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Description of key information

Sub-acute (28 d), sub-chronic (26 w) and chronic (2 a) repeated dose toxicity was assessed in rats.

Sub-acute (28 d) and sub-chronic (26 w) repeated dose toxicity was assessd in Beagle dogs.

In the sub-acute Studies the following NOAEL were assessted:

  • Wistar rat: 61.9 mg/kg BW
  • Beagle Dog: 14.7 mg/kg BW

The HED wich can be calculated from these NOAEL by deviding by the specific conversion factor are comparable.

It can be concluded that rat and dog show a similar sensitivity against alpha-Lipoic acid after daily administration for 28 d.

In the sub-chronic studies the following NOAEL were assessted:

  • Wistar rat: 21.5 mg/kg BW
  • Beagle Dog: > 50.0 mg/kg BW

In the chronic study with Sprague-Dawley rats the LOAEL is 60 - 180 mg/kg BW.

The NOAEL was not reported. Most findings in the low dose (20 mg/kg BW) and the intermediate dose (60 mg/kg BW) group can be regarded as age-related.

It can be concluded that the NOAEL is beween 20 and 60 mg/kg BW.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Referenceopen allclose all

Endpoint:
short-term repeated dose toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1993-09-13 - 1995-05-08
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Study owner prepared study while seeking authorisation of the substance as active incredient for medical treatment.
Reference:
Composition 0
Qualifier:
according to
Guideline:
EU Method B.7 (Repeated Dose (28 Days) Toxicity (Oral))
Version / remarks:
1991-07-19
Deviations:
no
GLP compliance:
yes
Test material information:
Composition 1
Species:
dog
Strain:
Beagle
Sex:
male/female
Details on test animals and environmental conditions:
Age: m 7 month, f 6-7 month
B.w. m 10.5 - 17.1 kg, f 7.7 - 14.5 kg
Caging: Boxes 6.0 m x 1.2 m
No of animals per box: 3
Diet: Standard dog diet ad libitum
Water: ad libitum in drinking water quality
Room temperature: 23.5 - 26 °C
Relative humidity: 30 - 55 %
Lighting: 6 a.m. - 6 p.m. artificial lighting, 6 p.m. - 6 a.m.natual dark rhythm
Route of administration:
oral: capsule
Details on route of administration:
gelatine capsules (12 x 30 mm)
Vehicle:
unchanged (no vehicle)
Duration of treatment / exposure:
4 weeks
Frequency of treatment:
once daily (a.m.)
Dose / conc.:
0 mg/kg bw/day (nominal)
Remarks:
Control
Dose / conc.:
14.7 mg/kg bw/day (nominal)
Remarks:
low dose
Dose / conc.:
31.6 mg/kg bw/day (nominal)
Remarks:
intermediate dose
Dose / conc.:
68.1 mg/kg bw/day (nominal)
Remarks:
high dose
From day 3 of administration onwards: 56.2 mg/kg b.w. (m)
From day 16 of administration onwards: 56.2 mg/kg b.w. (f)
From day 17 of administration onwards: 46,4 g/kg b.w. (m + f)
No. of animals per sex per dose:
3 m + 3 f
Control animals:
yes
Observations and examinations performed and frequency:
Mortality: twice daily (a.m. and p.m.)
Behaviour and general condition: daily
Food consumption: daily, staring with 2nd pretest week
B.w.: Once a week, staring with 2nd pretest week
Reflexes: Pain, pupil, corneal and patella reflexes, once a week staring with 2nd pretest week
Heart rate, body temperature: once a week staring with 2nd pretest week, before administration each
Ophthalmology: before first administration and in week 4, all animals
ECG: before first subtance administrationand in week 4 before administration
Clinical chemistry and hematology: before first substance administration and in weeks 1 and 4
Urine: week 5 by punctation of the bladder during autopsy
Sacrifice and pathology:
Anesthesia: Rompun(R) and T61(R), exsanguination

