Quantification of Degradation Products Formed during Heat Sterilization of Glucose Solutions by LC-MS/MS: Impact of Autoclaving Temperature and Duration on Degradation

Heat sterilization of glucose solutions can lead to the formation of various glucose degradation products (GDPs) due to oxidation, hydrolysis, and dehydration. GDPs can have toxic effects after parenteral administration due to their high reactivity. In this study, the application of the F0 concept to modify specific time/temperature models during heat sterilization and their influence on the formation of GDPs in parenteral glucose solutions was investigated using high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). Glucose solutions (10%, w/v) were autoclaved at 111 °C, 116 °C, and 121 °C for different durations. The GDPs glyoxal, methylglyoxal, glucosone, 3-deoxyglucosone/3-deoxygalactosone, 3,4-dideoxyglucosone-3-ene, and 5-hydroxymethylfurfural were quantified after derivatization with o-phenylenediamine by an optimized LC-MS/MS method. For all GDPs, the limit of detection was <0.078 μg/mL, and the limit of quantification was <0.236 μg/mL. The autoclaving time of 121 °C and 15 min resulted in the lowest levels of 3-DG/3-DGal and 5-HMF, but in the highest levels of GO and 2-KDG. The proposed LC-MS/MS method is rapid and sensitive. So far, only 5-HMF concentrations are limited by the regulatory authorities. Our results suggest reconsidering the impurity limits of various GDPs, especially the more toxic ones such as GO and MGO, by the Pharmacopoeias.

Identification and quantification of glucose degradation products in heat-sterilized glucose solutions for parenteral use by thin-layer chromatography

During heat sterilization of glucose solutions, a variety of glucose degradation products (GDPs) may be formed. GDPs can cause cytotoxic effects after parenteral administration of these solutions. The aim of the current study therefore was to develop a simple and quick high-performance thin-layer chromatography (HPTLC) method by which the major GDPs can be identified and (summarily) quantified in glucose solutions for parenteral administration. All GDPs were derivatized with o-phenylenediamine (OPD). The resulting GDP derivatives (quinoxalines) were applied to an HPTLC plate. After 20 minutes of chamber saturation with the solvent, the HPTLC plate was developed in a mixture of 1,4-dioxane-toluene-glacial acetic acid (49:49:2, v/v/v), treated with thymol-sulfuric acid spray reagent, and heated at 130°C for 10 minutes. Finally, the GDPs were quantified by using a TLC scanner. For validation, the identities of the quinoxaline derivatives were confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Glyoxal (GO)/methylglyoxal (MGO) and 3-deoxyglucosone (3-DG)/3-deoxygalactosone (3-DGal) could be identified and quantified in pairs, glucosone (2-KDG), 5-hydroxymethylfurfural (5-HMF), and 3,4-dideoxyglucosone-3-ene (3,4-DGE) each individually. For 2-KDG, the linearity of the method was demonstrated in the range of 1–50 μg/mL, for 5-HMF and 3,4-DGE 1–75 μg/mL, for GO/MGO 2–150 μg/mL, and for 3-DG/3-DGal 10–150 μg/mL. All GDPs achieved a limit of detection (LOD) of 2 μg/mL or less and a limit of quantification (LOQ) of 10 μg/mL or less. R² was 0.982 for 3.4-DGE, 0.997 for 5-HMF, and 0.999 for 2-KDG, 3-DG/3-DGal, and GO/MGO. The intraday precision was between 0.4 and 14.2% and the accuracy, reported as % recovery, between 86.4 and 112.7%. The proposed HPTLC method appears to be an inexpensive, fast, and sufficiently sensitive approach for routine quantitative analysis of GDPs in heat-sterilized glucose solutions.

Impact of Glucose in Peritoneal Dialysis: Saint or Sinner?

Peritoneal dialysis (PD) solutions using glucose as osmotic agent have been used for more than two decades as effective treatment for patients with end-stage renal disease. Although alternative osmotic agents such as amino acids and macromolecular solutions, including polypeptides and glucose polymers, are now available, glucose is still the most widely used osmotic agent in PD. It has been shown to be safe, effective, readily metabolized, and inexpensive. On the other hand, it is widely assumed that exposure of the peritoneal membrane to high glucose concentrations contributes to both structural and functional changes in the dialyzed peritoneal membrane. As in diabetes, glucose, either directly or indirectly through the generation of glucose degradation products or the formation of advanced glycation end products, may contribute to peritoneal membrane failure. Although efforts to reduce glucose toxicity have been made for years, only a few suggestions, such as dual-bag systems with bicarbonate as buffer system, have found broader acceptance. Recently, some interesting new approaches to the problem of glucose-related toxicity have been made, but further investigations will be necessary before they can be used clinically. This review will focus on adverse effects of glucose in PD solutions and summarize different aspects of glucotoxicity and potential therapeutic interventions.

