Available only in generic form, nafcillin is an antibiotic used to treat a variety of bacterial infections. It comes as an injection that is given intravenously (by IV) or into a muscle (IM injection) two to six times a day. While most people tolerate this medicine well, side effects are possible and may include allergic reactions or irritation at the site of the injection.
Nafcillin sodium is a prescription antibiotic licensed to treat a number of different infections. Specifically, it is used for infections caused by staphylococci bacteria that produce penicillinase (an enzyme than can destroy penicillin). It is given either intravenously (by IV) or injected into a muscle (IM injection).
Nafcillin is available only as a generic product and is made by various manufacturers (see Generic Nafcillin for more information).
Nafcillin is a penicillin antibiotic. Penicillins are a part of a larger group of medications known as beta-lactam antibiotics, which are named after the ring-like "lactam" structure of these antibiotics. Nafcillin works by stopping bacteria from making cell walls, which eventually causes the bacteria to die.
More specifically, nafcillin is a penicillinase-resistant penicillin. Some bacteria produce penicillinase, an enzyme which destroys the beta-lactam structure of penicillin (making penicillin and other similar antibiotics ineffective for treating infections due to such bacteria). Nafcillin is resistant to penicillinase.
However, such bacteria (notably, methicillin-resistant Staphylococcus aureus, or MRSA) have developed resistance against nafcillin and other penicillinase-resistant penicillins. Nafcillin is ineffective against MRSA.