Gross Necropsy: all animals -> external surface of body, orifices, cranial, toracic and abdominal cavities and their contents.
All gross lesions, adrenal glands (r/l), aorta, axillary lymph node, bone (femur and sternum), bone marrrow smear (from sternum), brain (cerebrum, cerebellum, medulla/pons), caecum, cervix, colon, duodenum, epididymides (r/l), gallbladder, heart, ileum, injection sites, jejunum, kidneys (r/l), liver, lungs, main stem bronchi, mammary gland, mesenteric lymph node, oesophagus, ovaries (r/l), pancreas, parathyrois glands (r/l), peripheral nerve, pituitary gland, prostate, rectum, salivary glands (parotid, submaxillary, sublingual), skeletal muscle, skin, spinal cord (cervical, thoracic, lumbar segments), spleen, stomach, testes (r/l), thymus, thyroid gland (both lobes), tongue, trachea, urinary bladder, uterus, vagina.

Organ weigths: Adrenals (r/l), brain, heart, kidneys (r/l), liver, lungs, ovaries (r/l), pituitary, prostate, spleen, testes (r/l), thyroids (r/l).
Expression as absolute values and relative to b.w. recoreded in week 4.

Fixation: All organes and tissues exept eyes and bone marrow smears -> 10 % formalin
Eyes -> SUSA fixative 4 - 16 h, thereafter 10 % formalin
Bone marrow smears -> air dried
Staining: All organs and tissues -> embedded in parafine wax, sectioned at 4 µm and stained with H&E
Additional sections of kidneys -> periodic acid Schiff reaction
Cryostate sections of liver and one kidney -> Oil red 0
Statistics:
Mean and SD: each group and sex
B.w. and organ weigts: DUNNET-Test
Clinical Parameters, ECG, hematology, clinical chemistry: DUNNETT-Test (normal distribution), otherwise STEEL-Test
Significances:
DUNNETT: * p < 0.05, ** p < 0,01
STEEL: + p < 0.05
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Behaviour and general condition were dose dependently influenced in mid and high dose animals in extend, incidence, and severity during the treatment period.

Low dose animals were free of toxic symptoms.

Intermediate dose males had serve hypokinesia, decrease of muscle tone (abdominal position), salivation, vomitus and sunken sides. Females of this group showed salivation and vomitus only.

High dose animals of both sexes had in addition th mid dose males symptoms like coordination disturbances, loss if righting reflex (lateral position), and diarrhea. The animals were in a poor general condition. One out of three females had serve clonic convulsions temprorarily.
Mortality:
mortality observed, treatment-related
Description (incidence):
One male animal of group 3 and two male animals of group 4 had to be killed in extremis.
One female animal or group 4 had to be killed in extremis.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Decreased b.w. in high dose animals.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
Dose depßendent reduced.
After dose reduction in the high dose group food intake normalized to control group level.
Ophthalmological findings:
no effects observed
Haematological findings:
effects observed, treatment-related
Description (incidence and severity):
Changes in some white blood cell parameters in individual high dose animals.
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
Substance related changes in individual high dose animals.
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not specified
Immunological findings:
effects observed, treatment-related
Description (incidence and severity):
Changes in white blood cell parameters may show an immunologicel effect.
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
High dose male: increased wight of liver and thyroid gland, decreased weight of prostate
Hight dose females: increased weights of lung and liver.
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
Pale discolored liver.
Ulcerations in pyloric mucosa of stomach.
Pale discolored kidneys.
Neuropathological findings:
not specified
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Histopathological findings: neoplastic:
effects observed, treatment-related
Other effects:
not specified
Key result
Dose descriptor:
NOAEL
Effect level:
ca. 14.7 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
clinical signs
mortality
food consumption and compound intake
haematology
clinical biochemistry
organ weights and organ / body weight ratios
gross pathology
histopathology: non-neoplastic
histopathology: neoplastic
Key result
Dose descriptor:
LOAEL
Effect level:
ca. 31.6 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
clinical signs
mortality
body weight and weight gain
food consumption and compound intake
haematology
clinical biochemistry
urinalysis
organ weights and organ / body weight ratios
gross pathology
histopathology: non-neoplastic
histopathology: neoplastic
Key result
Dose descriptor:
other: lethal dose range
Effect level:
>= 56.1 - <= 68.1 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male
Basis for effect level:
mortality
Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
31.6 mg/kg bw/day (nominal)
System:
hepatobiliary
Organ:
liver
Treatment related:
yes
Dose response relationship:
yes
Relevant for humans:
not specified
Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
31.6 mg/kg bw/day (nominal)
System:
urinary
Organ:
kidney
Treatment related:
yes
Dose response relationship:
yes
Relevant for humans:
not specified
Conclusions:
On the basis of the present 4-week oral toxicity study with alpha-Lipoic acid it can be concluded that most of the observed clinical, clinical pathological and pathological findings are substance related.
Executive summary:

The low dose of 14.7 mg/kg b.w. was free of toxic symptoms, clinical pathological and histopathological changes.

Further findings in mid and high dose groups give an indication that liver and kidney are clearly involved als target organs for the test subatance.

The results of the macro- and microscopic examinations inclusive organ weight determination did distinctly confirm the results of the clinical chemistry investigations and they are in good correspondence to these findings.

Under the present experimental conditions it can be stated, that alpha-Lipoic acid exerts distinct toxic effects in doses of 31.6 and 68.1/56.2/46.4 mg/kg b.w. A dose range between 68.1 and 56.2 mg/kg b.w. represents the beginning lethal dose range.

A dose of 14.7 mg/kg b.w. represents the NOAEL in the present dog study.

Endpoint:
short-term repeated dose toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1993-09-07 - 1995-02-06
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Study owner prepared study while seeking authorisation of the substance as active incredient for medical treatment.
Reference:
Composition 0
Qualifier:
according to
Guideline:
EU Method B.7 (Repeated Dose (28 Days) Toxicity (Oral))
Deviations:
no
GLP compliance:
yes
Test material information:
Composition 1
Species:
rat
Strain:
Wistar
Sex:
male/female
Route of administration:
oral: gavage
Vehicle:
propylene glycol
Duration of treatment / exposure:
4 weeks
Frequency of treatment:
once daily a.m. (7 days per week)
Dose / conc.:
0 mg/kg bw/day (nominal)
Remarks:
Control
Dose / conc.:
31.6 mg/kg bw/day (nominal)
Remarks:
low dose
Dose / conc.:
61.9 mg/kg bw/day (nominal)
Remarks:
intermediate dose
Dose / conc.:
121 mg/kg bw/day (nominal)
Remarks:
high dose
No. of animals per sex per dose:
15 m
15 f
Control animals:
yes, concurrent vehicle
Positive control:
no
Observations and examinations performed and frequency:
Mortality: twice a day (a.m., p.m.)
Behaviour and gen condition of the anomals: daily (occurence of toxicity symptomes)
Food Consumption: Once a week, sarting with pretest period
Body Weight: Once a week, sarting with pretest period
Reflexes (before administration): pain, pinna, coneal reflexes -> once a week, sarting with pretest period
Eye, hearing and dental (before administration): prior to first adminsitration and in test week 4.
Ophthalmological Investigations: prior to first adminstration and in test week 4, all animals of groups 1 + 4, except animals for plasma level determination
Blood Collection: Test weeks 1 + 4, retroorbital venous plexus of one eye, first 10 animals per group
Urine: metabolism cages in test week 4 for 3 hours a.m. from animals selected for blood sampling
Hematology: Test weeks 1 + 4 -> Erythocytes, hematocrit, hemoglobin, leucocytes, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, mean corpuscular volume, Trombocytes, differential leucocyte count
Clinical chemistry: Test weeks 1 + 4: ALAT, AKP, ASAT, blood urea; Ca, Cl, CK; creatinine, Gamma-GT, GLDH, iP, K, Na, tot. bili., Chol. tot. protein, triglycerides
Urinalysis: Bili, glucose, hem/erythrocytes, ketones, leucocytes, nitrite, osmolality, pH, protein, urobilinogen, volume
Plasma level: week 4 -> 2, 6, and 24 h after administration
Sacrifice and pathology:
Anesthesia with CO2, sacrificed by exsanguination
Autopsy: All animals -> full gross necropsy
Organ weights: adrenals (r/l), brain, female genital tract in toto, heart, kidneys (r/l), liver, ovaries (r/l), pituitary, prostate/seminal visicles in toto, spleen, testes (r/l), thymus.
absolute values and relative to b.w. after exsanguination
Histopathology:
Fixation: all organs exept eyes and bone marrow smears -> 10 % formalin
eyes -> SUSA fixative (4 to 16 h), therafter 10 % formalin
bone marrow smears -> air dried
