(1R,2S,5S)-6,6-dimethyl-3-[3-methyl-N-(trifluoroacetyl)-L-valyl]-3-azabicyclo[3.1.0]hexane-2-carboxylic acid

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

9th September 2021 - 26th October 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2021

Report date:

2021

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 423 (Acute Oral toxicity - Acute Toxic Class Method)

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: EC No 440/2008, part B: "Acute Oral Toxicity, Acute Toxic Class Method".

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1100 (Acute Oral Toxicity)

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: JMAFF Guidelines (2000), including the most recent revisions.

GLP compliance:

yes

Test type:

acute toxic class method

Test material

Test material information

Constituent 1

Reference substance name:

(1R,2S,5S)-6,6-dimethyl-3-[3-methyl-N-(trifluoroacetyl)-L-valyl]-3-azabicyclo[3.1.0]hexane-2-carboxylic acid

EC Number:

955-024-2

Cas Number:

2755812-45-2

Molecular formula:

C16 H23 F3 N2 O4

IUPAC Name:

(1R,2S,5S)-6,6-dimethyl-3-[3-methyl-N-(trifluoroacetyl)-L-valyl]-3-azabicyclo[3.1.0]hexane-2-carboxylic acid

Test material form:

solid

Test animals

Species:

rat

Strain:

Wistar

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany
- Females nulliparous and non-pregnant: yes
- Age at study initiation: Young adult animals (approximately 09-12 weeks old)
- Weight at study initiation: 170 to 208 g.
- Fasting: Animals were deprived of food overnight (for a maximum of 20 hours) prior to dosing and until 3-4 hours after administration of the test item.
- Housing:
On arrival and following assignment to the study, animals were group housed (up to 3 animals of the same sex and same dosing group together) in polycarbonate cages, height 18 cm, containing sterilized wooden fibers as bedding material, equipped with water bottles. The room in which the animals were kept were documented in the study records.
Animals were separated during designated procedures/activities. Each cage was clearly labeled.
- Diet: Pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiaten GmbH, Soest, Germany) was provided ad libitum throughout the study, except during designated procedures.
- Water: Municipal tap-water was freely available to each animal via water bottles.
- Acclimation period: The animals were allowed to acclimate to the Test Facility toxicology accommodation for at least 5 days before the commencement of dosing.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 to 21°C
- Humidity (%): 39 to 79%.
- Air changes (per hr): Ten or greater air changes per hour with 100% fresh air (no air recirculation) were maintained in the animal rooms.
- Photoperiod (hrs dark / hrs light): A 12-hour light/12-hour dark cycle was maintained.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

propylene glycol

Details on oral exposure:

A single dose of test item was administered to the appropriate animals by oral gavage on Day 1, using a syringe with a plastic gavage cannula attached.
The dose volume for each animal was based on the body weight measurement prior to dosing.
A dose volume of 10 mL/kg body weight was used for each dose.
The dosing formulations were stirred continuously during dose administration.
Animals were deprived of food overnight (for a maximum of 20 hours) prior to dosing and until 3-4 hours after administration of the test item. Water was available.

Doses:

The first group was treated at a dose level of 300 mg/kg. Based on the results, two additional groups were dosed at 2000 mg/kg.

No. of animals per sex per dose:

3 females

Details on study design:

Throughout the study, animals were observed for general health/mortality and moribundity twice daily, in the morning and at the end of the working day. Animals were not removed from their cages during observation, unless necessary for identification or confirmation of possible findings.
Post-dose observations were performed at periodic intervals on the day of dosing (at least three times) and once daily thereafter. The observation period was 14 days.
All the animals were examined for reaction to dosing. The onset, intensity and duration of these signs was recorded (if appropriate), particular attention being paid to the animals for the first hour after dosing.
Animals were weighed individually on Day | (pre-dose), 8 and 15. A fasted weight was recorded on the day of dosing.
All animals were sacrificed by oxygen/carbon dioxide procedure at the end of the observation period. All animals assigned to the study were subjected to necropsy and descriptions of all internal macroscopic abnormalities were recorded.

Statistics:

The oral LD50 value of the test item was ranked within the following ranges: 0-5, 5-50, 50-300 or 300-2000 mg/kg b.w. or as exceeding 2000 mg/kg b.w. The LD50 cut-off value was established based on OECD guideline 423. No statistical analysis was performed (The method used is not intended to allow the calculation of a precise LD50 value).

Results and discussion

Effect levels

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Remarks on result:

not determinable due to absence of adverse toxic effects

Mortality:

No mortality occurred.

Clinical signs:

other: At 300 mg/kg, hunched posture and erected fur was noted for all animals on Day 1. In addition, one animal showed slight uncoordinated movements on Day 1. At 2000 mg/kg, hunched posture was noted for all animals on Day 1 and/or Day 2. In addition, three an

Gross pathology:

No test item related abnormalities were found at macroscopic postmortem examination of the animals.
Incidental findings included discoloration of the thymus and dark foci on the clitoral gland, these findings are more often seen in rats of this strain in this kind of studies and therefore no toxicological relevance was attached to these findings.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The oral LD50 value of PF-07320267 in Wistar Han rats was established to exceed 2000 mg/kg body weight.
According to the OECD 423 test guideline, the LD50 cut-off value was considered to exceed 5000 mg/kg body weight.
Based on these results, PF-07320267 does not have to be classified and has no obligatory labelling requirement for acute oral toxicity according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2017) (including all amendments) and Regulation (EC) No 1272/2008 on classification, labelling and packaging of items and mixtures (including all amendments).

Executive summary:

The objective of this study was to assess the toxicity of the test item when administered in a single dose to female rats at one or more defined dosages. Furthermore, the results of the study allowed the test item to be ranked according to most classification systems, currently in use. This study should provide a rational basis for risk assessment in man.
The study was carried out in compliance with the guidelines described in:
OECD No.423 (2001) "Acute Oral Toxicity, Acute Toxic Class Method".
EC No 440/2008, part B: "Acute Oral Toxicity, Acute Toxic Class Method".
EPA, OPPTS 870.1100 (2002), "Acute Oral Toxicity".
JMAFF Guidelines (2000), including the most recent revisions.
Initially, PF-07320267 was administered by oral gavage to three female Wistar Han rats at 300 mg/kg body weight. In a stepwise procedure two additional groups of three females were dosed at 2000 mg/kg body weight. All animals were subjected to daily observations and weekly determination of body weight. Macroscopic examination was performed after terminal sacrifice (Day 15). 

No mortality occurred.
At 300 mg/kg hunched posture and erected fur was noted for all animals on Day 1. In addition, one animal showed slight uncoordinated movements on Day 1. At 2000 mg/kg hunched posture was noted for all animals on Day 1 and/or Day 2. In addition, three animals showed slight salivation, erected fur and slight uncoordinated movements on Day 1.
The body weight gain shown by the animals over the study period was considered to be similar to that expected for normal untreated animals of the same age and strain.
No test item related abnormalities were found at macroscopic postmortem examination of the animals.
The oral LD₅₀ value of PF-07320267 in Wistar Han rats was established to exceed 2000 mg/kg body weight.
According to the OECD 423 test guideline, the LD₅₀ cut-off value was considered to exceed 5000 mg/kg body weight.
Based on these results, PF-07320267 does not have to be classified and has no obligatory labelling requirement for acute oral toxicity according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2017) (including all amendments) and Regulation (EC) No 1272/2008 on classification, labelling and packaging of items and mixtures (including all amendments).