Ibuprofen

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

No adverse effects on fertility were observed in the study available.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

In an older study cited by Adams (1969), the thyroid and the ovaries were investigated for possible function impairment due exposure to the test substance. The gonadal function was checked by means of a reproductive study. Ten male and 20 female rats of proven fertility were maintained on a diet containing 0.035% test substance (ca 20 mg/kg bw) over a period of 60 days; control rats received the diet only. Thereafter, all rats received diet only and 2 treated females were cohabitated with one treated male for mating over a period of 14 days. The females were checked for pregnancy and litter size at birth. During the treatment period, the females showed a small loss in weight whereas the males gained weight normally. Following mating, 15 of the 20 females treated with the test substance became pregnant versus 16 of the 18 control females (two of the 20 control females were killed in extremis because of mammary abscess and umbilical hernia). All males mated successfully (treated and controls) with one exception. Shortly prior parturition two treated females had vaginal hemorrhage. One of them died and examination of the uterus revealed 10 fully formed fetuses and extensive hemorrhage surrounding the placentae; this female also suffered from gastric ulcers and anemia. The second female was sacrificed in extremis; this female suffered from lung congestion and in one of the uterine horns al large blood clot was found. No dead or resorbed fetuses were seen. The remaining females had inconspicuous pregnancies and gave birth to litters with a mean of 7.9 live young. Controls had a mean litter size of 7.3 young.

Effects on developmental toxicity

Description of key information

No developmental toxicity was observed in the most reliable study available.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

In the assessment of the effect of ibuprofen on pregnancy of the New Zealand White rabbit and in utero development of the offspring, daily dosages of 0, 7.5, 20.0 and 60.0 mg/kg were administered orally during and including days 1 to 28 of gestation (day 0 being the day of mating); an day 29, animals were killed, litter values determined and foetuses subsequently examined for structural abnormalities of the skeleton and viscera (BASF, 1980). Treatment did not appear to adversely affect (a) parent animals as assessed by daily observations, bodyweight change, pregnancy rate and macroscopic changes recorded among sporadic deaths or animals surviving to termination, (b) litter values, as assessed by numbers of implantations, viable young, pre- and post-implantation loss, litter and mean foetal weights, (c) embryonic and foetal development as assessed by incidences of major malformations, minor visceral or skeletal anomalies and skeletal variants; the occurrence of three malformations of the same type (umbilical hernia) at 60.0 mg/kg was considered likely to be a coincidental event, albeit rare. It was concluded that the oral administration of 7.5, 20.0 or 60.0 mg/kg bw/day throughout pregnancy of the New Zealand White rabbit elicited no adverse effect and the developing progeny.

Several studies investigating the effects of ibuprofen on development are available. None of those studies are performed according to current guidelines. In other words, all studies presented lack certain aspects such as developmental endpoints not investigated or no/limited information presented on maternal toxicity.

In a published article from Adams (1969), to evaluate the potential developmental toxicity in Boots Wistar rat , primiparous females and proven males were caged together, the presence of spermatozoa in the vaginal smear being taken as an indication of the first day of pregnancy. From this time, 180, 60,20, or 7.5 mg/kg/day of the test substance, was administered by oral intubation until day 20 of pregnancy. Control females received 10 mL/kg of water daily. The uterine contents were examined on day 21 of pregnancy, and the fetuses were examined for external, visceral, and skeletal abnormalities. Since the young of rats may show certain types of developmental abnormality at weaning which are not visible before birth, additional groups of rats were given 20 or 7.5 mg/kg/day of the test substance throughout pregnancy until parturition, and the young were examined 3 weeks after delivery. Litters were reduced to 9 at birth, and any underweight or neglected young were killed during the suckling period. All were examined in detail for gross abnormalities. From the litter records, the viability index at weaning was estimated.Only females on the highest dose had a diminished rate of growth. In the first experiment females receiving 180, 60, or 20 mg/kg of test substance on days 1 to 20 of pregnancy were found to have gastrointestinal lesions graded in severity according to the dose; no lesions were observed in those an 7.5 mg/kg/day or in the controls. Animals form all groups had litters of normal size with fetuses of normal weight (experiment 1). In the second experiment, in which dosing was continued throughout pregnancy until parturition, the animals had uneventful pregnancies and delivered their young without difficulty. A similar number of live young per litter was obtained from the test substance treated and control animals. Postnatal findings indicate that the viability index at weaning and weaning weight were not significantly affected. In both experiments various external and visceral malformations were observed; these were of low incidence and occurred in the treated and control groups. None of the fetuses obtained from animals given 180 mg/kg/day was malformed, and microscopic examination of their organs revealed no histologic abnormalities. Therefore, the NOEAL for general toxicity which was determined to be 7.5 mg/kg bw. The developmental NOEAL for the fetuses was determined to be the highest dose tested of 180 mg/kg bw/day.

