Excretion of cephaloridine and cephalothin in patients with renal impairment

Pharmacokinetics of Intraperitoneal Cefalothin and Cefazolin in Patients Being Treated for Peritoneal Dialysis-Associated Peritonitis

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BACKGROUND

The standard treatment of peritoneal dialysis (PD)-associated peritonitis (PD-peritonitis) is intraperitoneal (IP) administration of antibiotics. Only limited data on the pharmacokinetics and appropriateness of contemporary dose recommendations of IP cefalothin and cefazolin exist. The aim of this study was to describe the pharmacokinetics of IP cefalothin and cefazolin in patients treated for PD-peritonitis. ♦

METHODS

As per international guidelines, IP cefalothin or cefazolin 15 mg/kg once daily was dosed with gentamicin in a 6-hour dwell to patients with PD-peritonitis during routine care. Serial plasma and PD effluent samples were collected over the first 24 hours of therapy. Antibiotic concentrations were quantified using a validated chromatographic method with pharmacokinetic analysis performed using a non-compartmental approach. ♦

RESULTS

Nineteen patients were included (cefalothin n = 8, cefazolin n = 11). The median bioavailability for both antibiotics exceeded 92%, but other pharmacokinetic parameters varied markedly between antibiotics. Both antibiotics achieved high PD effluent concentrations throughout the antibiotic dwell. Cefazolin had a smaller volume of distribution compared with cefalothin (14 vs 40 L, p = 0.003). The median trough total plasma antibiotic concentration for cefazolin and cefalothin during the dwell differed (plasma 56 vs 13 mg/L, p < 0.0001) despite a similar concentration in PD effluent (37 vs 38 mg/L, p = 0.58). Lower antibiotic concentrations were noted during PD dwells not containing antibiotic, particularly cefalothin, which was frequently undetectable in plasma and PD effluent. The median duration that the unbound antibiotic concentration was above the minimum inhibitory concentration (MIC) was approximately 13% (plasma) and 25% (IP) for cefalothin, and 100% (plasma and IP) for cefazolin, of the dosing interval. ♦

CONCLUSIONS

When IP cefalothin or cefazolin is allowed to dwell for 6 hours, sufficient PD effluent concentrations are present for common pathogens during this time. However, with once-daily IP dosing, in contrast to cefazolin, there is a risk of subtherapeutic plasma and PD effluent cefalothin concentrations, so more frequent dosing may be required.

Antimicrobial drug resistance in Escherichia coli from humans and food animals, United States, 1950-2002

Determining drug resistance trends will optimize treatment and public health responses.

We conducted a retrospective study of Escherichia coli isolates recovered from human and food animal samples during 1950–2002 to assess historical changes in antimicrobial drug resistance. A total of 1,729 E. coli isolates (983 from humans, 323 from cattle, 138 from chickens, and 285 from pigs) were tested for susceptibility to 15 antimicrobial drugs. A significant upward trend in resistance was observed for ampicillin (p<0.001), sulfonamide (p<0.001), and tetracycline (p<0.001). Animal strains showed increased resistance to 11/15 antimicrobial agents, including ampicillin (p<0.001), sulfonamide (p<0.01), and gentamicin (p<0.001). Multidrug resistance (≥3 antimicrobial drug classes) in E. coli increased from 7.2% during the 1950s to 63.6% during the 2000s. The most frequent co-resistant phenotype observed was to tetracycline and streptomycin (29.7%), followed by tetracycline and sulfonamide (29.0%). These data describe the evolution of resistance after introduction of new antimicrobial agents into clinical medicine and help explain the range of resistance in modern E. coli isolates.

Drug administration in renal failure

Renal failure impairs urinary excretion of drugs and may also modify drug action by alternations in protein binding, distribution, biotransformation and, possibly, by retention of active metabolites. Dialysis adds another variable by altering the blood levels of those drugs soluble in plasma water and therefore available for diffusion or ultrafiltration. Renal insufficiency clearly modifies decisions about the choice and dose of a wide variety of drugs. Although data are accumulating at a rapid rate, available information about the use of drugs in patients with kidney disease is rather limited. The following is a summary of recent information on the use of a variety of drugs frequently utilized in patients with impaired renal function. The guidelines presented here are not absolute, but they are intended to be practical and reasonable, based on current information for adult patients of average size with kidney disease.

Pharmacokinetics of cefamandole in patients with renal failure

The pharmacokinetics of cefamandole were studied in four patients with stable renal failure, two patients undergoing peritoneal dialysis, and four patients undergoing hemodialysis. Peak concentrations of cefamandole in serum were achieved 1 to 2 h after intramuscular injection in the patients with stable renal impairment, and the concentrations declined slowly, with half-life values of 12.3 to 18 h. Cefamandole was removed only very slowly by peritoneal dialysis. Hemodialysis was more efficient in removing cefamandole, with serum half-life values ranging from 3.8 to 7.9 h. The mean apparent volume of distribution of cefamandole in these 10 patients was 21.92 liters, or 31% of the body weight.

