Monday, February 18, 2008

How Do Drugs Work - Cephalosporins

Hello Everyone,

The last post covered the first group of antibiotics, the penicillins. This post will cover the cephalosporins.

The cephalosporins are similar to the penicillins in that both contain an chemical structure called a beta-lactam ring.

The cephalosporins are classified by generation (1st - 4th generation) based on the types of bacteria they are active against (their spectrum of activity).

Here is a list of the cephalosporins:

1st Generation
• Cefazolin (Ancef, Kefzol)
• Cephalexin (Keflex)

2nd Generation
• Cefuroxime (Ceftin, Zinacef)
• Cefotetan (Cefotan)

3rd Generation
• Cefpodoxime (Vantin)
• Cefotaxime (Claforan)
• Ceftazidime (Tazicef)
• Ceftriaxone (Rocephin)

4th Generation
• Cefepime (Maxipime)

Generally speaking, the 1st and 2nd generation cephalosporins are active against gram positive organisms while the 3rd and 4th generation have activity against both gram positive and gram negative organisms.

The cephalosporins work the same way the penicillins do; they inhibit the formation of the bacterial cell wall.

Since the cephalosporins are structurally related to the penicillins, if a patient has a true penicillin allergy, they may also be allergic to the cephalosporins. The actual rate of cross-sensitivity is not well defined. Therefore if a patient has a penicillin allergy (anaphylaxis, urticaria or angioedema) the cephalosporins should be avoided.

For more information on cephalosporins, please check out:

Please let me know if you have any questions or comments.

Stay Well,

Dr. Paul

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