The convenient use of fluorescamine for spectrofluorimetric determination of midodrine hydrochloride in pure form and its tablets formulation: Application to content uniformity testing

A novel sensitive and simple spectrofluorimetric method was developed then validated for determination of midodrine in both its authentic pure form and its tablets. This method is based on the reaction between midodrine's aliphatic primary amine moiety with fluorescamine reagent, using borate buffer at pH 7.8 and yielding a highly fluorescent product whose fluorescence intensity was measured at 462 nm after excitation at 388 nm. This method represents the first attempt for determination of midodrine spectrofluorimetrically. A calibration curve was constructed showing that the linear range was 0.2–3.0 μg/ml. The limit of detection and limit of quantitation values were 0.06 and 0.19 μg/ml respectively. The correlation coefficient (r) and the determination coefficient (r²) values were 0.9992 and 0.9984 respectively. The proposed method was validated according to ICH guidelines and successfully applied for determination of midodrine in its tablets with an overall % recovery of 99.56 ± 0.95. Finally, the presented method was adapted to study the content uniformity test according to United States Pharmacopeia guidelines.     

Utility of ninhydrin reagent for spectrofluorimetric determination of heptaminol in human plasma

For the determination of heptaminol (HEP) in its authentic and dosage form as well as in human plasma, a new simple, sensitive and cheap fluorimetric method of analysis was developed and validated. The presented method is based on the reaction between aliphatic primary amino moiety present in HEP with ninhydrin and phenylacetaldehyde using Torell and Stenhagen buffer at pH 8.2 that yields a highly fluorescent derivative which after excitation at 390 nm showed a fluorescence emission at 464 nm. The effects of various experimental factors on both the development and stability of the fluorescent product was evaluated and optimized. In the concentration range (0.5–6.0 μg/ml), the constructed calibration curve was linear with a good correlation coefficient (0.9997) and the calculated limit of detection (LOD) and limit of quantitation (LOQ) were 0.14 and 0.43 respectively. The presented method was successfully applied for determination of Corasore® tablets and validated according to ICH guidelines.     

Spectrofluorimetric determination of eptifibatide in human plasma and dosage form

A spectrofluorimetric method for the determination of eptifibatide is presented based on its native fluorescence. The type of solvent and the wavelength of maximum excitation and emission were carefully selected to optimize the experimental conditions. Under the specified experimental conditions, the linearities obtained between the emission intensity and the corresponding concentrations of eptifibatide were in the range 0.1–2.5 μg/ml for the calibration curve constructed for direct determination of eptifibatide in dosage form and 0.05–2.2 μg/ml for the calibration curve constructed in spiked human plasma with a good correlation coefficient (r > 0.99). The lower limit of quantification for the calibration curve constructed in human plasma was 0.05 μg/ml. Recovery results for eptifibatide in spiked plasma samples and in dosage form, represented as mean ± % RSD, were 95.17 ± 1.94 and 100.29 ± 1.33 respectively. The suggested procedures were validated according to the International Conference on Harmonization (ICH) guidelines for the direct determination of eptifibatide in its pure form and dosage form and United States Food and Drug Administration (US FDA) Guidance for Industry, Bioanalytical Method Validation for the assay of eptifibatide in human plasma.     

Utility of a xanthene-based dye for determination of nilotinib using two spectroscopic approaches. Applications to bulk powder,capsules, and spiked human plasma

Novel, selective, facile, and precise spectroscopic approaches were validated to determine nilotinib hydrochloride, a tyrosine kinase inhibitor used to treat patients with chronic myeloid leukemia. These approaches depend on the reaction of the tertiary amine group of nilotinib with erythrosine B in the Britton–Robinson buffer at pH 4. Method I, depends on measuring the absorbance of the formed complex at 551 nm. The absorbance concentration plot showed linearity over the concentration range of 1.0 to 9.0 μg/ml. Method II, involved the measurement of the quenching of the native fluorescence of erythrosine B by adding nilotinib in an acidic medium. The fluorescence quenching of erythrosine B was measured at 549 nm after excitation at 528 nm. This approach showed excellent linearity in the concentration range of 0.04 to 0.7 μg/ml. The limit of detection values for Method I and Method II were 0.225 and 0.008 μg/ml, respectively, while the limit of quantitation values for Method I and Method II were 0.68 and 0.026 μg/ml, respectively. To get the optimal conditions, factors that may affect the formation of the ion-pairing complex were thoroughly examined. The two approaches were carefully validated following the International Conference of Harmonization (ICH Q2R1) guidelines. Statistical assessment of the results achieved using the suggested and previously published comparison approaches showed no significant difference. The approaches were successful in determining nilotinib in a pharmaceutical dosage form as well as spiked human plasma samples. The eco-friendly properties of the methods were evaluated by three different tools.     

