Ibuprofen

Endpoint summary

Description of key information

The lowest NOAEL observed in the four repeated dose toxicity studies available is 40 mg/kg bw. In that study, the test substance induced toxic effects in the kidney in monkeys after repeated oral exposure.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

February 1980 to September 1981

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Principles of method if other than guideline:

The study was carried out according to HRC Standard Protocol (documentation of the protocol attached to the report).
In a repeated dose toxicity study, groups of male and female baboons (Papio hamadryas) were exposed to the test material in doses of 0, 16, 40 and 100 mg/kg bw for 1 year. The test substance was administered via capsules twice per day. The control group received a placebo. Cage side observations, detailed clinical observations, food and water consumption was monitored daily. Body weight was determined weekly. In addition, the following observations and examinations were evaluated: ophthalmoscopic examination, haematology, clinical chemistry, urinalysis, faecal blood loss and the serum blood levels of the test substance were determined.

GLP compliance:

no

Limit test:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): Ibuprofen B.P.
- Analytical purity: 99.8%, loss on drying: 0.05%
- Impurities (identity and concentrations): sulfated ash (0.02%), nickel (< 5 ppm), lead (< 5 ppm), heavy metals (< 10 ppm), TLC impurities (< 1%) GLC impurities (0.22%)
- Purity test date: 1981-03-12
- Lot/batch No.: CMG 103772
- Stability under test conditions: confirmed
- Storage condition of test material: at room temperature, protected from light

Species:

monkey

Strain:

other: baboon (Papio hamadryas)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Shamrock farms Ltd., Henfield Sussex, UK (wild-caught animals)
- Age at study initiation: 2 - 3 years
- Weight at study initiation: 2.5 - 4.0 kg
- Fasting period before study: no
- Housing: individually
- Diet: Primate Mazuri (B.P. Nutrition, Witham, UK), 350 g/animal/day
- Water: ad libitum, except when specially withheld during urine collection
- Acclimation period: 8 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): ca. 22°C
- Humidity (%): ca. 50 %
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): no data, normal daylight was available to the animals and artificial lightning was used on workdays

IN-LIFE DATES: From: 1980-01-03 (delivery to testing facility), 1980-02-05 (start of dosing) continuing for 52 weeks To: not defined

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

The test substance was incorporated in gelatin capsules, size 0, obtained from Parke, Davis&Co. Limited, Hounslow, U.K.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

no details given

Duration of treatment / exposure:

1 year

Frequency of treatment:

Twice a day (approximately 10:00 and 16:00 h each day).

Dose / conc.:

16 mg/kg bw/day (actual dose received)

Remarks:

8 mg/kg bw/application

Dose / conc.:

40 mg/kg bw/day (actual dose received)

Remarks:

20 mg/kg bw/application

Dose / conc.:

100 mg/kg bw/day (actual dose received)

Remarks:

50 mg/kg bw/application

No. of animals per sex per dose:

5 males and 5 females per group

Control animals:

yes

Details on study design:

- Post-exposure recovery period in satellite groups: none

Positive control:

no

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: on working days

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: on working days

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION: Yes, twice daily

WATER CONSUMPTION: Yes
- Time schedule for examinations: for 4 week during pretreatment, and again during weeks 1-4, 9-12, 22-25, 35-38 and 46-49 of the dosing period, measurement on weekdays only

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: prior to dosing period, after 6, 13, 26, 39 and 50 weeks of dosing
- Dose groups that were examined: all animals

LABORATORY INVESTIGATIONS

(1) HAEMATOLOGY: Yes
- Time schedule for collection of blood: on one occasion pre-dosing and again after 6, 13, 26, 39 and 50 weeks of dosing
- Anaesthetic used for blood collection: No data
- Animals fasted: Yes, 16 h prior to collection of blood
- How many animals: all animals
- Parameters examined: erythrocyte sedimentation rate (ESR), packed cell volume (PCV), hemoglobin (Hb), red blood cell count (RBC), mean corpuscular cell volume (MCHC), mean cell volume (MCV), reticulocyte count, total white cell count (WBC), differential counts of neutrophils/lymphocytes/eosinophils/basophils/monocytes, platelet count, prothombin index (PTI) activated partial thromboplastin time (APTT), examination of blood film for morphology

(2) CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: on one occasion pre-dosing and again after 6, 13, 26, 39 and 50 weeks of dosing
- Animals fasted: Yes, 16 h prior to collection of blood
- How many animals: all animals
- Parameters examined: serum urea, plasma glucose, total serum proteins, serum albumin, serum alkaline phosphates (SAP), serum glutamic pyruvic transaminase (SGPT), serum glutamic oxaloacetic transaminase (SGOT), serum leucine arylamidase (LAP), serum bilirubin, serum sodium (Na), serum potassium (K), serum inorganic phosphorus (P), serum chloride (Cl), serum calcium (Ca), serum creatinine, serum cholesterol

