1H-Imidazole-5-methanol, 2-butyl-4-chloro-1-[[2'-(2H-tetrazol-5-yl)[1,1'-biphenyl]-4-yl]methyl]-

Toxicity to reproduction

Administrative data

Endpoint:

two-generation reproductive toxicity

Remarks:

based on test type (migrated information)

Type of information:

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

Adequacy of study:

key study

Study period:

19 February 1990 to 28 July 1990

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Although the study was conducted according to GLP and well documented methods, " Practical guide 10: How to avoid unnecessary testing on animals", Section 3.3.2 states it is important that the reliability indicator (Klimisch score) reflects the assumptions of similarity. Thus, a score of 1 (reliable without restrictions) should normally not be used for results derived from read-across.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1990

Report date:

1991

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

other: see method description below

Principles of method if other than guideline:

The objective of this study was to assess the effects on fertility and reproductive performance, as well as the potential developmental toxicity of the Angiotensin II receptor antagonist L-158,086 when administered to female rats for fifteen days prior to mating, during mating, and during Days 0 to 19 of gestation (c-section animals), or through Day 20 of lactation (natural delivery animals), and to evaluate the effects on growth, development, behavior, reproductive performance and fertility of the F1 generation.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Losartan potassium

IUPAC Name:

Losartan potassium

Constituent 2

Reference substance name:

L-158,086

IUPAC Name:

L-158,086

Details on test material:

- Name of test material (as cited in study report)::L-158, 086

- Physical state:solid
- Analytical purity:99.5% w/w

- Lot/batch No.:L-158, 086-005H010

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source:Charles River Laboratories, Raleigh, NC USA
- Age at study initiation: (P) 11 wks; (F1) 0 wks
- Weight at study initiation: Females: 224-292 g;
- Fasting period before study: not specified.
- Housing:
Females to be cesarean-sectioned were housed singly in wire-mesh metal bottom cages prior to and after mating. By Day 15 of gestation, females which were ot be allowed to deliver were transferred to individual clear plastic boxes containing dry bedding ("Beta-Chip", Northeastern Products Corp., Warrensburg, NY) in preparation for delivery of F1 pups.

- Diet (e.g. ad libitum):Purina Certified Rodent Chow #5002, ad libitum
- Water (e.g. ad libitum):tap water ad libitum
- Acclimation period: not specified

ENVIRONMENTAL CONDITIONS
- Temperature (°C):20 to 27 deg C.
- Humidity (%):
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light):12/12

IN-LIFE DATES: From: To:

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: Solutions of L-158,086 in deionized water were prepared daily and kept constantly stirred during dosing.
DIET PREPARATION: not applicable
Dose was 5 ml/kg at the following concentrations:
0 (control), 25, 100, 300/200 mg/kg/day

Details on mating procedure:

Each female was housed with one untreated male of the same strain for a maximum of 16 days after the females had been dosed for 15 days. A check was made for seminal plugs in the pan and/or vaginal lavage from each female was examined daily for the presence of sperm. The day of finding sperm in the lavage or seminal plug was consdiered Day 0 of gestation. On the 16th day of cohabitation, any remaining females were transferred to individual metal cages.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples of the dosing solutions were collected during dosing weeks 1, 6, and 10 and assayed for concentration. All assay results were within acceptable limits (not less than 90% of desired concentration). The compound has been shown to be stable in this vehicle under the conditions of this study.

Duration of treatment / exposure:

Fifteen days prior to mating, during mating, and through Days 0 to 19 of gestation. Also, females scheduled for parturition were treated on Day 20 of gestation through Day 20 of lactation.

Frequency of treatment:

once daily

Details on study schedule:

.- F1 parental animals not mated until 10-12 weeks after selected from the F1 litters.
- Selection of parents from F1 generation when pups were 23-26 days of age.
- Age at mating of the mated animals in the study:10-12 weeks

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0, control
Basis:
nominal conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
25 mg/kg/day
Basis:
nominal conc.

