Effects of Fluid Treatment With Hydroxyethyl Starch on Renal Function in Patients With Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND: Recent reports have doubted the efficacy and safety of hydroxyethyl starch (HES) for volume resuscitation. HES has been reported to promote renal insufficiency particularly in sepsis and trauma patients. This analysis investigated the effects of HES 6% 130/0.4 for fluid therapy in patients with intact renal function who suffered aneurysmal subarachnoid hemorrhage (SAH). METHODS: This retrospective analysis included 107 patients and was conducted in the framework of a clinical trial assessing the efficacy of magnesium sulfate in SAH. Because magnesium is renally eliminated, patients with renal insufficiency had been excluded. Standard therapy after aneurysm occlusion included the daily administration of HES 6% 130/0.4. Serum and urine creatinine and fluid balance were measured daily. RESULTS: Patients received a daily mean of 1101±524 mL HES and 3353±1396 mL Ringer's solution. The highest creatinine values were recorded on day 3 after admission (0.88±0.25 mg/100 mL) and continuously decreased thereafter. In 6 patients, creatinine values temporarily increased by >0.3 mg/100 mL but recovered to admission values at the end of the observation period. CONCLUSIONS: Concerning renal function, the first days after SAH seem to be a vulnerable phase in which a variety of interventions are performed, including contrast-enhanced neuroradiologic procedures. In this period, HES 6% 130/0.4 should be administered with caution. However, no patient suffered from renal failure and required temporary or permanent renal replacement therapy. These results suggest that the administration of HES 6% 130/0.4 is safe in SAH patients without preexisting renal insufficiency.

Impact of 6% hydroxyethyl starch 130/0.42 and 4% gelatin on renal function in a pediatric animal model.

OBJECTIVES: Artificial colloids, frequently used to prevent hemorrhagic shock in children, may induce serious renal side effects in critically ill adult patients. The impact of perioperative colloid infusion on the renal function in adults and children remains unclear. AIM: To determine the impact of single doses of artificial colloids on renal function tests, we conducted an experimental animal study. We hypothesized that neither the infusion of moderate doses of 6% hydroxyethyl starch (HES) nor of 4% gelatin (GEL) would have a serious impact on the renal function of healthy piglets. METHODS: Fifteen sedated piglets were randomly assigned to receive an infusion of either 20 ml·kg(-1) HES or GEL or a balanced electrolyte solution (BS, control group) over 30 min. Before and 7 days after infusion, serum and urine renal function tests were recorded and renal biopsies were taken. RESULTS: Serum and urine renal function tests (e.g., creatinine, urea, cystatin C, and neutrophil gelatinase-associated lipocalin) were within normal ranges, and a microscopic examination of the renal tissue in all groups revealed no major alterations such as tubular necrosis, interstitial bleeding, interstitial inflammation, or vacuoles. CONCLUSIONS: In this pediatric animal model, the infusion of moderate doses of artificial colloids was not found to have any relevant impact on renal function. Further clinical investigations are necessary to provide a conclusive assessment of the risk for renal impairment after HES and GEL administration during major pediatric surgery.

Does the type of fluid affect rapidity of shock reversal in an anaesthetized-piglet model of near-fatal controlled haemorrhage? A randomized study.

BACKGROUND: The optimal resuscitation fluid for the early treatment of severe bleeding patients remains highly debated. The objective of this experimental study was to compare the rapidity of shock reversal with lactated Ringer (LR) or hydroxyethyl starch (HES) 130/0.4 at the early phase of controlled haemorrhagic shock. To assess the influence of vascular permeability in this model, we measured plasma vascular endothelial growth factor (VEGF) levels during the experiment. METHODS: Thirty-six anaesthetized and mechanically ventilated piglets were bled (<30 ml kg(-1)) to hold mean arterial pressure (MAP) at 40 mm Hg for more than 30 min and were resuscitated in two randomized groups: LR (n=14) or HES (n=14) at 1 ml kg(-1) min(-1) until MAP reached its baseline value of ±10%. MAP was maintained at its baseline value for 1 h. The time and fluid volume necessary to restore the baseline MAP value were measured. RESULTS: The time to restore the baseline MAP value of ±10% was significantly lower in the HES group (P<0.001). During the initial resuscitation phase, the infused volume was 279 (119) ml in the HES group and 1011 (561) ml in the LR group (P<0.0001). During the stabilization phase, the infused volume was 119 (124) ml in the HES group and 541 (506) ml in the LR group. Biological data and plasma VEGF levels were similar between the groups. CONCLUSIONS: Restoration of MAP was four times faster with HES than with LR in the early phase of controlled haemorrhagic shock. However, there was no evidence of increased vascular permeability.