(3) URINALYSIS: Yes
- Time schedule for collection of urine: on one occasion pre-dosing and again after 6, 13, 26, 39 and 50 weeks of dosing; 16-hour collection period
- Metabolism cages used for collection of urine: No
- Animals fasted: Water was withheld from the housing cages 5 h before start of sampling
- Parameters examined: specific gravity, volume, pH, protein, reducing substances, glucose, ketones, bile pigments, urobilinogen, hemoglobin
microscopical examination for epithelial cells, polymorphonuclear and mononuclear leukocytes, erythrocytes, organisms, casts, abnormal constituents

(4) TEST ON OCCULT BLOOD
Faeces were collected and tested for the presence of occult blood on three consecutive days immediately prior to the commencement of dosing and again during week 1 and after 6, 13, 26, 39 and 50 weeks of dosing.

(5) BONE MARROW EXAMINATION
Samples of bone marrow were obtained by aspiration from the sternum immediately prior to death.

(6) SERUM LEVELS OF IBUPROFEN
Blood samples were collected from 2 males and 2 females from each dose group immediately before the 2nd daily dose on day 1, and on one day during weeks 4, 16, and 32 and terminally.

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

On completion of 52 weeks' dosing all animals were killed. Each animal was immobilised with phencyclidinehydrochloride given by the intramuscular route, and then received an intravenous injection of pentobarbitone sodium. When deeply unconscious the animal was rapidly exsanguinated by incision of the carotid blood vessels.

GROSS PATHOLOGY: Yes
- full macroscopic examination of tissues
- determination of organ weights for brain, pituitary, thyroids, spleen, heart, liver, kidneys, lungs, adrenals, ovaries, testes including epididymis, thymus, pancreas, prostate including seminal vesicles

HISTOPATHOLOGY: Yes
Aorta (arch and abdominal), trachea, heart (auricle and ventricle) lungs, thymus, lymph nodes (cervical and mesenteric), liver, gall bladder, spleen, pancreas, kidneys, urinary bladder, uterus, ovaries, testes and epididymis, prostate and seminal vesicles, thyroids, adrenals, sub-mandibular salivary gland, esophagus, stomach (body and antrum), duodenum, jejunum, ileum, cecum, colon, skin, skeletal muscle (biceps femoris), mammary gland, tongue, eyes and optic nerves, brain (cerebral cortex, thalamic nuclei, mid-brain, medulla, cerebellum), pituitary, sciatic nerve, femoral bone sternum

Other examinations:

An interim examination (no sacrifices) was conducted after six months of treatment.

Statistics:

Whenever it was necessary to determine whether significant differences existed between mean values relating to test and control animals, analysis of variance was carried out. If heterogeneity of variance was present at the 1% level of significance, the data were transformed using logarithmic or other transformation in order to stabilise the variance. If transformation of the data was not successful in stabilising the variance, non-parametric methods based on Kruskal-Wallis mean ranks were used. The group mean values were compared using the method of least significant differences (LSD) in conjunction with Williams' test for contrasting increase in dosage levels of treatment groups with control. Significance testing was carried out at the 5% and 1% levels only. The Kruskal-Wallis mean ranks were compared using a non-parametric version of this test.
The organ weights were compared using analysis of covariance and adjusted for final body weight where there was a relationship between organ weights and body weight. Where there was no relationship, analysis of variance was carried out on the unadjusted values. The group mean values (adjusted or unadjusted) were compared using the method of LSD in conjunction with Williams' test.
The results obtained from the laboratory investigations during the pre-dosing period were described by the grand mean, the standard deviation and the full range.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

The only adverse sign that could be related to the test substance was subdued behaviour in a single high dose male during study week 17. A few incidental observations (vomiting, loose feces, sore areas [self-inflicted by biting]) were considered not unusual for laboratory animals.

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Apart from small losses in weight during the first week for some of the high dose animals, administration of the test substance had no effect on body weight gain.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Administration of the test substance at levels up to 100 mg/kg/day had no adverse effect on food consumption.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

no effects observed

Description (incidence and severity):

Administration of the test substance at levels up to 100 mg/kg/day had no adverse effect on water consumption.

Ophthalmological findings:

no effects observed

Description (incidence and severity):

No abnormalities were detected during any of the examinations that could be related to administration of the test substance.

