antibioticsbooks

Penicillins
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Introduction to Penicillins
Penicillins are one of the largest and oldest classes
of antimicrobial agents. Since the development
of the natural penicillins in the 1930s, further
penicillin development has been directed by the
need to combat increasing antimicrobial resistance.
Classes of penicillins with expanded Gramnegative
spectra overcome the shortfalls of natural
penicillins, and they can be grouped fairly easily by
spectrum of activity.
Penicillins have several things in common:
• Penicillins have very short half-lives (< 2 hours)
and must be dosed multiple times per day. The
half-lives of most of them are prolonged in the
presence of renal dysfunction.
• Like other beta-lactams, penicillins can cause
hypersensitivity reactions. If a patient has a
true hypersensitivity reaction to a penicillin,
other penicillins should be avoided, even if they
are from different subclasses of penicillins. If
the reaction is not severe, cephalosporins or
carbapenems may be useful.
• Many penicillins are relatively poorly absorbed,
even those available as oral formulations.
This can lead to diarrhea when oral therapy
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