Aseptic peritonitis due to peptidoglycan contamination of pharmacopoeia standard dialysis solution.

BACKGROUND: Manufacturers of parenteral solutions adhere to European and US Pharmacopoeia standards to define safety and sterility. In response to excess cases of aseptic peritonitis in peritoneal dialysis patients using icodextrin-containing dialysate that met all pharmacopoeia standards, a global recall was issued in May, 2002. We aimed to establish the cause of aseptic peritonitis. METHODS: We analysed 186 reports of aseptic peritonitis between September, 2001, and January, 2003. Extensive physical, chemical, and microbiological investigations of recalled dialysate were done. We calculated dose-response curves for peptidoglycan-induced interleukin 6 elaboration in peripheral blood mononuclear cells (PBMCs) from healthy donors and for sterile peritonitis in rats. FINDINGS: Although its chemical constituents and concentrations of endotoxin were within pharmacopoeia specifications, the dialysis solution elicited an interlukin 6 response in vivo and in vitro. We identified peptidoglycan from thermophilic acidophilic bacteria (Alicyclobacillus acidocaldarius) as the contaminating proinflammatory substance. In the PBMC assay, strong dose-response relations were noted between peptidoglycan concentrations and interleukin 6. In rats injected with peptidoglycan, dose-dependent increases of intraperitoneal neutrophils and pyrogenic cytokines were recorded. We measured a positive relation between peptidoglycan concentrations in recalled dialysate and reports of aseptic peritonitis. After implementation of corrective actions, the rate of peritonitis returned to baseline. INTERPRETATION: Excess cases of aseptic peritonitis in peritoneal dialysis patients were due to peptidoglycan contamination of dialysate by Alicyclobacillus. This outbreak serves as an example of how contemporary parenteral products with microbial contaminants can be considered safe under current pharmacopoeia tests, but provoke adverse clinical effects.

Effect of hyaluronan-supplemented dialysate on in vitro function of human peritoneal mesothelial cells.

BACKGROUND: Addition of hyaluronan (HA) to the dialysis solution has been suggested as a means to protect the peritoneum from injury during peritoneal dialysis (PD). METHODS: Concentrations of inflammatory mediators were determined in dialysate samples obtained from PD patients after 6-hour dwells with glucose-based (13.6 g/l) solution containing 0.1 and 0.5 g/l of exogenous high-molecular-weight HA. We additionally evaluated the effect of HA-supplemented dialysate, drained after dwell in PD patients, on function of human peritoneal mesothelial cells (MC) in in vitro culture. RESULTS: Concentration of nitrites was significantly higher in HA 0.5 g/l supplemented dialysate (+43%, p < 0.05) as compared to control. Levels of monocyte chemoattractant protein (MCP-1), soluble intercellular adhesive molecule (s-ICAM), vascular endothelial growth factor (VEGF) and fibronectin were comparable in all the studied groups. However, when MC were exposed in in vitro conditions for 24 h to the studied dialysates, we observed that HA containing fluids inhibited the synthesis of MCP-1, s-ICAM, VEGF and fibronectin in these cells. HA-supplemented dialysate accelerated growth rate of in vitro proliferating MC. CONCLUSION: High-molecular-weight HA added to the dialysis fluid exerts anti-inflammatory and antifibrotic actions on the in vitro cultured MC and accelerates their growth rate what may be important for peritoneal healing during PD.

Effects of intraperitoneal hyaluronan on peritoneal fluid and solute transport in peritoneal dialysis patients.

