Benzathine penicillin G is a long-acting formulation that is available as Pure benzathine penicillin A mixture of equal amounts of benzathine and procaine penicillin G A 3: 1 mixture of 0.9 million units benzathine and 0.3 million units procaine penicillin G Of the 3 products, only pure benzathine penicillin is recommended for treating syphilis and preventing rheumatic fever.