Quantification of the six major α-dicarbonyl contaminants in peritoneal dialysis fluids by UHPLC/DAD/MSMS

During heat sterilization of peritoneal dialysis solutions, glucose is partially transformed into glucose degradation products (GDPs), which significantly reduce the biocompatibility of these medicinal products. Targeted α-dicarbonyl screening identified glyoxal, methylglyoxal, 3-deoxyglucosone, 3,4-dideooxyglucosone-3-ene, glucosone, and 3-deoxygalactosone as the major six GDPs with α-dicarbonyl structure. In the present study, an ultra-high-performance liquid chromatography method was developed which allows the separation of all relevant α-dicarbonyl GDPs within a run time of 15 min after derivatization with o-phenylenediamine. Hyphenated diode array detection/tandem mass spectrometry detection provides very robust quantification and, at the same time, unequivocal peak confirmation. Systematic evaluation of the derivatization process resulted in an optimal derivatization period that provided maximal derivatization yield, minimal de novo formation (uncertainty range ±5%), and maximal sample throughput. The limit of detection of the method ranged from 0.13 to 0.19 μM and the limit of quantification from 0.40 to 0.57 μM. Relative standard deviations were below 5%, and recovery rates ranged between 91% and 154%, dependent on the type and concentration of the analyte (in 87 out of 90 samples, recovery rates were 100 ± 15%). The method was then applied for the analysis of commercial peritoneal dialysis fluids (nine different product types, samples from three lots of each).

Nocturnal ultrafiltration profiles in patients on APD: impact on fluid and solute transport

In order to prevent morbidity and mortality in peritoneal dialysis (PD), sodium and water balance as well as a minimal level of small-solute clearances are needed. The impact of three nocturnal peritoneal ultrafiltration (UF) profiles on UF and small solute clearance in patients on automated PD (APD) was studied: constant glucose concentration of 1.36% (flat) or modifying the glucose concentration of the heater bag (descendant: 3.86-1.36%; ascendant: 1.36-3.86%). Sixty-two patients were enrolled in the study and received each profile within a four-month period, thus serving as their own controls. UF was lower with the flat profile (367+/-420ml; P<0.01), but no difference was seen between the two higher glucose concentration profiles. Peritoneal Kt/V (pKt/V) and peritoneal creatinine clearance (CrpC) showed statistically higher values from the descendant vs ascendant vs flat profiles (pKt/V: 1.54+/-0.30 vs 1.45+/-0.30 vs 1.38+/-0.27, and CrpC: 36.9+/-7.9 vs 33.5+/-7.48 vs 29.92+/-7.5 mlmin(-1)). Multivariate analysis showed statistical significance for the following: in the intrasubject comparisons, the profile for pKt/V (F=9.109, P<0.001) and CrpC (F=11.697, P<0.001), and in the intersubjects comparisons, the effects of both gender (F=14.334, P<0.01) for pKt/V and peritoneal permeability for both parameters (pKt/V: F=4.37, P<0.05; CrpC: F=11.697, P<0.001). In conclusion, the application of ascendant and descendant UF profiles in automated PD is feasible and results in better UF and small solute clearances, thus preventing inadequate dialysis and volume overload..

Effects of Neutral pH and Reduced Glucose Degradation Products in a New Peritoneal Dialysis Solution on Morphology of Peritoneal Membrane in Rats

BACKGROUND

In vitro studies have shown that pH and glucose degradation products (GDPs) in the dialysate are determinant factors for the biocompatibility of peritoneal dialysis (PD) treatment. The present study was thus designed to evaluate whether a newly developed PD solution, which features neutral pH levels and a low GDP concentration, influences tissue damage of the peritoneal membrane in an in vivo setting, and which factor is more critical to the histological changes.