BACKGROUND: Hyaluronan (HA) is a glycosaminoglycan found in connective tissues and tissue spaces, including the peritoneal cavity. In vivo studies in a rat model of peritoneal dialysis (PD) have shown that addition of HA to PD solution during an intraperitoneal dwell can alter peritoneal fluid transport and protect the peritoneal membrane from the effects of inflammation and repeated infusions of dialysis solution. The current study sought to evaluate the safety of intraperitoneal HA and its effect on peritoneal fluid and solute transport when administered during a dialysis dwell in humans. METHODS: 13 PD patients were enrolled in a prospective, randomized crossover study involving three dialysis treatments using the following PD solutions: (1) a commercially available PD solution (Dianeal PD-4, 1.36% glucose; Baxter Healthcare Corporation, Alliston, Ontario, Canada); (2) Dianeal PD-4 containing 0.1 g/L HA, and (3) Dianeal PD-4 containing 0.5 g/L HA. Each 6-hour dialysis exchange was separated from the other exchanges by a 2-week washout period. Radioiodinated human serum albumin (RISA) was administered with the dialysis solution to evaluate intraperitoneal volume, net ultrafiltration (UF), and fluid reabsorption. Peritoneal clearances, dialysate/plasma ratios (D/P), and mass transfer area coefficients (MTACs) were determined for sodium, urea, creatinine, albumin, and glucose. Safety was evaluated by monitoring adverse events and changes in serum chemistries. Ten patients completed all three dialysis exchanges and two additional patients completed at least one treatment exchange. RESULTS: There were no reported adverse events related to HA administration and no significant changes in serum chemistries. There were no significant differences in net UF or peritoneal volume profiles among the three treatments. Mean net UF calculated using residual volumes, estimated by RISA dilution, tended to be slightly higher during treatment with solution containing 0.1 g/L HA and 0.5 g/L HA [74 +/- 86 (SE) and 41 +/- 99 mL, respectively] compared to control treatment (-58 +/- 129 mL). Although not statistically significant, there was a trend toward decreased fluid reabsorption during treatment with HA. Solute clearances, D/P ratios, and MTACs were similar for the three treatments. Serum levels of HA were also unaffected by the two treatment solutions. CONCLUSIONS: These data support the acute safety of HA when administered intraperitoneally with the dialysis solution to PD patients. Due to the small sample size and variability in net UF and fluid reabsorption, statistically significant differences were not demonstrated for these parameters. However, a trend toward decreased fluid reabsorption was observed, suggesting that HA may act by a mechanism similar to that observed in animal studies. Further studies are necessary to evaluate whether the beneficial effects of HA observed in animal studies can be shown in humans.

A rapid assay for icodextrin determination in plasma and dialysate.

Icodextrin is a glucose polymer osmotic agent used to achieve sustained ultrafiltration during long peritoneal dialysis dwells. Previous assays for icodextrin in plasma and dialysate samples involved laborious methods, such as gel permeation chromatography with post-column derivatization of the eluted glucose polymers. We developed and validated a simple and more rapid assay for icodextrin using amyloglucosidase to hydrolyze all glucose polymers to glucose. Glucose was determined pre- and post-hydrolysis using a glucose hexokinase assay, and icodextrin concentration was calculated as the difference between glucose levels before and after hydrolysis. The complete hydrolysis of icodextrin to glucose was confirmed using anion exchange chromatography. Recovery studies using icodextrin powder added to plasma or dialysate showed 100% +/- 15% recovery for plasma concentrations from 10 mg/dL to 800 mg/dL and for dialysate concentrations from 50 mg/dL to 800 mg/dL. The percent relative standard deviation (%RSD) based on multiple replicates was within 6%, except at plasma icodextrin concentrations of 10 mg/dL and below. This simple and reliable assay has been used routinely in our laboratory to analyze thousands of plasma and dialysate samples from patients using Extraneal peritoneal dialysis solution (Baxter Healthcare Corporation, Deerfield, IL, U.S.A.).

Kinetic analysis of icodextrin interference with serum amylase assays.