Staining: All fixed organs -> embedding in parafine, sectioned at 4µm, stained with H&E
Add. frozen section of liver tissue -> Oil Red O
Bone marrow smears -> according to PAPPENHEIM
Statistics:
Mean and SD seperately for each group and sex.
Evaluaion of food consumption, b.w. and organ weighs: DUNNETT-Test
Hematology and clinical chemistry: DUNNETT-Test in case of normal distribution, otherwise STEEL-Test
Significances:
* p < 0.05
** p < 0.01 (according to DUNNETT)
+ p < 0.05 (according to STEEL)
Clinical signs:
effects observed, non-treatment-related
Description (incidence and severity):
No changes in low and mid dose.
High dose: 1 male rat showed slight hypokinesia on 3 d in week 4.
Same animal showed coordination disturbances during entire treatment period.
Symptones occuered between 45 and 180 min after administration and lasted up to one day.
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
no effects observed
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Description (incidence and severity):
No changes in low and mid dose.
High dose: Possible substance related changes
Males: Week 1 -> significant decrease of cholesterol until week 4
slight but significant increase of ALAT and GLDH and decrease of tot. protein and triglycerides
Females: Week 4 -> sligtht but significant increases of blood urea and cholesterol
Urinalysis findings:
no effects observed
Behaviour (functional findings):
no effects observed
Immunological findings:
not specified
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Neuropathological findings:
effects observed, non-treatment-related
Description (incidence and severity):
Unspecific cliniical symptoms aof an affection of CNS and VNS
Histopathological findings: non-neoplastic:
not specified
Histopathological findings: neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Liver: male and female rats
Mammary gland
Key result
Dose descriptor:
NOAEL
Effect level:
ca. 61.1 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
organ weights and organ / body weight ratios
gross pathology
histopathology: neoplastic
Key result
Critical effects observed:
no
Lowest effective dose / conc.:
61.9 mg/kg bw/day (nominal)
System:
hepatobiliary
Organ:
liver
Conclusions:
On the basis of the present 4-week oral toxicity study in Wistar rats it is conducted that the most sensitive organ in the toxicity of alpha-Lipoic acid is the liver. In the last quarter of the treatment period unspecific clinical symptoms of an affection of CNS and VNS were noted. Additionally the mammary gland was affected in a sex specific way.
The severity and incidence of liver findings in the low and mid dose groups indicate an adaptive response to a repeated administration of alpha-Lipoic acid rather than a straight toxic response.
With regard to the absence of changes of other parameters including clinical chemistry the toxicological significance of these findings is equivocal.
Therefore the NOAEL can be assumed at 61.9 mg/kg b.w. alpha-Lipoic acid in male and female Wistar rats.
Executive summary:

The study was performed to gather information o the toxicity profile of alpha-Lipoic acid after repeated daily administration and to assess a NOAEL.

The oral route of administration was chosen because this is the intendet route in man.

Four groups of Wistar rats were used in this study, all containing 15 ale anf female rats each. Five animals per group and sex were exclusively used for blood sampling to ascertain the toxicokinetic profile of the test substance.

Alpha-Lipoic acid was adminstered as a solution in 1,2 -propylene glycol to groups 2, 3 and 4 animals. Group 1 rats recieved 1,2 -propylene glycol as control animals. The dose range was 31.6 mg/kg b.w. as low dose (group 2), 61.9 mg/kg b.w. as intermediate dose (group 3) and 121 mg/kg b.w. as high dose (group 4).

