Cefotaxime (3rd gen)

Cefotaxime

Mechanism of action Inhibits enzymes involved in formation of peptidoglycan layer of bacterial cell wall
No effect on human cell walls
Bactericidal; only works on dividing bacteria
More resistant than 1st generation to ß-lactamases
More effective against Gram -ves than 2nd generation, but less active against S. aureus
Good tissue distribution, including bone, soft tissue and muscle
3rd generation cephalosporin

Half-life 1 hour

Elimination Rapid clearance from plasma due to active secretion into renal tubular fluid - can be blocked by probenecid; forms desacetyl metabolite

Indications Infections due to sensitive Gram +ve and Gram -ve bacteria
Soft tissue infections e.g. S. pyogenes
S. pneumoniae, M. catarrhalis, H. influenzae including community aquired pneumonia
Also active against E. coli - urinary tract (inc. pyelonephritis) and abdominal infections
Enterobacteriaceae
Meningitis e.g. H. influenzae
Septicaemia
Surgical prophylaxis

Preparations and dosage
These may be out of date or wrong. i.m./i.v. 1g every 12 hours
Meningitis - 8g i.v. daily in 4 divided doses

Side effects
Allergic reactions
- itching, rashes, fever
- angioneurotic oedema
- anaphylaxis (1 in 50,000 to 100,000)
Cross-allergy with other cephalosporins
Partial cross-allergy with penicillins (10%)

Diarrhoea, nausea and vomiting
Rashes, pruritus, urticaria
Serum-sickness-type reactions with fever, rashes, arthralgia
Erythema multiforme; toxic epidermal necrolysis
Disturbed LFTs, transient hepatitis, cholestatic jaundice
Eosinophilia
Thrombocytopenia, leucopenia, agranulocytosis, aplastic anaemia, haemolytic anaemia
Reversible intersititial nephritis
Sleep disturbances; dizziness

Interactions Loop diuretics may increase nephrotoxicity
Uricosurics - probenecid reduces excretion
May increase anticoagulant effect of warfarin

Cautions and monitoring Penicillin hypersensitivity
Renal impairment
Pregnancy and breast feeding (still OK to use)
False positive urinary glucose
False positive Coomb's test

Contraindications Cephalosporin hypersensitivity
Porphyria

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Mechanism of action	Inhibits enzymes involved in formation of peptidoglycan layer of bacterial cell wall No effect on human cell walls Bactericidal; only works on dividing bacteria More resistant than 1st generation to ß-lactamases More effective against Gram -ves than 2nd generation, but less active against S. aureus Good tissue distribution, including bone, soft tissue and muscle 3rd generation cephalosporin
Half-life	1 hour
Elimination	Rapid clearance from plasma due to active secretion into renal tubular fluid - can be blocked by probenecid; forms desacetyl metabolite
Indications	Infections due to sensitive Gram +ve and Gram -ve bacteria Soft tissue infections e.g. S. pyogenes S. pneumoniae, M. catarrhalis, H. influenzae including community aquired pneumonia Also active against E. coli - urinary tract (inc. pyelonephritis) and abdominal infections Enterobacteriaceae Meningitis e.g. H. influenzae Septicaemia Surgical prophylaxis
Preparations and dosage These may be out of date or wrong.	i.m./i.v. 1g every 12 hours Meningitis - 8g i.v. daily in 4 divided doses
Side effects	Allergic reactions - itching, rashes, fever - angioneurotic oedema - anaphylaxis (1 in 50,000 to 100,000) Cross-allergy with other cephalosporins Partial cross-allergy with penicillins (10%) Diarrhoea, nausea and vomiting Rashes, pruritus, urticaria Serum-sickness-type reactions with fever, rashes, arthralgia Erythema multiforme; toxic epidermal necrolysis Disturbed LFTs, transient hepatitis, cholestatic jaundice Eosinophilia Thrombocytopenia, leucopenia, agranulocytosis, aplastic anaemia, haemolytic anaemia Reversible intersititial nephritis Sleep disturbances; dizziness
Interactions	Loop diuretics may increase nephrotoxicity Uricosurics - probenecid reduces excretion May increase anticoagulant effect of warfarin
Cautions and monitoring	Penicillin hypersensitivity Renal impairment Pregnancy and breast feeding (still OK to use) False positive urinary glucose False positive Coomb's test
Contraindications	Cephalosporin hypersensitivity Porphyria