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Pharmacology · Beta-lactams

Cefixime !

A third-generation oral cephalosporin for urinary infections, pharyngitis, otitis and uncomplicated gonorrhoea.

Updated 2026-11-01

  • Class: Beta-lactams
  • Enzyme: Penicillin-binding protein 2 (PBP2) and other PBPs
  • ATC code: J01DD08
  • WHO Model List of Essential Medicines

The figure shows the transpeptidase domain of Neisseria gonorrhoeae PBP2 acylated by cefixime, bonded to the active-site serine.

Target in 3D: Penicillin-binding protein 2 (PBP2) and other PBPs. PDB structure 6P55 (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Cefixime acylates the PBPs and stops peptidoglycan cross-linking. As a third-generation cephalosporin it is stable to many β-lactamases and active against Haemophilus, Moraxella, Neisseria gonorrhoeae and enteric bacteria such as E. coli and Proteus. It is less active against S. aureus and does not cover Pseudomonas. Changes in gonococcal PBP2 (penA gene) can lower its affinity for cephalosporins.

  1. Absorbed orally and reaches mucosa and urine
  2. Acylates gonococcal PBP2 and the PBPs of enteric bacteria
  3. Peptidoglycan cross-linking stops
  4. The bacterium lyses

Pharmacokinetics

Absorption
Oral; partly absorbed, with or without food.
Elimination
About half of the absorbed drug leaves unchanged in the urine; adjusted in kidney failure.
Half-life
3 to 4 hours on average; longer in kidney failure.

Indications

Adverse effects

Common

  • Diarrhoea and loose stools
  • Abdominal pain, nausea, flatulence
  • Rash

Contraindications

  • Known allergy to cefixime or other cephalosporins

Key interactions

Carbamazepine
Raised carbamazepine levels have been reported; its concentrations are monitored.
Warfarin and other anticoagulants
Raised prothrombin time, with or without bleeding.

What is monitored

  • Clinical response
  • INR if the patient takes warfarin
  • Kidney function in kidney failure

Administration and safety

  • Oral, with or without food.
  • Shake the suspension before use; the different presentations are not always interchangeable.
  • Do not confuse cefixime with cefuroxime or ceftriaxone.

Nursing care

  • Before the first dose: ask about allergy to penicillins, cephalosporins and other β-lactams, and what the reaction was.
  • Teach the patient to report watery or bloody diarrhoea, even weeks after the course ends.
  • In gonorrhoea, stress testing and treatment of sexual partners and screening for other sexually transmitted infections.

Pregnancy and breastfeeding

Animal studies showed no fetal harm and there are no controlled studies in pregnant women; used if clearly needed.

Test yourself

Think of the answer, then tap the question to see it.

Which gonococcal gene is linked to resistance to cefixime and ceftriaxone?

The penA gene, which encodes PBP2; its variants can lower the affinity for cephalosporins.

Does cefixime cover Pseudomonas aeruginosa?

No. Among third-generation cephalosporins, useful antipseudomonal activity belongs to ceftazidime.

What sets cefixime apart from ceftriaxone in practice?

Both are third generation, but cefixime is oral and reaches lower levels; ceftriaxone is parenteral.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: Cefixime: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); DailyMed - CEFIXIME capsule (DailyMed (U.S. National Library of Medicine), 2026); RCSB PDB - 6P55: Crystal structure of transpeptidase domain of PBP2 from Neisseria gonorrhoeae acylated by cefixime (RCSB Protein Data Bank, 2026); Farmacología básica y clínica (Katzung), cap. 43 (McGraw Hill, 2025).

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Representative model, for educational purposes only.