Lactam

In chemistry, a lactam is a cyclic amide. The name is derived from two chemical terms, lactone, referring to a cyclic ether, and amide, a compound containing a nitrogen atom next to a carbonyl group. Lactams are names according to the size of the cyclic ring in the lactam: $\alpha$-lactams, $\beta$-lactams, $\gamma$-lactams and $\delta$-lactams contain rings made of three, four, five and six atoms, respectively. $\alpha$-lactams are also called aziridinones. Many widely used antibiotic drugs, penicillins and cephalosporins owe their activity to the presence of a $\beta$-lactam.