ß-CYCLODEXTRIN
First draft prepared by
Ms F D Pollitt
Health Aspects of the Environment and Food (Medical) Division
Department of Health
London, England
Explanation
Biological data
Toxicological studies
Short-term toxicity studies
Long-term toxicity/carcinogenicity studies
Reproductive toxicity studies
Special studies on interactions with bile
acids and lipophilic nutrients
Comments
Evaluation
References
1. EXPLANATION
ß-Cyclodextrin was previously evaluated at the forty-first
meeting of the Committee (Annex 1, reference 107), at which time a
temporary ADI of 0-6 mg/kg bw was allocated, based on a NOEL of 2.5%
in the diet (equal to 1230 mg/kg bw/day) in study in dogs and a safety
factor of 200. The results of an ongoing 1-year oral toxicity study in
dogs and information on the effects of ß-cyclodextrin on the
bioavailability of lipophilic nutrients were required by 1995. These
data, along with the results of a 1-year toxicity study in rats, a
3-generation reproductive toxicity study in rats and carcinogenicity
studies in mice and rats were available for review at the present
meeting, and are summarized in the following monograph addendum.
2. BIOLOGICAL DATA
2.1 Toxicological studies
2.1.1 Short-term toxicity studies
2.1.1.1 Rats
In a 52-week study, groups of 20 male and 20 female CrI:CD(SD)BR
rats were fed diets containing 0, 1.25, 2.5 or 5% ß-cyclodextrin (>
99% pure). Treatment commenced at 6 weeks of age. The rats were housed
5 to a cage and food and water were available ad libitum. Animals
were observed daily for clinical signs. Body weight and food intake
were recorded weekly. Haemato-logical (including RBC, WBC, haemoglobin
and haematocrit), plasma biochemical (including protein, ASAT, ALAT,
ALP, gamma-GT, sodium, potassium, calcium and triglycerides) and urine
analyses (including pH and protein) were undertaken during weeks 13,
26, 39 and prior to termination at 52 weeks. Food was withdrawn
overnight prior to sampling and water was also withdrawn overnight
prior to urine sampling. Major organs were weighed. At termination,
full macroscopic and microscopic examination of tissues and organs was
undertaken.
During the course of the study, 4 deaths were recorded, 3 males
from the control group and 1 female which had received diet containing
1.25% ß-cyclodextrin. None of these deaths were attributed to
treatment. No abnormal clinical signs were observed.
Since the dietary concentration was fixed throughout the study
period, the intakes of ß-cyclodextrin, expressed as mg/kg bw/day,
decreased. The intakes of ß-cyclodextrin (mg/kg bw/day) at the
beginning and end of the study are shown in Table 1.
Table 1. Variation of intake in the 52-week study (HRC, 1994a)
% ß-Cyclodextrin Intake, mg/kg bw/day
in diet
Male Female
Week 1 Week 52 Week 1 Week 52
1.25 1506 395 1593 565
2.5 3292 797 3227 1146
5 6106 1639 6358 2391
In males, intake had decreased in week 52 to approximately 25% of
that at week 1 and, in females, to approximately 33%. The mean intake
in the 1.25% group over the course of the study was 650 mg/kg bw/day
and 860 mg/kg bw/day in male and female rats, respectively.
There was no statistically significant effect of treatment on
body weight during the course of the study, although the body-weight
gains in the high-dose males and females were slightly reduced in
comparison to controls (4% and 7%, respectively).
No effects due to ß-cyclodextrin were observed on haematological
or urinalysis parameters. In the biochemical investigations, ALAT and
ASAT were increased significantly compared to controls at week 13
in both males and females in the high- and mid-dose groups. The
concentrations of these enzymes continued to be increased in both
males and females in these groups throughout the study except at week
39, when the increase was only observed in the high-dose females. At
week 13, significant increases in OCT levels were observed in mate and
female animals receiving 5% ß-cyclodextrin and in males receiving 2.5%
ß-cyclodextrin. Increased OCT concentrations were also observed at
other times throughout the study, but these differences were not
always statistically significant when compared with control values. At
week 52, significant increases were observed in males receiving 5 and
2.5% ß-cyclodextrin.
