If penicillin had been tested on guinea pigs, it might never have reached the public. It is lethal to guinea pigs and other animals. In fact, many important strides have been made in human health without the use of testing on animals.
These include the discovery of drugs such as digitalis, nitrite, quinine and penicillin; anaesthetics such as chloroform, ether and nitrous oxide gas; surgical procedures for cardiac aneurysm, appendicitis, brain tumors, cataracts, and bladder and gall stones. Even the link between cancer and smoking in humans was
discovered without the use of animals.