Cephalosporin generations have confused tens of thousands of students; their names and individual characteristics proving to be nothing other than a nexus of confusion. Here, we go some way toward clarifying what is otherwise an arcane subject.

Whilst we are examining third generation cephalosporins here, you can find the other generations in the links below:

Each review goes through the main examples of each class, their pharmacology, what differentiates them from earlier and later classes, as well as assessing some of the main side effects and drug interactions associated with each generation.

What are 3rd Generation Cephalosporins?

Third generation cephalosporins are, like their predecessors and successors, members of the beta-lactam class of antibacterial drugs.

Like penicillins, cephalosporins are bactericidal in effect – meaning that they actively kill bacteria rather than merely suppressing their growth (an effect that defines bacteriostatic antibacterials).

Third generation cephalosporins include drugs such as:

  • Cefdinir
  • Cefixime
  • Cefotaxime
  • Cefovecin
  • Ceftriaxone
  • Ceftazidime

Many third generation cephalosporins are easy to remember. The ‘t’ in their name – whether it be ceftazidime, ceftriazone, or cefotaxime – give you a clear indication that they belong to the third generation.

Third-Generation Cephalosporins

This list of cephalosporins also has something for ‘x’ in their names: ‘cefixime’, ‘cefotaxime’, and ‘ceftriaxone’. Others, such as cefdinir and cefovecin, need to be committed to memory via other means. Think of ‘third vegan dinner’ – ‘third gen: cefovecin cefdinir’.

Spectrum of Activity

Third generation cephalosporins have a broad-spectrum of activity. Let’s review some of their main pharmacological features:

  • They have greater activity against Gram-negatives when compared to their first and second generation counterparts.
  • Some members of this class, such as ceftazidime, have notable antipseudomonal properties.
  • They can penetrate the central nervous system, meaning they are useful against meningitis caused by a wide variety of organisms.
  • Cefovecin is a cephalosporin used to treat skin infections in cats and dogs.
  • Many third-generation drugs are acid labile, meaning they must be given via parenteral routes. This includes cefotaxime and ceftriaxone.
  • Avibactam is a non-β-lactam beta-lactamase inhibitor used in combination with ceftazidime in the treatment of complicated UTIs and intra-abdominal infections.

Unwanted effects with this class are similar with other classes.

Side effects include nausea, vomiting, abdominal discomfort and diarrhea. Some injections, such as ceftriaxone, are known to be particularly painful.

Check out the links at the top of this page for more information on the pharmacology of the remaining cephalosporin generations.

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