In the same article a developmental toxicity study on New Zealand White rabbits was reported. Virgin females weighing 2.5-5 kg were paired with proven males, the day of mating being termed day 0 of pregnancy. From the next day, 60, 20, or 7.5 mg/kg bw/day the test substance as a solution of the sodium salt was given orally until day 29 of pregnancy. Control females were given 1 mL/kg daily of water. All females were killed on day 30 of pregnancy, and their uterine contents were examined. The number of live, dead, and resorbed fetuses, and the number of corpora Iutea were recorded. Females given 60 mg/kg/day on days 1 to 29 of pregnancy grew less than controls and had stomach ulcers. A few also had pneumonia and a mild degree of focal hepatitis that was probably due to infection secondary to the gastric lesions. Females given 20 mg/kg/ day were similarly though less affected; females receiving 7.5 mg/kg/day grew normally, but some had gastric ulcers or erosions. Minimal gastric damage was observed in 2 out of 23 controls. Two females receiving 60 mg/kg/day gave birth prematurely to normal young an days 26 and 28 of pregnancy. The number of live fetuses per litter from animals given 60 mg/kg bw/day was less than from the controls, but there was no significant difference between these groups in the number of dead and resorbed per litter. However, there was a corresponding reduction in the ratio of implants to corpora lutea, which suggests that the decrease in live litter size was due to interruption of early pregnancy. The average fetal weight was normal. Litter size was unaffected in animals receiving the lower doses. Congenital malformations of various kinds occurred in the fetuses of treated and control animals. Apart from 4 young in 1 litter with multiple malformations characteristic of cyclopia, there was no consistent pattern of malformations, and the small number of cases showed no tendency relatable to dose. Based on the observed maternal toxic effects the NOEAL for general toxicity was determined to be 7.5 mg/kg bw/daily. The NOAEL for fetuses was determined to be 60 mg/kg bw/day based on the absence of adverse effects at the highest dose tested.

In two other studies, female Wistar rats were exposed to concentrations of 25.5, 127.5 and 255 mg/kg bw/day from the eighth gestational to the seventh lactation day (Burdan, 2011) and from day 8 to day 21 of gestation (Burdan, 2005) to assess possible developmental effects after oral exposure. In both cases, the test substance was administered orally gavage.

- In the study of Burdan (2011) the weight, length and number of fetuses after delivery was determined. After 7 days, pups and dams were killed, and skeleton morphology and mineralization of pups was determined with digital radiography and double-staining, respectively. Mortality was observed in 3 dams of the highest dose group. Relative body weight gain during the whole gestation period did not differ from the controls. Clinical biochemistry parameters that were examined of the dams showed no effects. Microscopic signs of gastrointestinal, hepatic and renal toxicity were found sporadically, mainly in the groups of dams exposed to the highest dose, although no (maternal) effect level has been determined by the authors. As to the pups, only a decrease of mineralization of the lumbar vertebrae was caused by the highest dose, so the authors determined the NOAEL to be 127.5 mg/kg bw/day. Since this effect is not considered to be adverse, the developmental NOAEL is considered to be the highest dose of 255.0 mg/kg bw/day.

- In the study from 2005, Burdan aimed to evaluate the prenatal skeletal effect of the test material (25.5, 255, 600 mg/kg bw). After gestation day 21, dams were sacrificed and the ovaries and uterine content was examined. Also the fetuses were assessed on toxicological developmental effects. Routine teratological examinations were performed and furthermore histological, immunohistochemical and molecular experiments were performed. Maternal animals showed a higher incidence of mortality and a reduced body weight gain in the highest dose group of 600 mg/kg bw/day. Also, the blood chemistry parameters urea, alanine and aspartate aminotransferase activity were significantly higher from controls, whereas total protein was significantly lower in this highest dose group. The additional immunohistochemical- and molecular conducted experiments did not show any deviations in the assessed parameters in comparison to the control. As to developmental toxicity, intrauterine growth retardation, and decreased fetal body weight and length was determined in the highest dose group. These effects are considered to be secondary to the toxicity observed in the maternal animals. Therefore, the maternal NOAEL was determined to be 255 mg/kg bw/day and the developmental NOAEL was set at 600 mg/kg bw/day.

