Ceftazidime - How It Works
Clinical pharmacology details from the US FDA-approved label: how Ceftazidime works in your body, how it's absorbed, how long it stays active, and how it's eliminated.
Mechanism of Action
Mechanism of Action Ceftazidime is a bactericidal agent that acts by inhibition of bacterial cell wall synthesis. Ceftazidime has activity in the presence of some beta-lactamases, both penicillinases and cephalosporinases, of Gram-negative and Gram-positive bacteria.
CLINICAL PHARMACOLOGY After IV administration of 500 mg and 1 g doses of ceftazidime over 5 minutes to normal adult male volunteers, mean peak serum concentrations of 45 and 90 mcg/mL, respectively, were achieved.
After IV infusion of 500 mg, 1 g, and 2 g doses of ceftazidime over 20 to 30 minutes to normal adult male volunteers, mean peak serum concentrations of 42, 69, and 170 mcg/mL, respectively, were achieved.
The average serum concentrations following IV infusion of 500 mg, 1 g, and 2 g doses to these volunteers over an 8-hour interval are given in Table 1 .
Average Serum Concentrations of Ceftazidime Ceftazidime IV Dose Serum Concentrations (mcg/mL) 0.5 hr 1 hr 2 hr 4 hr 8 hr 500 mg 42 25 12 6 2 1 g 60 39 23 11 3 2 g 129 75 42 13 5 The absorption and elimination of ceftazidime were directly proportional to the size of the dose.
The half-life following IV administration was approximately 1.9 hours.
Less than 10% of ceftazidime was protein bound.
The degree of protein binding was independent of concentration.
There was no evidence of accumulation of ceftazidime in the serum in individuals with normal renal function following multiple IV doses of 1 and 2 g every 8 hours for 10 days.
Following intramuscular (IM) administration of 500 mg and 1 g doses of ceftazidime to normal adult volunteers, the mean peak serum concentrations were 17 and 39 mcg/mL, respectively, at approximately 1 hour.
Serum concentrations remained above 4 mcg/mL for 6 and 8 hours after the IM administration of 500 mg and 1 g doses, respectively.
The half-life of ceftazidime in these volunteers was approximately 2 hours.
The presence of hepatic dysfunction had no effect on the pharmacokinetics of ceftazidime in individuals administered 2 g intravenously every 8 hours for 5 days.
Therefore, a dosage adjustment from the normal recommended dosage is not required for patients with hepatic dysfunction, provided renal function is not impaired.
Approximately 80% to 90% of an IM or IV dose of ceftazidime is excreted unchanged by the kidneys over a 24-hour period.
After the IV administration of single 500 mg or 1 g doses, approximately 50% of the dose appeared in the urine in the first 2 hours.
An additional 20% was excreted between 2 and 4 hours after dosing, and approximately another 12% of the dose appeared in the urine between 4 and 8 hours later.
The elimination of ceftazidime by the kidneys resulted in high therapeutic concentrations in the urine.
The mean renal clearance of ceftazidime was approximately 100 mL/min.
The calculated plasma clearance of approximately 115 mL/min indicated nearly complete elimination of ceftazidime by the renal route.
Administration of probenecid before dosing had no effect on the elimination kinetics of ceftazidime.