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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
sub-chronic toxicity: oral
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Published study, meets generally accepted scientific standards and is described in sufficient detail. L-lactide is the enantiomer of D-lactide and therefore suitable as read-across partner.

Data source

Reference
Reference Type:
publication
Title:
Toxicity of lactide in dogs after 2 and 13 weeks of daily oral dosing
Author:
Hebert, C.D., Giles, H.D., Heath, J.E., Hogan, D.B., Modderman, J.P. & Conn, R.E.
Year:
1999
Bibliographic source:
Food and Chemical Toxicology, 37. pp. 335-342

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 409 (Repeated Dose 90-Day Oral Toxicity in Non-Rodents)
Deviations:
not specified
Principles of method if other than guideline:
Doses for the 13-wk study were selected based on the results of a 2-week study. In the 13-wk study, four dogs per sex were assigned to each of four treatment groups (dosed with lactide at 0, 4, 20 and 100 mg/kg body weight/day). Each dog received daily oral doses of one to six gelatin capsules containing lactide. Doses were administered at approximately 1 hr after feed was withdrawn, and at approximately the same time each day for 13 weeks. Control dogs received the same number of empty capsules as dogs of the corresponding sex in the highest dose group. Doses were calculated based on the body weight of each dog during the previous week.
GLP compliance:
not specified
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): lactide; 18:1 mixture of L-lactide (CAS no. 4511-42-6): m-lactide (CAS no. 13076-19-2)
- Lactide was manufactured and provided by Cargill, Inc USA
- bulk chemical stored at -20 °C

For dose administration:
- removal from -20 °C, 2 hours to reach ambient temperature
- lactide was loaded into 0.5 oz gelatin capsules
- each capsules contained between 0.1 g and 4 g of lactide
- no filling material was used to fill those capsules that contained less than 4g of chemical
- Capsules were prepared weekly, were stored on capsule boards, refrigerated in plastic bags containing desiccant
--> a prior stability study indicated that lactide was stable for at least 14 days when stored under these conditions
- Capsules were removed from refrigerator and allowed 2 hours to reach ambient temperature before dose administration

Test animals

Species:
dog
Strain:
Beagle
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Sprague Dawley, Inc ( Madison, WI, USA)
- Age at study initiation: ranged from 5 to 10 months
- Fasting period before study: 1 hour before dosing
- Housing: individual housed in stainless-stell cages on racks and were exercised at least twice weekly throughout the quarantine and study period
- Diet (e.g. ad libitum): dogs were fed Certified Canine Chow 5007 (PMI Feeds, Inc) for approximately 2 hours each day
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 26°C
- Humidity (%): 35 - 85%
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: capsule
Vehicle:
unchanged (no vehicle)
Details on oral exposure:
Each dog received daily oral doses of one to six gelatin capsules containing lactide. Doses were administered at approximately 1 h after feed was withdrawn, and at approximately the same time each day for 13 weeks.
Control dogs received the same number of empty capsules as dogs of the corresponding sex in the highest dose group. Doses were calculated based on the body weight of each dog during the previous week.
Analytical verification of doses or concentrations:
not specified
Duration of treatment / exposure:
13 weeks
Frequency of treatment:
SIngle daily dose
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 4, 20, 100 mg/kg bw/d for 13 weeks.
Basis:
actual ingested
No. of animals per sex per dose:
4
Control animals:
yes, concurrent vehicle

Examinations

Observations and examinations performed and frequency:
Observations:
- Dogs were observed twice daily for mortality or moribundity.
- Cageside observations were performed daily, approximately 1 h after dosing.
- Once a week, each dog was removed from its cage and examined closely for detailed clinical signs of toxicity.
- Throughout each study:
dogs were weighed weekly, and food consumption was measured once a week over a 2-hour period.

Clinical pathology:
- blood and urine samples were obtained from each dog for clinical pathology and urinalysis determinations during quarantine, during week 5 and 9, and within 3 days prior to terminal sacrifice

Dogs were fasted overnight prior to blood collection for haematologic, clinical chemistry and coagulation analyses

Haematologic analyses included:
total leucocyte count, erythrocyte count, haemaglobin, haematocrit, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, platelet count and differential leucocyte count. Reticulocyte counts and red blood cell morphology were evaluated.

Clinical chemistry analysis included:
By using a Roche Cobas Fara clinical chemistry analyser: blood urea nitrogen, creatinine, serum glucose, serum aspartate aminotransferase, serum alanine aminotransferase, alkaline phosphatase, glutamyl transferase, sodium, potassium, chloride, calcium, inorganic phosphate, total protein, albumin, albumin/total protein ratio, total bilirubin and cholesterol.

Coagulation analyses included:
Prothrombin time and activated partial prothrombin time, fibrinogen

Urine analyses included:
Urine specific gravity, urine microscopic sediment, urine pH, ketones, protein, glucose, bilirubin and occult blood
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
Statistics:
- Groups means and standard deviations for: body weights, food consumption, clinical pathology parameters, for terminal body weights and for absolute and relative organ weights
- Body weights, food consumption and clinical pathology parameters were evaluated by two-way repeated ANOVA, and if significant by Dunnett's test
- Mean body weights, mean organ weights and organ/body, organ:brain ratios for each treated group were compared to those of the control group by a two-tailed Student's t-test for each sex

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Emesis once in each of two female dogs (one in the 0 mg/kg and one in the 100 mg/kg group during week 9). Bloody diarrhoea was seen once during week 6 in one female dog of the 100 mg/kg group
Mortality:
mortality observed, treatment-related
Description (incidence):
Emesis once in each of two female dogs (one in the 0 mg/kg and one in the 100 mg/kg group during week 9). Bloody diarrhoea was seen once during week 6 in one female dog of the 100 mg/kg group
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not specified
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
stomach foci in one male/female from the 100 mg/kg , and one female from the 4mg/kg dose group
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
moderately severe ulceration of the stomach mucosa seen in one female dog of the high dose group
Histopathological findings: neoplastic:
no effects observed

Effect levels

open allclose all
Dose descriptor:
NOAEL
Remarks:
(systemic)
Effect level:
100 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Dose descriptor:
LOAEL
Remarks:
(local)
Effect level:
100 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: gastrointestinal irritation
Dose descriptor:
NOAEL
Remarks:
(local)
Effect level:
20 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

Table 1: Incidence of gross lesions in dogs treated for 13 weeks with oral doses of lactide
             
Dose group 0 mg/kg 4 mg/kg 20 mg/kg 100 mg/kg
Males
Stomach focus 0 0 0 1
 
Females
Stomach focus 0 1 0 1

Incidence= number of dogs in a given dose group with a given lesion. n=4 for all dose groups

Applicant's summary and conclusion

Conclusions:
Lactide acts primarily, if not only, as an irritant after oral administration. 13 week NOAEL is 100 mg/kg bw/d.
Executive summary:

In a subchronic toxicity study lactide (18:1 mixture of l-lactide and m-lactide) was administered to 4 beagle dogs/sex/dose by capsule at dose levels of 4, 20, 100 mg/kg bw/day for 13 weeks.

The only apparent toxic effect at 100 mg/kg/day was gastrointestinal irritation. Therefore, the local LOAEL is 100 mg/kg/d. No systemic effects were reported at 100 mg/kg/d. Thus, the systemic NOAEL for orally administered lactide under the conditions in this study was considered to be 100 mg/kg/day.

This subchronic study in dog is acceptable and satisfies the principle requirement for a subchronic oral study similar to OECD 409 in dog.