Interaction between hydroxyethyl starch and propofol: computational and laboratorial study.

BACKGROUND: Hydroxyethyl starch (HES) is one of the most used colloids for intravascular volume replacement during anesthesia. AIM: To investigate the existence of a chemical interaction between HES and the anesthetic propofol by in vitro propofol dosing, computational docking, and examination of a complex between propofol and HES by infrared (IR), ultraviolet (UV), and (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy. METHODS: Ten samples with human plasma mixed with HES or lactated Ringers (n = 5 for each fluid) were prepared, and the propofol free fraction was quantified until 50 min, using gas chromatography-mass spectrometry. The docking study was performed between HES and propofol and compared with controls. The binding affinities between HES and the small molecules were evaluated by binding free energy approximation (ΔGb, kJ mol(-1)). The IR, UV, and NMR spectra were measured for propofol, HES, and a mixture of both obtained by the kneading method. RESULTS: Propofol concentrations were significantly lower in the HES samples than in the LR samples (p = .021). The spectroscopic characterization of propofol combined with HES revealed differences in spectra and docking studies reinforced a potential interaction between propofol and HES. CONCLUSIONS: Propofol and HES form a complex with different physical-bio-chemical behavior than the single drugs, which may be an important drug interaction. Further studies should evaluate its clinical effects.

Development and application of a UPLC-MS/MS method for the pharmacokinetic study of 10-hydroxy camptothecin and hydroxyethyl starch conjugate in rats.

With the purpose to carry out the pharmacokinetic studies of 10-hydroxy camptothecin (10-HCPT) and hydroxyethyl starch (10-HCPT-HES) conjugate, an ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method has been developed and validated. The analytes, 10-HCPT and the internal standard, Diphenhydramine hydrochloride were extracted with ethyl acetate-isopropanol (95:5, v/v) and separated on an ACQUITY UPLC™ BEH C18 column using a mobile phase composed of acetonitrile and water (containing 0.1% formic acid) with a linear gradient program. With positive ion electrospray ionization (ESI), the analytes were monitored on a triple quadrupole mass spectrometer in the multiple reaction monitoring (MRM) mode. Linear calibration curves were obtained over the concentration ranges of 0.5-2500ng/mL. The intra- and inter-day precisions were less than 9.8% and 10.8%, respectively. The accuracy was within 12.1%. The mean recoveries of 10-HCPT at three concentrations of 2.5, 100, 2000ng/mL were higher than 87.2%. Commercial 10-HCPT injection and 10-HCPT-HES conjugate were administered intravenously at an equal dose of 10-HCPT at 0.5mg/kg. The biological half-life of conjugate was increased significantly from 10min to 3.15h and the bioavailability was 40 times higher than 10-HCPT injection. Consequently, the proposed UPLC-ESI-MS/MS method was proved to be sensitive, specific and reliable to analyze 10-HCPT in biological samples; 10-HCPT and HES conjugate is a promising strategy for delivery of 10-HCPT with prolonged half time and improved bioavailability.

Interactions between the volume effects of hydroxyethyl starch 130/0.4 and Ringer´s acetate.

INTRODUCTION: The turnover of Ringer´s solutions is greatly dependent on the physiological situation, such as the presence of dehydration or anaesthesia. The present study evaluates whether the kinetics is affected by previous infusion of colloid fluid. METHODS: Ten male volunteers with a mean age of 22 years underwent three infusion experiments, on separate days and in random order. The experiments included 10 mL/kg of 6% hydroxyethyl starch 130/0.4 (Voluven™), 20 mL/kg of Ringer's acetate, and a combination of both, where Ringer´s was administered 75 minutes after the starch infusion ended. The kinetics of the volume expansion was analysed by non-linear least- squares regression, based on urinary excretion and serial measurement of blood haemoglobin concentration for up to 420 minutes. RESULTS: The mean volume of distribution of the starch was 3.12 L which agreed well with the plasma volume (3.14 L) estimated by anthropometry. The volume expansion following the infusion of starch showed monoexponential elimination kinetics with a half-life of two hours. Two interaction effects were found when Ringer´s acetate was infused after the starch. First, there was a higher tendency for Ringer´s acetate to distribute to a peripheral compartment at the expense of the plasma volume expansion. The translocated amount of Ringer´s was 70% higher when HES had been infused earlier. Second, the elimination half-life of Ringer´s acetate was five times longer when administered after the starch (88 versus 497 minutes, P<0.02). CONCLUSIONS: Starch promoted peripheral accumulation of the later infused Ringer´s acetate solution and markedly prolonged the elimination half-life. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01195025.

