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Developmental toxicity / teratogenicity

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developmental toxicity
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Comparable to guideline study with acceptable restrictions using medium chain triglycerides. Parenteral route of application, only two dose levels, number of corpora lutea not reported. Information is used in a read-across approach. For justification of read-across and for further details please refer to the read-across report.
Reason / purpose for cross-reference:
reference to same study

Data source

Reference Type:

Materials and methods

Test guideline
equivalent or similar to guideline
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
parenteral route of application, only two dose levels, only two dose levels, number of corpora lutea not reported
Principles of method if other than guideline:
In this study, we evaluate the developmental toxicity of a 20% lipid emulsion that contains a 3:1 ratio of medium chain triglyceride (MCT) to one long chain containing lipid emulsion (LCT).
GLP compliance:
not specified
Limit test:

Test material

Constituent 1
Reference substance name:
Medium Chain Triglycerides (MCT)
Medium Chain Triglycerides (MCT)
Details on test material:
- Name of test material (as cited in study report): Medium Chain Triglycerides (MCT)
- Physical state: liquid
- Analytical purity: 20% lipid emulsion designed for the use in parenteral nutrition
- Composition of test material, percentage of components: a 20% lipid emulsion containing a 3:1 ratio of MCT:LCT (Long Chain Triglycerides) from soybean oil. Medium chain fatty acids are 6 to 12 carbons in length. The 20% lipid emulsion is composed primarily of 8- and 10- carbon fatty acids and a trace of 6- and 12-carbon fatty acids. The same lot of test article was used throughout the studies, and was analytically determined to be stable for the duration of both studies. Saline (0.9% NaCl for injection, USP) was used as a nonlipid control article.
- Stability under test conditions: analytically determined to be stable for the duration of both studies

Test animals

other: Crl:CD BR rats
Details on test animals or test system and environmental conditions:
- Source: Charles River Laboratories (Portage, MI)
- Weight at study initiation: 150 to 200 g on Gestation Day (GD) 0
- Housing: individually in suspended stainless steel cages
- Diet (e.g. ad libitum): ad libitum except during dose administration
- Water (e.g. ad libitum): ad libitum except during dose administration

Environmental controls in the animal rooms were set to maintain temperature, relative humidity, and light/dark cycle

Administration / exposure

Route of administration:
other: 20% lipid emulsion was created, no further specified
Details on exposure:
The dose was administered daily to rats by intravenous infusion via a caudal vein using a Quik-Cath Teflon catheter connected to a syringe using an extension set. Doses for rats and rabbits were delivered using syringe pumps.
Analytical verification of doses or concentrations:
not specified
Details on mating procedure:
Time-mated Crl:CD BR rats were shipped by the supplier on GD 4.
Duration of treatment / exposure:
GD 6 through 15
Frequency of treatment:
daily, for approximately 4 h/day
A 4-h infusion was used to approximate longer-term infusion in humans and to avoid an acute toxic effect resulting from shorter term infusion at faster rates.
Duration of test:
On GD 20 animals were euthanized
No. of animals per sex per dose:
rats: 25 or 29/group
Control animals:
other: 0.9% saline at a dose volume of 21.4 mL/kg
Details on study design:
- Dose selection rationale: The dose rate was based on previous preclinical studies (unpublished). The 1 g/kg dose approximates the proposed clinical dosage. The 4.28 g/kg dose is the highest dose administered in preclinical studies that did not produce narcosis (unpublished).

- Selection of exposure route: The intravenous route of administration was used because the lipid emulsion is intended for intravenous human administration as a component of parenteral nutrition. The dose was administered daily to rats by intravenous infusion for approximately 4 h/day on GD 6 through 15 via a caudal vein using a Quik-Cath Teflon catheter connected to a syringe using an extension set.

- Dose volumes: 5 and 21.4 mL/kg bw


Maternal examinations:
- Time schedule: Animals were observed twice daily (AM and PM) for mortality and moribundity. On dosing days, animals were observed predose, immediately (within 5 min) postdose, and approximately 1 h after completion of dosing.

- Time schedule for examinations: daily on GD 5 through 20

- Time schedule for examinations: Food consumption data were collected daily beginning on the day of receipt

- Sacrifice on gestation day GD 20

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: half litter; live fetuses were weighed, examined externally, sexed, then euthanatized
- Soft tissue examinations: half litter; Following completion of fetal examinations, soft tissue malformations were preserved in 10% phosphate-buffered formalin
- Skeletal examinations: half litter; Viscera were removed and discarded, and fetuses were processed and examined for skeletal variations and malformations; skeletal specimens were retained in glycerine
- Head examinations: half litter; A mid-coronal slice of the head was made to expose the internal structure of the brain for examination; the eyes were excised and examined.
The litter was the experimental unit for evaluation. All comparisons were made with the control group (Group 1). For rats, feed consumption, dam body weights, and fetal body weights were summarized wim means and standard deviations calculated using an Excel spreadsheet program (Microsoft Corporation). For rabbit data, Levene's test (Levene, 1960) was done to test for variance homogeneity. In the case of heterogeneity of variance at p « 0.05, rank transformation was used to stabilize the variance. Analysis of variance [ANOVA (Winer, 1971a)] was done on the homogeneous or transformed data. If the ANOVA was significant, Dunnett's t test (Dunnett, 1964) was used for pairwise comparisons between groups. One-way ANOVA was used to analyze body weights, body weight changes, feed consumption, and cesarcan section data. As appropriate, rat and rabbit fetal abnormality data were analyzed by the Cochran-Armitage test (Thalcur et al, 1985) for trend and departure and by the Fisher-Irwin exact test (Thalcur et al., 1985). One-way analysis of covariance [ANCOVA (Winer, 1971b)] was used to analyze fetal body weights (males, females, and combined) with the number of fetuses in the litter as the covariate. As appropriate, for values calculated to analyze litter data or mean fetal weight data, values were first derived within the litter, and the group mean values were derived as a mean of individual litter values. Group comparisons were analyzed at the 5.0 and 1.0% two-tailed probability levels.
early and late resorptions, % fetuses dead/live, % postimplantation loss