Haematological findings:

effects observed, non-treatment-related

Description (incidence and severity):

Isolated abnormal values were noted for animals receiving ibuprofen and the controls. Statistical analysis of laboratory investigation results revealed a reduction in the values for activated partial thromboplastin time (APTT) after 6 weeks for the high dose group and a reduction in the urine specific gravity after 6, 39 and 50 weeks, also for the high dose group. However, for both these parameters, the majority of individual values were within the normal ranges.

Clinical biochemistry findings:

not specified

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

Statistical analysis of laboratory investigation results revealed a reduction in the urine specific gravity after 6, 39 and 50 weeks, for the high dose group.

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Apart from the kidney weights of one animal receiving 100 mg/kg/day all individual organ weights were considered to be within normal limits. Statistical analysis revealed higher kidney weights for the animals receiving 100 mg/kg/day, which was considered to be related to dosing with the test substance.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Examination of the kidneys revealed areas of cortical pitting in 2/10 animals receiving 40 mg/kg/day and 9/10 receiving 100 mg/kg/day. There were no other macroscopic abnormalities that could be related to dosing with the test substance.

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

There was an increased incidence of renal cortical scarring in animals receiving 100 mg/kg/day compared with other groups receiving the test substance and the control group. In addition, three animals at 100 mg/kg/day showed minor focal papillary changes, characterised by focal hyalinised connective tissue with irregular folding of the papillary epithelium. These changes were considered possibly related to administration of the test substance at 100 mg/kg/day.

Histopathological findings: neoplastic:

not specified

Other effects:

no effects observed

Description (incidence and severity):

DETERMINAL OF OCCULT BLOOD
There was no evidence of persistent gastro-intestinal bleeding.

BONE MARROW EXAMINATION:
There were no abnormalities observed that could be related to dosing.

Key result

Dose descriptor:

NOAEL

Effect level:

40 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

gross pathology

histopathology: non-neoplastic

Critical effects observed:

no

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

40 mg/kg bw/day

Study duration:

subacute

Species:

monkey

System:

urinary

Organ:

kidney

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Repeated dose toxicity: oral

In a repeated dose toxicity study (BASF 1981), groups of male and female baboons (Papio hamadryas) were exposed to the test material in doses of 0, 16, 40 and 100 mg/kg bw for 1 year. The test substance was administered via capsules twice per day. The control group received la placebo. Cage side observations, detailed clinical observations, food and water consumption was monitored daily. Body weight was determined weekly. In addition, the following observations and examinations were evaluated: ophthalmoscopic examination, haematology, clinical chemistry, urinalysis, faecal blood loss and the serum blood levels of the test substance were determined. An interim examination (no sacrifices) was conducted after six months of treatment. At termination of the study, the animals were killed after an initial anaesthesia, after which they were macroscopically examined. The weight of several organs was determined, and histopathology was performed on organs and tissues. The only adverse clinical sign that could be related to the test substance was subdued behavior in a single high dose male during study week 17. A few incidental observations (vomiting, loose feces, sore areas [self-inflicted by biting]) were considered not unusual for laboratory animals. Apart from small losses in weight during the first week for some of the high dose animals, administration of the test substance had no effect on body weight gain. No effect on food or water consumption was noted. Isolated abnormal values were noted for animals receiving the test substance and the controls. Statistical analysis of laboratory investigation results revealed a reduction in the values for activated partial thromboplastin time (APTT) after 6 weeks for the high dose group and a reduction in the urine specific gravity after 6, 39 and 50 weeks, also for the high dose group. However, for both these parameters, the majority of individual values were within the normal ranges. Statistical analysis of laboratory investigation results revealed a reduction in the urine specific gravity after 6, 39 and 50 weeks, for the high dose group. Apart from the kidney weights of one animal receiving 100 mg/kg/day all individual organ weights were considered to be within normal limits. Statistical analysis revealed higher kidney weights for the animals receiving 100 mg/kg/day, which was considered to be related to dosing with the test substance. Examination of the kidneys revealed areas of cortical pitting in 2/10 animals receiving 40 mg/kg/day and 9/10 receiving 100 mg/kg/day. There were no other macroscopic abnormalities that could be related to dosing with the test substance. Furthermore, there was an increased incidence of renal cortical scarring in animals receiving 100 mg/kg/day compared with other groups receiving the test substance and the control group. In addition, 3 animals at 100 mg/kg/day showed minor focal papillary changes, characterized by focal hyalinised connective tissue with irregular folding of the papillary epithelium. These changes were considered possibly related to administration of the test substance at 100 mg/kg/day. Based on these results the NOAEL for repeated dose toxicity via the oral route was determined to be 40 mg/kg bw per day.

