Information about Penicillins
The aminopenicillins (sometimes referred to as third generation penicillins) are semisynthetic modifications of natural penicillin that have the advantage of a broader spectrum of activity. Like the natural penicillins, aminopenicillins have a thiazolidine ring structure connected to a beta-lactam ring which makes these agents susceptible to inactivation by beta-lactamase, the usual cause of bacterial resistance to the penicillins. The aminopenicillins, like the natural first generation penicillins, bind to bacterial proteins and inhibit synthesis of the bacterial cell wall, causing cell lysis particularly in rapidly growing organisms. The aminopenicillins are widely used for therapy of mild-to-severe urinary, respiratory, gastrointestinal tract, skin, bone and joint infections. They have activity against Escherichia coli, Hemophilis influenzae, Listeria monocytogenesis, Neisseria gonorrhoeae, Proteus mirabilis, Salmonella, Shigella, Staphylococcus aureus (non-penicillinase producing), Staphylococcus aureus, and Streptococcus pneumoniae.
Two third generation penicillins are available in the United States: ampicillin (am" pi sil' in) and amoxicillin (a mox" i sil' in). Ampicillin is also used as a combination antibiotic with sulbactam (sul bak' tam) sodium which provides coverage against penicillinase-resistant bacteria. The references for ampicillin, amoxicillin and ampicillin/sulbactam are given together at the end of this Overview section, because they are rare causes of acute liver injury and appear to share a common pattern of associated liver injury. Typical hepatotoxicity due to the aminopenicillins resembles that of the first generation penicillins. The typical presentation is a cholestatic hepatitis arising 2 to 4 weeks after starting the antibiotic and sometimes 1 to 2 weeks after stopping a limited course. The injury is usually mild-to-moderate in severity, although fatal cases of acute liver failure have been described, and there have been several reports of vanishing bile duct syndrome or prolonged cholestasis following amoxicillin or ampicillin related cholestatic liver injury.
In addition, amoxicillin is commonly used in combination with the beta-lactamase inhibitor clavulanic acid. Amoxicillin/clavulanate is one of the most frequent causes of drug induced liver disease, but the liver injury is usually attributed to the clavulanate rather than the aminopenicillin, and the pattern of injury may be slightly different than that described with penicillin, ampicillin and amoxicillin alone. For these reasons, amoxicillin/clavulanate is discussed separately and references are provided with that discussion.
Bacampicillin and pivampicillin are two aminopenicillins that are not available in the United States. References regarding ampicillin, amoxicillin and ampicillin/sulbactam hepatotoxicity are given below.
List of third generation Penicillins
- penicillins first generation (natural penicillins)
- penicillins second generation (penicillinase-resistant penicillins)
- penicillins third generation (aminopenicillins)
- see also amoxicillin-clavulanate
- penicillins fourth generation (extended-spectrum penicillins)