Assessment of the nephrotoxic potential of ceftazidime and a ceftazidime/tobramycin combination in volunteers

Assessment of the enzymuria resulting from gentamicin alone and combinations of gentamicin with various beta-lactam antibiotics

OBJECTIVE

To determine the propensity of beta-lactam antimicrobials to ameliorate or potentiate aminoglycoside-induced renal enzymuria.

DESIGN

Two open, randomized, double-blind, parallel-group studies were conducted in young, healthy, male volunteer subjects. Using a common protocol, 24-hour urine collections were analyzed for the renal tubular enzymes alanine aminopeptidase (AAP) and N-acetyl-beta-D-glucosaminidase (NAG), as well as for creatinine. Antimicrobial combinations studied included gentamicin plus placebo and gentamicin plus ticarcillin/clavulanate (protocol 1); and gentamicin plus placebo, gentamicin plus piperacillin, and gentamicin plus ceftazidime (protocol 2). The antimicrobial regimens were administered for 7 days. Eight subjects completed each treatment group.

RESULTS

There were no significant differences between treatment groups with regard to urine creatinine excretion or serum gentamicin concentrations in either protocol. Enzymuria (AAP [p = 0.039] and NAG [p = 0.337]) was decreased in the gentamicin plus ticarcillin/clavulanate treatment compared with that in the gentamicin plus placebo treatment. Increased enzymuria, as indicated by increased urine concentrations of AAP and NAG, was observed in the gentamicin plus ceftazidime treatment (p < 0.05) compared with the other two treatments.

CONCLUSIONS

Based on relative enzymuria, ticarcillin/clavulanate may be renal protective. Piperacillin neither potentiated nor ameliorated aminoglycoside-induced enzymuria. Since acute elevations in AAP and NAG reflect insults to the kidney, these studies suggest that ceftazidime may enhance aminoglycoside-induced renal injury. Piperacillin had no effect on enzymuria and would appear not to enhance or protect against aminoglycoside-induced renal injury.

Nephrotoxic drugs

The nephrotoxic effects of cyclosporine, aminoglycoside antibiotics, cisplatin, amphotericin B, beta-lactam antibiotics and indomethacin are reviewed. These drugs were chosen because they are among the most frequent causes of renal injury in children. In addition, their nephrotoxicity is caused by different mechanisms. Several generalizations can be made, however. First, agents which cause tubular damage tend to be synergistic in their toxic effects. This synergism is seen when several nephrotoxic drugs are given simultaneously. In addition, the use of a nephrotoxic agent in a patient with pre-existing renal disease can result in severe tubular injury. Second, serum levels of the drug frequently fail to correlate with the degree of nephrotoxicity in individual patients. Third, early signs of renal injury can be subtle (e.g., minor changes in electrolyte excretion) or dramatic (e.g., acute renal failure). The subtle changes are particularly important, since they can be useful predictors of serious nephrotoxicity.

Ceftazidime as prophylactic treatment in renal stone surgery. Clinical evaluation and pharmacokinetics in renal tissue

The effect of ceftazidime in surgery of renal stones associated with urinary tract infection was investigated and its pharmacokinetics in serum and renal tissue was compared in 14 patients (15 kidneys) operated on for renal calculi associated with multiple urinary tract infection. Two to four days preoperatively ureteric catheterization was performed to localize the level of the infection and 2 g of ceftazidime was given intravenously twice daily for 10 days. Renal biopsy, serum samples and in one patient renal lymphatic fluid were taken simultaneously for antibiotic assay. Urine cultures were performed at regular intervals pre- and postoperatively. Ten patients had bacterial growth in the stone-carrying renal pelvis. The same strain was found in the bladder as in the pelvis. Nine patients had sterile urine after 3-5 days of treatment. One patient with bilateral stones did not get sterile urine until after seven days of treatment. Bacterial growth was found in two out of six cultured stones obtained from patients with bacterial growth in the pelvis. The decreases in concentration of ceftazidime in serum and renal tissue seemed to be parallel. Slight reversible elevation of liver transaminases was noted in 5/14 patients. It is concluded that the concentration of ceftazidime in serum parallels that in renal tissue. Ceftazidime seems to be an effective prophylactic in renal stone surgery and the preoperative dose should be given close to the operation.