Triglyceride concentrations tended to be reduced compared to
controls from week 26 onwards in the high-dose male rats and from
week 39 in high-dose female rats, the difference occasionally
reaching statistical significance. There was a tendency to reduced
ß-lipoprotein concentrations at the high dose and, occasionally, the
mid dose but the biological significance of this was unclear since
statistically significantly lower levels than in controls were also
observed in predose high-dose animals and, in males, in mid-dose blood
samples.
Analysis of the urine for ß-cyclodextrin at weeks 13 and 52
demonstrated the presence of a low level of unchanged compound.
Analysis of the faeces showed virtual absence of ß-cyclodextrin.
Analysis of organ weights at 52 weeks revealed no statistically
significant differences between treated groups and controls. No
effects attributable to ß-cyclodextrin were observed at macroscopic
examination of the tissues. However, histological examination revealed
treatment-related changes in the liver and kidney. In the liver,
significantly increased incidences of single cell necrosis,
centrilobular hepatocyte enlargement and portal inflammatory cell
infiltration were seen in both males and females fed 5% ß-cyclodextrin
compared to controls. Females from this same dose group were also
observed to have an increased incidence of focal basophilic
hepatocytes. Males fed 2.5% ß-cyclodextrin had an increased incidence
of portal inflammatory cell infiltration, while females of this group
showed an increased incidence of single cell necrosis and focal
basophilic hepatocytes. Examination of the kidneys revealed an
increased incidence of pigment in the epithelium of the cortical
tubules in females fed 2.5% or 5% ß-cyclodextrin, but no treatment-
related changes were observed in males. No other treatment-related
abnormalities were observed in any of the other tissues examined. The
NOEL in this study was 1.25% in the diet, equal to 650 mg/kg bw/day
(HRC, 1994a).
2.1.1.2 Dogs
The oral toxicity of ß-cyclodextrin (purity >99%) was studied in
beagle dogs for a period of 52 weeks. The animals were acclimatized
for a minimum of 4 weeks during which time they were inoculated and
received anthelmintic treatment. Following acclimatization, the dogs
were divided into 4 groups each of 4 males and 4 females and were
administered by inclusion in the diet, 0%, 0.62%, 1.25%, or 5.0%
ß-cyclodextrin. The age of the animals at the start of treatment was
35-36 weeks and their body weights ranged from 8.4-11.8 kg. The dogs
were fed once daily and had free access to water. They were housed in
kennels capable of accommodating 2 animals of the same sex and dose
group. However, dogs were segregated for the assessment of clinical
signs and food consumption which were recorded daily. Body weights
were recorded weekly. Ophthalmic, haematological (including
haematocrit, haemoglobin and blood cell counts), plasma biochemical
(including protein, urea, inorganic salts, ALAT, ASAT and gamma-GT)
and urine (including volume, pH and protein) analyses were undertaken
after 13, 26, 39 and 52 weeks of treatment. Urine and faecal samples
were collected during weeks 13 and 52 for toxicokinetic purposes.
Serum vitamin A, D and E were determined at 13, 26, 39 and 52 weeks
while vitamins A and E were determined in aliquots of liver at
termination of the study. Major organs were weighed but the caecum was
not routinely weighed. A full microscopic examination of H and E
stained sections was performed. Liver sections were also stained with
Oil Red O (for fat) and PAS (for glycogen).
There were no deaths during the course of this study. All animals
receiving ß-cyclodextrin showed a slightly higher incidence of
intermittent liquid faeces compared to controls. Body-weight gain in
both sexes in the high-dose group was reduced in comparison with
controls, although the difference was not statistically significant.
One female from the high-dose group showed a weight loss of 0.9 kg
from week 31, although food consumption was, for the most part,
maximal. The average intakes of ß-cyclodextrin over the study
period were equal to 230, 470 and 1900 mg/kg bw/day for the low-,
intermediate- and high-dose groups, respectively. There was no effect
of treatment on food intake, haematological measurements or the
results of ophthalmic examination.