Resuscitation with hydroxyethyl starch improves renal function and lactate clearance in penetrating trauma in a randomized controlled study: the FIRST trial (Fluids in Resuscitation of Severe Trauma).

BACKGROUND: The role of fluids in trauma resuscitation is controversial. We compared resuscitation with 0.9% saline vs hydroxyethyl starch, HES 130/0.4, in severe trauma with respect to resuscitation, fluid volume, gastrointestinal recovery, renal function, and blood product requirements. METHODS: Randomized, controlled, double-blind study of severely injured patients requiring >3 litres of fluid resuscitation. Blunt and penetrating trauma were randomized separately. Patients were followed up for 30 days. RESULTS: A total of 115 patients were randomized; of which, 109 were studied. For patients with penetrating trauma (n=67), the mean (sd) fluid requirements were 5.1 (2.7) litres in the HES group and 7.4 (4.3) litres in the saline group (P<0.001). In blunt trauma (n=42), there was no difference in study fluid requirements, but the HES group required significantly more blood products [packed red blood cell volumes 2943 (1628) vs 1473 (1071) ml, P=0.005] and was more severely injured than the saline group (median injury severity score 29.5 vs 18; P=0.01). Haemodynamic data were similar, but, in the penetrating group, plasma lactate concentrations were lower over the first 4 h (P=0.029) and on day 1 with HES than with saline [2.1 (1.4) vs 3.2 (2.2) mmol litre⁻¹; P=0.017]. There was no difference between any groups in time to recovery of bowel function or mortality. In penetrating trauma, renal injury occurred more frequently in the saline group than the HES group (16% vs 0%; P=0.018). In penetrating trauma, maximum sequential organ function scores were lower with HES than with saline (median 2.4 vs 4.5, P=0.012). No differences were seen in safety measures in the blunt trauma patients. CONCLUSIONS: In penetrating trauma, HES provided significantly better lactate clearance and less renal injury than saline. No firm conclusions could be drawn for blunt trauma. STUDY REGISTRATION: ISRCTN 42061860.

Evaluation of MP4OX for prevention of perioperative hypotension in patients undergoing primary hip arthroplasty with spinal anesthesia: a randomized, double-blind, multicenter study.

BACKGROUND: MP4OX (oxygenated polyethylene glycol-modified hemoglobin) is an oxygen therapeutic agent with potential applications in clinical settings where targeted delivery of oxygen to ischemic tissues is required. The primary goal of this study was to investigate MP4OX for preventing hypotensive episodes. An additional goal was to establish the safety profile of MP4OX in a large surgical population. METHODS: Patients (n = 367) from 18 active study sites in six countries, undergoing elective primary hip arthroplasty with spinal anesthesia, were randomized to receive MP4OX or hydroxyethyl starch 130/0.4. Patients received a 250-ml dose at induction of spinal anesthesia and a second 250-ml dose if the protocol-specified trigger (predefined decrease in systolic blood pressure) was reached. The primary end point was the proportion of patients who developed one or more hypotensive episodes. RESULTS: The proportion of patients with one or more hypotensive episodes was significantly lower (P < 0.0001) in the MP4OX group (66.1%) versus controls receiving hydroxyethyl starch 130/0.4 (90.2%). More MP4OX-treated patients experienced adverse events compared with controls (72.7% vs. 61.4%; P = 0.026). Transient elevations in laboratory values (e.g., alanine aminotransferase, aspartate aminotransferase, lipase, and troponin concentrations) occurred more frequently in the MP4OX group. There were no significant differences in the incidence of serious adverse events or in the composite morbidity and ischemia outcome end points, but nausea and hypertension were reported more often in MP4OX-treated patients. CONCLUSION: MP4OX significantly reduced the incidence of hypotensive episodes in patients undergoing hip arthroplasty, but the adverse event profile does not support use in routine low-risk surgical patients for the indication evaluated in this study.