 

In another repeated dose toxicity study (BASF 1977) groups of male and female baboons (Papio hamadryas) were exposed to the test material in doses of 0, 40 and 100 mg/kg bw for 30 days. The test substance was administered via capsules twice per day. The control group received lactose. Cage side observations, detailed clinical observations, food and water consumption was monitored daily. Body weight was determined weekly. As in the previous 1 year study, the following observations and examinations were evaluated: ophthalmoscopic examination, haematology, clinical chemistry, urinalysis, faecal blood loss and the serum blood levels of the test substance were determined. At termination of the study, the animals were killed after an initial anaesthesia, after which they were macroscopically examined. The weight of several organs was determined, and histopathology was performed on organs and tissues. No obviously significant adverse effects relatable to treatment were seen on bodyweight, haematology, blood biochemistry, urine analysis or faecal blood loss. On macroscopic examination at autopsy, minimal superficial erosions were seen in the antral mucosa of the stomach of one animal given 40 mg/kg daily and two given 100 mg/kg daily; microscopic erosions associated with parasitism were seen in one of these animals given 100 mg/kg daily but no lesions were seen microscopically in the others. No other lesion possibly attributable to treatment was seen macroscopically or microscopically. The peak serum concentration of ibuprofen after the first dose of 20 mg/kg ranged from 19.7 to 38.211g /mL and the time to the peak varied from 0.75 to 3 h. Based on these test results, the systemic NOAEL was determined to be 100 mg/kg bw/day.

 

Furthermore, to evaluate the oral repeated dose toxicity in rats (Adams 1969), groups of 10 male and 10 female newly weaned rats initially matched for body weights received 180, 60, 20, or 7.5 mg/kg in 0.4% cellosize daily by oral intubation for 26 weeks. A control group of 20 males and 20 females received 0.4% cellosize, 10 mL/kg daily. Observations/examinations included body weights (3 times per week), hematology and blood chemistry (during the last week of treatment), activity of plasma glutamic pyruvic transaminase (GPT; during terminal anesthesia), organ weights, and histopathology. One male of the 180-mg/kg bw-group died. Pathology revealed intestinal lesions; this death was substance-related. No other substance-related deaths were reported. All dosed rats grew normally, with exception of males given 180 mg/kg bw/d which gained significantly less weight than controls. Anaemia as judged by low erythrocyte counts and low haemoglobin was observed in males and females of the highest dose group (180 mg/kg bw/d); leukocyte counts were not significantly affected. Males of the 180-mg/kg bw group had relative organ weights (organ-to-body weights) that were nearly all greater than control. For some organs, this was because these males weighed less than control. According to the authors, the organs that were probably genuinely enlarged were liver, kidney and spleen. The same organs were also enlarged in females of this dose group, although body weight of these females was not significantly different from control. Furthermore, the combined seminal vesicle and prostrate weight was genuinely subnormal, and the uterine weight was increased. The thyroid glands of males but not of females on 180, 60, and 20 mg/kg bw/d exhibited a slight increase in weight, this was the same at all three doses. None of the rats showed significant histologic changes of tissues, with exception for one male and 3 females at 180 mg/kg bw with intestinal ulcers. Based on these test results, the systemic NOAEL was determined to be 60 mg/kg bw/day.

To assess whether the effects of treatment are reversible when dosing ends, the test substance was administered to rats in daily doses of 180, 60, or 20 mg/kg for 13 weeks. Hematologic examinations were performed after 4, 8, and 12 weeks (Adams 1969). The day after dosing ended, half the animals in each group were killed, the rest being kept un-dosed for 3 weeks and then killed. After 4 days of dosing, an additional group given 540 mg/kg daily was killed because of high mortality. Anemia was observed in rats dosed with 180 mg/kg bw/d from study week 4 onwards. Males given 180 mg/kg bw/d had enlarged kidneys, spleen, and testes; the organ weights of males given lower doses were normal. Dosed females exhibited enlargement of the kidneys (20, 60, 180 mg/kg bw/d; the extent was graded with dose), liver (180 mg/kg bw/d), spleen (60 mg/kg bw/d), and ovaries (60, 180 mg/kg bw/d). However, none of the enlarged organs were histologically abnormal. Organ-to-body weights were completely or almost completely normal after recovery.

Justification for classification or non-classification

Based on the available information classifcation for repeated dose toxicity is not warranted in accordance with EU Classification, Labeling and Packaging of Substances and Mixtures (CLP) Regulation No. 1272/2008.