There was a statistically significant increase in plasma
potassium levels in females in the mid- and high-dose dogs at weeks 39
and 52 compared to controls. However, there were no differences in
plasma biochemistry parameters between the control and treated groups
which were considered to be conclusively related to treatment. Other
differences which were statistically significant showed a lack of
consistency and/or dose-relationship or could be attributed to
abnormal group mean values for control dogs.
Urinalysis revealed an increase in protein concentration in males
fed 5.0% ß-cyclodextrin. Although at week 13 this was due to one high
individual value, a trend developed over the remainder of the
treatment period with 3/4 males showing elevated urinary protein
concentrations at week 52. Fractionation of the proteins revealed most
of the protein to be globular fractions with statistically
significantly increased globulin levels usually mirroring those of
increased total protein. This was considered to be an effect
of treatment. There was also an increase in urinary protein
concentrations in high-dose females compared to controls, achieving
statistical significance at week 26, but this effect was not observed
at termination of the study. Urinary calcium concentration was also
increased in the high-dose male group from week 13 onwards. The same
trend was also observed in females from week 13 onwards, but again was
not observed at week 52. Urinary gamma-GT and N-acetyl-ß-D-glucos-
aminidase (NAG) levels were measured at week 52 only. The gamma-GT
level was higher than for the control group in mid- and high-dose
males, but the difference was only statistically significant for the
high-dose group. NAG levels were also raised in these groups compared
to controls but the differences were not statistically significant nor
was there a dose-related effect. No similar effect was seen in
females.
Toxicokinetic analysis demonstrated the presence of unchanged
ß-cyclodextrin in urine and, to a lesser extent, in faeces. During the
24 h that the dogs were in the metabolism cages for collection of
urine, the amount of ß-cyclodextrin excreted varied from 1.3 to 6.2%
of the daily dose on week 13, and from 1.4 to 3.3% of the daily dose
on week 52 (group mean data). There was no effect of treatment on
serum vitamin A, D or E levels nor on vitamin A and E levels in the
liver.
At necropsy, group mean thymus weights in all treated male groups
were statistically significantly higher than in the control group. No
such effect was seen in females and no histological changes were
observed in the thymus. This effect was therefore not considered to be
related to treatment. In high-dose males, group mean prostate weight
was statistically significantly reduced compared to the control group.
No treatment-related abnormalities were recorded at histopathological
examination in this or any other tissue examined at termination of
this study. The Committee concluded that the NOEL in this study was
1.25%, equal to 470 mg/kg bw/day, based on urinary effects in males
and the slightly reduced body-weight gain seen at the high-dose level
(HRC, 1994b).
2.1.2 Long-term toxicity/carcinogenicity studies
2.1.2.1 Mice
ß-cyclodextrin (purity > 86.6%) was administered in the diet
to groups of Crl-CD-I(ICR)BR mice (52/sex/dose) at dose levels of
0, 25, 75, 225 or 675 mg/kg bw/day. Treatment commenced at about
5 weeks of age and continued for 93 weeks (males) or 105 weeks
(females). The mice were housed 4 to a cage and food and water were
available ad libitum. All animals were observed daily for clinical
signs.
There were no treatment-related effects on survival nor on the
incidence or type of clinical signs. Body weights were recorded weekly
for the first 13 weeks of treatment, biweekly until week 73 and weekly
thereafter. Food consumption was measured weekly for the first 13
weeks and biweekly thereafter, and water intake on week 1 and monthly
thereafter for the control and high-dose groups only. There was no
effect of treatment on body-weight gain, food consumption or food
conversion ratio. There was a general trend to lower water consumption
by the high-dose group than by the controls, but the difference was
not statistically significant.
At 12 and 18 months and prior to terminal sacrifice, blood was
taken from the tail of all animals and smears for differential white
blood cell counts were prepared. Data were presented for the control
and high-dose groups only. A number of sporadic, statistically
significant differences were seen at 12 and 18 months between the
control and high-dose groups, but no such differences were seen in the
blood samples taken prior to terminal kill. These sporadic cases of
statistically significant findings were not considered to be
treatment-related.
