The Most Expensive Liquids In The World Penicillin is a large group of antibiotics that include penicillin V, penicillin G, benzathine penicillin, and procaine penicillin. Penicillin is mainly used to treat different infections. 14. Penicillin — $226 per gallon « Previous Page Next Page » Pages: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 2017-11-01 news