Intra-operative colloid administration increases the clearance of a post-operative fluid load.

BACKGROUND: It is unknown whether an intra-operative colloid infusion alters the dynamics of a crystalloid load administered post-operatively. METHODS: Ten patients received 12.5 ml/kg of Ringer's lactate over 30 min 1-3 days before and 4 h after laparoscopic cholecystectomy, during which 10 ml/kg of a colloid solution, hydroxyethylstarch (HES 130/0.4), was infused. The total body clearance of the pre- and post-operative test infusions was taken as the ratio between the urinary excretion and the Hb-derived dilution of venous plasma over 150 min. The plasma clearance of the infused fluid was calculated using volume kinetics based on the plasma dilution alone. The pre-operative plasma clearance was compared with the post-operative plasma clearance and patients served as their own control. RESULTS: The urinary excretion averaged 350 ml for the pre-operative infusion and 612 ml post-operatively, which corresponds to 46% and 68% of the pre- and post-operative infusions, respectively. The total body clearance of the crystalloid fluid was 30 ml/min before surgery and 124 ml/min after surgery (P<0.01). The plasma clearance, as obtained from the plasma dilution alone, was 28 and 412 ml/min, respectively. The maximal increase in plasma volume was 410 ml pre-operatively vs. 220 ml post-operatively. CONCLUSIONS: Infusion of a colloid solution in combination with a crystalloid during laparoscopic cholecystectomy increased the plasma clearance of a post-operative crystalloid infusion.

Aislamiento de células mononucleares de sangre periférica para trasplante de células madre: método simplificado / Isolation of mononuclear cells of peripheral blood for stem cell transplant: simplified method

En los últimos años el tema de las células madre ha despertado creciente interés por su potencial terapéutico en enfermedades que hasta el momento no tienen un tratamiento efectivo. Se realizó un estudio prospectivo y exploratorio en pacientes con arteriosclerosis obliterante de miembros inferiores, en el que se evaluó la seguridad y efectividad de un método manual de recolección y procesamiento de células mononucleares y de células CD34+ a partir de sangre periférica movilizada. La sangre se procesó en sistemas cerrados de recolección, utilizando el hidroxietilalmidón como potenciador de la sedimentación eritrocitaria. Los pacientes fueron tratados con factor estimulador de colonias granulocítico en dosis total de 40ìcg/kg de peso durante 2 días, y después si el conteo de leucocitos era superior a 20 x 109/L se procedió a la autodonación. Para valorar la eficacia del método se analizaron las cantidades de células nucleadas, de células mononucleares y de células CD 34+ en el concentrado celular; se determinó la viabilidad celular y además se hizo el estudio microbiológico del material obtenido. Se demostró que el método es eficaz y seguro, ya que logra niveles celulares adecuados, con elevada viabilidad y ausencia de contaminación bacteriana. Por otra parte, es sencillo y de bajo costo, lo que permite su extensión a otros centros de salud, en particular a los de menos recursos. Esto facilita que un mayor número de pacientes se puedan beneficiar con el tratamiento a base de células madre.

In the last years, the topic of stem cells has arisen an increasing interest for its therapeutic potential in diseases that have not an effective treatment so far. A prospsective and exploratory study was conducted in patients with obliterant atherosclerosis of the lower limbs to evaluate the safety and effectiveness of a manual method of collection and processing of mononuclear cells and of CD34+ cells, starting from mobilized peripheral blood. The blood was processed in closed collection systems, using hydroxyethyl starch as a potentiator of erythrocyte sedimentation. The patients were treated with granulocyte colony stimulating factor at total doses of 40µcg/kg of weight during 2 days. Self-donation was performed when the leukocyte count was higher than 20 x 109/L. To assess the efficacy of the method, the amounts of nucleated cells, of mononuclear cells and of CD 34+ cells in the cellular concentrate were analyzed. Cellular viability was determined and a microbiological study of the material obtained was conducted. It was proved that the method is efficient and safe, since adequate cellular levels with a high viability and absence of bacterial contamination are attained. On the other hand, it is simple and cheap, which allows its application in other health centres, particularly in those with less resources. This makes possible that more patients benefit from the stem cell treatment.