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1968
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Study owner prepared study while seeking authorisation of the substance as active incredient for medical treatment.
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 452 (Chronic Toxicity Studies)
Qualifier:
according to
Guideline:
EU Method B.30 (Chronic Toxicity Studies)
Deviations:
not specified
GLP compliance:
not specified
Test material information:
Composition 1
Species:
dog
Strain:
Beagle
Sex:
male/female
Route of administration:
oral: capsule
Details on route of administration:
Diet: ALTROMIN H, 50 g/kg bw. offered daily for an hour (between 8 and 9 a.m.)
Drinking water: ad libitum

Caging: 1 animal per cage, 5 m^2 + 8 m^2
Temperature: 21 +/- 3 °C
Vehicle:
other: amylum
Details on oral exposure:
Administration between 8 and 9 a.m.
Duration of treatment / exposure:
6 month
Frequency of treatment:
Daily
Dose / conc.:
12.5 mg/kg bw/day (nominal)
Remarks:
low dose (I)
Dose / conc.:
25 mg/kg bw/day (nominal)
Remarks:
intermediate dose (II)
Dose / conc.:
50 mg/kg bw/day (nominal)
Remarks:
high dose (III)
Dose / conc.:
0 mg/kg bw/day (nominal)
Remarks:
control (IV), sugar capsule
No. of animals per sex per dose:
3 m
3 f
Control animals:
yes
Observations and examinations performed and frequency:
Daily: behaviour and general condition
Weekly: b.w.

Hematology
Clinical chemistry
Urinalysis
ECG

Directly before necropsy: examination of eyes (cornea, eye chamber, pupil, lens, vitreous body, eyeground), hearing
Sacrifice and pathology:
Anesthesia: T61 (0.3 ml/kg b.w.), exsanguination
Gross pathology
Organ weights
Histology (paraffin slices, HE staining): heart, lung, liver, spleen, kidneys, adrenal gland, thymus, hypophysis, gonads, thyroid gland, brain, prostate/uterus, somach, duodenum, jejunum, ileum, colon, rectum, pancreas, eye with optic nerve, bladder, bone marrow, mesenchymals lymph nodes, deferent duct/mamma
Statistics:
Student-t-Test P <= 0.01
Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
no effects observed
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
no effects observed
Immunological findings:
not specified
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Neuropathological findings:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
no effects observed
Other effects:
not specified
Key result
Dose descriptor:
LOAEL
Effect level:
> 50 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
mortality
body weight and weight gain
food consumption and compound intake
water consumption and compound intake
ophthalmological examination
haematology
clinical biochemistry
urinalysis
behaviour (functional findings)
organ weights and organ / body weight ratios
gross pathology
histopathology: non-neoplastic
histopathology: neoplastic
Key result
Critical effects observed:
no
Conclusions:
Under conditions of the study the LOAEL can be expected above 50 mg/kg b.w.
Executive summary:

In this study the tolerance of alpha-Lipoic acid in beagle dogs was tested. The test item (in an amylum capsule) was administered daily (a.m.) over a period of 6 month.

The daily doses of the test item were 12.5, 25,0 and 50,0 mg/kg b.w.

Contol animals recieved 1 g sucrose / day in a capsule.

None of the dosages showed critical effects.

Behaviour, appearance, feaces, Fodd and water consumption, b.w., hematology, clinical chemimistry, ECG, urinalysis, eyes, set of teeth, gross patholgy and organ weigts gave no hints of intolerance towards the test item.

Histology showed no substance related changes.

