Ceftazidime

Brand Name(s) in US

Fortaz, Ceptaz, Tazicef, Tazidime.

Description

Ceftazidime is the latest third generation cephalosporin to reach the market. It has one of the broadest spectrums of the cephalosporins, similar in many regards to that of cefotaxime. It is particularly active against Pseudomonas aeruginosa, being perhaps 4-5 times more potent in vitro than moxalactam and cefotaxime.

Chemical Properties

White Solid

Originator

Glaxo (United Kingdom)

Uses

Ceftazidime pentahydrate is an antibacterial agent. It is used especially for Pseudomonas and other gram-negative infections in debilitated patients. It is used in the treatment of patients with infections caused by susceptible strains of organisms in the following diseases: lower respiratory tract infections,skin and skin structure infections, urinary tract infections, bacterial septicemia, bone and joint infections, gynecologic infections, intra abdominal infections (including peritonitis), and central nervous system infections (including meningitis).

Uses

Third generation cephalosporin antibiotic. Antibacterial.

Definition

ChEBI: A hydrate that is the pentahydrate of ceftazidime, a cephalosporin having 7beta-[(2Z)-2-(2-amino-1,3-thiazol-4-yl)-2-{[(2-carboxypropan-2-yl)oxy]imino}acetyl]amino and 3-pyridinium-1-ylmethyl side-groups.

brand name

Fortaz (GlaxoSmithKline); Tazicef (Hospira); Tazidime (Lilly);FORTAM.

Antimicrobial activity

Its activity is comparable to that of cefotaxime and ceftizoxime, but it is more active against Ps. aeruginosa, including almost all gentamicin-resistant strains, and Burk. cepacia. It is, however, less active against Staph. aureus. It is stable to a wide range of β-lactamases, but is hydrolyzed by some TEM variants.

Pharmacokinetics

C_max 500 mg intramuscular: 18–20 mg/L
2 g intravenous (20-min infusion): 185 mg/L end infusion
Plasma half-life: 1.5–2 h
Volume of distribution: 16 L
Plasma protein binding: c. 10%
No accumulation was seen in subjects receiving 2 g every 12 h over 8 days. In premature infants given 25 mg/kg every 12 h, mean peak plasma concentrations were 77 mg/L after intravenous and 56 mg/L after intramuscular administration, with plasma elimination half-lives of 7.3 and 14.2 h, respectively. Postnatal age was the most important determinant of elimination rate, which was halved after 5 days. In newborn infants given 50 mg/kg intravenously over 20 min, mean peak plasma concentrations varied inversely with gestational age from 102 to 124 mg/L, with half-lives of 2.9–6.7 h.
Distribution
The concentration into serous fluids reaches 50% or more of the simultaneous serum level. In patients given 1 g intravenously during abdominal surgery, detectable concentrations appeared within a few minutes in the peritoneal fluid, reaching a peak around 67 mg/L with a half-life of 0.9 h. Following a similar intravenous dose, a mean peak of 9.4 mg/L was reached at 2 h in ascitic fluid. Concentrations in middle ear fluid after 1 g intravenously were broadly comparable to those of the plasma.
In patients with meningitis, CSF concentrations of 2–30 mg/L have been found 2–3 h after doses of 2 g intravenously over 30 min given every 8 h for four doses. Concentrations are substantially less in the absence of meningitis. Concentrations of 3–27 mg/g were found in patients with intracranial abscesses treated with 0.5–2 g every 8 h. Concentrations around 0.4 mg/g in skin, 0.6 mg/g in muscle and 0.2 mg/g in fatty tissue have been found in patients given 2 g intravenously over 5 min preoperatively. A similar dose has produced mean prostate tissue:serum ratios of around 0.14. Effective concentrations are achieved in bone: in patients given 1 g intravenously mean bone concentrations were 14.4 mg/kg 35–40 min after the dose. There is secretion in breast milk, peak concentrations being around 5 mg/L at about 1 h in patients receiving 2 g intravenously every 8 h.
Metabolism and excretion
No metabolites have been detected. Elimination is almost exclusively renal, predominantly via the glomerular filtrate, with 80–90% of the dose appearing in the urine in the first 24 h. Elimination half-life is inversely correlated with creatinine clearance: as the values fall to 2–12 mL/min, the mean plasma half-life rises to 16 h. In patients maintained on hemodialysis the half-life fell to 2.8 h on dialysis. No accumulation occurred over 10 days in severe renal impairment on a daily dose of 0.5–1 g.
Concentrations of 6.6–58 mg/L have been found in bile 25–160 min after the dose at times when the mean serum concentration was 77.4 mg/L. In T-tube bile there was considerable interpatient variation, with mean concentrations of 34 mg/L at 1–2 h after the dose. No accumulation occurs in patients with impaired hepatic function, but the presence of ascites, low plasma albumin and accumulation of proteinbinding inhibitors may increase the volume of distribution.

Clinical Use

It is used, often combined with an aminoglycoside, to treat a wide range of severe urinary, respiratory and wound infections, mostly due to enterobacteria or Ps. aeruginosa. Reference is made to its use in pneumonia, septicemia, meningitis (especially if caused by Ps. aeruginosa), peritonitis, osteomyelitis, neonatal sepsis, burns and melioidosis. Concern has been expressed at the relative frequency with which failure is associated with superinfection or the emergence of resistance.

Side effects

It is generally well tolerated. Preparations containing arginine have replaced those with sodium carbonate, which causes pain on intramuscular injection. Reactions common to cephalosporins have been observed in some patients, including positive antiglobulin tests without hemolysis, raised liver function test values, eosinophilia, rashes, leukopenia, thrombocytopenia and diarrhea, occasionally associated with toxigenic C. difficile.
Failure of therapy has been associated with superinfection with resistant organisms, including Staph. aureus, enterococci and Candida. Resistance caused by induction of chromosomal β-lactamases may emerge in Ps. aeruginosa, Ser. marcescens or Enterobacter spp.

Veterinary Drugs and Treatments

Ceftazidime is potentially useful in treating serious gramnegative bacterial infections particularly against susceptible Enterobacteriaceae including Pseudomonas aeruginosa, that are not susceptible to other, less-expensive agents, or when aminoglycosides are not indicated (due to their potential toxicity). It is of particular interest for treating gram-negative infections in reptiles due to a very long half-life.