Third-generation agents

Third-generation agents include cefoperazone, cefotaxime, ceftazidime, ceftizoxime, ceftriaxone, cefixime, cefpodoxime proxetil, cefdinir, cefditoren pivoxil, ceftibuten, and moxalactam. 

Tricyclics and the second- and third-generation agents differ mainly in the degree of sedation they produce (greatest with amitriptyline, doxepin, trazodone, and mirtazapine) and their antimuscarinic effects (greatest with amitriptyline and doxepin Table 30-3). SSRIs are generally free of sedative effects and remarkably safe in overdose. Combined with the ease of once-a-day dosing, these qualities may explain why they have become the most widely prescribed antidepressants. 

Most cephalosporins do not penetrate into the CSF third-generation agents achieve therapeutic levels in CSF r>... 

Third-generation" agents are those agents that are in preclinical or clinical development. 

Clearance of first-generation cephalosporins after intravitreal injection suggests a posterior clearance route (23). Newer agents may be removed by the anterior route or by the combined posterior and anterior route (30). In phakic eyes, the half-life of cefazolin in the monkey and the rabbit is 6.5 7 hours (22,45). The half-life is decreased by inflammation, presumably by interference with active transport across posterior structures. In studies of third-generation agents (ceftizoxime and ceftriaxone), there was increased drug half-lives in infected rabbit eyes as compared to controls (30). Ceftazadime has a half-life of 13.8 20 hours in the rabbit, but the half-life is dramatically lowered by removal of the lens and vitreous (46). 

Which third-generation agent is effective against pseudomonas aeruginosa ... 

Cejpodoxime proxetil is an orally administered third-generation agent that is very similar in activity to the fourth-generation agent cefepime (see below) except that it is not more active against Enterobacter or Pseudomonas spp. 

Second-generation cephalosporins generally have been displaced by third-generation agents. The oral second-generation cephalosporins can be used to treat respiratory tract infections, although they are inferior to amoxiciUin for treatment of peniciUin-resistant S. pneumoniae pneumonia and otitis media. Cefoxitin and cefotetan both are effective in situations where facultative gramnegative bacteria and anaerobes are involved e.g., intra-abdominal infections, pelvic inflammatory disease, and diabetic foot infection). 

There are comparatively few orally active third-generation agents. This group currently is represented by ceftibuten, cefixime, cefdinir, and cefpodoxime proxetil. 

The cephalosporins are classified as first-, second-or third-generation agents. They differ in terms of antibacterial spectmm, stability to bacterial P-lactamases and... 

The third-generation agents display a broader spectmm of antibacterial activity compared to the first- and second-generation cephalosporins. Although these agents display... 

Ceftriaxone has a long elimination half-life and therefore allows once-a-day dosing. Some third-generation agents are artive against Pseudomonas aerugirwsa and include the clinically useful agent ceftazidime (Fig. 22.29). 

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