Impact of the C2/C6 ratio of high-molecular-weight hydroxyethyl starch on pharmacokinetics and blood coagulation in pigs.

BACKGROUND: High-molecular-weight, low-substituted hydroxyethyl starch (HES) may not affect blood coagulation more than low-molecular-weight, low-substituted HES. The authors assessed in vivo the effect of a lowered C2/C6 ratio on pharmacokinetic characteristics and the impact on blood coagulation of high-molecular-weight, low-substituted HES. METHODS: A prospective, randomized, parallel study in 30 pigs compared HES 650/0.42/2.8 with HES 650/0.42/5.6. Before, during, and after infusion of 30 ml/kg body weight HES, blood samples were collected over 630 min to measure HES concentrations and plasmatic coagulation and to assess blood coagulation in whole blood by Thrombelastography (TEG; Haemoscope Corporation, Niles, IL). Pharmacokinetic parameters were estimated using a two-compartment model. RESULTS: The elimination constant was 0.009 +/- 0.001 min(-1) for HES 650/0.42/2.8 and 0.007 +/- 0.001 min(-1) for HES 650/0.42/5.6 (P < 0.001); the area under the plasma concentration-time curve was 1,374 +/- 340 min x g/l for HES 650/0.42/2.8 and 1,697 +/- 411 min x g/l for HES 650/0.42/5.6 (P = 0.026). The measured plasma HES concentrations were not different between HES 650/0.42/2.8 and HES 650/0.42/5.6. Both HES solutions equally affected blood coagulation: Thrombelastographic coagulation index decreased similarly at the end of infusion of HES 650/0.42/2.8 and at the end of infusion of HES 650/0.42/5.6 (P = 0.293). Also, activated partial thromboplastin and prothrombin times increased similarly for HES 650/0.42/2.8 and HES 650/0.42/5.6 (P = 0.831). CONCLUSION: Reducing the C2/C6 ratio in high-molecular, low-substituted HES solutions results in a slightly faster HES elimination. However, the blood coagulation compromising effect was unaffected.

Bioequivalence comparison between hydroxyethyl starch 130/0.42/6 : 1 and hydroxyethyl starch 130/0.4/9 : 1.

OBJECTIVE: The aim of this study was to investigate whether a recently developed low molecular, low substituted hydroxyethyl starch (HES 130/0.42/6 : 1), altered in molar substitution and C2/C6 ratio, is bioequivalent to the former standard HES preparation (130/0.4/9 : 1). METHODS: The two HES solutions were infused (60g as a single dose within 30 minutes) in healthy volunteers using a randomised, crossover design. HES serum concentrations were used for computation of pharmacokinetic parameters; area under the concentration-time curve from infusion start until 24 hours thereafter (AUC(24)) and maximum serum concentration (C(max)) were the primary criteria. Haemodilution, colloid osmotic pressure and plasma viscosity were measured as secondary criteria. Pentastarch (HES 200/0.5/5:1) was investigated in the same volunteers and manner during a subsequent period. RESULTS: Using non-compartmental analysis, significant differences were found for AUC(24) (45.97 +/- 8.97 mg . h/mL vs 58.32 +/- 9.23 mg . h/mL; HES 130/0.42/6 : 1 vs HES 130/0.4/9 : 1) and total apparent clearance (CL; 1.14 +/- 0.4 L/h vs 0.81 +/- 0.34 L/h). C(max) and elimination half-life (t(1/2)) were similar, while the AUC(24), t(1/2) and CL of pentastarch were significantly different from those of low substituted HES solutions. CONCLUSION: Being equivalent with pentastarch and HES 130/0.4/9 : 1 in terms of colloid osmotic and haemodilution effect, HES 130/0.42/6 : 1 shows the fastest clearance from the circulation.

HES 130/0.42 shows less alteration of pharmacokinetics than HES 200/0.5 when dosed repeatedly.