Sensitive spectrofluorometric method for the determination of ascorbic acid in pharmaceutical nutritional supplements using acriflavine as a fluorescence reagent

An easily performed, specific, sensitive, rapid, reliable and inexpensive procedure for the spectrofluorometric quantitation of ascorbic acid was proposed using acriflavine as a fluorescence quenching reagent. The procedure was based on the determined quenching effect of ascorbic acid on the natural fluorescence signal of acriflavine and the reaction between ascorbic acid and acriflavine in Britton–Robinson buffer solution (pH 6) to produce an ion‐associated complex. The reduction in acriflavine fluorescence intensity was detected at 505 nm, while excitation occurred at 265 nm. The relationship between quenching fluorescence intensity (?F) and concentration of ascorbic acid was linear (R² = 0.9967) within the range 2–10 μg/ml and with a detection limit of 0.08 μg/ml. No significant interference was detected from other materials often found in pharmaceutical nutritional tablets. The obtained results were compared with those from high‐performance liquid chromatography and appeared in good agreement, with no important differences in precision or accuracy. The proposed spectrofluorimetric method was used to determine the amount of ascorbic acid in a number of commercial pharmaceutical nutritional supplement tablets with a 95% confidence performance.     

Micelle‐enhanced direct spectrofluorimetric method for the determination of linifanib: Application to stability studies

A new simple stability‐indicating spectrofluorimetric method has been developed and validated for the determination of the tyrosine kinase inhibitor, linifanib (LNF). The proposed method makes use of the native fluorescence characteristics of LNF in a micellar system. Compared with aqueous solutions, the fluorescence intensity of LNF was greatly enhanced upon the addition of Tween‐80. The relative fluorescence intensity of LNF was measured in a diluting solvent composed of 2% Tween‐80: phosphate buffer pH 8.0 (20: 80, v/v) using excitation and emission wavelengths of 290 and 450 nm, respectively. The proposed method was fully validated as per the ICH guidelines. The recorded fluorescence intensity of LNF was rectilinear over a concentration range of 0.3–2 μg/ml with a high correlation coefficient (r = 0.9990) and low limits of detection (0.091 μg/ml) and quantitation (0.275 μg/ml). The applicability of the method was extended to study the inherent stability of LNF under different stress degradation conditions including, alkaline, acidic, oxidative, photolytic and thermal degradation. Moreover, the method was utilized to study the kinetics of the alkaline and oxidative degradation of LNF. The pseudo‐first order rate constants and half‐lives were calculated.     

Micellar liquid chromatographic determination of metformin hydrochloride using fluorimetric detection after pre‐column derivatization: application to pharmacokinetic parameters in immediate and sustained release formulations

An accurate and selective method using micellar liquid chromatography was developed to determine metformin hydrochloride both in its pharmaceutical dosage forms and human plasma. Separation was conducted using a Zorbax SB‐Phenyl (250 × 4.6 mm id) stainless steel column at ambient temperature after pre‐column derivatization with 9,10‐phenanthraquinone. A mobile phase composed of 0.1 M sodium dodecyl sulfate, 10% 1‐propanol and triethylamine (0.3%) in 0.02 M phosphoric acid, adjusted to pH 2.5, was used at a flow rate of 1 ml/min with fluorimetric detection at 450 nm after excitation at 306 nm. The proposed method showed high sensitivity with limit of quantification of 0.35 μg/ml and limit of detection of 0.23 μg/ml, being linear from 0.5 to 3.0 μg/ml. Being highly sensitive, the method could be applied to spiked human plasma, and also to follow the pharmacokinetic parameters of the studied drug in healthy volunteers after administration of both its immediate and sustained release tablet formulations. Such procedures were carried out without any extraction steps, which improves the accuracy and precision of the proposed method when applied to human plasma. Detailed validation procedures were also carried out giving results in accordance with the comparison method. The proposed method has also the advantage of being environmentally safe, where the use of organic solvents is highly limited in comparison with other traditional chromatographic separation methods that depend mainly on a high proportion of organic modifiers. This concept, in turn, emphasizes the application of green chemistry in the analysis of pharmaceutical products. The simplicity, relatively low cost and short analysis time of the suggested method makes it a candidate for routine quality control work.     

