UNDER REVIEW (September 2016)
Mechanism of Action:
A cephalosporin. Cephalosporins are betalactams and work the same way as penicillins – they interfere with the peptidoglycan synthesis of the bacterial wall by inhibiting the final transpeptidation needed for the cross-links. This effect is bactericidal.
Lecture and CAL materials:
- Lecture: Antimicrobials 3: Other Antimicrobial Agents
- Lecture: Antimicrobials I: Antibiotics
- Lecture: Antimicrobials 2: Resistance and Control
Drug specifics
| Alternative drug name | Keflex ® |
| Effects | Bactericidal against most Gram positive cocci (but enterococci are always resistant) and bacilli – newer drugs have a broader spectrum of activity. Used for chest infections, urinary tract infections and others (see below). |
| Adverse actions | There are similarities between the adverse effects of cephalosporins and those of the penicillins including hypersensitivity (eg rashes, urticaria, eosinophilia, fever), nephrotoxicity, hepatitis and cholestatic jaundice, and antibiotic-associated (pseudomembranous) colitis. These adverse effects are uncommon and not dose-related, and cephalosporins are among the safest antimicrobials. See eBNF. |
| Dose | 250mg qds oral (see BNF for other drugs). |
| Interactions | The nephrotoxic effects of first generation cephalosporins are increased by concurrent treatment with other nephrotoxic drugs, such as furosemide (frusemide). See eBNF. |
| Contraindications | not specified |
| Comments | Cephalosporins are semisynthetic antimicrobials derived originally from the mould Cephalosporium acremonium. They are characterized by a common chemical nucleus (7-aminocephalosporanic acid), which, like penicillins, includes a beta-lactam ring. Classification can be confusing. It is best to become familiar with a few agents (eg cefalexin, cefuroxime, cefotaxime and ceftazadime). They can be classified broadly according to their age as chemical entities, into first generation (eg cefazolin, cefradine, cefalexin, cefaclor), second generation (eg cefamandole, cefuroxime) and third generation (eg cefotaxime, ceftriaxone, ceftazidime). Other agents with betalactam rings include cephamycins (eg cefoxitin), carbapenems (eg imipenem, meropenem), and monobactams (eg aztreonam). ‘First generation’ cefalosporins are active against Gram positive organisms, including those that produce beta-lactamase, but have only modest activity against Gram negative organisms, and are ineffective against enterococci. Subsequent generations displayed progressively increasing activity against Gram negative organisms but decreasing activity against Gram positive organisms, despite having greater resistance to beta-lactamase. Cephamycins benefit from greater activity than other drugs against anaerobes, whereas carbapenems have the broadest spectrum of activity of all drugs in this group. Monobactams, however, are active only against Gram negative organisms. Because of their broad spectrum of activity, there are numerous indications for the use of cephalosporins in the treatment of bacterial infection. A few (eg cefradine) can be given both by mouth and by injection, but most have to be given either by mouth (eg cefalexin) or parenterally (eg cefotaxime). |
| Contributors |
eDrug by