Doses / concentrations 3

Remarks:

Doses / Concentrations:
100 mg/kg/day
Basis:
nominal conc.

Doses / concentrations 4

Remarks:

Doses / Concentrations:
300/200 mg/kg/day
Basis:
other: due to severe weight decreases in this group during the premating interval, the dose was lowered from 300 to 200 mg/kg/day on the first day of cohabitation.

No. of animals per sex per dose:

40

Control animals:

yes, concurrent vehicle

Examinations

Parental animals: Observations and examinations:

Physical Signs: Females were observed for physical signs once daily from initiation to sacrifice and 1-5 hours postdosing.

Body Weights: Recorded on Days 1, 8, and 15 of the premating period, weekly during mating when required and on Days 0, 6,12,16,18,20,22,24 of gestation and on Days 0, 3,7,10,14,17, and 21 of lactation. Additional weights were taken on Days 22, 29, 36, 43, 51 and 55 of presumed gestation for females that did not deliver or mate.

Food consumption: Measured for all animals during the following intervals: Days 1 to 5 and 8 to 12 of the premating period, Days 1 to 5, 8 to 12, and 15 to 19 of gestation, and Days 1 to 5 and 8 to 12 of lactation.

Sacrifice and Reproductive Status: Nineteen to 20 females per group were selected and killed on Day 20 of gestation by CO2 asphyxiation. Approximately one-half of females from each four-day mating period were selected for cesarean-section and one half for delivery. There was a bias in selection of females to cesarean-section which had the lowest weight gains during the gestation interval and were presumed non-pregnant. This was done to assure that an adequate group size was maintained for delivery and subsequent testing of the F1 generation. The uterus of each female at cesarean-section was examined to determine reproductive status (pregnant or non-pregnant) and the number of corpora lutea.

Litter observations:

STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: [yes/no]
- If yes, maximum of [...] pups/litter ([...]/sex/litter as nearly as possible); excess pups were killed and discarded.

PARAMETERS EXAMINED
The following parameters were examined in [F1 / F2 / F3] offspring:
[number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight gain, physical or behavioural abnormalities, other:]

GROSS EXAMINATION OF DEAD PUPS:
[no / yes, for external and internal abnormalities; possible cause of death was/was not determined for pups born or found dead.]

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: observed daily for mortality and twice weekly for physical signs.

DETAILED CLINICAL OBSERVATIONS: Yes / No / No data
- Time schedule:

BODY WEIGHT: Yes
- Time schedule for examinations:
Males: once a week from weaning until sacrifice
Females: once a week from weaning until breeding or sacrifice. The first postweaning weights were recorded for these animals on Postnatal Days 23 to 29.

OTHER:
Developmental SIgns: The descent of the testes was recorded on 2 males per litter on Postnatal Day 39 and preputial separation on Postnatal Day 39, 43, and 47. The presence of vaginal canalization was recorded when possible on all females on Postnatal Days 31, 34, and 37

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

no effects observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

decrease in 300-200 mg/kg/day group

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

decrease in 300-200 mg/kg/day group

Histopathological findings: non-neoplastic:

no effects observed

Other effects:

effects observed, treatment-related

Description (incidence and severity):

Test substance intake: decrease in food consumption in highest dose group but substance was delivered via gavage so subsstance intake not affected

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

no effects observed

Reproductive performance:

no effects observed

Effect levels (P0)

Dose descriptor:

NOEL

Effect level:

25 mg/kg bw/day

Based on:

test mat.

Sex:

female

Results: F1 generation

Effect levels (F1)

Dose descriptor:

NOAEL

Generation:

F1

Sex:

male/female

Basis for effect level:

other: In this study 25 mg/kg/day was a no observed effect dose for all parameters except slight decreased pup weights (5.8-7.8%) during Days 14 to 21 oflactation and slight (4.3%) decrease in F1 body weight during 1-9 weeks postweaning.  

