Ceftazidime

Ceftazidime (INN) (pronounced /sɛfˈtæzɨdiːm/, /kɛf-/) is a third-generation cephalosporin antibiotic. Like other third-generation cephalosporins, it has broad spectrum activity against Gram-positive and Gram-negative bacteria. Unlike most third-generation agents, it is active against Pseudomonas aeruginosa, however it has weaker activity against Gram-positive microorganisms and is not used for such infections. Ceftazidime pentahydrate is marketed under various trade names including Fortum (GSK).

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Clinical use

Main article: Cephalosporin

Ceftazidime is usually reserved for the treatment of infections caused by Pseudomonas aeruginosa. It is also used in the empirical therapy of febrile neutropenia, in combination with other antibiotics. The usual dose is 1–2 g IV/IM every 8–12 hours(2 - 3times), though this can vary by the indication, infection severity, and/or renal function of the recipient.

Ceftazidime overdosage has occurred in patients with renal failure. Reactions have included seizure activity, encephalopathy, asterixis, neuromuscular excitability, and coma. Ceftazidime is a semisynthetic, broad-spectrum, beta-lactam antibiotic for parenteral administration. Ceftazidime is bactericidal in action exerting its effect by inhibition of enzymes responsible for cell-wall synthesis. A wide range of gram-negative organisms is susceptible to ceftazidime in vitro, including strains resistant to gentamicin and other aminoglycosides. In addition, ceftazidime has been shown to be active against gram-positive organisms. It is highly stable to most clinically important beta-lactamases, plasmid or chromosomal, which are produced by both gram-negative and gram-positive organisms and, consequently, is active against many strains resistant to ampicillin and other cephalosporins. Ceftazidime has activity against the gram-negative organisms Pseudomonas and Enterobacteriaceae. Its activity against Pseudomonas is a distinguishing feature of ceftazidime among the cephalosporins.

Chemistry

In addition to the syn-configuration of the imino side chain, compared to other third-generation cephalosporins, the more complex moiety (containing two methyl and a carboxylic acid group) confers extra stability to β-lactamase enzymes produced by many Gram-negative bacteria. The extra stability to β-lactamases increases the activity of ceftazidime against otherwise resistant Gram-negative organisms including Pseudomonas aeruginosa. The charged pyridinum moiety increases water-solubility.