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Repeated dose toxicity: other routes

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repeated dose toxicity: other route
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
no data
4 (not assignable)
Rationale for reliability incl. deficiencies:
documentation insufficient for assessment
Justification for type of information:
Study focused on a specific point: experiment performed in aged rats.
Reason / purpose:
reference to same study

Data source

Reference Type:

Materials and methods

Principles of method if other than guideline:
TFE was injected via intraperitoneal route to aged rat 0.1 g/kg once a week for 5 weeks after which rats were sacrificed for pathologic examinations.
GLP compliance:
not specified

Test material

Details on test material:
- Name of test material (as cited in study report): 2,2,2 trifluoroethanol (TFE)
- Physical state: no data
- Lot/batch No.: no data
- Expiration date of the lot/batch: no data
- Stability under test conditions: assumed to be stable during the test (sponsor responsibility)
- Storage condition of test material: no data
- Other: Source: Aldrich Chemical Company

Test animals

not specified
Details on test animals and environmental conditions:
- Source: Griffin Laboratory, New-York state department of health, USA
- Age at study initiation: 36 Month old
- Weight at study initiation: approximately 450 g
- Fasting period before study: no data
- Housing: standardized plastic cages
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: no data

- Temperature (°C): 22°C
- Humidity (%): 55%
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): no data

IN-LIFE DATES: From: To: no data

Administration / exposure

Route of administration:
physiological saline
Details on exposure:
Fifteen 36-month-old rats (10 male and 5 female) were administered sublethal concentrations (0.10 g/kg) of TFE in saline, ip, once per week for 5 weeks. Ten 36-month-old rats (7 male and 3 female) were administered equal volumes of saline, ip as a control.
Analytical verification of doses or concentrations:
not specified
Duration of treatment / exposure:
5 weeks
Frequency of treatment:
once per week
Doses / concentrations
Dose / conc.:
100 mg/kg bw/day (nominal)
This dose is was considered as sub-lethal.
No. of animals per sex per dose:
10 male rats and 5 female rats.
Control animals:
yes, concurrent vehicle
Details on study design:
Fifteen 36-month-old rats (10 male and 5 female) were administered sublethal concentrations (0.10 g/kg) of TFE in saline, ip, once per week for 5 weeks. Ten 36-month-old rats (7 male and 3 female) were administered equal volumes of saline, ip as a control. The animals were observed daily for clinical signs and weighed weekly. Ninety-seven hours after the last injection, they were sacrificed with an overdose of carbon dioxide and autopsied for gross and histopathologic examinations.


Observations and examinations performed and frequency:
The animals were observed daily for clinical signs and weighed weekly
Sacrifice and pathology:
97 hrs after the last dose, animals were killed with CO2 inhalation and necropsied.
GROSS PATHOLOGY: Yes (see table) / No / No data
HISTOPATHOLOGY: Yes: lungs, spleen, lymph nodes, pancreas, kidneys, brain, liver, intestines, stomach, skin, thyroid gland, parotid gland, testicle, bladder and heart were taken and fixed in 10 % buffered formalin for light microscopic examination.
Other examinations:
For microsomal enzymatic determinations, small portions of fresh liver from both control and TFE treated animals were removed, microsomes were prepared and the cytochrome P-450 content determined by the standardized technique used in this laboratory.
For hepatic ultrastructural studies, samples of the liver from TFE-treated and non-treated rats were fixed in phosphate-buffered 2% glutaraldehyde at 4°C.

Results and discussion

Results of examinations

Clinical signs:
effects observed, non-treatment-related
Description (incidence and severity):
The rats used in this study were from an aging colony which has been previously described.
They were generally inactive due to obesity and the majority had a discolored, matted hair coat and obvious corneal opacity, all indicative of advanced senescence.
not specified
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
TFE produced a body weight reduction after 3 to 4 weeks of administration whereas the weight of the control animals stabilized approximately at 450 g throughout the study period.
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not specified
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not specified
Immunological findings:
not specified
Organ weight findings including organ / body weight ratios:
not specified
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
Dark swollen liver and a thickened stomach wall, particularly in the glandular portion between the greater curvature and pylorus. Intestinal walls were more thickened possibly due to more collagen relative to saline-treated aged rats.
Varying degrees of bilateral testicular atrophy were observed in many of the TFE-treated rats.
Kidneys of both TFE-treated and non-treated rats were somewhat smaller, turgid, and hard due to connective tissue elasticity and proliferation in comparison to young rats.
The skin was noticeably thickened and yellowish and the hair was matted.
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Major TFE-related histopathologic changes were found in the stomach, intestine, brain, liver, spleen, kidney, and testicle.

GASTRO INTESTINAL TRACT: At the histologic level, the mucosa of the glandular stomach of saline-treated aged rats was composed of rows of columnar cells that formed numerous gastric pits which were based at the lamina muscularis mucosa and opened into the lumen. The lamina muscularis mucosa separates the submucosal layer (tunica submucosa) from the mucosal layer (tunica propria mucosa); here, it was highly thickened in the case of TFE-treated rats due to increased collagen. This type of hyalinized change more often occurred in the glandular and particularly'in the fundic part of the stomach in the TFE-treated rats. Blood and lymph vessels were abundant in the hyalinized part ofthe stomach. In addition, the inner muscle layer was much thicker than in the control rats. Another TFE-mediated change was a rather profuse coagulation necrosis of the mucosal layer of the ileocecum.

