Pharmacological effects produced by the acute and chronic administration of hydroxyethyl starch.

Centers throughout the world have utilized various erythrocyte sedimenting macromolecules to improve the collection of neutrophils from normal donors, but in the United States, high-molecular weight hydroxyethyl starch (HES 450/0.70) is presently the only agent approved by the Food and Drug Administration for use during leukocytapheresis. HES 450/0.70, prepared from a waxy species of either maize or sorghum, is hydrolysed by alpha-amylase present in the bloodstream following intravenous administration. The major portion (70 to 80%) of the injected dose of HES 450/0.70 is eliminated through the kidneys; a smaller portion (20 to 30%) becomes extravasated, and a minor amount is eliminated through the gastrointestinal tract. If HES 450/0.70 is given as a single 500 ml dose, the erythrocyte sedimentation rate (ESR) will be increased and difficulties in blood typing and crossmatching may be encountered. Concentrations of most blood and plasma components will decrease, usually in direct proportion to the amount of HES 450/0.70 and other fluids administered. Determinations, both of hepatic and of renal function, will remain within normal limits, although the levels of an alpha-amylase in plasma will become elevated. Serious bleeding complications are normally not observed when the dose of HES 450/0.70 does not exceed 1.0 to 1.5 g/kg body weight. Rarely, anaphylactoid reactions may be encountered. If HES 450/0.70 is given on more than one occasion, and especially if administered over a relatively short period of time, mild untoward effects related to expansion of the plasma volume may occur. When HES 450/0.70 is give chronically, tests of hepatic and renal function remain within normal limits, but certain tests of coagulation may become slightly prolonged. HES 450/0.70 has an excellent record of safety and is highly recommended for use during leukocytapheresis.

Serum bile acids and alanine aminotransferase concentrations. Comparison of efficacy as indirect means of identifying carriers of non-A, non-B hepatitis agents and of onset, severity, and duration of posttransfusion non-A, non-B hepatitis in recipients.

Indirect tests of liver function such as determinations of concentrations of alanine aminotransferase (ALT) and conjugated bile acids (BA) have been advocated as indicators of both the infectivity of the blood of donors in transmitting non-A, non-B (NANB) hepatitis and of the onset, severity, and duration of this disease in recipients. We therefore compared the predictive value of concentrations of ALT and postprandial concentrations of BA in the blood of 311 donors and in the blood of 41 recipients in whom either NANB or type B hepatitis developed after transfusion. Our results demonstrated that higher than normal concentrations of ALT (greater than 45 IU/L) in the blood of donors were generally accompanied with normal concentrations of BA (less than 6 mumole/L), and, therefore, concentrations of ALT may be more useful in predicting the infectivity of donor blood in transmitting NANB hepatitis. In addition, concentrations of ALT, compared with BA concentrations, were a significantly better indicator of the onset, severity, and duration of the disease in recipients in whom NANB hepatitis developed after transfusion. In recipients who had posttransfusion type B hepatitis, serum concentrations of ALT were significantly better indicators of the onset and severity of the disease than concentrations of BA.

Urinary excretion kinetics of hydroxyethyl starch 350/0.60 in normovolaemic man.

Rates of urinary excretion concomitant with the molecular size distribution of filtered polymer fragments were determined in five normovolaemic men dosed with 30 g/m2 BSA of a species of HES (HES 350/0.60) possessing a M-W of 350 000 combined with an MS of 0.60. Approximately 13% of the total injected dose of HES 350/0.60 was excreted in urine 1 hr after dosing, and 45% by 72 hours. Gel filtration of Sepharose CL-4B revealed that aliquots of urine collected 1 hour after injection contained polymer fragments of HES 350/0.60 with values of Kav ranging between 0.88 and 0.84, and possessed a Stokes radius (r = 32A) similar to that of Dextran 20 (M-W 22 700). Polymer fragments of HES 350/0.60 excreted 6 to 48 hours after dosing, however, possessed a Kav ranging between 0.78 and 0.73 with a Stokes radius (r = 45A) similar to that of Dextran 40 (M-W 41 000). All filtered polymer fragments were less polydisperse relative to both the injection solution (Kav 0.60) and residual material recovered from blood immediately after injection (Kav 0.72). These data support the hypothesis that the excretion of HES 350/0.60 occurs in two distinct phases: a rapid phase of elimination dependent on the M-n of the injected solution, and a slower phase dependent on the MS (degree of resistance to alpha-amylase attack). This study, in conjunction with our previous investigation of the changes in circulating HES 350/0.60, define the basic differences between clearance and excretion of the dextrans and of the rapidly degraded species of HES. These data are relevant to the utilisation of HES 350/0.60 during centrifugal leucapheresis.

