Pharmacokinetics of Once-Daily Ip Gentamicin in Capd Patients

Objective

This study aimed to investigate the pharmacokinetic characteristics of once-daily intraperitoneal (IP) gentamicin in continuous ambulatory peritoneal dialysis (CAPD) patients.

Design

Prospective, nonrandomized, open study.

Setting

CAPD outpatient clinic in a teaching hospital.

Patients

Ten volunteer CAPD patients without peritonitis.

Interventions

Each patient received a single IP dose of 0.6 mg/kg of gentamicin. Blood and dialysate samples were collected at 0,0.5,1, 2, 3,6 (end of first dwell), and 24 hours after the administration of IP gentamicin. Any urine produced over the 24hour study period was also collected. The dialysate concentration/time data were fitted to a monoexponential curve for all patients.

Results

The bioavailability was 56±11% over a six hour dwell. The mean serum elimination half-life (t1/2) was 35.8 hours. The volume of distribution was 0.23±0.08 L/kg. Equilibration of gentamicin across the peritoneal membrane was rapid, with a t½ equilibration of 4.5 hours. The peritoneal clearance was 5.74±1.5 mL/min. Patients with residual renal function had significantly higher systemic gentamicin clearances (7.36±1.46 mL/min) than those of anuric patients (4.76±1.08 mL/min, p < 0.024).

Conclusion

Currently recommended doses of oncedaily IP gentamicin for the treatment of peritonitis may not produce the desired therapeutic serum and dialysate concentrations over 24 hours for effective treatment of peritonitis.

Correlation of Intraperitoneal Antibiotic Pharmacokinetics and Peritoneal Membrane Transport Characteristics

Objective

To identify correlations between the pharmacokinetic variables that describe drug disposition in peritoneal dialysis (PD) patients and the measures used to assess dialysis adequacy.

Design and Methods

This retrospective study re-evaluated data collected during previous pharmacokinetic studies for intraperitoneally administered cefazolin, ceftazidime, and gentamicin in continuous ambulatory peritoneal dialysis (CAPD) patients, and intravenous cefazolin and tobramycin in automated PD patients. Pharmacokinetic variables were compared to creatinine clearance (CCr), Kt/V, and peritoneal equilibration test data using the Pearson product correlation coefficient ( r).

Results

Prominent correlations were found between renal CCr and renal Kt/V, with renal clearances of CAPD cefazolin and ceftazidime, and automated PD tobramycin and cefazolin ( r values ranged from 0.698 to 0.986; p < 0.05).

Conclusion

These findings support current peritonitis treatment recommendations that patients with residual renal function may require higher doses or more frequent drug administration.

A Survey of CAPD Peritonitis Management and Outcomes in North and South Thames NHS Regions (U.K.): Support for the ISPD Guidelines

Objective

This survey examined the current management of continuous ambulatory peritoneal dialysis (CAPD) peritonitis and the effectiveness of the various antibiotic protocols in use.

Design

The information required was elicited via a postal questionnaire.

Setting

The questionnaire was posted to each renal dialysis unit offering CAPD throughout the North and South Thames National Health Service regions.

Patients

All patients using CAPD at each responding unit were eligible for inclusion.

Main Outcome Measures

Each unit provided details of their CAPD peritonitis episodes for 1997. Each unit's empirical treatment regimen for CAPD peritonitis was sought in addition to response rates. Also requested were numbers for peritonitis episodes, recurrences, and negative cultures, plus the peritonitis rate per patient-month.

Results

Thirteen units returned the questionnaire (87% of the survey population). Nine of the 13 units were using vancomycin regimens, with the remainder using cephalosporin regimens. The results were compared to the audit standards of the British Renal Association. Seventy percent of units reached the 80% mark for response rate; similar results were achieved with both the vancomycin and cephalosporin regimens. Ninety-two percent achieved the suggested peritonitis rate of 1 episode every 18 patient-months; 30% achieved the culture-negative rate of 10%. The average recurrence rate was 19%.

Conclusion

The units contacted achieved most of the standards suggested by the British Renal Association; however, wide variations did exist. Recent guidelines have suggested avoiding vancomycin-based regimens in order to reduce the incidence of vancomycin resistance. The suggested regimen of a cephalosporin with an aminoglycoside seems to represent a suitable alternative.

Pharmacokinetics of Intermittent Intraperitoneal Cefazolin in Continuous Ambulatory Peritoneal Dialysis Patients

Objective

To investigate the pharmacokinetic parameters of intermittent intraperitoneal (IP) cefazolin, and recommend a cefazolin dosing regimen in continuous ambulatory peritoneal dialysis (CAPD) patients.

Design

Prospective nonrandomized open study.

Setting

CAPD outpatient clinic in Albany, New York.

Patients

Seven volunteer CAPD patients without peritonitis. Three of the patients were nonanuric while 4 were anuric.

Interventions

Cefazolin (15 mg/kg total body weight) was given to each patient during the first peritoneal exchange. Blood and dialysate samples were collected at times 0, 0.5, 1, 2, 3, 6 (end of the first antibiotic-containing dwell), 24, and 48 hours after the administration of IP cefazolin. Urine samples were collected in nonanuric patients over the study period.