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1995-07-18 - 1997-12-05
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Study owner prepared study while seeking authorisation of the substance as active incredient for medical treatment.
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 452 (Chronic Toxicity Studies)
Qualifier:
according to
Guideline:
EU Method B.30 (Chronic Toxicity Studies)
Deviations:
no
GLP compliance:
yes
Test material information:
Composition 1
Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
Age:
Males: 7 weeks
Females: 8 weeks

Body weight
Males: 147 - 188 g
Females: 126 - 170 g

Caging: Macrolon type III

Animals per cage: 1

Bedding: Sterilized animal bedding softwood granulation

Diet: Standard diet ad libitum

Water: Drinking water (Stadtwerke Halle) ad libitum

Room temperaure: 20.4 - 22.6 °C

Relative Humidity: 41 - 68 %

Room Lighting: 6 a.m. - 6 p.m. CET artificial lighting; 6 p.m. - 6 a.m. CET darkness
Route of administration:
oral: gavage
Vehicle:
propylene glycol
Analytical verification of doses or concentrations:
yes
Duration of treatment / exposure:
26 weeks - daily administration
6 weeks recovery - 5 animals of each sex of vehicle group and high dose group
Frequency of treatment:
once daily between 7 a.m and 1 p.m.; 7 days a week
Dose / conc.:
0 mg/kg bw/day (nominal)
Remarks:
(1) Drinking water
Dose / conc.:
0 mg/kg bw/day (nominal)
Remarks:
(2) Vehicle (1,2-proylene glycol)
Dose / conc.:
21.5 mg/kg bw/day (nominal)
Remarks:
(3) low dose
Dose / conc.:
46.4 mg/kg bw/day (nominal)
Remarks:
(4) intermediate dose
Dose / conc.:
100 mg/kg bw/day (nominal)
Remarks:
(5) high dose
No. of animals per sex per dose:
(1) 10 m + 10 f
(2) 25 m + 25 f (5 animals each for recovery period)
(3) 20 m + 20 f
(4) 20 m + 20 f
(5) 25 m + 25 f (5 animals each for recovery period)
Control animals:
yes, concurrent no treatment
yes, concurrent vehicle
Positive control:
no
Observations and examinations performed and frequency:
Mortality: twice daily (a.m. and p.m.)
Behaviour and General Condition: daily
Food Consumption: Once a week
Body Weight: Once a week
Reflexes (before administration)
Eye, Hearing and Dental Examinations (before administration)
Ophthalmological Investigations (before administration)
Sacrifice and pathology:
Sacifice: CO2 and exanguination
Autopsy
Organ Weights
Histopathology
Other examinations:
Blood
- Hematology
- clinical chemistry
Urine
Statistics:
Mean and SD for each group and sex
Food consumption, b.w. and organ weights: DUNNETT-Test
Hematology and clinical chemistry: DUNNETT-Test in case of normal distribution, otherwise STEEL-Test
Significane levels:
- DUNNETT: * p < 0.05; ** p < 0.01
- STEEL: + p < 0.05
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
M + f in high dose group (5)
M of intermediate dose group (4)
Mortality:
mortality observed, treatment-related
Description (incidence):
(2) f: 1 animal spontaneously died
(3) m: 1 animal sacrificed
(5) m: 1 animal spontaneously died; 2 animals sacrificed
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
no effects observed
Haematological findings:
effects observed, treatment-related
Clinical biochemistry findings:
effects observed, non-treatment-related
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not specified
Immunological findings:
not specified
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
Increased liver weigths in mid and high dose males.
Increased spleen weights in high dose males.
Increased absolute liver weigts in high dose females.
Gross pathological findings:
effects observed, non-treatment-related
Neuropathological findings:
not specified
Histopathological findings: neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Liver of mid and high dose males and high dose females.
Stomach of high dose males and females.
Other effects:
not specified
Key result
Dose descriptor:
NOAEL
Effect level:
ca. 21.5 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
mortality
organ weights and organ / body weight ratios
histopathology: neoplastic
Key result
Dose descriptor:
LOAEL
Effect level:
ca. 46.4 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
mortality
organ weights and organ / body weight ratios
histopathology: neoplastic
Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
46.4 mg/kg bw/day (nominal)
System:
hepatobiliary
Organ:
liver
Treatment related:
yes
Dose response relationship:
yes
Relevant for humans:
not specified
Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
46.4 mg/kg bw/day (nominal)
System:
gastrointestinal tract
Organ:
stomach
Treatment related:
yes
Dose response relationship:
yes
Relevant for humans:
not specified
Conclusions:
The dose of 21.5 mg/kg b.w. alpha-Lipoic acid is considered the NOAEL in both males and females during this 26-week oral toxicity study in Wistar rats.
Only minimal findings were present in individual animals at a dose of 46.4 mg/kg b.w.
Executive summary:

On the basis of the present 26-week toxicity study after oral adminstration in Wistar rats it is concluded that alpha-Lipoic Acid induced slight toxic effects on the CNS and VNS at a dose of 100 mg/kg b.w. Only minimal findings were noted in males an 46.4 mg/kg b.w.

A reduction of food consumption was only present in males at mg/kg b.w.; a reduction in b.w. gain was present in both males and females at 100 mg/kg b.w. High dose animals showed slight decreases in red blood cell parameters. Clinical chemistry parameters and measurement of organ weigts indicated the liver as possible target organ of toxicity.

Histopathologicalliy, in the liver increases were noted for microganulomas, basophilia of hepatocellular cytoplasm, polymorphism of periportal hepatocoytes, focal mononuclear cell infiltrates, hepatocellular storage of glycogen observed as hepatocellular rarefication, introcytoplasmatic inclusions and hepatocellular hypertrophy occuring in rats at 100 mg/kg b.w.

Males at 46.4 mg/kg b.w. had increased hepatocellular storage of glycogen and one male of this group had intractoplasmatic inclusions.

Only the intercytoplasmatic inclusions are considered of special toxicological relevance as they may indicate an increased turnover of hepatocytes.

Sings of local irritancy were recorded in the Stomach of high dose group animals.

Predominantly all changes recorded in high dose group animals were reversible during the 6-week recovery peridod.

Endpoint:
chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
01/1971 - 05/1973
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Study owner prepared study while seeking authorisation of the substance as active incredient for medical treatment.
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 452 (Chronic Toxicity Studies)
Qualifier:
according to
Guideline:
EU Method B.30 (Chronic Toxicity Studies)
GLP compliance:
not specified
Test material information:
Composition 1
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
Age: 38 d (m) and 42 d (f)
B.w.: 100 - 105 g
Diet: ALTROMIN R ad libitum
Drinking water: ad libitum
Cages:groups of 3 ro 2 in type III Macrolon cages
Temperature: 24 + 0.5 °C
Rel. humidity: 60 +/- 3 %
Illumination: 12 h a day, intensity 250 Lux
Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Duration of treatment / exposure:
2 years
Frequency of treatment:
daily
Dose / conc.:
20 mg/kg bw/day (nominal)
Remarks:
(I) low dose
Dose / conc.:
60 mg/kg bw/day (nominal)
Remarks:
(II) mid dose
Dose / conc.:
180 mg/kg bw/day (nominal)
Remarks:
(III) high dose
Dose / conc.:
0 mg/kg bw/day (nominal)
Remarks:
(IV) control
No. of animals per sex per dose:
(I) + (II): 40 m + 40 f
(III) + (IV): 50 m + 50 f
Control animals:
yes, concurrent no treatment
Observations and examinations performed and frequency:
Behaviour, general condition, food consumption: daily
B.w.: twive a week in first 6 month, intervals of 4 weeks there after.

After 12 and 24 month to the experiment in 10 animals per group and per sex:
Haematology
Clnical chemistry
Urinalysis

Immediately before dissection: eyes (cornea, eye chamber, pupil, lens, vitreous body, eyeground), hearing, teeth
Sacrifice and pathology:
After 12 month: 10 m + f from (III) and (IV) - decapitation and exsanguination
All the surviving animals were examined at the end or the experiment, and any rat that died in the interim was correspondingly examined after death.

