Cloxacillin is a semisynthetic antibiotic in the same class as penicillin. It is sold under a number of trade names, including Cloxapen (R) and Orbenin (R).

Cloxacillin is for use against staphylococci that produce beta-lactamase.

Molecular formula: C19H17ClN3O5S*Na*H2O

Molecular weight: 475.9

CAS registry no.: 7081-44-9