Cephalosporins
Cephalosporins are β-lactam antibiotics structurally and mechanistically similar to penicillins, but with broader activity and greater resistance to β-lactamases. They are widely used for a variety of bacterial infections.
Pharmacodynamics
- Cephalosporins bind to Penicillin-Binding Proteins (PBPs).
- Inhibit transpeptidation, preventing cross-linking of peptidoglycan in the bacterial cell wall.
- Leads to autolysin activation, which causes cell wall degradation and bacterial lysis.
- Bactericidal action.
Pharmacokinetics
- Most are not metabolized extensively.
- Primarily renally excreted (adjust in renal impairment).
- Ceftriaxone is biliary excreted – preferred in renal failure.
- 3rd gen and higher penetrate the CNS well.
Side Effects
Common:
- Nausea, vomiting, diarrhea
- Rash, allergic reactions
Rare but serious:
- Anaphylaxis
- Stevens-Johnson Syndrome / TEN
- Hemolytic anemia
- Interstitial nephritis
- Seizures (especially in renal failure)
Therapeutic Uses
- Respiratory infections: Sinusitis, bronchitis, pneumonia
- Ear infections: Otitis media
- STIs: Gonorrhea (ceftriaxone is first-line)
- Intra-abdominal infections
- Sepsis / Bacterial septicemia
- Endocarditis
- Lyme disease (ceftriaxone in neuroborreliosis)
Used in:
- Community-acquired and hospital-acquired infections
- Surgical prophylaxis (esp. 1st and 2nd gen)