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Toxicological information

Exposure related observations in humans: other data

Administrative data

Endpoint:
exposure-related observations in humans: other data
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
1972
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was conducted prior to current protocol and glp requirements. The study is well documented and sufficient for the current hazard assessment requirements.

Data source

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
1972
Report Date:
1972
Reference Type:
study report
Title:
Unnamed
Year:
1971
Report Date:
1971
Reference Type:
other company data
Title:
Unnamed
Year:
1972
Report Date:
1972
Reference Type:
study report
Title:
Unnamed
Year:
1977
Report Date:
1977
Reference Type:
publication
Title:
Metabolism and Pharmacokinetics of Sucrose Acetate Isobutyrate (SAIB) and Sucrose Octaisobutyrate (SOIB) in Rats, Dogs, Monkeys or Humans: a Review
Author:
Reynolds RC
Year:
1998
Bibliographic source:
Food and Chemical Toxicology 36:95-99 (1998)

Materials and methods

Type of study / information:
This study contains information on the metabolism and disposition of the subject material after oral administration to human volunteers.
Endpoint addressed:
other: metabolism and disposition
Principles of method if other than guideline:
The study was conducted by oral administration of 14C-labeled SAIB to human volunteers as a single or repeated dose.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
other: presumably viscous liquid
Details on test material:
Preparation of Labeled 14C(U)-Acetate Isobutyrate (for use in studies with aqueous emulsions):

Prepared from 2.010 g sucrose, 0.129 g of labeled sucrose (obtained from New England Nuclear Corp., specific activity 4.91 microCuries/mmole), 1.233 g of acetic anhydride, and 13.615 g of isobutyric anhydride (Touey and Davis, U.S. Patent 2,931,902, 1960). Unreacted materials were removed by distillation and solvent washing. This yielded 4.782 g of a pale yellow SAIB-14C having a saponification equivalent of 104.16 +/- 0.191; the specification of food grade material is 104 to 107. The specific activity was determined as 0.359 +/- 0.008 microCuries/mg.

Preparation of the dose:

The SAIB-14C was incorporated into a simulated non-carbonated soft drink. Citrus oil (297 mg) was added to 273.2 mg of SAIB-14C, which had been warmed in a beaker on a steam bath, and the mixture was stirred. To this was added 3.183 g of mucilage which was prepared by adding 18.48 g of gum acacia to 84.45 g of water, stirring to dissolve, and allowing to deaerate. The mixture of SAIB, citrus oil, and mucilage was stirred for about 1 hour and then emulsified by sonification, using a Biosonic III (Bronwill Scientific, Inc.) at 60-70% of full power for 3-4 minutes, to give a fine, stable emulsion. A portion of the emulsion (ca. 1.0 ml or 0.2 ml) was added to a rapidly stirred 180 ml portion of a solution of sucrose (12%) and citric acid (0.2%) in water. To reduce the radiochemical dose in some experiments, portions of an emulsion, similarly prepared using unlabeled SAIB, were added for dilution. The mixtures were made up to 200 ml and samples (3 x 75 µL) were removed for assay to determine the exact doses. The resultant beverage contained 400-500 ppm SAIB (experiments 1A-3A) or 85 ppm (experiment 3B).

Sucrose-14C was given in aqueous solution. Sucrose-14C (20-25 microCuries) was added to 25-28 g of food-grade sucrose and diluted to 200 mL with water. This solution was sampled to obtain the exact radiochemical dose.

Method

Ethical approval:
confirmed, but no further information available
Details on study design:
Experimental Procedure:

Prior to dosing, samples of blood, urine, and expired air were taken for control assays. The subject drank approximately 200 ml of the diluted emulsion or sucrose solution, prepared as described above. The subjects were generally confined to the laboratory area for approximately 16 hours; during this time subjects were occupied in sedentary tasks. Breath samples were taken approximately once an hour starting 0.5 hours after dosing during the first 16 hours and irregularly on subsequent days. Complete urine and feces were collected ad libitum for at least two days after dosing and urine samples were collected irregularly following the period of complete collections. Blood samples were taken several hours after dosing and on the following day. Subjects ate breakfast about two hours before dosing (except in experiment 1B) and were allowed a normal lunch and dinner, except in experiment 2A where the subject did not eat during the 16 hours following ingestion of the dose.