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:yes. Remark: effects in the highest dose group

Details on maternal toxic effects:
The only test article-related findings observed were associated with tail lesions in both test article groups and the occasional occurrence of red tinged urine (8 of 29) and vaginal bleeding (1 of 29) in the high-dose group. The tail findings were predominantly those of discoloration and ulceration. Incidences were 1/25, 14/25, and 23/29 for these tail lesions in the control, low-, and high-dose groups, respectively, and ranged from mild to severe with some necrosis and partial loss of the tail.
These findings were generally considered to be related to occurrences of observed extravasation of the MCT:LCT lipid test article into perivascular areas. Evaluation of urine collected from one high-dose animal suggested a bacterial infection of the urogenital tract. Clinical observations for this animal included occasional red-tinged urine and vaginal bleeding. This rat was noted as having a large urinary bladder stone and kidney hydronephrosis at necropsy.
There were no marked differences in mean body weights or feed consumption for the low-dose group compared with those of the control group. However, the high-dose group consistently exhibited lower body weights beginning 1 day after dose administration throughout the remainder of the study. Feed consumption was also notably lower for nine of the ten days during dosing, with an increase in feed consumption after completion of dose administration (GD 15). The decrease in feed consumption at the high-dose level was expected based on the high-caloric nature of the test article.
Necropsy findings were primarily related to tail effects and were observed for most rats in the high-dose group and some rats in the low-dose group. In addition to tail effects, there was a trend toward an increasing incidence of necropsy findings in the high-dose group, including enlarged lymph nodes, enlarged spleen, hydronephrosis/enlarged renal pelvis, small thymus, and small red lung foci. These changes indicated that the high-dose group was likely exhibiting test article effects.
There was a slight trend toward decreasing mean gravid uterine weights in proportion to increasing test article dose; however, due to the large variability between groups, group mean uterine weights appeared to be similar. With the exception of one control dam, all females were pregnant and had at least one viable fetus/litter (i.e., no dams had total resorptions).

Effect levels (maternal animals)

open allclose all
Dose descriptor:
Effect level:
4 280 mg/kg bw/day
Based on:
test mat.
(i.v. application)
Basis for effect level:
other: developmental toxicity
Dose descriptor:
Effect level:
1 000 mg/kg bw/day
Based on:
test mat.
(i.v. application)
Basis for effect level:
other: maternal toxicity

Results (fetuses)

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

Details on embryotoxic / teratogenic effects:
There were no significant group differences in preimplantation or postimplantation loss or in the mean percentage of live or resorbed fetuses; no dead fetuses were present. Mean fetal sex ratios of the test article-treated groups were comparable with those of controls. There were no apparent effects on mean fetal body weight (combined, males, or females). There were no test article-related fetal external, soft tissue, or skeletal observations.
A high incidence of folded retina in control and test article-treated groups was attributed to shrinkage of the retina during storage in alcohol prior to being transferred to Bouin's fixative.
Omphalocele and cleft palate were observed in one fetus each in the control and high-dose groups, respectively. The only fetal skeletal malformation observed (malformed/misshapen skull bones) was present in one fetus each from two control litters. Fetal skeletal variations were present in control and test article-treated groups in a nondose-related pattern.

Effect levels (fetuses)

Dose descriptor:
Effect level:
4 280 mg/kg bw/day
Based on:
test mat.
i.v application
Basis for effect level:
other: Developmental toxicity

Fetal abnormalities

not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Applicant's summary and conclusion

Upon intravenous infusion of 4280 mg/kg bw/d during gestational days 6-15, medium chain triglycerides exerted no teratogenic effects in rats.
Executive summary:

In a developmental toxicity study medium chain triglycerides (MCT) was administered to 25 or 29 Crl:CD BR rats/dose by intravenous infusion at dose levels of 1000, and 4280 mg/kg bw/day from days 6 through 15 of gestation.

The maternal LOAEL is 4280 mg/kg bw/day, based on an increasing incidence of necropsy findings, including enlarged lymph nodes, enlarged spleen, hydronephrosis/enlarged renal pelvis, small thymus, and small red lung foci. The maternal NOAEL is 1000 mg/kg bw/day.

No adverse effects related to prenatal development have been reported. The developmental NOAEL is 4280 mg/kg bw/day.

The developmental toxicity study in the rat is classified acceptable and satisfies the main guideline requirement for a developmental toxicity study (OECD 414) in rat.