Remarks on result:

not measured/tested

Remarks:

Effect level not specified (migrated information)

Results: F2 generation

Effect levels (F2)

Dose descriptor:

NOAEL

Generation:

F2

Sex:

male/female

Basis for effect level:

other: In this study 25 mg/kg/day was a no observed effect dose for all parameters except slight decreased pup weights (5.8-7.8%) during Days 14 to 21 oflactation and slight (4.3%) decrease in F1 body weight during 1-9 weeks postweaning.  

Remarks on result:

not measured/tested

Remarks:

Effect level not specified (migrated information)

Overall reproductive toxicity

Reproductive effects observed:

not specified

Any other information on results incl. tables

There were no treatment-related effects on reproductive performance, including mating or fertility in F0 female rats given 25 mg/kg/day of L-158,086 for 15 days prior to mating, during mating, during gestation and through Day 20 of lactation. In the 300/200 mg/kg/day dose there was a slight but significant (P=< 0.05) effect on live foetuses, number of implants, and corpora lutea/pregnant female in the caesarean section group of females and in the 100 mg/kg/day there was a slight but significant effect on number of corpora lutea/pregnant female. These changes were not observed in the natural delivery females in this same group. These changes are of uncertain relationship to treatment. All other indices of mating and fertility were comparable to controls. 

There was no evidence of teratogenicity in any dose group in the F1 or F2 generation. Developmental toxicity was observed in all dose groups based on decreased F1 pup weights which were dose and time-dependent in nature. Females had more severe weight reductions than males. There were no other signs of developmental toxicity in the 25 mg/kg/day group in the postweaning period. In the 100 and 300/200 mg/kg/day group treatment-related developmental toxicity was further evidenced by increased pup mortality preweaning in both dose groups. Postweaning F1 weights were also significantly effected in females (decreased weight) and in males (increased weights) in the 25 (females only) 100 and 300/200 mg/kg/day group.

 

Developmental signs were also adversely affected in the 100 and 300/200 mg/kg/day groups. Auditory startle response was significantly delayed in females in these dose groups and vaginal canalization and preputial separation was delayed in the 300/200 mg/kg/day group. These delays are considered a result of body weight decreases and resultant generalized immaturity of the pups at the time of testing and are not considered a specific effect of L-158, 086 on these parameters. A treatment-related decrease in open field activity was observed in males in the 100 and 300/200 mg/kg/day groups. The reason for this decreased activity is uncertain but unlike the above-mentioned developmental signs these effects are not due to decreased body weights.

 

There were no treatment-related effects on the F1 generation as assessed by reproductive performance, external examination of pups at birth, ophthalmologic examination and histomorphologic examination of the testes and epididymides.

 

There were no treatment-related effects on F2 generation deaths, weights or external morphology at birth.

 

In this study 25 mg/kg/day was a no observed effect dose for all parameters except slight decreased pup weights (5.8-7.8%) during Days 14 to 21 of lactation and slight (4.3%) decrease in F1 body weight during 1-9 weeks postweaning.

 

The timing and nature of the effects on the F1 generation observed during this study suggest that the toxicity observed may be due to late gestation/lactation drug exposure. This is supported by the findings of a developmental toxicity study in which rats were administered up to 200 mg/kg/day L-158,086 from Days 6 to 17 of gestation which resulted in no indications of developmental toxicity. It is not clear if this developmental toxicity observed during lactation is due to a direct effect of the compound on the pups or is secondary to effects on the dam such as decreased milk production or poor maternal care. This issue of possible postnatal toxicity due to late gestation/lactation exposure will be addressed in the on-going rat late gestation lactation study of L-158, 086.

Applicant's summary and conclusion

Conclusions:

Based on the results of this study with losartan potassium, the Maternal NOEL= 25 mg/kg/day. The F1 and F2 NOAEL is considered to be 25 mg/kg/day based on slight decreased pup weights (5.8-7.8%) during Days 14 to 21 of lactation and slight (4.3%) decrease in F1 body weight during 1-9 weeks postweaning. These results alos apply to the read-across substance losartan free acid.