To test the effect of elimination of SAIB of various changes in the dosing regimen, 3 subjects were each given 2 or 3 single doses of SAIB-14C at widely spaced intervals. The first dose was given at the level of ca. 1 mg/kg bwt to each subject, none of whom had been previously exposed to SAIB. Two of these subjects were given a second dose at the same level 7 or 27 weeks after the first dose and following ingestion of unlabeled SAIB at a level of ca. 1 mg/kg bwt (100 mg/day) for 7 days. The third subject was given a single dose at a level of 0.18 mg/kg bwt 25 weeks after receiving a 1.14 mg/kg bwt dose. To determine the effect of changing the stomach emptying time on the shape of the elimination curve, one subject was given a third dose at a level of 1 mg/kg bwt 10 weeks after the second dose and immediately after he ingested a high fat meal.
Exposure assessment:
not specified

Results and discussion

Results:

In all, 5 subjects ingested 9 doses of SAIB-14C or sucrose-14C as summarized in Table 1. The periods of total collection varied because of absences and difficulties involved in collecting samples over weekends. However, all subjects except subject 5 were monitored for elimination of radioactivity in breath and urine to at least 30 days after dosing. It was necessary for subject 5 to use radioactive materials in another connection 3 days after dosing and he did not complete the study.

Elimination of Radioactivity by Subjects Fed SAIB-14C:

After ingestion of SAIB-14C, a small portion of the radioactivity was rapidly absorbed and eliminated in the urine. The maximal urinary excretion rate occurred in less than 3 hours in all experiments and the excretion rate then fell off rapidly to levels of 0.5-0.8% of the dose/day by 48 hours.

Elimination of radioactivity in the breath commenced rapidly but only a small portion of the total was eliminated in the first 6-8 hours after which time the elimination rate rapidly increased. Maximal elimination of 14CO2 in these experiments occurred 9-l5 hours after dosing. The timings and shapes of the elimination curves for the first and second experiments were quite similar for subjects 2 and 3. For subject 1, however, the second and third experiments, which followed the first by 27 and 37 weeks respectively, produced an elimination pattern quite similar to the first but in which the maximum elimination time was delayed by about 6 hours. 14CO2 elimination then rapidly fell off reaching similar levels in the three experiments as well as in experiments 3A and 3B (0.29-0.46% of the dose/day). The maximum elimination rate of 14CO2 for subject 2 was rather less than for subjects 1 and 3 and at 48 hours subject 2 was eliminating 0.18 and 0.22% of the dose/day. At 25 days after dosing, elimination of radioactivity in the breath was significant (about 0.07% of the dose/day in all experiments except 3B where elimination was 0.15% per day) whereas elimination in the urine was barely detectable above background at that time (<0.02% of the dose/day).

All subjects were consistent in the total amounts eliminated in the breath and urine in the first and second experiments (Table l). This was not true for experiment lC; however, the timing of the 14CO2 data did not permit reasonable interpolation for the time when collections were not made and as a result the integrated 14CO2 value is probably much too low. Elimination in the urine was about the same in all experiments but subject 2 eliminated significantly less of the dose as 14CO2 than did subjects 1 and 3.

A small portion of the dose was unabsorbed and appeared in the feces of all subjects (Table 1). In experiment 2B the last fecal collection was almost free of radioactivity (<0.1% of the dose) and the figure thus probably gives almost the total fecal elimination. In experiments lA, lB, 2A, 3A, and 3B the last feces collections were significantly radioactive (0.4 to 2.5% of the dose) and an unknown amount of SAIB-14C was not accounted for in subsequent fecal eliminations in those experiment.

Elimination of Radioactivity by Subjects Fed Sucrose-14C:

Two subjects ingested sucrose, in aqueous solution, at about the same level (24 g) as that ingested by the subjects fed SAIB. In both experiments, the sucrose-l4c was rapidly converted to l4CO2; subject 5 showed an elimination rate of 0.7% of the dose/hour 10 minutes after dosing. Maximal elimination in both subjects occurred within 3 hours and the rates then fell off rapidly before leveling off at 0.3-0.4% of the dose/hour at about 15 hours. Although the shapes of the elimination curves were similar, subject 5 eliminated 58.3% of the dose as l4CO2 in 48 hours whereas only 41.9% of the dose was recovered as l4CO2 from subject 4 in that time.

Both subjects eliminated small amounts of radioactivity in the urine (1.9 and 1.7% of the dose respectively in 48 hours). A very small amount of radioactivity appeared in the feces of subject 4.