Macroamylasemia induced by hydroxyethyl starch--confirmation by gel filtration analysis of serum and urine.

The concentration of alpha-amylase in blood rose significantly (Student's t-test) in seven normovolemic healthy subjects after they were given 30 g/m2 body surface area of hydroxyethyl starch 350/0.60 (HES 350/0.60, a new volemic colloid). Concomitant with elevated activity in blood, amylase clearance (Cam) was markedly reduced, even though clearance of creatinine (Ccr) was within normal limits. Similar findings were observed for one male subject given 500 ml (30 g) of HES 450/0.70. Sephadex G-100 gel elution profiles of serum recovered from one male subject after the infusion of HES 350/0.60 revealed the presence of a macroamylase complex eluted with the void volume. Small macroamylase complexes were also detected in urine voided from the same subject. By 24 to 48 hours postinjection, the high activity of alpha-amylase in blood was returning to basal levels, and this was observed to parallel the reduction of macroamylase complexes both serum and urine. The macroamylasemia induced by HES 350/0.60 represents the nonpathologic formation of large colloid-enzyme complexes not easily filtered at the renal glomerulus, and should be differentiated clinically from disease- or drug-induced hyperamylasemia.

Changes in the molecular size distribution and post-transfusion survival of hydroxyethyl starch 350/0.60 as influenced by a lower degree of hydroxyethylation: a study in normal man.

The need to provide a greater rate of colloid clearance from blood than is presently available with the long-acting dosage form of HES 450/0.70 prompted the clinical investigation of a new species of hydroxyethyl starch (HES) possessing a M-w of 350000 concomitant with a molar substitution of 0.60 (HES 350/0.60). The concentration of HES 350/0.60 in serum fell to half its peak value in 10.2 +/- 0.7 (SD) hour (in contrast to an IT50 of approximately 25 hours with HES 450/0.70). Levels of glucose in serum remained elevated in normal fasted subjects after dosing, suggesting that catabolism of the infused HES 350/0.60 was occurring. Hydrolysis of residual HES 350/0.60 was confirmed by Sepharose CL-4B gel filtration analysis of material obtained from serum, showing continual production of smaller molecules relative to the injected solution (in contrast to HES 450/0.70, in which intermediate polymer fragments are recovered). Recovered HES 350/0.60 material displayed a Kav ranging between 0.74 and 0.72 and possessed a Stokes radius (r = 45A) similar to that of dextran 40 (M-w 41000). HES 350/0.69 appears to offer the same advantages as the currently available long-acting HES 450/0.70 but is removed from blood approximately twice as rapidly. This more rapid hydrolysis of HEs 350/0.60 may be useful, for example, in avoiding cumulative build-up of colloid in the blood of normal donors undergoing consecutive leucapheresis procedures.

Alkaline phosphatase as a marker of maturity in human neutrophils. Studies in normals dosed with aetiocholanolone and prednisolone.

Changes in the level of neutrophil alkaline phosphatase (NAP) in a population of peripheral blood neutrophils were determined in healthy subjects dosed with either aetiocholanolone (Aetio, 4 mg/m2 im) or prednisolone sodium succinate (Pred, 30 mg/m2 iv). Before dosing the mean NAP score, as measured by a modified Gomori azo-dye method, was 109 and 118 in the Aetio and Pred groups, respectively. Fifteen hours after injection the NAP score in the Aetio group had risen to 187 concomitant with the appearance of large numbers of juvenile (band) and mature neutrophils. Twenty-four hours after dosing, the NAP score increased to 213 with still further concentrations of juvenile cells, while the numbers of mature neutrophils returned to approximately baseline values. Five hours after injection, in subjects given Pred, the NAP score had fallen to 108 concomitant with a marked increase in the numbers of mature neutrophils. These data in normals dosed with either Aetio or Pred appear to substantiate a 'first-in, first-out' cellular progression with initial release of the oldest of the mature bone marrow reserve neutrophils containing less (relative to juvenile forms) NAP activity. These data also indicate that NAP activity is inversely related to cellular age and may support previous findings in the rat that enzyme levels are higher in bone marrow relative to peripheral blood.

[Pharmacokinetics of middle-molecular hydroxyethyl starch (HAS 200/0,5]. / Pharmakokinetik mittelmolekularer Hydroxyäthylstärke (HAS 200/0,5).