LIVER: Hepatocytes, consisting of clear and acidophilic cell foci clearly demarcated from the surrounding tissue, were more frequently observed and with greater severity in the TFE-treated rats than in the controls. In addition, nodules, which were characterized by the presence of distinct zones of compression, were more often observed in TFEinjected rats. Lymphocytic cells were clustered and scattered between the 2 borders around the nodules. Random large hepatocytes with enlarged nuclei, multinucleated giant cells, and lipofuscin pigments were occasionally seen. One case of hepatocellular carcinoma occurred in the TFE-treated group of rats.
Hepatic tissues from both TFE-treated and salinetreated aged rats were examined and compared by electron microscopy. Changes in the fine structure of foci of altered hepatocytes involved qualitative and quantitative differences of glycogen, endoplasmic reticulum, ribosomes, and mitochondria.Hepatocytes from TFE-treated rats were observed to have abundant smooth endoplasmic reticulum and somewhat swollen mitochondria. The endoplasmic reticulum was granular, fragmented, and vesiculated. A few lamella bodies, fat vacuoles, and electron dense bodies were scattered throughout the cytoplasm.

TESTIS:The most striking TFE-associated change in aged rats was the occurrence of rather diffuse generalized bilateral testicular atrophy. All of the male TFE-treated aged rats had a generalized bilateral testicular atrophy. The atrophy consisted of complete loss ofgerminal cells leaving only tubular testicular epithelial cells. In some tubules, even the Sertoli cells and other associated germinal epithelial cells were .either scanty or absent. Atrophic tubules were much smaller than normal withgreater spaces between individual tubules. Focal and multifocal intratubular calcium deposits were commonly visualized in atrophic testicles.

KIDNEY: As indicated, more advanced chronic progressive glomerulonephropathy occurred more often in TFE treated aged rats. Epithelium-lining convoluted tubules were flattened, some tubular epithelium showed hydropic droplets, and tubular basement membranes were more thickened and irregular. Glomerular changes included more distinctive dilatation of Bowmans space with atrophic glomerular tufts and proliferated epithelial cells. Capillary basement membrane was further thickened and occasional sclerosis of glomeruli was more often seen in TFE-injected rats

BRAIN: In the brain, more generalized vacuolization of the white matter of the thalamic area, pons, midbrain, and cerebellum, including lipofuscin, was more often visualized in the TFE-treated rats. Other minor but subtle pathologic changes seen were considerable hemosiderin accumulation, extramedullary hematopoiesis and focal hemorrhage of TFEtreated spleen, and more advanced nodular hyperplasia of urinary-bladder transitional epithelium of TFE-treated aged rats.

Other spontaneous age-associated lesions observed in both TFE- and saline-treated aged rats were more or less generalized atrophy of parotid gland, myocardial degeneration, presence of aortic tumor, perivascular aggregation of lymphoid cells in terminal bronchioles, multifocal aggregation of macrophages, peribronchial fibrosis, hemosiderin accumulation, nodular hyperplasia, and squamous metaplasia of the thyroid gland. Multifocal atrophy of the pancreatic lobule and foci of cellular alterations in the cortical part of the adrenal gland were also seen regardless of the sex in this group of aged rats, although mammary gland adenoma was observed in 1 of the control rats but not in the TFE treated females
Histopathological findings: neoplastic:
not specified

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

The rats used in this study were from an aging colony which has been previously described. They were generally inactive due to obesity and the majority had a discolored, matted hair coat and obvious corneal opacity, all indicative of advanced senescence.

Applicant's summary and conclusion

Executive summary:

Various anesthetics are metabolized by different forms of cytochrome P-450 yielding the same toxic metabolite, 2,2,2-trifluoroethanol (TFE). The toxicity of TFE is a consequence of its metabolism catalyzed by cytochrome P-450. Since a marked age difference exists in the composition and inducibility of the hepatic mixed function oxidase system, we have elucidated the toxicity of TFE in 36-month-old aged Wistar rats. The aged rats were injected with sublethal doses of TFE (0.10 g/kg once per week for 5 weeks), after which they were sacrificed for pathologic examination. The major TFE-related lesions observed were severe hepatocyte degenerative changes such as basophilic, eosinophilic, vacuolated hepatocytes, bile duct hyperplasia, accumulation of lipofuscin pigments, and preneoplastic nodules. Other changes seen were the hyalinization of gastric submucosal wall, generalized testicular atrophy due to the loss of seminiferous tubules, coagulation necrosis of intestinal mucosal wall, hyperpigmentation, and more advanced and severe chronic progressive glomerulonephropathy in the TFE-treated rats. More severe lipofuscin and vacuolation of white matter of thalamic area, pons, midbrain, and cerebellum reflective of enhanced aging were also seen. Ultrastructural studies of liver from TFE-treated rats revealed rather diffuse loss of glycogen, fragmentation of endoplasmic reticulum, mineralization of mitochondria, and loss of other organelles within the hepatocytes versus salinetreated aged rats. Hepatic cytochrome P-450 concentrations, measured as a possible index of endoplasmic reticulum damage, were not affected by TFE administration.