All mice dying during the course of the study, killed in moribund
condition, or surviving to terminal sacrifice were subjected to a
gross necropsy. In the control and high-dose groups, histopathological
examination was conducted on all organs. At 25, 75 and 225 mg/kg
bw/day, only abnormalities and major organs were examined
histopathologically. With the exception of one high-dose male,
treatment-related lesions were seen only in decedent animals.
Macroscopically, these lesions comprised: fluid, soft, mucoid or foamy
and yellowish contents in caecum, colon and rectum; lumen of colon
distended and mucosa oedematous. Microscopically, these lesions
comprised: serious atrophy of fat pads in the abdominal cavity; active
desquamation of surface epithelium in the caecum, colon and/or rectum;
flattening of the mucosa, atrophy of intestinal glands and/or acute
catarrhal typhlitis in the caecum; and mucosa covered by mucous
secretion containing exfoliated epithelial cells in the colon and/or
rectum. One or more of these symptoms were seen in the following
animals where death was considered to be caused by treatment: 1 male
at 75 mg/kg bw/day, 3 males and 2 females at the high dose. In other
animals exhibiting these symptoms (1 male at 75 mg/kg bw/day, 1 male
at 225 mg/kg bw/day, 4 males and 4 females at the highest dose tested)
the cause of death was considered to be an incidental spontaneous
lesion. The high-dose male animal sacrificed at terminal kill and
whose symptoms were considered to be treatment-related exhibited
caecal mucosal flattening associated with atrophy of the intestinal
glands. No other treatment-related non-neoplastic lesions were seen in
this study. The NOEL based on the inflammatory changes seen in the
lower gastrointestinal tract was 25 mg/kg bw/day.
Among the neoplastic findings, uterine endometrial polyps
occurred as follows in the female mice: 0/51 in controls, 3/48 in the
low-dose group, 2/52 at 75 mg/kg bw/day, 3/52 at 225 mg/kg bw/day and
3/51 in the high-dose group. This increased incidence of uterine
endometrial polyps showed no dose-related trend and it was concluded
that this was not a treatment-related effect. Phaeochromocytoma of the
adrenal gland was seen in 1/52 high-dose males and 1/51 high-dose
females, and in 1/52 females at 75 mg/kg bw/day. No phaeochromocytomas
were seen in the control animals, nor in 228 historical control
animals from the same laboratory. The authors concluded that this was
not a treatment-related effect. Although an increased incidence of
phaeochromocytoma has been seen in rats fed polyol sweeteners which,
like ß-cyclodextrin, are poorly digestible substances, they were not
seen in mice fed similarly high levels of polyols. In view of the lack
of association in mice and the lack of a dose-related trend in the
incidence of this tumour in this study, the Committee agreed with the
authors' conclusion. There were no other neoplastic findings of note
(Gur et al., 1993a).
2.1.2.2 Rats
ß-cyclodextrin (> 86.6% pure) was administered in the diet to
groups of 50 male and female Fischer 344 rats at concentrations
sufficient to provide nominal doses of 0, 25, 75,225 or 675 mg/kg
bw/day. Treatment commenced at 4-5 weeks of age and continued for 122
weeks (males) or 130 weeks (females). The rats were housed 5 to a cage
and food and water were available ad libitum. All animals were
observed daily for clinical signs. Body weights were recorded weekly
for the first 15 weeks of treatment and biweekly thereafter.
Achieved dosages (mg/kg bw/day) in the first 2 weeks were only
approximately half the nominal level but were close to the required
level for the rest of the study. There were no treatment-related
effects on survival nor on the incidence or type of clinical signs.
There was no effect of treatment on body-weight gain, food consumption
or food conversion ratio. Water consumption in the high-dose female
rats was slightly lower than in controls throughout the study. The
authors did not consider this to be a treatment-related effect.
At 12, 18 and 24 months and prior to terminal sacrifice, blood
was taken from the tail of all animals and smears for differential
white blood cell counts were prepared. Data were presented for the
control and high-dose groups only. There was no adverse effect of
treatment.