A new fluorescence probe for sofosbuvir analysis in dosage form and spiked human plasma

A simple, rapid, and low-cost technique was developed to allow reliable analysis of the anti-hepatitis C drug sofosbuvir in bulk, tablet form, and spiked human plasma. This method depends on the ability of sofosbuvir to quench the fluorescence of the newly synthesized 2-amino-3-cyano-4,6-dimethylpyridine (reagent 3 ). Elemental analysis and spectral data were used to validate the structure of the synthesized reagent. The newly synthesized reagent exhibited a satisfactory level of fluorescence emission at 365 nm after excitation at 247 nm. All experimental variables that might affect the quenching process were analyzed and optimized. Linearity, range, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ) were all validated in accordance with the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines. The concentration range was shown to be linear between 0.1 and 1.5 μg/mL. The technique was effectively utilized for sofosbuvir analysis in both its tablet dosage form and spiked human plasma, with mean percentage recoveries of 100.13 ± 0.35 and 94.26 ± 1.69, respectively.     

Simultaneous determination of piroxicam and norfloxacin in biological fluids by high‐performance liquid chromatography with fluorescence detection at zero‐order emission mode

A new highly sensitive high‐performance liquid chromatographic method with fluorescence detection (HPLC–FLD) in zero‐order emission mode was developed for the first time for the simultaneous determination of piroxicam (PRX) and norfloxacin (NRF) in biological fluids. The fluorescence detector wavelengths were set at 278 nm for excitation and zero‐order mode for emission. The zero‐order emission mode produced greater sensitivity for the measurement of both drugs than a fixed emission wavelength (446 nm). The new developed method was validated according to International Conference of Harmonization (ICH) guidelines. Linearity was found to be over concentration ranges 0.001–20 μg/ml and 0.00003–0.035 μg/ml for PRX and NRF, respectively. The limits of detection were 4.87 × 10^?4 and 1.32 × 10^?5 μg/ml for PRX and NRF, and the limits of quantitation were 1.47 × 10^?3 and 4.01 × 10^?5 μg/ml, respectively. The current fluorescence method was found to be more sensitive than most commonly used analytical methods and was successfully applied for simultaneous determination of PRX and NRF in biological fluids (serum and urine) with recoveries ranging from 91.67% to 100.36% for PRX and from 96.00% to 101.43% for NRF.     

Eco-friendly approach for the determination of moxifloxacin in pharmaceutical formulations and biological fluids based on fluorescence quenching of l-tryptophan

A rapid, novel and cost-effective spectrofluorimetric method developed to determine moxifloxacin (MFX) in pharmaceutical preparations because MFX in a pH 10 medium could reduce the fluorescence intensity of l -tryptophan. The maximum fluorescence excitation and emission wavelengths were found to be 280 and 363 nm respectively. A range of factors affecting fluorescence quenching and the effect of co-existing substances were investigated. Fluorescence quenching values (ΔF = F_L-tryptophan − F_{Moxi-L-tryptophan}) displayed a strong linear relationship with the MFX concentration ranging from 0.2 to 8.0 μg/ml under optimum conditions. The limit of detection was found to be 6.1 × 10⁻⁴ μg/ml. The proposed method was shown to be suitable for MFX determination in pharmaceutical tablets and biological fluids by the linearity, recovery and limit of detection. The spectrofluorimetric approach that has been developed is extremely eco-friendly, as evidenced by the fact that all the experimental components and solvents were safe for the environment.     