Additionally, developmental toxicity was assessed in an experiment that aimed to determine if inhibition of COX and carbonic anhydrase would produce a teratogenic profile that included ventricular septal defect and diaphragmatic hernia in rat fetuses (Cappon, 2005). One of the test groups was solely exposed to the test substance of interest. In this test, pregnant female Crl:CD(SD)IGS BR rats were exposed to 300 mg/kg bw/day of test substance during gestation days 9 and 10, administered orally gavage. Sections were performed on gestation day 21, where fetuses were evaluated on visceral and external development. The maternal animals showed a significant decrease in corrected body weight and also a lower food consumption on gestation days 10, 11 and 12. Treatment did not cause an increase in external malformations and some noted visceral findings were found to not differ significantly from the control group. The maternal NOAEL was determined to be <300 mg/kg bw/day whereas the developmental NOAEL was determined to be >300 mg/kg bw/day.

Furthermore, the effects of the test material on developing kidneys was assessed in a study performed on Sprague-Dawley rats, where both maternal animals and neonates were exposed (Kent, 2007). The test substance was administered either orally to maternal animals in doses of 10 and 20 mg/kg bw/day during gestation days 16 – 20 or intraperitoneal to neonates in doses of 5 and 10 mg/kg bw/day during postnatal days 1 – 5. Effects of the test substance on the development of the kidneys of the pups were assessed with light- and electron microscopy. The maternal animals were not examined for toxic effects. Kidneys showed glomerular and tubular injury after both antenatal and postnatal exposure.

D. rerio test

Possible developmental effects of the test substance were also evaluated in zebrafish D. rerio, where fish embryos at 2/4 celled stage were exposed to concentrations of 1, 5, 10, 50 and 100 µg/L of test material (David, 2009). Parameters examined were embryonic development, hatching success, larval growth, behavioral pattern and survival competence. The authors concluded that developing embryos tolerated lower (1 and 5g/L) doses of the drug readily but, exposure to higher doses (>10g/L) caused retarded development, decreased hatching rate and growth, cardiac anomalies, spinal curvature, pectoral fin malformation and behavioral alterations resulting in greater mortality of experimental embryos. It was determined that the test material is embryotoxic at concentrations >10 µg/L to zebrafish embryos. However, at doses of 1 and 5 µg/L also mortality was increased and the number of hatchlings differed significantly from the controls.

In vitro

In a study by Guest et al. (1993), embryos were removed from Wistar rat dams on day 10 of gestation, cultured, and exposed to concentrations of ibuprofen for 48 hours. Subsequently, the embryos were assessed on developmental effects. Additionally, in a biochemical assay DNA and protein content were quantified. A concentration-dependent decrease was noted in embryonic growth, morphological development and survival. Additionally, abnormal maxillary processes were significantly increased at the two highest doses, whereas protein and DNA per embryo were significantly lower for the two highest doses. The authors conclude that the rodent embryo culture is not a suitable test system for the evaluation of substances concerning their teratogenic potential, because at the time of publication no data was available that indicated that the test material was associated to embryotoxicity.

In a study by Kameoka et al. (2013), the teratogenic potential of Ibuprofen was determined in a model that uses human pluripotent stem cells by assessing the effect on transcription factor SOX17. Cells were exposed for 72 hours to a maximum of 200 µM test substance. The test outcome was negative as the IC50 value for SOX17 was >200 µM.

Human

An evaluation of all human data regarding developmental toxicity was presented by Burdan (2012). Exposure to the test substance was not associated with cryptorchidism. The test material is classified as Risk Factor Category B: either animal-reproduction studies have not demonstrated a fetal risk but there are no controlled studies in pregnant women, or animal-reproduction studies have shown an adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the first trimester (and there is no evidence of a risk in later trimesters). Major congenital malformations were revealed in offspring delivered by mothers treated with the test material (4.5%). Furthermore, in incidence of cardiac defects was established for the test substance, although this increase was not significant (OR: 1.08, 95% CI: 0.78–1.50). A higher risk of gastroschisis was observed for this compound (OR: 4.0, 95% CI: 1.0–16.0), although study results referred to were highly dependent on maternal age and smoking.

Conclusion

In conclusion, 5 studies assessed possible developmental effects in rats, 1 study in rabbits, 1 study in zebrafish. In addition, 2 in vitro studies and 1 review on human data are available. The rats were exposed orally and overall, covered the gestation period of days 8 – 21, up to lactation day 7. No developmental effects were noted in any of the studies performed in rats. Also no effect were observed in the study with rabbits. The zebra fish and in vitro studies showed mixed results. However, the validity of these models is difficult to assess especially as no information is available on the mode of action. Furthermore, the human data only indicate that ibuprofen might affect development, but the amount of information is limited and the results are not convincing (not statistical significant or not taken all confounding factors into account). Overall it can be concluded that there are no mammalian studies indicating that ibuprofen may be a developmental toxicant.

Justification for classification or non-classification

The available studies are all of limited reliability, but the available studies do not indicate that a classification for reprotoxicity is warranted in accordance with EU Classification, Labeling and Packaging of Substances and Mixtures (CLP) Regulation No. 1272/2008.