All rats dying during the course of the study, killed in moribund
condition, or surviving to terminal sacrifice were subjected to gross
necropsies. In the control and high-dose groups, histopathological
examination was conducted on all organs. In the other groups, only
abnormalities and major organs were examined histopathologically.
There was no effect of treatment on organ weight nor on the incidence
of macroscopic lesions or non-neoplastic microscopic lesions.
Historical control data for the F344 rats was provided from the
testing facility for both life-span studies (n = 60 of each sex) and
2-year carcinogenicity studies (n = 305 of each sex) and from the US
National Toxicology Program for life-span studies (n = 529 of each
sex) and 2-year studies. The incidence of a few types of neoplasm
showed a trend of statistical significance with treatment but the
findings were not considered to be related to treatment with
ß-cyclodextrin because of the lack of a clear dose-relationship and/or
because the incidence in treated groups was well within the background
rate for this strain of rat. These included: testicular interstitial
cell tumours, subcutaneous fibroma, and endometrial stromal polyp and
sarcoma combined by disease severity. The incidence of parathyroid
adenoma also reached a low trend of significance in males and in the
data combined by sex (males: 0, 0, 3.6, 6.9 and 7.5%; combined: 0, 2,
2, 6.5 and 5.6% for the control, 25, 75, 225 and 675 mg/kg bw/day
groups, respectively). The incidences in the 225 and 675 mg/kg bw/day
dose male groups exceeded those reported for all groups of historical
controls but, given the lack of a clear dose-relationship in the data
combined by sex, this finding is considered unlikely to be associated
with treatment. The finding of a renal neoplasms (one adenoma and one
carcinoma) in two rats from the high-dose male group and none in any
other group was not statistically significant. The incidence was high
compared with background control data from the testing facility but
within the range seen in the NTP studies. There was no increase in
renal hyperplasia in treated groups (Gur et al., 1993b).
2.1.3 Reproductive toxicity studies
2.1.3.1 Rats
In a 3-generation reproductive toxicity study, ß-cyclodextrin
(> 99% pure) was administered in the diet at dose levels of 0, 1.25,
2.5 or 5% to groups of 30 male and 30 female Ico:OFA.SD.(IOPS Caw)
rats. The parental (P) generation males and females were maintained on
these diets for 10 and 2 weeks respectively before pairing and during
the gestation and lactation periods of three successive mating
periods. Male rats were approximately 6-week old at the start of
treatment and female rats were approximately 9-week old. Two
subsequent generations, comprised of 25 males and 25 females, randomly
selected from the F1b and F2b litters, were treated with dietary
concentrations of 0, 0.31, 0.62 or 1.25% ß-cyclodextrin: the dose
levels were reduced 3 weeks before mating of the F1 generation to
confirm the definition of a NOEL.
The F1 and F2 generations were each mated twice and allowed
to raise their offspring to weaning. The study was terminated with a
third mating phase of the F2 animals with caesarean examination of
the pregnant females and soft tissue and skeletal examination of the
fetuses.
The offspring from the third mating of the P generation (F1c
animals) were used to investigate the effects of vitamin D
supplementation on pup growth, because vitamin D deficiency was
thought to be responsible for effects on pup growth. The mated females
were divided into 2 sub-groups and 1 sub-group was given 500 IU
vitamin D3 diluted 1/80 in 90% ethanol i.p. on day 2 of lactation.
Milk and blood samples were taken from 5 females with viable foetuses
from each sub-group on day 15 post-partum for clinical chemistry
analyses.
Animals were housed 5 to a cage during the premating periods, 1
male and 1 female per cage during the mating period, 1 female (and its
litter) to a cage during gestation and lactation, and with all male or
female litter-mates in the same cage after weaning from 3 to 6 weeks
of age. Litters were culled to 10 pups each on day 4 post-partum, to
yield, where possible 5 males and 5 females. Food and water were
available ad libitum throughout. All animals were observed daily for
clinical signs of toxicity. Body weight and food consumption were
monitored during the respective pre-mating, gestation and lactation
periods. Fertility and reproductive performance of the P, F1 and
F2 generations were assessed by evaluation of mating performance,
duration of gestation, parturition and viability, growth and
development of pups.
