Methyl salicylate

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

no data are available

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: No GLP stated, purity unknown but this recent study is performed in an ICH guideline (CPMP/ICH/386/95) which requires compliance with GLP or equivalent standard.

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

publication

Title:

Comparison of developmental toxicology of Aspirin in rabbits when administered throughout organogenesis or during sensitive windows of development

Author:

Cappon GD, Gupta U, Cook JC et al

Year:

2003

Bibliographic source:

Birth Defects Research (part B) 68:38-46

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: ICH Topic S 5(R2)

Principles of method if other than guideline:

ASA was administered to pregnant New Zealand rabbits from gestation days GDs 7 to 19 (comparable to guideline 414) and as single high doses on GD 9, 10 or 11. Cesarean sections were performed on GD29, and the fetuses were examined for external, visceral, and skeletal development.

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

O-acetylsalicylic acid

EC Number:

200-064-1

EC Name:

O-acetylsalicylic acid

Cas Number:

50-78-2

Molecular formula:

C9H8O4

IUPAC Name:

2-acetoxybenzoic acid

Constituent 2

Reference substance name:

Aspirin

IUPAC Name:

Aspirin

Details on test material:

- Name of test material: Acetylsalicylic acid (ASA)
- Molecular formula: no data
- Molecular weight: no data
- Substance type: no data
- Physical state: no data
- Analytical purity: no data
- Impurities (identity and concentrations): no data
- Composition of test material, percentage of components: no data
- Isomers composition: no data
- Purity test date: no data
- Lot/batch No.: no data
- Expiration date of the lot/batch: no data
- Stability under test conditions: no data
- Storage condition of test material: no data
- Source: Sigma-Aldrich, Inc. ST. Louis, MO

Test animals

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Covance Research Products, Inc (Denver, CO)
- Age at study initiation: 5 to 6.5 months
- Weight at study initiation: 2.8 kg
- Fasting period before study: 1 day
- Housing: rabbits were housed in stainless steel suspended wire cages.
- Diet: Purina Regular Rabbit Chow (Ralston, VA)
- Water: ad libitum
- Acclimation period: no data


ENVIRONMENTAL CONDITIONS
- Temperature (°C ): no data
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12 hrs dark /12 hrs light


IN-LIFE DATES: no data

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: methylcellulose

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
no data

DIET PREPARATION
no data

VEHICLE
- Justification for use and choice of vehicle: no data
- Amount of vehicle (if gavage): 0.5%
- Purity: no data
- Source: Dow Chemical Co., Midland, MI

Analytical verification of doses or concentrations:

no

Details on analytical verification of doses or concentrations:

none

Details on mating procedure:

no data are available

Duration of treatment / exposure:

For the multiple study: from GD7 to GD19
For the single study: individual days, DG9, 10 or 11

Frequency of treatment:

Single daily doses

Duration of test:

around the time of gestation (29 days)

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
For the multiple study: 125, 250 or 350 mg/kg bw/day (96, 192, 268 mg/kg as SA)
Basis:
nominal conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
For the single study: 500, 750 and 1000 mg/kg
Basis:
nominal conc.

No. of animals per sex per dose:

For the multiple study: 20
For the single study: 10

Control animals:

yes, concurrent no treatment

Details on study design:

- Dose selection rationale:

For the multiple study: dose levels were based on findings from a dose range-finding study in pregnant rabbits. MTD = 350 mg/kg per day (3/20 animals died as result of treatment) for this dosing duration (13 days) in pregnant rabbits.

For the single study: ASA was administered to rabbits at higher dose > MTD = 350 mg/kg per day (during sensitive periods of cardiovascular development and midline closure)

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: all animals were observed at least twice daily for morbidity and mortality during the study.

DETAILED CLINICAL OBSERVATIONS: No

BODY WEIGHT: Yes
- Time schedule for examinations: it was determined on the day of arrival and then daily beginning on GD8.


FOOD CONSUMPTION: Yes
- Time schedule for examinations: it was determined on the day of arrival and then daily beginning on GD8.
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 29
- Organs examined: the abdominal, thoracic and pelvic viscera , Uterus and ovaries

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: Yes
- Skeletal examinations: Yes
- Head examinations: No

Statistics:

several types of analyses were used for determining dose-response relations to ASA treatment:
Welch trend test (linear and in proportions) and analysis of covariance.

Indices:

no data are available

Historical control data:

no data are available

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
In the repeated dose study, three does from the 350 mg/kg group died between GD14 and GD16. An additional doe in the 350 mg/kg group aborted on GD22.Necropsy examinations showed evidence of gastrointestinal toxicity(GI) for these does, consisting of dark red foci or pitted areas on the glandular mucosa of the stomach. Maternal body weight gain was significantly reduced in the mid and high dose groups from GD7 to GD13. Food consumption was significantly reduced throught the exposure duration in these groups.
In the single dose study, one doe from the 500 mg/kg group and one from the group 1000 mg/kg group that were dosed on GD10 and two does from the 750 mg/kg group dosed on GD 11 showed signs of GI toxicity. In this study, maternal toxicity was exhibited at all doses by reductions in body weight gain and food consumption for 3 days after treatment.

Effect levels (maternal animals)

1

Dose descriptor:

NOAEL

Effect level:

125 mg/kg bw/day

Basis for effect level:

other: maternal toxicity

2

Dose descriptor:

NOAEL

Effect level:

250 mg/kg bw/day

Basis for effect level:

other: developmental toxicity

3

Dose descriptor:

NOAEL

Effect level:

350 mg/kg bw/day

Basis for effect level:

other: other:

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
In the repeated dose study, fetal body weight was significantly reduced at 350 mg/kg per day.
Fetal body weights were not affected by single doses of ASA on GD9, 10 or 11.
There were no treatment related external, visceral, or skeletal malformations associated with ASA administration throughout organogenesis (GD7 to 19) or single dose administered during critical developmental windows (even from treatment at up to 1000 mg/kg ).

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

250 mg/kg bw/day (nominal)

Basis for effect level:

fetal/pup body weight changes

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Under the test conditions, ASA did not induce malformations in rabbits when it was administered as a single dose or during the period of organogenesis (GD7 to 19), even at doses causing significant maternal toxicity. The NOAELs were identified: NOAEL (maternal): 125 mg/kg bw/day NOAEL (malformations): 350 mg/kg bw/day NOAEL (development): 250 mg/kg bw/day.

Executive summary:

In an ICH-compliant study, Acetylsalicylic acid (ASA) was administered by oral gavage to pregnant New Zealand White rabbits at 125, 250 or 350 mg/kg bw/day (96, 192, 268 mg/kg as Salicylic acid (SA)), followed by termination on GD29 (Cappon and al, 2003). 3 does from the high and one doe from the mid dose died between GD14 and 16 and an additional doe aborted on GD22. Necropsy showed evidence of gastrointestinal toxicity. Maternal body weight gain was significantly reduced in the mid and high dose groups from GD7 to GD13. Food consumption was also reduced in these groups. There were no treatment-related effects on corpora lutea, implantation sites, pre-implantation losses or embryofoetal mortality. Mean foetal weight was significantly reduced in the high dose group. There were no treatment-related visceral or external anomalies. The same study also administered ASA at higher doses on individual days, DG9, 10 or 11.No treatment-related malformations were induced in rabbit fetuses by single dose administrations. The NOAELs were identified: NOAEL (maternal): 125 mg/kg bw/day NOAEL (malformations): 350 mg/kg bw/day NOAEL (development): 250 mg/kg bw/day.