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Toxicological information

Developmental toxicity / teratogenicity

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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:
2006
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study with a read-across substance, without deviations from the adopted test guideline (US FDA, 1994).

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
2006

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
other: US FDA (Food and Drug Administration). 1994. International Conference on Harmonization; Guideline on Detection of Toxicity to Reproduction for Medicinal Products. Federal Register 59.
Deviations:
no
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
dose volume of corn oil was 10 mL/kg versus the recommended 4 mL/kg
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: Liquid
Details on test material:
- Name of test material (as cited in study report): α-Methyl-3,4-methylene-dioxyhydrocinnamic aldehyde
- Physical state: Colourless to pale yellow liquid
- Analytical purity: 98.2%
- Lot/batch No.: 413118

Test animals

Species:
rat
Strain:
other: Crl:CD (SD) IGS BR VAF/Plus
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Raleigh, North Carolina
- Weight on the day after arrival: 262 to 356 g (M) and 188 to 224 g (F)
- Fasting period before study: None
- Housing: Cage sizes and housing conditions were in compliance with the Guide for the Care and Use of Laboratory Animals (Institute of Laboratory Animal Resources 1996).
- Diet (e.g. ad libitum): Certified Rodent Diet no. 5002; ad libitum
- Water (e.g. ad libitum): Reverse osmosis deionized water; ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18-26°C (64 to 79°F)
- Humidity (%): 30 to 70%
- Air changes (per hr): At least 10 per hour
- Photoperiod (hrs dark / hrs light): 12 hours dark/12 hours light

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: Dosing formulations were prepared weekly. The dosage volume was 10 mL/kg, adjusted daily according to individual body weights recorded directly before gavage and administered at approximately the same time each day.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Samples from each concentration of the dosing solutions were evaluated on the first and last treatment days. Results from the analysis of dosage preparations verified that actual dosages reflected the calculated dosages ± 10%. Results of 10-day stability testing were also within the acceptable range of ± 10%.
Details on mating procedure:
- Impregnation procedure: co-housed
- M/F ratio per cage: 1:1
- Proof of pregnancy: sperm found in vaginal smear or copulatory plug in the vagina referred to as day 0 of gestation
Duration of treatment / exposure:
Once/day from gestation days (GDs) 7 through 17.
Frequency of treatment:
Once/day
Duration of test:
Dosing period: From GD 7 to 17.
Sacrifice: GD 21.
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 62, 125, or 250 mg/kg body weight/day
Basis:
actual ingested
No. of animals per sex per dose:
25 Females/group
Control animals:
yes, concurrent vehicle

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Before dose administration and 1 hour post-dose administration

BODY WEIGHT: Yes
- Time schedule for examinations: Prior to the start of the study and daily during the dosage and post-dosage periods.

FOOD CONSUMPTION: Yes
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No. Data reported as g/day.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on GD 21
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Not reported
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: Additional examinations included number of live and dead foetuses.
Fetal examinations:
- External examinations: Yes: [all per litter]
- Soft tissue examinations: Yes: [half per litter]
- Skeletal examinations: Yes: [half per litter]
Statistics:
Dunnett’s test (Dunnett, 1955) was used to identify statistical significance of differences among individual groups. If the analysis of variance was not appropriate, the Kruskal-Wallis test (Sokal and Rohlf, 1969) or Dunn’s method of multiple comparisons (Dunn, 1964) was used to identify the statistical significance of differences among the individual groups. If there were greater than 75% ties, Fisher’s exact test (Siegel 1956) was used to analyze the data.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
No mortality occurred during the study.

The only clinical signs related to MMDHCA included significantly increased (p ≤ 0.01) incidences of a clear, red or yellow perioral substance and/or red perivaginal substance in the 250 mg/kg/day dose group. Excess salivation occurred in all dosage groups, but was most common at 250 mg/kg/day.

Feed consumption and body weight gains were reduced at 250 mg/kg/day. Compared to controls, mean absolute (g/day) and relative (g/kg/day) feed consumption were significantly reduced (p ≤ 0.01) at 250 mg/kg/day for the entire dosage period, whereas at 125 mg/kg/day a significant reduction was only noted on GD10 to 12. For the entire dosage period, absolute feed consumption at 62, 125, and 250 mg/kg/day was 97.9%, 96.8%, and 88.4% of the control value, respectively. In parallel with feed consumption, body weight gains were significantly reduced (p ≤ 0.01) at 250 mg/kg/day on GD7 to 10 whereas, for the entire dosage period, body weight gain at 62, 125, and 250 mg/kg/day was 100.8%, 102.5%, and 92.4% of the control value, respectively.

Pregnancy occurred in 21 (84.0%), 25 (100.0%), 24 (96.0%), and 23 (92.0%) rats in the four respective dosage groups.

No Caesarean sectioning or litter parameters were affected by dosages of MMDHCA as high as 250 mg/kg/day.

The litter averages for corpora lutea, implantations, early and late resorptions, and percentage of dead or resorbed conceptuses were comparable among the four dosage groups. No significant differences were observed, and all values were within the ranges observed historically. All placentae appeared normal.