Patients treated with Extraneal peritoneal dialysis solution (Baxter Healthcare Corporation, Deerfield, IL, U.S.A.) have a significant decrease in serum amylase activity. The decline is reported to be due to interference of icodextrin in a routinely used laboratory assay. The present study was designed to investigate the kinetics of icodextrin interference in the amylase activity assay and to determine whether assay interference can account for the total decline in amylase activity. Plasma obtained from healthy volunteers was spiked with 0, 0.21, 0.71, and 3.6 mg/mL icodextrin. Amylase activity was determined using Sigma kit 577-10 (Sigma Diagnostics, St. Louis, MO, U.S.A.). Amylase activity in plasma samples spiked with 3.6 mg/mL icodextrin was also monitored while varying the concentration of the substrate (ET-G7-PNP) from the assay kit. Amylase activity decreased with increasing amounts of icodextrin and decreasing amounts of assay substrate. A 72.6% decrease in amylase activity was observed in samples spiked with 3.6 mg/mL icodextrin as compared with samples without icodextrin at a substrate level similar to that in the assay kit (0.71 mmol/L). Double reciprocal and Dixon plots indicate competitive inhibition of amylase activity by icodextrin. Icodextrin functions as a competitive inhibitor in the assay for amylase activity, as predicted by the structural similarities between icodextrin and the amylase assay substrate. The degree of icodextrin interference suggests that the entire decline in amylase activity observed in patients using Extraneal can be accounted for qualitatively by icodextrin interference. The amylase activity decline in patients treated with Extraneal is an artifact attributable to assay interference.

L-2-oxothiazolidine-4-carboxylate: an agent that modulates lipopolysaccharide-induced peritonitis in rats.

OBJECTIVE: L-2-Oxothiazolidine-4-carboxylate (OTZ), a cysteine precursor, is a substrate for intracellular glutathione synthesis. As shown previously, OTZ prevents free-radical induced cellular damage during in vitro simulation of peritoneal dialysis. In the present study, we examined the effect of adding OTZ to peritoneal dialysis solution on peritoneal function and structure during lipopolysaccharide (LPS)-induced peritonitis in rats. In addition, we studied the effects of pretreatment with OTZ (given orally) on the effects of LPS-induced peritonitis in rats. METHODS: Peritonitis was induced in rats by adding LPS (5 microg/mL) to the dialysis fluid. For acute experiments, rats were exposed to a single infusion of dialysis solution containing LPS or to LPS plus 5 mmol/L OTZ; peritoneal cell counts and permeability were determined after 4 hours. Alternatively, rats were pretreated with OTZ added to the drinking water (0.1%) for 10 days prior to infusion of LPS. For chronic experiments, peritoneal dialysis was performed over a 3-week period in rats with implanted peritoneal catheters. On days 8, 9, and 10 of the experiment, the rats were infused intraperitoneally with solution containing LPS (5 micro/mL), or LPS plus 5 mmol/L OTZ, to induce acute peritonitis. At the end of dialysis (10 days after the episodes of peritonitis), peritoneal function was assessed using a peritoneal equilibration test (PET), and peritoneal biopsies were taken to assess effects on peritoneal morphology. RESULTS: In the acute experiments, exposure to LPS led to increased peritoneal cell counts (+61% vs control, p < 0.05) and enhanced permeability of the peritoneum, leading to a loss in ultrafiltration (-63%, p < 0.0005). The glutathione concentration in peritoneal leukocytes also decreased during acute peritonitis (-31%, p < 0.05). During LPS-induced peritonitis, OTZ prevented the increase in dialysate cell count and the decrease in cellular glutathione content. Simultaneous administration of OTZ did not prevent the increased peritoneal permeability induced by LPS. However, in rats pretreated with OTZ, LPS-induced permeability to protein was significantly lower than in the nontreated animals (0.049 +/- 0.011 vs 0.087 +/- 0.034, p < 0.05). In the chronic experiments, LPS-induced peritonitis did not lead to any functional differences in peritoneal transport at the end of 3 weeks of dialysis. However, LPS-induced peritonitis led to increased thickness of the peritoneum and neovascularization within peritoneal interstitium compared to peritonitis-free animals. In contrast to the LPS-treated animals, the peritoneum of the rats exposed to LPS in the presence of OTZ was of a thickness similar to that in the control rats. CONCLUSION: Supplementation of dialysis fluid with OTZ prevented changes in cellular glutathione levels and dialysate cell counts during acute peritonitis in rats. During chronic dialysis in rats exposed to intermittent peritonitis episodes, OTZ prevented increased thickening and neovascularization of the peritoneum. Our results suggest this may help to protect the peritoneal membrane during episodes of peritonitis.

