightly soluble
in alcohol; fairly soluble in chloroform.
There was added to 250 ml of a concentrated butyl acetate extract containing 74,000 units of the acid form of penicillin per ml, 50 ml of a butyl acetate solution containing 0.238 g per ml of procaine base. The solution was agitated for one hour. The precipitate which formed was very gummy and not in the form of discrete crystals. This precipitate was crystallized by scratching the side of the vessel and agitating further. After this treatment 18.25 g of crystalline procaine penicillin was obtained which assayed 1010 units per mg representing a yield of 99.6% of the activity contained in the concentrated extract.
Duracillin(Lilly); Pfizerpen (Pfizer).
The first widely used amine salt of penicillin G wasmade with procaine. Penicillin G procaine (Crysticillin,Duracillin, Wycillin) can be made readily from penicillin Gsodium by treatment with procaine hydrochloride. This saltis considerably less soluble in water than the alkali metalsalts, requiring about 250 mL to dissolve 1 g. Free penicillinis released only as the compound dissolves and dissociates.It has an activity of 1,009 units/mg. A large number ofpreparations for injection of penicillin G procaine are commerciallyavailable. Most of these are either suspensions inwater to which a suitable dispersing or suspending agent, a buffer, and a preservative have been added or suspensions inpeanut oil or sesame oil that have been gelled by theaddition of 2% aluminum monostearate. Some commercialproducts are mixtures of penicillin G potassium or sodiumwith penicillin G procaine; the water-soluble salt providesrapid development of a high plasma concentration of penicillin,and the insoluble salt prolongs the duration of effect.
Moderately toxic by intraperitoneal and intramuscular routes. Slightly toxic by ingestion and subcutaneous routes. When heated to decomposition it emits toxic vapors of NOx, and SOx.
