Цефотаксим

Описание

Like other third-generation cephalosporins, it has excellent anti-Gram-negative activity and is useful institutionally. It has a metabolically vulnerable acetoxy group attached to C-3 and loses approximately 90% of its activity when this is hydrolyzed. This metabolic feature also complicates the pharmacokinetic data, because both active forms are present and have different properties. Cefotaxime should be protected from heat and light and may color slightly without significant loss of potency. Like other third-generation cephalosporins, cefotaxime has less activity against staphylococci but has greater activity against Gram-negative organisms.

Использование

Cefotaxime has a broad spectrum of antibicrobial use. It acts bactericidally. It is highly active with respect to Gram-negative microorganisms (E. coli, Citrobacter, Proteus mirabilis, P. indole, Providencia, Klebsiella, Serratia), and a few strains of Pseudomonas, H. influenzae that are resistant to other antibiotics. Cefotaxime is less active with respect to streptococci, pneumococci, meningococci, gonococci, and bacteroides. It is resistant to the majority of beta-lacatamases of Gram-positive and Gram-negative microorganisms.
This drug is used for severe bacterial infections caused by microorganisms that are sensitive to the drug such as peritonitis, sepsis, abdominal infections, infections of the pelvis minor, infections of the lower respiratory tract, urinary tract, bones, joints, skin, soft tissues, and infected wounds and burns. Synonyms of this drug are claforan, zarivis, and others.

Антимикробная активность

The aminothiazoyl and methoximino groups at the 7-amino position confer, respectively, potent activity against many Gram-negative rods and cocci and stability to most β-lactamases. Ps. aeruginosa, Sten. maltophilia and other pseudomonads are often resistant. Brucella melitensis and some strains of Nocardia asteroides are susceptible. Activity against L. monocytogenes and B. fragilis is poor.

Приобретенная устойчивость

Many enterobacteria resistant to other b-lactam agents are susceptible, but selection of resistant strains with derepressed chromosomal molecular class C cephalosporinases may occur. Gram-negative bacilli producing variants of the TEM enzymes (pp. 230–231) are resistant.

Фармакокине?тика

C_max 500 mg intramuscular: 10–15 mg/L after 0.5–1 h
1 g intravenous (15-min infusion): 90 mg/L end infusion
Plasma half-life: c.1 h
Volume of distribution: 32–37 L
Plasma protein binding: c. 40%
Distribution
It is widely distributed, achieving therapeutic concentrations in sputum, lung tissue, pleural fluid, peritoneal fluid, prostatic tissue and cortical bone. In patients receiving 2 g every 8 h, mean CSF concentrations in aseptic meningitis were 0.8 mg/L. Levels of 2–15 mg/L can be found in the CSF in the presence of inflammation after doses of 50 mg/kg by intravenous infusion over 30 min. A single intraventricular dose of 40 mg/kg produced levels at 2, 4 and 6 h of 6.4, 5.7 and 4.5 mg/L, respectively.
Metabolism
About 15–25% of a dose is metabolized by hepatic esterases to the desacetyl form, which may have some clinical importance because of its concentration in bile and accumulation in renal failure. Desacetylcefotaxime has about 10% of the activity of the parent against enterobacteria, less against Staph. aureus. Its half-life in normal subjects is around 1.5 h.
Excretion
Elimination is predominantly by the renal route, more than half the dose being recovered in the urine over the first 24 h, about 25% as the desacetyl derivative. Excretion is depressed by probenecid and declines in renal failure with accumulation of the metabolite. In patients with creatinine clearances in the range 3–10 mL/min, the plasma half-life rose to 2.6 h while that of the metabolite rose to 10 h.

Клиническое использование

Cefotaxime is widely used in neutropenic patients, respiratory infection, meningitis, intra-abdominal sepsis, osteomyelitis, typhoid fever, urinary tract infection, neonatal sepsis and gonorrhea.

Побочные эффекты

Minor hematological and dermatological side effects common to group 4 cephalosporins have been described. Superinfection with Ps. aeruginosa in the course of treatment has occurred. Occasional cases of pseudomembranous colitis have been reported.