Effect levels (maternal animals)

Dose descriptor:
NOAEL
Effect level:
125 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
The litter averages for litter sizes, live foetuses, foetal body weights, and percentage of live male foetuses were comparable among the four dosage groups. No significant differences were observed, and all values were within the ranges observed historically.

In the 0, 62, 125, or 250 mg/kg/day dosage groups, litters containing foetuses with alterations numbered 5 (23.8%), 7 (28.0%), 3 (13.0%), and 5 (21.7%), respectively. The numbers of foetuses with any alteration observed were 6 (2.0%), 9 (2.6%), 3 (0.9%), and 5 (1.6%) and the percentages of foetuses with any alteration per litter were 2.2, 2.7, 0.9, and 1.8 in the respective dosage groups.

There were no foetal gross external alterations.

Foetal soft tissue alterations included: an irregularly shaped brain in one 62 mg/kg/day foetus, and folded retinas, a variation usually associated with tissue processing, in 0, 2, 1, and 2 foetuses in 0, 2, 1, and 2 litters in the four respective dosage groups. There were no additional alterations in these foetuses. There was only one skeletal malformation: a foetus in the 62 mg/kg/day dosage group had fusion of one or more ribs (right, 7th and 8th ribs medially to distally, and 9th and 10th distally), as well as skeletal variations in skull bones, ribs, and sternum.

All foetuses appeared normal at external examination and all soft tissue or skeletal alterations (malformations or variations) in the foetuses were considered unrelated to MMDHCA.

Effect levels (fetuses)

Dose descriptor:
NOAEL
Effect level:
> 250 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
not specified
Basis for effect level:
other: developmental toxicity

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
The NOAELs for maternal and developmental toxicity of MMDHCA were reported to be 125 and >250 mg/kg/day, respectively. Thus, MMDHCA was not a developmental toxicant under the conditions of the study.
Executive summary:

Justification for Read-Across

 

As summarized in the attached document and more briefly below, piperonal and MMDHCA are structurally similar, have similar physicochemical properties, are expected to have similar pharmacokinetic profiles, and have comparable toxicological profiles.

 

Piperonal and MMDHCA are considered to be structurally similar as each possess an identical benzodioxole parent structure, with a single aldehyde-functional group attached to its 5-position. Piperonal and MMDHCA are both small substances with low lipophilicity and high water solubility, and are not expected to accumulate in adipose tissues. Based on experimental and/or physicochemical data, both substances are expected to have similar toxicokinetic profiles and be excreted primarilyviathe kidneys.

 

Piperonal and MMDHCA are of low acute toxicity by both the oral and dermal routes. Both substances have no or limited evidence of skin irritation, are associated with no significant eye irritation and are considered moderate skin sensitizers based on ECHA criteria. The genetic toxicity profiles of Piperonal and MMDHCA are similar, with both substances demonstrating negative effects in in vivo studies. With regard to reproductive toxicity, cumulative results from three non-guideline studies provide evidence that Piperonal does not affect fertility in male mice and rats or in female rats. These studies include a dominant lethal assay in mice (oral gavage), a repeated dose toxicity study in rats (dietary), and a reproductive and developmental toxicity screening study in female rats (oral gavage), all of which utilized the oral route of administration. For MMDHCA, no effects were observed on male rat sperm motility, gross pathology, or histopathology following 14 days of oral dosing with MMDHCA.

 

Given these similarities, it is considered appropriate and scientifically justifiable to use the available developmental toxicity data for MMDHCA to address this endpoint for piperonal.

 

Summary of the Developmental Toxicity Study for MMDHCA

 

The developmental toxicity of MMDHCA was evaluated in a GLP-compliant study in rats that was conducted in a manner equivalent to OECD guideline 414. Pregnant Sprague-Dawley rats (25/group) were administered MMDHCA at oral gavage doses of 0 (vehicle), 62, 125, or 250 mg/kg body weight/day on GD 7 through 17. Rats were observed for viability, clinical signs, body weights, and feed consumption. Necropsy and Caesarean sectioning occurred on GD 21. Uteri were examined for number and distribution of implantations, live and dead foetuses, and early and late resorptions. Numbers of corpora lutea also were recorded. Foetuses were weighed and examined for sex, gross external changes, and soft tissue or skeletal alterations. Analysis of dosage preparations verified calculated dosages ±10%. No deaths occurred. Excessive salivation occurred in all groups, but the incidence was increased at 250 mg/kg body weight/day. The 250 mg/kg body weight /day dose level also was associated with a significant increase in the incidences of a clear, red or yellow perioral and/or red perivaginal substance and significant reductions in mean feed consumption and body weight gains (11.6% and 7.4%, respectively) during the entire dosage period. No gross changes attributable to MMDHCA were observed at necropsy. Caesarean section or litter parameters, as well as foetal alterations, were not affected by MMDHCA at any dose level. Based on these data, maternal and developmental NOAELs of 125 and>250 mg/kg/day (the highest dose level evaluated), respectively, were established for MMDHCA. It is concluded that MMDHCA was not a developmental toxicant in rats under the conditions of this study.