Chromatography:

Chromatograms of experimental urines revealed the presence of several peaks and plateaus of radioactivity in each sample. These peaks appeared to be composed of a larger number of compounds of poorly defined migrational properties. The number of peaks and their distribution varied from subject to subject, from experiment to experiment, and from sample to sample. Although none of these compounds was identified, chromatography of urine samples with added sucrose-l4C indicated the possible presence of free sucrose in some samples. However, the maximum amount of radioactivity that could have been present as free sucrose in any experiment was less than 20% of the total urinary radioactivity (less than 1.8 mg total free sucrose).

Chramatograms of ethanolic extracts of feces showed the presence of radioactive materials only near the solvent elution front (Rf >0.85). There was no radioactivity corresponding to these peaks on urine chromatograms, and, therefore, SAIB or other highly acylated sucrose molecules were not present in the urine.

Chromatograms of urine from subjects fed sucrose-14C did not show the presence of detectable levels of free sucrose. Most of the urinary radioactivity appears to be urea-14C.

Clinical Findings:

All results of hematology and clinical chemistries were within the normal ranges and showed no significant changes after dosing (Tables 2 and 2A).

Any other information on results incl. tables

 

Table 1: Elimination of radioactivity by human subjects fed single doses of SAIB-14C or sucrose-14C

 

 

 

 

Dose

Elimination - % dose (a)

Subject

Experiment

Compound

mg

mg/kg bwt

microCuries

CO2

Urine

Feces

Total

1

1A

SAIB-14C

83

0.98

29.9

60.3 (27)

16.6 (2)

1.1 (2)

78.0

 

1B(b)

106

1.22

27.0

64.4 (25)

18.1 (25)

7.0 (5)

89.5

 

1C(c)

103

1.18

24.5

53.1 (11)

14.8 (3)

not assayed

67.9

2

2A

115

1.21

41.4

41.3 (30)

17.9 (32)

11.7 (4)

70.9

 

2B(d)

110

1.15

28.6

41.8 (25)

20.7 (25)

10.4 (4)

72.9

3

3A

106

1.14

37.9

61.0 (29)

14.0 (21)

10.3 (3)

85.3

 

3B(e)

17

0.18

6.8

66.4 (29)

18.0 (29)

10.4 (3)

94.8

4

4

Sucrose-14C

2.5x10^4

391

24.7

50.1 (31)

2.7 (36)

<0.3 (3)

53.1

5

5

2.8x10^4

400

20.6

59.0 (2)

1.7 (2)

not assayed

60.7

a Figures in parentheses are total collection period in days.

b Experiment 1B followed 1A by 27.4 weeks. Unlabeled SAIB fed for 7 days before dosing.

c Experiment 1C followed 1B by 10.0 weeks. Dose fed immediately after a meal.

d Experiment 2B followed 2A by 7 weeks. Unlabeled SAIB fed for 7 days before dosing.

e Experiment 3B followed 3A by 24.8 weeks.

Table 2: Hematology and Blood Chemistry for subjects fed a single dose of SAIB-14C

 

Subject

1A

1B

Time, h(a)

-0.8

5.4

24.1

47.8

-161.8

5.6

77.27

 

 

 

 

 

 

 

 

Hemoglobin

14.2

13.6

15.0

14.4

14.2

14.4

13.8

White Blood Cells

3.9

4.2

4.9

4.2

5.9

4.7

4.6

Hematocrit

43

45

43

43

43

42

42

Red Blood Cells (x 10^6)

4.8

5.0

5.3

5.4

4.88

4.5

4.7

 

 

 

 

 

 

 

 

Differential                        Neut.

60

67

76

76

71

60

68

Lymph.

33

31

16

20

25

39

32

Mono.

5

2

8

4

3

1

0

Eos.

-

-

-

-

1

0

0

 

 

 

 

 

 

 

 

Glucose

52

98

55

52

-

100

94

Urea Nitrogen

20.5

17.5

18.0

17.0

-

19.5

16.5

Cholesterol

208

218

222

220

212

218

214

Triglycerides

125

145

135

125

115

130

70

 

 

 

 

 

 

 

 

Uric Acid

5.2

4.7

4.6

4.8

5.3

5.1

5.3

O.C.T. (b)

0.9

0.9

0.6

-

1.4

2.2

2.2

S.G.O.T. (c)

30

28

26

30

20

20

21

Alkaline Phosphatase (d)

92.6

96.4

85.2

92.6

100.0

103.9

105.6

a. Dose at time 0. Negative values are controls.

b. Ornithine carbamyl transferase. Normal values quoted as 0-2.5.

c. Serum glutamic oxalacetic transaminase. Normal values (range) quoted for an industrial plant population: 21-42 Karen Units.

d. Alkaline phosphatase by the method of Morgenstern, S. et al. (1965). Clin. Chem. 11:876. Range (from plant population): 12.9-159.1.