METHODS

Rats were injected 3 times per day during 1 or 4 weeks with 10 ml of various PD fluids (group G, acidic pH, high GDPs; group S, neutral pH, low GDPs; or group A, acidic pH, low GDPs). When the experimental period was over, the mesothelial cell monolayers of the animals were taken and studied with population analysis, and peritoneal membranes were obtained from the abdominal wall for immunohistochemical examination with proliferating cell nuclear antigen (PCNA) and for measurement of thickness of the peritoneal specimens.

RESULTS

The density of the mesothelial cell monolayer and the number of fibroblast-like cells in group S were significantly less than in group G at 1 and 4 weeks' injection. PCNA-positive nuclei in group S were significantly less than in group G for only the 1-week injection set (group G, 2.03 +/- 0.95; group S, 0.85 +/- 1.18 nuclei/1 x 10(4) microm2). At 4 weeks, the peritoneal thickness of group S (6.32 +/- 0.53 microm) was significantly less than that of group G (7.94 +/- 0.77 microm), There was no significant difference between groups S and A throughout the whole study period except for the result of the number of fibroblast-like cells.

CONCLUSION

These results indicate that a PD solution with a neutral pH and low GDPs proved more biocompatible with the peritoneal membrane than a solution with an acidic pH and high GDPs. Furthermore, the level of the GDPs has more impact on tissue damage of the peritoneal membrane than the pH in the short term.

Advanced glycation end products in uremia

The term "advanced glycation end products" (AGEs) stands for a heterogeneous group of amino acid derivatives that are formed via glycation processes between peptide-bound lysine or arginine derivatives and carbonyl compounds, processes originally known from food systems as "Maillard reactions." AGEs accumulate in plasma and tissues with advancing age, diabetes, and particular renal failure. In vivo and in vitro studies indicate that AGEs represent an important class of uremic toxins. This review focuses on the chemistry behind the formation of AGEs, possible mechanisms underlying the accumulation of AGEs in uremia, clinical and therapeutic implications, and possible nutritional consequences.

Heat sterilization of peritoneal dialysis solutions influences ingestive behavior in non-uremic rats

BACKGROUND

The appetite inhibitory effect of glucose-based peritoneal dialysis (PD) solutions may be due to glucose as such, or the hyperosmolality of the PD solution, or an effect of glucose degradation products (GDPs) formed in the PD solution during heat sterilization. This was studied in an experimental appetite model in rat.

METHODS

The effect of different experimental PD solutions on ingestive behavior was investigated in non-uremic rats equipped with an implanted intraoral (i.o.) cannula through which a 1 mol/L sucrose solution was infused during tests. The amount of intake was recorded at 30 min after rats were infused intraperitoneally (IP) with 30 mL of different solutions. This method allowed an accurate and reproducible analysis of i.o. intake. The experimental PD solutions tested included (1) glucose based PD solutions with different glucose concentrations, sterilized by heat or microbiological filter, (2) glucose- and mannitol-based PD solutions with the same osmolality, sterilized by heat or microbiological filter; and (3) glucose based PD solutions, using different pH values (pH 3.0, pH 5.5 or pH 7.4) during heat sterilization.

RESULTS

Following IP infusion of solutions, (1) the i.o. intake was significantly inhibited by glucose based, heat sterilized PD solutions and the degree of appetite suppression was related to the concentration of dialysate glucose in a dose-dependent way; (2) the i.o. intake was significantly less suppressed by filter sterilized than by heat sterilized glucose-based solutions; (3) the i.o. intake was significantly less following the IP infusion of glucose-based than following the mannitol-based heat sterilized solutions; however, i.o. intake did not differ between the glucose-based and mannitol-based filter sterilized solutions; and (4) furthermore, the degree of suppression of i.o. intake induced by glucose-based PD solutions was influenced by the pH value during heat sterilization. The lower the pH of the PD solution during heat sterilization, the higher the i.o. intake.

CONCLUSIONS

The IP infusion of glucose-based heat-sterilized PD solutions inhibited food intake in this experimental appetite model, and the degree of suppression depended on the concentration of dialysate glucose and the pH of the solution during heat sterilization. The results suggest that GDPs formed during heat sterilization may exert a more adverse effect than glucose itself on ingestive behavior, and that a reduction of the concentration of GDPs in the PD solution using filter sterilization or a low pH value in the PD solution during heat sterilization may improve food intake.