Determination of metronidazole in vaginal tissue by high-performance liquid chromatography using solid-phase extraction

A sensitive high-performance liquid chromatographic (HPLC) method for the determination of metronidazole in vaginal tissue is reported. The method uses a Zorbax SB phenyl column with a 0.01 M aqueous monobasic potassium phosphate buffer (pH 4.0)-absolute methanol (85:15, v/v) as mobile phase at a flow-rate of 1.0 ml/min and detection at 313 nm. Tinidazole was used as the internal standard. The method employed homogenization of tissue followed by solid-phase extraction. The quantitation was achieved within 30 min with sensitivity in the ng/g range. Metronidazole was linear in the 100–2000 ng/g range. The accuracy and precision were in the 1–4% range for the drug and the limit of detection was approximately 100 ng/g based on a signal-to-noise ratio of 3 and a 100-μl injection.     

Green spectrophotometric and spectrofluorimetric determination of biperiden hydrochloride using erythrosine B sensing probe

Erythrosine B (EB) is a food colorant antiviral xanthene dye that has many applications as a color additive in pharmaceuticals and cosmetics. Its use as a sensor for spectrofluorimetric and spectrophotometric analysis of amine-based pharmaceuticals renders many advantages because of its availability, low cost, rapid labeling, and high sensitivity. Herein, two fast and sensitive spectrofluorimetric and spectrophotometric methods were established for the estimation of the anti-Parkinson drug, biperiden (BIP) hydrochloride (HCl), in its raw material and tablet forms. The proposed methods depended on the interaction between the phenolic group of EB and the tertiary amino group of the studied analyte to form an ion-pair complex at pH 4 using the Britton Robinson buffer. The spectrofluorimetric method is based on the measurement of the quenching power of BIP HCl on the fluorescence intensity of EB at λ_ex/em = 527.0/550.9 nm. This method was rectilinear over the concentration range of 0.1–1.0 μg/mL with a limit of detection (LOD) = 0.017 μg/mL and a limit of quantification (LOQ) = 0.05 μg/mL. Meanwhile, the colorimetric method involved monitoring the absorbance of the formed ion-pair complex at 555 nm, showing a linearity range of 0.4–5.0 μg/mL with LOD = 0.106 μg/mL and LOQ = 0.322 μg/mL. The proposed methods were assessed for the greenness, indicating the greenness of the developed methods.     

Measurement of 5,10-dideaza-5,6,7,8-tetrahydrofolate (lometrexol) in human plasma and urine by high-performance liquid chromatography

Three high-performance liquid chromatographic methods are described for the detection of the novel antifolate anticancer drug (6R)-5,10-dideaza-5,6,7,8-tetrahydrofolate (lometrexol): one with fluorometric detection and two with detection by UV absorbance. An assay for plasma lometrexol using UV detection (288 nm) and reversed-phase chromatography was developed, with a quantitation limit of 0.2 μg/ml and linearity up to 10 μg/ml. This assay was modified for measurement of lometrexol in urine, with a quantitation limit of 2 μg/ml and linearity up to 25 μg/ml. An alternative assay for plasma lometrexol using derivatization and fluorescence detection (excitation at 325 nm, emission at 450 nm) was also developed, which proved twenty-fold more sensitive (quantitation limit of 10 ng/ml) than the UV assay, and which was linear up to 250 ng/ml. The fluoremetric method requires sample oxidation with manganese dioxide prior to analysis, and uses ion-pair chromatography with tetramethylammonium hydrogensulphate as an ion-pair reagent. All assays use a similar preliminary solid-phase extraction method (recovery as assessed by UV absorption >73%), with C10-desmethylene lometrexol added for internal standardisation. Each assay is highly reproducible (inter-assay precision in each assay is <10%). Applicability of the fluorescence-based assay to lometrexol in plasma and the UV-based assay lometrexol in urine is demonstrated by pharmacokinetic studies in patients treated as part of a Phase I clinical evaluation of the drug.     

Highly fluorescent nitrogen-doped carbon quantum dots prepared using sucrose and urea: Green synthesis,characterization, and use for determination of torsemide in its tablets and plasma samples

A simple and facile microwave-assisted method was developed for the synthesis of highly fluorescent nitrogen-doped carbon quantum dots (N-CQDs) using sucrose and urea. The produced quantum dots exhibited a strong emission band at 376 nm after excitation at 216 nm with quantum yield of 0.57. The as-prepared N-CQDs were characterized using Fourier-transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) images, and ultraviolet-visible (UV-visible) spectra. The average particle size was 7.7 nm. It was found that torsemide (TRS) caused an obvious quenching of the fluorescent N-CQDs; so, they were used for its spectrofluorometric estimation. An excellent linear correlation was found between the fluorescence quenching of N-CQDs and the concentration of the drug in the range of 0.10 to 1.0 μg/mL with limit of quantitation (LOQ) of 0.08 μg/mL and limit of detection (LOD) of 0.027 μg/mL. The method was successfully applied for the assay of the drug in its commercial tablets and spiked human plasma samples, and the results obtained were satisfactory. Complex GAPI was used for greenness assessment of the analytical procedures and the pre-analysis steps. Interference likely to be introduced from co-administered drugs was also studied.     