Pharmacokinetics of icodextrin in peritoneal dialysis patients.

UNLABELLED: Pharmacokinetics of icodextrin in peritoneal dialysis patients. BACKGROUND: Icodextrin is a glucose polymer osmotic agent used to provide sustained ultrafiltration during long peritoneal dialysis (PD) dwells. A number of studies have evaluated the steady-state blood concentrations of icodextrin during repeated use; however, to date the pharmacokinetics of icodextrin have not been well studied. The current study was conducted to determine the absorption, plasma kinetics and elimination of icodextrin and metabolites following a single icodextrin exchange. METHODS: Thirteen PD patients were administered 2.0 L of solution containing 7.5% icodextrin for a 12-hour dwell. Icodextrin (total of all glucose polymers) and specific polymers with degrees of polymerization ranging from two to seven (DP2 to DP7) were measured in blood, urine and dialysate during the dwell and after draining the solution from the peritoneal cavity. RESULTS: A median of 40.1% (60.24 g) of the total administered dose (150 g) was absorbed during the 12-hour dwell. Plasma levels of icodextrin and metabolites rose during the dwell and declined after drain, closely corresponding to the one-compartment pharmacokinetic model assuming zero-order absorption and first-order elimination. Peak plasma concentrations (median C peak = 2.23 g/L) were observed at the end of the dwell (median Tmax = 12.7 h) and were significantly correlated with patients' body weight (R2 = 0.805, P < 0.001). Plasma levels of icodextrin and metabolites returned to baseline within 3 to 7 days. Icodextrin had a plasma half-life of 14.73 hours and a median clearance of 1.09 L/h. Urinary excretion of icodextrin and metabolites was directly related to residual renal function (R2 = 0.679 vs. creatinine clearance, P < 0.01). In the nine patients with residual renal function, the average daily urinary excretion of icodextrin was 473 +/- 77 mg per mL of endogenous renal creatinine clearance. Icodextrin metabolites DP2 to DP4 were found in the dialysate of subsequent dextrose exchanges, contributing to their elimination from blood. Changes in intraperitoneal concentrations of icodextrin metabolites during the dwell revealed a dual pattern, with a progressive rise in the dialysate concentration of smaller polymers (DP2 to DP4) and a progressive decline in the dialysate concentrations of the larger polymers (DP5 to DP7), suggesting some intraperitoneal metabolism of the glucose polymers. This increase in dialysate metabolite levels, however, did not contribute significantly to dialysate osmolality. In addition, some diffusion of maltose (DP2) from blood to dialysate may have occurred. There were no changes in serum insulin or glucose levels during icodextrin administration, indicating that icodextrin does not result in hyperglycemia or hyperinsulinemia as occurs during dextrose-based dialysis. Serum sodium and chloride declined in parallel with the rise in plasma levels of icodextrin, supporting the hypothesis that these electrolyte changes are the result of the increased plasma osmolality due to the presence of icodextrin metabolites. CONCLUSIONS: The pharmacokinetics of icodextrin in blood following intraperitoneal administration conforms to a simple, single-compartment model that can be approximated by zero-order absorption and first-order elimination. A small amount of intraperitoneal metabolism of icodextrin occurs but does not contribute significantly to dialysate osmolality. The metabolism of absorbed icodextrin and the resultant rise in plasma levels of small glucose polymers (DP2 to DP4) do not result in hyperglycemia or hyperinsulinemia, but may result in a small decrease in serum sodium and chloride.