Applicant's summary and conclusion

Conclusions:
1. SAIB-14C, ingested in a simulated soft drink vehicle by humans at a dose level of 1 mg/kg, was largely absorbed from the gastrointestinal tract.
2. The absorbed material was largely utilized as a food; the carbon of the sucrose moiety was converted to CO2 or incorporated into tissues via the intermediary metabolism.
3. A small portion of the dose was rapidly absorbed and excreted in the urine, presumably as sucrose esters. Less than 1$ (1-2 mg) of the intake appeared in the urine as sucrose.
4. The absorption and elimination patterns were not affected by feeding SAIB at a level of 100 mg/kg per day to two subjects for the 7 days prior to dosing. Some variation in the urinary chromatographic pattern was found between subjects and between collections from each subject, but the elimination products still behaved as hydrolysis products derived from SAIB.
5 The 14CO2 and urinary elimination patterns were substantially the same in one subject fed SAIB-14C at a level of 0.18 mg/kg as at a level of 1.14 mg/kg. Chromatograms of urines showed that SAIB breakdown products were eliminated at both levels, i.e. the overall handling of SAIB is not dose related within the range studied.
6. Sucrose derived from SAIB after ingestion, and sucrose given orally, show some differences in their rates of conversion to CO2 and incorporation into various physiological pools. Sucrose-U-14C undergoes a fairly rapid catabolism, about 40% being converted to 14CO2, and the remainder being apparently incorporated in various physiological pools from which l4C is less rapidly released. Sucrose from SAIB-14C gives rise to a somewhat larger proportion of less rapidly produced 14CO2, with a lesser amount being distributed to physiological pools (Subjects lB, 3A, 3B). The more complete conversion of SAIB sucrose may arise from the slower rate at which it enters the organism.
7. Ingestion of a single dose of SAIB at a level of 1 mg/kg produces no effect on blood hematology or on certain selected blood chemical values.

In previous work summarized by Reynolds and Fassett (1972), metabolites appearing in the urine of rats, dogs and humans following ingestion of 14C-SAIB were tentatively identified as sucrose esters. In subsequent work (Reynolds and Ziegler, 1977), gas chromatographic analysis as well as size exclusion chromatography of human urine indicated no glucose, sucrose or esters of sucrose or fructose were present.
Executive summary:

Sucrose-14C(U) Acetate Isobutyrate (SAIB-14C), prepared from uniformly labeled sucrose-14C, was fed to 3 human subjects in 6 experiments at a. level of 1 mg/kg (83-115 mg, 27-41 µCi) and in 1 experiment at a. level of 0.2 mg/kg (17 mg, 6.8 µCi). The fate of the ingested SAIB-14C was studied by quantitative and qualitative assay of radioactivity in breath, urine, and feces. SAIB-14C was largely absorbed from the gastrointestinal tract. The absorbed carbon-14 was largely converted to 14CO2(41-66%of the dose in 25 days) or, possibly, incorporated into tissues through the intermediary metabolism. The maximal rates of 14CO2 elimination occurred 9-16 h after dosing. A small portion was rapidly absorbed and eliminated (14-21% of the dose) in the urine, presumably as sucrose esters with, possibly, small amounts of free sucrose also present. Unlabeled SAIB fed to 2 subjects at a level of 100 mg/day for 7 days prior to dosing with SAIB-14C had no effect on the elimination patterns. The elimination patterns were similar in one subject fed SAIB-14C at dose levels of 1.1 and 0.2 mg/kg. Hematological and blood clinical chemistry values were not affected by the dose.

 

Two subjects were fed sucrose-14C Uu) at a level of 400 mg/kg and the fate of the radioactivity was similarly studied. The subjects metabolized only 41 and 59% of the sucrose-14C to 14CO2 within 48 h and the maximal rate of elimination occurred within 3 h of dosing. These differences in the rates of elimination of l4CO2 from SAIB-l4C and sucrose-l4C presumably reflect the slower rate at which sucrose from SAIB is presented to the body.

In work conducted subsequent to that described above, (Reynolds and Ziegler, 1977), gas chromatographic analysis as well as size exclusion chromatography of human urine indicated no glucose, sucrose or esters of sucrose or fructose were present.