Paraffin sections were prepared from the folling organs for all the animals, and these were then subjected to histological examination with HE-staining:
Heart, lungs, liver, spleen, kidneys, adrenals, thymus, pituitary, gonads, thyroid, brain, prostate/uterus, stomach, duodenum, jejunum, ileum, colon, rectum, salivary gland, eye with optical nerve, urinary bladder, bone marrow, trachea, aorta, oesopagus, pancras, mes. lymph nodes, peripheral nerves, skeletal muscles, tumors
Statistics:
Student's t test: p <= 0.01
Clinical signs:
no effects observed
Mortality:
mortality observed, non-treatment-related
Description (incidence):
Mortality rate between 10 % and 25 %
Control and low dose males showed hightest rate.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
High dose: weight gain was inhibited
Food consumption and compound intake (if feeding study):
no effects observed
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
no effects observed
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
no effects observed
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
Dissection after 12 month: within normal range
Dissection after 24 month: significantly reduced
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
Dissection after 12 month: no pathological findings
Dissection after 24 month: changes in color or size
Histopathological findings: non-neoplastic:
not specified
Histopathological findings: neoplastic:
effects observed, treatment-related
Key result
Dose descriptor:
LOAEL
Effect level:
>= 60 - <= 180 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
mortality
body weight and weight gain
organ weights and organ / body weight ratios
gross pathology
histopathology: non-neoplastic
histopathology: neoplastic
Dose descriptor:
NOAEL
Effect level:
>= 20 - <= 60 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
organ weights and organ / body weight ratios
gross pathology
histopathology: non-neoplastic
histopathology: neoplastic
Key result
Critical effects observed:
no
System:
other:
Organ:
not specified
Conclusions:
Under the present experimental conditions, the minimum toxic dose (LOAEL) is probably to be expected between 60 and 180 mg alpha-Lipoic acid/kg b.w./day via the diet.
Executive summary:

These experiments were carried out in order th investigate the tolerability of alpha-Lipoic acid on oral administration for 2 years to 260 Sprague-Dawley rats. Another 100 animals served as controls. 10 m and 10 f each from the high dose group and from the control group were subjected to an interim dissection after one year of the experiment.

The dose given were 20, 60 or 180 mg alpha-Lipoic acid/kg b.w. a day via the diet. The control rats remain untreated.

At the lower doses (20 and 60 mg/kg b.w.) there were no unambigous indications of any lesions. The finding of a significantly reduced adrenal weight is probably an incidential deviation. The age-related mortality rate, 19 % and 14 %, respectively, was lower than that of the control animals (24 %). At both doses the tumor rate was 25 %, as compared to about 29 % in the control rats.

At the maximum dose (180 mg/kg b.w.) the b.w. was significantly reduced and food consumption paralleled the weight development. Evidently as a consequence of the emaciation the absolute organ weigthts were often reduced, while the relative organ weigts were slightly higher.

Again the mortality was normal for this age. The mortality rate, 13 %, was lower than the corresponding control value of 24 %, and the tumor rate of 30 % did not differ considerably from that in the control group, were it was 29 %.

Behaviour and appearance of these animals, faeces, consumption of water, haematology and clinical chemistry, composition of urine and the checks of hearing, vison and teeth did not provide any unambigous evidence of intolerance reactions at any of the doses tested. The symptoms preciding death and the gross-pathological changes observed during dissection were the same in the test and control animals.

Histological examination after death and after 2 years of administration of any doses tested confirmed the gross-pathological findings. Pathological changes were predominantly observed in heart, lungs, liver, spleen, kidneys, gonads and lymph nodes, and also in the salivary gland, but were less frequent than in the other organs. Their number, nature and extent did not differ markedly between the individual alpha-Lipoic acid doses or between treated and untreated animals. The same applies to tumors wich were also found to about the same extend in each 4 groups.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
NOAEL
14.7 mg/kg bw/day
Study duration:
subacute
Species:
dog
System:
hepatobiliary
Organ:
liver

Mode of Action Analysis / Human Relevance Framework

Additional information

Justification for classification or non-classification

Alpha-Lipoic acid is not classified as specific organ toxic.

All gross-pathological and histological findings were either not considered treatment related, not critical or not statistically significant from the control group.