The pharmacokinetics of middle molecular weight hydroxyethyl starch (HES; MW 200,000, Mn: 35,000, MW/Mn = 5.71, MS = 0.50) were examined in two groups of normovalaemic subjects. Subjects in group 1 (non-fasted) were administered an approximately equal dose of HES, twice as rapidly as subjects in group 2 (fasted pre- and postinjection). The intravascular half-life (IT50) of HES in groups 1 and 2 was 2.7 +/- 1.3 and 3.9 +/- 1.1 (SD), respectively. 96 h post-injection, 2% of the initially measured HES 200/0.5 concentration remained in the serum of group 1 subjects. The serum glucose level in both groups rose following dosing and remained elevated 12 h post-injection. 24 h post-injection, 66 (group 1) and 50% (group 2) of total infused HES 200/0.5 had been excreted in the urine. In group 2 subjects, the viscosity of the urine measured up to 12 h post-injection, was not significantly affected by the presence of HES 200/0.5. Immediately post-injection in group 1 subjects, the plasma volume was increased an average of 27%, returning to normal baseline values over the next 24 h. The serum alpha-amylase activity rose in group 2 subjects post-injection, concomitantly with a significant reduction in urinary excretion of this enzyme. The molecular size distribution of HES recovered from the intravascular space of group 2 subjects, was distinctly narrower than that of the injected solution and consisted of low molecular size material. Similar changes occurred in the molecular size distribution of HES polymers excreted in the urine of these subjects. The erythrocyte sedimentation rate was not significantly affected by the presence of large quantities of HES 200/0.5 in the blood. The results of this preliminary study in normal man has shown that HES 200/0.5 appears to be an ideal volemic colloid for clinical situations requiring restoration of a diminished plasma volume of short duration.

The catabolism of low molecular weight-hydroxyethylated amylopectin in man. III. Further degradation of excreted polymer fragments.

Fragments of low molecular weight-hydroxyethylated amylopectin (LMW-HES) contained in the urine voided by a single normal man, 6 to 12 hours after receiving a dose of 56 g of this material, were either separated straightforwardly by gel filtration on a column of Sephadex G-200 or incubated for 18 hours at 37 degrees C in the presence of alpha-amylase contained in human saliva, and then subjected to filtration on the same column. Comparison of the two elution profiles revealed that LMW-HES material remaining in the bloodstream for 6-hours or more, had not been degraded by serum alpha-amylase to the maximum possible extent, since incubation with alpha-amylase in-vitro caused further catabolism. These data suggest that LMW-HES polymer fragments are excreted in the urine as soon as they obtain a molecular weight below the threshold of glomerular filtration.

Post-transfusion survival of hydroxyethyl starch 450/0.70 in man: a long-term study.

Intravascular persistence concomitant with changes occurring in the circulating molecular size distribution were determined in five healthy normovolaemic men dosed with 7 ml/kg of a 6% (w/v) solution of a species of hydroxyethyl starch (HES 450/0.70) possessing a M(w)- of 450 000 daltons combined with a molar hydroxyethyl group substitution (MS) of 0.70 (70 hydroxyethyl groups/100 glucose residues). The concentration of HES 450/0.70 in serum fell to 24% of its peak value (measured 2 minutes post injection) one week after the infusion. By 17 weeks after injection, < 1.0% remained in the intravascular space. The HES 450/0.70 material recovered from the bloodstream 2 minutes after injection was shown by gel filtration on a column of Sepharose CL-4B to be less polydisperse than the injected solution. The K(av) calculated for the peak of material eluted after one week showed a definite shift of molecular size toward that of a lower molecular weight composition. However, at four weeks the value of K(av) indicated a shift toward the high molecular weight region of the injected solution, and by seven weeks this movement was quite pronounced. These data clearly indicate the complex nature of the removal of HES 450/0.70 from the intravascular space of man and appear to substantiate previous clinical studies reporting that the MS plays the major role influencing the rate of elimination of this material from the bloodstream.

The hydroethylated amylopectins. Model substances comprising a two-variable system for the design of specific-acting volaemic colloids.

The requirement of volaemic colloids in specific-acting dosage forms, for utilisation in varied and numerous clinical applications, has led to the development of the hydroxyethylated and amylopectins (HESs). These glycogen-like substances comprise a two-variable drug design system, in which the interplay between the weight average molecular weight (Mw-) and the molar hydroxyethyl group substitution (MS) on the parent amylopectin molecule can be specifically adjusted to provide a family of volaemic colloids in short- to long-acting dosage forms. The MS however, appears to exert a finer mechanism of control on the intravascular persistence and the urinary excretion of the HESs in man. This can be seen to occur when assessing changes taking place in the molecular weight size distribution pattern in the bloodstream following injection. However, the Mw- must be considered in the design of HES drugs possessing specific effects on the suspension stability of blood.