Pups which had not been selected for mating were submitted to a
gross necropsy examination on or soon after day 21 post-partum. At
terminal necropsy, the adult males and females of each generation were
given a macroscopic examination; selected organs were weighed and
selected tissues were examined histopathologically.
Because ß-cyclodextrin was fed at a fixed rate in the diet,
intake on a mg/kg bw/day basis varied considerably during the study.
This was particularly marked in the first pre-mating period and, in
females, during lactation, when intakes varied 2-3-fold within each
dose group.
P Generation
Body-weight gains in male groups receiving ß-cyclodextrin were
slightly lower than in the control group, in a dose-related manner, at
most times, but the differences were not statistically significant.
Conversely, body-weight gain in the high-dose female group was
statistically significantly higher than in controls during the
premating period but statistically significantly less during the first
lactation. During the first and second lactations, females receiving
5% ß-cyclodextrin consumed statistically significantly less food than
the other groups; a trend to lower food consumption was also seen at
times in the 1.25 and 2.5% female groups.
There was no effect of treatment on mating performance nor on
gestation at any of the three matings. There were consistently more
dams with stillborn young in the treated groups. However, although the
proportion of pups which were stillborn was also consistently higher
in the treated groups, there was no dose-relationship and this finding
can be attributed to an abnormally low incidence of stillbirths in
controls. Litter size overall was large, averaging 14-15 live young.
Pup viability during lactation was not affected by treatment but mean
pup weight was statistically significantly reduced in the high-dose
group from about day 7 to day 14 post-partum until weaning at all
three matings. Eye opening was slightly delayed in the high-dose group
compared to controls at all three matings but this can be attributed
to lower pup body weight in the second half of lactation. Other
markers of pup development, i.e. the day of occurrence of pinna
unfolding and incisor eruption, and testing for auditory and pupil
reflexes at weaning, were not adversely affected by treatment. The
administration of vitamin D on day 2 of lactation had no effect on any
parameter. There were no clear differences in clinical chemistry
parameters of the maternal blood and milk following treatment with
ß-cyclodextrin.
F1 Generation
Body weights of intermediate- and high-dose animals were
statistically significantly lower than controls at the start of this
phase but began to recover when the doses of ß-cyclodextrin were
reduced, although body weights in the high-dose group remained lower
than other groups during both mating periods. Food consumption showed
a similar trend although the differences from controls were only
statistically significant in the high-dose group during gestation
after the second mating. There was no effect of treatment on female
body weight or food consumption during gestation or lactation after
the first mating. After the second mating, high-dose female body
weights were statistically significantly less than controls on days 1
and 14 of lactation only. There was no effect of treatment on
reproductive performance or litter parameters, nor on pup viability,
body-weight gain or development.
F2 Generation
There was no effect of treatment at any of the three matings on
paternal or maternal body-weight gain or food consumption. No adverse
effect was seen on reproductive performance, pup viability,
body-weight gain or development. A slightly higher proportion of dams
with stillbirths and of pups which were stillborn was seen in the
intermediate- and high-dose groups at the first and second matings but
there was no clear dose-response and this was not considered to be a
treatment-related effect. The incidence of malformations and anomalies
in fetuses delivered by Caesarian section after the third mating were
similar in dosed and control groups. The NOEL in this study was 1.25%
ß-cyclodextrin in the diet, equal to a mean achieved ß-cyclodextrin
intake which ranged from 560 - 2900 mg/kg bw/day over the different
phases of the study (Pharmakon Europe, 1994; and Personal
communication from Dr Ph. Olivier, Roquette Frères, Lestrem, France to
F. D. Pollitt, Department of Health, UK, submitted to WHO by F. D.
Pollitt).
2.1.4 Special studies on interactions with bile acids and
lipophilic nutrients
An in vitro study was carried out, using NMR spectrometry, to
evaluate interactions of ß-cyclodextrin with key bile acids, including
sodium lithocholate, which are present in human bile and to study the
competition between bile acids and the lipophilic vitamins A and D3
for ß-cyclodextrin inclusion.