Results

The mean ± SD amount of cefazolin dose absorbed from the dialysate after the 6-hour dwell was 69.7% ± 8.0% of the administered dose. The cefazolin absorption rate constant from dialysate to serum was 0.21 ± 0.1 /hr (absorption half-life 3.5 ± 0.8 hr). The mean serum concentrations reached at 24 and 48 hours were 52.4 ± 3.7 mg/L and 30.3 ± 5.9 mg/L, respectively. The mean dialysate cefazolin concentrations reached at 24 and 48 hours were 15.1 ± 3.4 mg/L and 7.9 ± 1.4 mg/L, respectively. The cefazolin serum elimination rate constant was 0.02 ± 0.01 /hr (elimination half-life 31.5 ± 8.8 hr). The total cefazolin body clearance was 3.4 ± 0.6 mL/min. In the 3 nonanuric patients the mean renal clearance of cefazolin was 0.6 ± 0.4 mL/min. The peritoneal clearance of cefazolin was 1.0 ± 0.3 mL/min. The systemic volume of distribution of cefazolin was 0.2 ± 0.05 L/kg. No statistical difference was detected in pharmacokinetic parameters between anuric and nonanuric patients, although this may be due to the small number of patients in each group.

Conclusion

A single daily dose of cefazolin dosed at 15 mg/kg actual body weight in CAPD patients is effective in achieving serum concentration levels greater than the minimum inhibitory concentration for sensitive organisms over 48 hours, and dialysate concentration levels over 24 hours. Caution is warranted in extrapolation of dosing recommendations to patients who maintain a significant degree of residual renal function.

Review of Antibiotic Dosing with Peritonitis in APD

Peritonitis is the leading cause of transfer from peritoneal dialysis (PD) to hemodialysis (HD). It is also the leading cause of hospitalization of PD patients. The usual treatment of peritonitis for automated PD (APD) patients consists of antibiotics given once daily in the long dwell. However, the once-daily antibiotic dosing recommendations are based primarily on studies with continuous ambulatory PD (CAPD) regimens. Published studies on antibiotic dosing in APD are very limited. We will review the scant literature on this topic. It is possible that extrapolating once-daily dosing from CAPD to APD may lead to underdosing. There is a need for further pharmacokinetic studies of antibiotic dosing in APD.

Continuous peritoneal dialysis-associated peritonitis: a review and current concepts

The percentage of end-stage renal disease (ESRD) patients in the United States maintained on continuous peritoneal dialysis (CPD) therapy is decreasing. Complications from CPD therapy, including peritonitis, may be the reason for the decline. Improvements in CPD technology and a better understanding of the risk factors that predispose patients to the development of peritonitis have been responsible for a decline in the rate of peritonitis. Yet peritonitis remains a significant cause of patient morbidity and mortality and the overall outcome of peritonitis is not acceptable. Factors that have limited our ability to lessen the impact of peritonitis include a lack of data on dosing antibiotics in patients on continuous cycling peritoneal dialysis (CCPD) therapy, a lack of knowledge concerning the biology of bacterial biofilm, and the development of resistance to the current prophylactic antibiotic protocols. Further studies are needed concerning the optimal management of the peritoneal catheter and whether it is feasible to resume CPD therapy after catheter removal.

Pharmacokinetics of intermittent intraperitoneal ceftazidime

Ceftazidime is currently recommended as an alternative first-line agent in the treatment of peritonitis and for Pseudomonas peritonitis. The pharmacokinetics of intermittent intraperitoneal (i.p.) ceftazidime have been poorly characterized. This study was designed to characterize the pharmacokinetic disposition of a single dose of ceftazidime in anuric and non-anuric CAPD patients, over 48 hours. This was a prospective, open label, pharmacokinetic study. The study was conducted in an independent, outpatient dialysis center. Ten volunteer continuous ambulatory peritoneal dialysis (CAPD) patients with and without residual renal function, no peritonitis or antibiotics in the previous 4 weeks, and on CAPD for at least 2 months were recruited. Patients received a single dose of i.p. ceftazidime (15 mg/kg) in the first daytime exchange over a 6-hour dwell, after an overnight dwell. Serum, urine, and dialysate were collected over a 48-hour period. A high-pressure liquid chromatography (HPLC) assay was used to analyze ceftazidime in these samples. Pharmacokinetic parameters were calculated. Six of the 10 patients were non-anuric with a mean residual renal creatinine clearance of 2.9 +/- 1.6 mL/min. The mean +/- SD bioavailability was 72% +/- 14%, and the volume of distribution was 0.34 +/- 0.08 L/kg. The mean serum elimination half-life of 22 +/- 5 hours. The peritoneal clearance was 5.74 +/- 1.6 mL/min. No difference was detected between anuric and nonanuric patients. Mean plasma and dialysate concentrations at 24 hours were 24 +/- 6 microg/mL and 18 +/- 7 microg/mL, respectively, and were 12.0 +/- 3.6 microg/mL and 7.4 +/- 3.1 microg/mL at 48 hours, respectively. Once-daily i.p. dosing of ceftazidime achieves serum and dialysate levels greater than the MIC of sensitive organisms over 48 hours.