BACKGROUND: Hydroxyethyl starches (HES) accumulate in the circulation when administered repeatedly. Accumulation is thought to be partly responsible for undesirable effects (tissue storage, blood coagulation impairment, and itching). HES 130/0.42 with low molecular weight and a low level of substitution has recently been developed in order to reduce those risks. METHODS: In healthy volunteers, the pharmacokinetics of HES 130/0.42/6:1 were investigated using a crossover design with HES 200/0.5 serving as control. Fifty grams of either HES were administered in 4 h day-1 for a period of five consecutive days. HES serum concentrations were used for computation of pharmacokinetic coefficients. Change between the first and fifth infusion in the area under the concentration curve (AUC) served as the primary measurement. RESULTS: Although the circulation was freed from the load with HES 130/0.42 within 20 h after end of the previous infusion, the amount of HES 200/0.5 increased continuously from one administration to the other. AUC and elimination half-life (t1/2) were significantly lower with HES 130/0.42. AUC and t1/2 of HES 200/0.5 showed an increase between the first and the fifth administration whereas only a minimal shift was present with HES 130/0.42. Haemodilution via HES 200/0.5 did not change over time. CONCLUSIONS: Repeated administration of HES 130/0.42 shows no accumulation and fewer tendencies to time-dependent changes in pharmacokinetic parameters than HES 200/0.5. The improved reproducibility may improve drug safety, particularly as the accumulation of residual starch with HES 200/0.5 does not contribute to the colloid's volume effect, but may rather increase the risk of undesired reactions.

Pharmacokinetics of hydroxyethyl starch.

Hydroxyethyl starch has recently become the subject of renewed interest because of the introduction of a new specification, hydroxyethyl starch 130/0.4, as well as the clinical availability of a solution using a previous hydroxyethyl starch type (hydroxyethyl starch 670/0.75) with a carrier other than 0.9% saline. Various types of hydroxyethyl starch show different pharmacokinetic behaviour. Since hydroxyethyl starch is a polydisperse solution acting as a colloid, pharmacodynamic action depends on the number of oncotically active molecules, not on the plasma concentration alone; therefore, solutions with a lower in vivo molecular weight contain more molecules at similar plasma concentrations. On the other hand, high plasma concentrations as well as high in vivo molecular weight can affect blood coagulation, especially factor VIII and von Willebrand factor. Hydroxyethyl starch types with a molar substitution >0.4 accumulate in plasma after repetitive administration, most pronounced with hetastarch (hydroxyethyl starch 670/0.75). Correspondingly, tissue storage as measured by (14)C tracer studies in animals showed significantly higher values for hydroxyethyl starch 200/0.5 compared with hydroxyethyl starch 130/0.4 (about 4-fold at the latest timepoint after the last administration), and considerably higher values for hetastarch compared with both hydroxyethyl starch 130/0.4 and 200/0.5. Hydroxyethyl starch 130/0.4 does not accumulate in plasma after single- and multiple-dose administration in contrast to all other available hydroxyethyl starch specifications. Plasma clearance of hydroxyethyl starch 130/0.4 is at least 20-fold higher than that for hetastarch, and considerably higher than for pentastarch. In patients with renal insufficiency, pharmacokinetic data are only available for hydroxyethyl starch 130/0.4. Cumulative urinary excretion, even in the presence of severe non-anuric renal failure, is higher for hydroxyethyl starch 130/0.4 than values published for older hydroxyethyl starch specifications. Hydroxyethyl starch 130/0.4 may be given to patients with severe renal impairment as long as urine flow is preserved. The pharmacodynamics with respect to the volume effect does not directly mirror pharmacokinetics in the case of hydroxyethyl starch solutions. Equivalent volume efficacy has been proven for hydroxyethyl starch 130/0.4 compared with 200/0.5. Prolonged persistence of hydroxyethyl starch in plasma and tissues can be avoided by using rapidly metabolisable hydroxyethyl starch types with molar substitution <0.5. Influence on coagulation is minimal with hydroxyethyl starch 130/0.4, and no adverse effects on kidney function have been observed even with large repetitive doses when used according to the product information.

Molecular-size fractionation of pentastarch, radiolabelling with 99mTc, and evaluation of biological behaviour in mice.

BACKGROUND: Pentastarch is used clinically as a plasma volume expander for the management of substantial blood loss. 99mTc labelled pentastarch may be useful as a diagnostic agent in place of 99mTc labelled red blood cells. METHODS: Commercial pentastarch (PS; molecular weight (MW) 240 kDa) was separated according to molecular size by using chromatography, and the fractions were pooled as small (MW 128 kDa), medium (MW 277 kDa) and large (MW 510 kDa) pentastarch. We studied the effect of various physicochemical parameters on the efficiency of radiolabelling with 99mTc and on the stability of the products, and evaluated the biological properties of the 99mTc labelled preparations. RESULTS: We developed an optimised kit formulation containing 3.25 mg pentastarch and 0.13 mg gentisic acid that can be reliably labelled with 99mTc at pH 6.6-8.2 with good stability. In mice, the 99mTc labelled medium pentastarch showed the more favourable blood retention properties (56% of initial blood activity is retained after 3 h) with lower liver levels.

