Cefradine Other names: Cephradine

Chemical formula: C₁₆H₁₉N₃O₄S  Molecular mass: 349.405 g/mol  PubChem compound: 38103

Mechanism of action

Cefradine is a broad-spectrum, bactericidal first generation cephalosporin antibiotic active against both Gram-positive and Gram-negative bacteria. It is also highly active against most strains of penicillinase producing Staphylococci. The anti-bacterial action of cefradine is through inhibition of bacterial cell wall synthesis, probably by acylation of membrane – bound transpeptidase enzymes. This prevents cross-linkage of peptidoglycan chains which is necessary for bacterial cell wall strength and rigidity.

Pharmacodynamic properties

Susceptibility

The following organisms have shown in vitro sensitivity to cefradine.

Gram-positive Aerobes: Staphylococci (both penicillin sensitive and resistant strains), Streptococci, Streptococcus pneumoniae and Streptococcus pyogenes (beta haemolytic).

Gram-negative Aerobes: Escherichia coli, Haemophilus influenzae, Klebsiella spp, Neisseria spp., Proteus mirabilis, Salmonella spp.(including Salmonella typhi) and. Shigella spp.

Because cefradine is unaffected by penicillinase, many strains of Escherichia coli and Staphylococcus aureus which produce this enzyme are susceptible to cefradine but resistant to ampicillin.

Insusceptible microorganisms

The prevalence of resistance may vary geographically and with time for selected species and local information on resistance is desirable, particularly when treating severe infections.

In general, bacterial resistance to cephalosporins usually results both from the production of a β-lactamase and the presence of permeability barriers to the drug.

Pharmacokinetic properties

Absorption

Cefradine has a high degree of stability to many beta-lactamases. It has a low degree of protein binding and a large volume of distribution. Therefore, tissue levels are generally found to be high. Oral cefradine can be given twice or four times daily and is well absorbed. Cefradine is acid stable and is rapidly absorbed following oral administration in the fasting state.

Distribution

Following doses of 250mg, 500mg and 1000mg average peak serum levels of approximately 9, 16.5, and 24.2 micrograms/ml, respectively, were obtained at one hour. The presence of food in the gastrointestinal tract delays the absorption but does not affect the total amount of cefradine absorbed. Measurable serum levels are present six hours after administration.

Elimination

Over 90% of the drug is excreted unchanged in the urine within 6 hours. Peak urine concentrations are approximately 1600 micrograms/ml following a 250mg dose, 3200 micrograms/ml following a 500mg dose, and 4000 micrograms/ml following a 1000mg dose. After 48 hours administration of 100mg/kg/day of cefradine for the treatment of otitis media, cefradine has been measured in the middle ear exudate at an average level of 3.6 microgram/ml.

Preclinical safety data

No further data.

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