Penicillin is an antibacterial agent, which has a broad spectrum effect on various bacteria. The antibacterial action is selective for group of organism mainly gram positive groups. Penicillin is produced by fungi of genus Penicllium notatum. The penicillin shows antibacterial action by rupturing the cell wall of growing bacterial cells.
Penicillin is replaced by its analogue because of certain drawbacks. The drawback includes acid sensitivity, resistant of certain bacterial species against the action of penicillin. Thus, semi synthetic penicillin was formed to cope up penicillin drawbacks.
One of those was methicillin, which found to be one of the ideal drugs. It showed a broad spectrum of activity, but the drug is no longer in use. The methicillin drug has β-lactamase activity and found to show action against various species of bacteria.
The methoxy group of methicillin when replaced by an ethoxy group show few added functions, which are found to be a drawback in methicillin. This semisynthetic drug is named as nafcillin.