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 second generation cephalosporins here, you can find the other generations in the links below:
- First-Generation Cephalosporins
- Second-Generation Cephalosporins
- Third-Generation Cephalosporins
- Fourth-Generation Cephalosporins
- Fifth-Generation Cephalosporins
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 2nd Generation Cephalosporins?
Second generation cephalosporins are members of the β-lactam class of antibiotics; a class of drugs defined by the presence of the β-lactam ring.
Like other beta-lactams, cephalosporins are bactericidal in effect – meaning that they actively kill bacteria rather than merely suppressing their growth (an effect that defines bacteriostatic antibacterials).
Second generation cephalosporins include drugs such as:
In contrast to their third-generation counterparts, there are only four main second generation cephalosporins to remember. These four drugs are consistently named, in that they contain the letter ‘f’ – cefprozil, cefotetan, cefuroxime and cefaclor.
Helpful mnemonics, too, can assist: ‘Fox for tea with Prozac – Cefuroxime, Cefaclor, Cefotetan, Cefprozil’. The more bizarre the mnemonic, the better. If you struggle to associate the mnemonic with the second-generation, think of two Prozac’s instead.
Spectrum of Activity
Second generation cephalosporins have broad-spectrum of activity. Let’s review some of their main pharmacological features:
- They have less activity against Gram-positive organisms when compared to the first generation.
- They have more activity against Gram-negative organisms than their first-generation counterparts. This includes HEN: Haemophilus influenzae, Enterobacter aerogenes, and some strains of Neisseria.
- This is on top of their activity against PEcK (first-generation activity): Proteus mirabilis, some Escherichia coli and Klebsiella pneumoniae.
- Cefuroxime is a notable exception to other second-generation members, in that it can cross the blood-brain barrier.
- Cefuroxime is also acid-labile, meaning it must be taken via a parenteral route – such as by intravenous or intramuscular administration. However, it is also available as an oral prodrug (cefuroxime axetil) which is hydrolysed at first-pass metabolism to the active ingredient, cefuroxime.
Unwanted effects with this class are similar with other generations.
Side effects include diarrhea, nausea and vomiting. Some patients also experience dizziness, headache and abdominal pain. The propensity of each effect depends on the drug in question.
Check out the links at the top of this page for more information on the pharmacology of the remaining cephalosporin generations.