Interaction between cephaloridine and furosemide in man

The effect of a moderate oral dose of furosemide (80 mg daily) on the serum half-life of cephaloridine was studied. In 14 patients not previously treated with diuretics this dose was found to prolong the half-life significantly. A corresponding decrease of the half-life of cephaloridine was observed when furosemide was withdrawn from 2 patients who were treated with diuretics at admission to hospital. The concurrent treatment with furosemide and cephaloridine did not affect the renal function of the patients studied. From the results obtained it seems possible that even moderate doses of a potent diuretic increase the nephrotoxicity of a cephalosporin.

Pharmacokinetics of cefamandole in patients undergoing hemodialysis and peritoneal dialysis

The pharmacokinetics of cefamandole nafate, a new parenteral cephalosporin derivative, were evaluated in 11 patients with chronic renal failure (creatinine clearance less than 5 ml/min), including five patients during hemodialysis, four patients during routine peritoneal dialysis, and two patients during the interdialytic period. Peak serum levels of cefamandole were comparable to those observed in patients with normal renal function. Clearance of the drug during the interdialytic period and during hemodialysis and peritoneal dialysis was minimal, with a resultant significant prolongation of serum half-life. The nondialyzability of cefamandole is in contrast with reported studies of cephalothin, where significant reduction of the serum half-life was achieved during hemodialysis but not peritoneal dialysis. The concentration of cefamandole in the peritoneal dialysate after parenteral administration was observed to be bactericidal for many gram-negative pathogens and, with the exception of Streptococcus faecalis, most gram-positive organisms found in bacterial peritonitis in patients with severe renal failure. The present data suggest that if stable bactericidal serum levels of cefamandole are to be maintained during hemodialysis and peritoneal dialysis, a parenteral loading dose must be administered followed by one-half the loading dose every half-life.

Clinical pharmacology of cefamandole as compared with cephalothin

We compared the pharmacology of cefamandole and cephalothin in six healthy adult male volunteers. After a 1-g, 20-min intravenous (i.v.) infusion, the average peak blood level of cefamandole was 87.6 versus 64.1 mug/ml for cephalothin. An i.v. infusion of 500 mg/h for 2 h (after a loading dose of 750 mg) gave an average steady-state blood level of 28.5 mug/ml for cefamandole and 18.2 mug/ml for cephalothin. Mean peak serum levels after 1 g intramuscularly were similar for the two antibiotics (about 21 mug/ml), but with cefamandole they persisted longer, and the area under the blood level curve was about 25% greater. The average t((1/2)) as determined from both i.v. studies was 34 min for cefamandole versus 30 min for cephalothin. The mean serum clearance for cephalothin, due to its partial conversion to a metabolite, was much greater than for cefamandole (425 versus 272 ml/min per 1.73 m(2)), but the renal clearances were similar for the two antibiotics (268 versus 257 ml/min per 1.73 m(2)). Other values for cefamandole and cephalothin were: 24-h urinary excretion, 80 and 66%; serum protein binding, 74 and 70%; and apparent volume of distribution, 12.8 and 18.5 liters/1.73 m(2), respectively. Thus, the pharmacology of the two antibiotics was similar. Blood levels were somewhat higher with cefamandole i.v., but the results suggest that dosage regimens should be the same for the two antibiotics.

Effect of hemodialysis and renal failure on serum and urine concentrations of cephapirin sodium

Six patients undergoing chronic hemodialysis and 10 patients with chronic renal insufficiency hospitalized for nondialytic therapy received 1.0 g of cephapirin sodium by the intravenous route. The concentrations of cephapirin in arterial and venous plasma, dialysate, venous blood, and urine were measured during the ensuing 6 hr. The serum half-life of cephapirin was 105 to 108 min for the dialyzed patients and 95.9 min for the nondialyzed patients. Dialysis removed 22.8% of the administered dose. Nondialyzed patients excreted 19.5% of the administered dose in the urine. The concentration of cephapirin in the urine of all nondialyzed patients exceeded 50 mug/ml. The recovery of cephapirin in the urine collected for 6 hr after injection was from 34 to 770 mg (mean 195 mg). To maintain a concentration of cephapirin in the blood and urine which exceeds the minimal inhibitory concentration for most gram-positive and gram-negative microorganisms, nondialyzed patients should receive 15 to 18 mg of cephapirin per kg every 12 hr. Dialyzed patients should receive the same dose just prior to dialysis and every 12 hr thereafter.

Use of sodium cephalothin in the management of lung gangrene

Thirty-one of 256 cases of chronic destructive pneumonia who were judged, by the severity of illness and haemoptysis, to have lung gangrene, were managed with intravenous sodium cephalothin. Five patients died, two in relation to emergency pneumonectomy. In comparison with results of management of this disease in previous, similar patients, the results are encouraging.

Cephaloridine serum levels in patients on maintenance haemodialysis

Cephaloridine serum half-life was determined in 11 patients undergoing maintenance haemodialysis. Three of them were anephric. The mean cephaloridine half-life was 10.4 hours. There was an inverse correlation between cephaloridine half-life and the duration of maintenance haemodialysis treatment. Reasons for this are discussed.The effect of haemodialysis with the Kiil dialyser on cephaloridine half-life was studied in three patients.Dosage recommendations for patients on maintenance haemodialysis are suggested.