Determination of a novel α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptor antagonist (LY300164) and its N-acetyl metabolite in mouse,rat, dog,and monkey plasma using high-performance liquid chromatography with ultraviolet detection

A method for the analysis of the AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate) receptor antagonist LY300164 (compound I) and its N-acetyl metabolite (compound II) in plasma was developed. The assay utilized solid-phase extraction on a C₁₈ Bond Elut cartridge followed by reversed-phase HPLC with UV detection at 310 nm. The method exhibited a large linear range from 0.05 μg/ml to 50 μg/ml with an intra-sassay accuracy for compound I and compound II ranging from 89.0% to 114.5% and intra-assay precision ranging from 0.5 to 15.3% in mouse, rat, dog, and monkey plasma. The inter-assay accuracy of compound I and compound II was 93.3% to 101.8% and the inter-assay precision was 1.6% to 11.2% in dog plasma. The lower limit of quantitation was 0.05 μg/ml for compound I in plasma from all species tested. The lower limit of quantitation for compound II was 0.05 μg/ml in dog and monkey plasma and 0.1 μg/ml in mouse and rat plasma. Extracts of compound I and II from dog plasma were shown to be stable for 24 h at room temperature, and both compounds were stable when spiked into rat and monkey plasma frozen at −70°C for 27 days. The method has shown to be useful in the investigation of the pharmacokinetics of the parent compound (I) and metabolite (II) in preclinical studies.     

Determination of the class III antiarrhythmic drugs dronedarone and amiodarone,and their principal metabolites in plasma and myocardium by high-performance liquid chromatography and UV-detection

Dronedarone, a noniodinated benzofuran derivative of amiodarone, is believed to have a better side effect profile, and is currently undergoing phase III clinical trials. A novel method was developed for the determination of dronedarone and its principal metabolite debutyldronedarone in both plasma and myocardial tissue by high-performance liquid chromatography (HPLC) coupled with UV-detection. The assay was also validated for determination of amiodarone and desethylamiodarone. Samples were obtained from healthy humans (plasma) and goats (plasma and myocardium). Sample preparation included deproteinization with acetonitrile and extraction with a mixture of heptane and dichloromethane (50/50, v/v). Chromatographic separation was performed on a Pathfinder PS polymeric C18 column (50 mm × 4.6 mm, 2.5 μm) with a mobile phase of acetonitrile, isopropanol, water and ammonia (80/10/10/0.025, v/v/v/v) at a flow-rate of 1 ml/min. Calibration curves of all analytes were linear in the range of 0.01–5 μg/ml for plasma samples, with a lower limit of quantification (LLOQ) of 0.04 μg/ml. For myocardial tissue samples, linear curves of all analytes were observed in the range of 0.02–500 μg/g, with a LLOQ of 0.08 μg/g. Within- and between-day precision was <18%, and within- and between-day accuracy ranged from 97.5 to 109.7%, with a recovery of 67.6–79.9%. The present method enables sensitive and specific detection of dronedarone, amiodarone and principal metabolites in plasma as well as myocardial tissue.     

Resonance Rayleigh scattering approach based on association complex formation with erythrosine B for determination of venlafaxine,application to the dosage form and spiked human plasma

The interaction of venlafaxine hydrochloride (VLX) with erythrosine B was investigated using a resonance Rayleigh scattering (RRS) spectroscopic technique. In acetate buffer (pH 3.4), erythrosine B reacted with VLX to form a 1:1 ion-pair complex with concomitant enhancement in RRS intensity that was measured at 330 nm. In addition, the stability constant and the change in free energy of the reaction were estimated. Based on this interaction a new method was developed for a sensitive VLX analysis using erythrosine B as a probe. The results indicated that this method had good selectivity in the presence of coexisting compounds. The scattering intensity (ΔI_RRS) was linearly dependent on VLX concentration over the range 0.04–1.0 μg ml⁻¹ with a determination coefficient (r) of 0.9998. The limit of detection and limit of quantitation were 0.01 and 0.03 μg ml⁻¹, respectively. This method could be suitably used for analysis of VLX in pharmaceutical capsules and human plasma.     