It was found that, in water solutions, sodium cholate, sodium
taurocholate, sodium chenodeoxycholate and sodium lithocholate give
1:1 complexes with ß-cyclodextrin, the affinity of sodium cholate and
sodium taurocholate for ß-cyclodextrin being weaker than that of
sodium chenodeoxycholate or sodium lithocholate i.e. the affinity
increased with an increase in the hydrophobicity of the bile acid. The
complex of vitamin A with ß-cyclodextrin was shown to have a low
solubility in water. When sodium cholate or sodium taurocholate
entered into competition with vitamin A in the presence of a
sub-stoichiometric quantity of ß-cyclodextrin, there was incomplete
complexation of bile acids, confirming that competition occurs between
these acids and vitamin A. However, when sodium lithocholate or sodium
chenodeoxycholate were mixed with a vitamin A/ß-cyclodextrin complex
in solution, the NMR spectrum of the mixture was identical to that of
the lithocholate-ß-cyclodextrin complex, showing that vitamin A does
not interact with ß-cyclodextrin in the presence of these bile acids.
Similar results were seen with vitamin D3. It was concluded that these
findings, together with the fact that the quantity of bile acids
present during digestion is far higher than the ingested amounts of
vitamins, indicated that depletion of lipophilic vitamins will not
occur when ß-cyclodextrin is used as an ingredient in foods or orally
administered drugs (Comini et al., 1994).
3. COMMENTS
The Committee considered that the further toxicity studies
confirmed the low systemic toxicity of ß-cyclodextrin. The NOEL in the
1-year studies in rats and dogs was 1.25% in the diet, equal to 650
and 470 mg/kg bw/day, respectively. At higher doses there were minor
changes in blood biochemical and/or urine analytical parameters and,
in the rat, minor necrotic and inflammatory changes in the liver and
an increased incidence of pigment in conical tubular epithelium in the
kidney. The NOEL was also 1.25% in the diet (equal to between 560 and
2900 mg/kg bw/day, depending on the stage of the study) in the
3-generation reproductive toxicity study in rats, in which the only
adverse effect seen at higher doses was impaired pup growth during
lactation, which was probably secondary to reduced food consumption
and body-weight gain in the dams at this dose level.
In the carcinogenicity study in mice, ß-cyclodextrin caused
inflammatory changes in the lower gastrointestinal tract, which were
considered to be the cause of death of some animals. The lowest dose
level at which this occurred was 75 mg/kg bw/day (1/52 male affected)
and the NOEL was 25 mg/kg bw/day. The Committee considered that these
lesions probably represent a species-specific reaction to
ß-cyclodextrin in some mice. No such effects were seen either in the
carcinogenicity study in rats, in which the concentration of
ß-cyclodextrin in the diet was about three times that in the diet of
mice or in shorter-term studies in rats and dogs at far higher
ß-cyclodextrin concentrations in the diet. No treatment-related
neoplastic lesions were observed in the carcinogenicity studies.
An in vitro study indicated that ß-cyclodextrin is unlikely to
deplete lipophilic vitamins when used as an ingredient in food, since
it has a higher affinity for bile acids than for vitamins A and D3.
The fact that laboratory animals experienced no apparent nutritional
deficiencies affecting clinical status or survival following lifetime
exposure to high levels of ß-cyclodextrin in the diet also provides
reassurance that the use of this additive will not adversely affect
the nutritional status of humans.
4. EVALUATION
The Committee allocated an ADI of 0-5 mg/kg bw for
ß-cyclodextrin, based on the NOEL of 1.25% in the diet (equal to
470 mg/kg bw/day) in the 1-year study in dogs and a safety factor
of 100.
5. REFERENCES
COMINI, S., OLIVIER, P., RIOTTOT, M., & DUHAMEL, D. (1994).
Interaction of ß-cyclodextrin with bile acids and their competition
with vitamins A and D3 as determined by 1H-NMR spectrometry.
Clinica Chimica Actam, 228: 181-194.
GUR, E., NYSKA, A., & WANER, T. (1993a). ß-cyclodextrin: Oncogenicity
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