Molecular weight of hydroxyethyl starch: is there an effect on blood coagulation and pharmacokinetics?

BACKGROUND: The development of hydroxyethyl starches (HES) with low impact on blood coagulation but higher volume effect compared with the currently used HES solutions is of clinical interest. We hypothesized that high molecular weight, low-substituted HES might possess these properties. METHODS: Thirty pigs were infused with three different HES solutions (20 ml kg(-1)) with the same degree of molar substitution (0.42) but different molecular weights (130, 500 and 900 kDa). Serial blood samples were taken over 24 h and blood coagulation was assessed by Thromboelastograph analysis and analysis of plasma coagulation. In addition, plasma concentration and in vivo molecular weight were determined and pharmacokinetic data were computed based on a two-compartment model. RESULTS: Thromboelastograph analysis and plasma coagulation tests did not reveal a more pronounced alteration of blood coagulation with HES 500 and HES 900 compared with HES 130. In contrast, HES 500 and HES 900 had a greater area under the plasma concentration-time curve [1542 (142) g min litre(-1), P<0.001, 1701 (321) g min litre(-1), P<0.001] than HES 130 [1156 (223) g min litre(-1)] and alpha half life (t(alpha)(1/2)) was longer for HES 500 [53.8 (8.6) min, P<0.01] and HES 900 [57.1 (12.3) min, P<0.01] than for HES 130 [39.9 (10.7) min]. Beta half life (t(beta)(1/2)), however, was similar for all three types of HES [from 332 (100) to 381 (63) min]. CONCLUSIONS: In low-substituted HES, molecular weight is not a key factor in compromising blood coagulation. The longer initial intravascular persistence of high molecular weight low-substituted HES might result in a longer lasting volume effect.

Volume efficacy and reduced influence on measures of coagulation using hydroxyethyl starch 130/0.4 (6%) with an optimised in vivo molecular weight in orthopaedic surgery : a randomised, double-blind study.

BACKGROUND AND OBJECTIVE: Different types of hydroxyethyl starch (HES) affect blood coagulation differently. We studied the effects of HES 130/0.4 on coagulation in major orthopaedic surgery in relation to the pharmacological parameter in vivo molecular weight. METHODS: 52 patients were randomly allocated to either HES 130/0.4 (6%, mean molecular weight 130 kDa, molar substitution 0.4) or HES 200/0.5 (6%, control) in a double-blind fashion. Colloidal volume requirements for intra- and postoperative haemodynamic stabilisation were compared. Safety analyses of this pharmacological study included a comparison of coagulation factor tests, in vivo molecular weight, and HES plasma concentrations. RESULTS: The colloidal volumes given were similar at the end of surgery (1602 +/- 569 for HES 130/0.4 vs 1635 +/- 567mL for HES 200/0.5), 5h later (1958 +/- 467 vs 1962 +/- 398mL), and up to the first postoperative day (2035 +/- 446 vs 2000 +/- 424mL). HES in vivo molecular weight at the end of surgery was 88,707 +/- 13,938 versus 158,374 +/- 33,933Da (p < 0.001) and 5h later was 86,663 +/- 16,126 versus 136,299 +/- 26,208Da (p < 0.001). In parallel to the lower in vivo molecular weight, factor VIII and von Willebrand factor returned to almost normal in the HES 130/0.4 group up to 5h postoperatively, but not in the control group (p < 0.05). Residual HES plasma concentrations after 24h were low in the HES 130/0.4 group (1.0 mg/mL), but higher in the control group (2.6 mg/mL). CONCLUSION: HES 130/0.4 and HES 200/0.5 were found to be similar with regard to volume efficacy. Sensitive coagulation parameters returned more rapidly to normal in the HES 130/0.4 group. Lower in vivo molecular weight and more rapid excretion of HES 130/0.4 are the likely explanations for the smaller influence on coagulation in this group.