Determination of 2,3-dimercaptosuccinic acid in mice blood and tissues by HPLC with fluorescence detection

2,3-Dimercaptosuccinic acid (DMSA) is an orally effective chelating agent for the treatment of heavy metal poisoning. The increasing therapeutic use of DMSA has stimulated the need for sensitive and selective methods for its determination in biological samples, as well as study on pharmacokinetics and tissue distribution. According to the previously reported method, an improved method was established for the determination of DMSA in mice blood and tissues, in which oxidized DMSA was reduced by the disulfide-reducing agent, dithiothreitol (DTT), and DMSA was converted to a highly fluorescent and stable derivative by reaction with monobromobimane (mBBr) in alkaline solution. Acetonitrile was used for deproteinization and dichloromethane was used for condensation and purification, which significantly shortened the amount of time used to process the sample. Meanwhile isocratical elution was performed and excellent separation of the DMSA derivative was obtained, this enabled a run finish within 20 min. The limits of quantitation were 0.025 μg/ml in brain and 0.1 μg/ml in blood, lung, heart, intestine, liver, spleen and kidney, respectively. The calibration curves were linear in all samples (r² > 0.992) with a range of 0.025–1.6 μg/ml for brain homogenate and 0.1–6.4 μg/ml for blood and homogenates of lung, heart, intestine, liver, spleen and kidney, respectively. Therefore, the method is simple, rapid and sensitive, and it could be applicable to the studies in an animal model to evaluate the distribution of DMSA in blood and tissues.     

Condensation of heptaminol hydrochloride for its spectrofluorimetric determination in pure form and tablets: application in human plasma

A sensitive, simple, accurate and less expensive fluorimetric method was designed and validated for analysis of heptaminol HCl in both its pure and dosage forms, as well as in human plasma. The main principle used in the proposed approach was the condensation reaction between heptaminol's primary amino moiety and ethyl acetoacetate/formaldehyde reagents, giving a derivative that was highly fluorescent at 416 nm after excitation at 350 nm. Various experimental parameters that affected either the product's development or its stability were evaluated and optimized. The constructed calibration curve was linear over the range 0.2–2 μg/ml, with a good correlation coefficient (0.9996). Both the calculated limit of detection and limit of quantitation were 0.06 and 0.18 μg/ml, respectively. The presented approach was a success when used to determine Corasore® tablets and was validated according to International Council for Harmonisation guidelines.     

Direct determination of polyglucose metabolites in plasma using anion-exchange chromatography with pulsed amperometric detection

High-performance anion-exchange chromatography with pulsed amperometric detection (HPAE–PAD) was evaluated for the quantitation of polyglucose metabolites (DP2–DP7) in human plasma. The method was investigated for accuracy, precision, specificity, linearity, range and analyte stability. Samples were prepared by dilution into the standard range (0.1–10 μg/ml) followed by deproteinization using a 30?000 molecular mass cut-off filtration device. The limit of detection was 0.05 μg/ml for all metabolites. Method precision for DP2–DP7 varied from approximately 2% R.S.D. in the upper range to approximately 15% R.S.D. at the limit of quantitation. Samples were stable following one or two freeze–thaw cycles and, after preparation, they could be refrigerated for up to 72 h. Application of this method to clinical plasma samples from continuous ambulatory peritoneal dialysis (CAPD) patients administered one daily night-time intraperitoneal exchange of 2 l of 7.5% polyglucose solution for four weeks indicated that plasma levels of DP2, DP3 and DP4 increased from baseline levels of <0.01 g/l to steady-state levels of 1.2±0.3, 1.2±0.3 and 0.4±0.1 g/l (mean±S.D.), respectively. These steady state plasma levels for DP2 and DP3 are comparable to previously reported levels in patients administered daily overnight 7.5% polyglucose dialysis solution.