Penicillins are a class of beta-lactam antibiotics. Penicillin was the first antibiotic discovered from the mold Penicillium notatum in 1928 by Alexander Fleming at St. Mary’s Hospital in London, England.

The basic structure of penicillins is a nucleus consisting of a beta-lactam ring (4 membered cyclic amide) and a side chain. The beta-lactam ring is necessary for antibacterial activity, and the side chain determines the antibacterial spectrum and pharmacologic properties.

Various penicillins differ mainly by the structure of the side chain. In addition to their structural differences, the penicillins differ in their antimicrobial spectrum, pattern of β-lactamase resistance (susceptibility to penicillinase), the ability to penetrate the outer membrane of gram-negative bacteria, stability to gastric acids, and their behavior within the body.

Penicillins are generally bactericidal, inhibiting formation of the cell wall. Penicillins are used to treat skin infections, dental infections, ear infections, respiratory tract infections, urinary tract infections, gonorrhea.

There are different types of Penicillin Antibiotic products: