1,1,2,2,3,3,4-heptafluorocyclopentane

Specific investigations: other studies

Link to relevant study record(s)

Reference

Endpoint:

specific investigations: other studies

Remarks:

cardiac sensitisation potential

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 1998-01-02 to 1998-01-21

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

no guideline available

Principles of method if other than guideline:

The potential of test item to cause cardiac sensitisation by inhalation in the beagle dog was determined.
There are no regulatory guidelines for this type of study, therefore the study design was in accordance with accepted pharmacological principles and methods.
The technique involved the intravenous injection of adrenaline before and during inhalation of the test gas. The effect of adrenaline on the electrocardiogram was examined in both cases and compared to assess any positive response to the test gas.

GLP compliance:

yes

Type of method:

in vivo

Endpoint addressed:

other: cardiac sensitisation

Specific details on test material used for the study:

Lot No.: 9709-1A
Purity: 98.98%

Species:

dog

Strain:

Beagle

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Interfauna UK Ltd, Abbots Ripton Road, Wyton, Huntingdon,England or Consort Ltd, Harewood Park, Harewood End, Hereford, England
- Age at study initiation: 18 - 48 months
- Weight at study initiation: 10-18 kg
- Fasting period before study:
- Housing: housed in pens within a purpose designed dog holding facility
- Diet: 500 g of dry diet daily
- Water: ad libitum
- Acclimation period: No data

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 15-21
- Humidity (%): No data
- Air changes (per hr): 10-12
- Photoperiod: 12 hrs dark / 12 hrs light

Route of administration:

inhalation: gas

Vehicle:

air

Details on exposure:

The dogs were exposed to the test gas by a snout-only system.
A large Halls face mask (Phoenix Medical Ltd) was used. The mask consisted of a rubber cone, one end of which was connected to the air supply line, while the other end was placed over the dogs snout. To ensure a reasonably air tight fit around the dog's snout a latex sheet with a hole was placed over the snout end of the mask and the dog's snout protruded through the sheet into the mask. The mask was held in place by a leather muzzle. The dog was restrained in a canvas sling through which the limbs extended, the dogs could thus support itself standing or be supported by the sling.
The dog face mask was connected via a non-return valve to a reservoir Tedlar gas bag (SKC Inc, USA) of 200 litres capacity. The dogs inhaled from the gas bag through the non-return valve and exhaled to waste. During the first experimental session the gas bag was filled with room air only.
For the gas exposure, the reservoir gas bag contained a known concentration of the test substance as a vapour. The test atmospheres were prepared by metering known volumes of air into evacuated 200 litre Tedlar gas bags. The air volume was measured with a wet-type gasmeter (Alexander Wright and Co. (Westminster) Ltd.). An accurately measured volume of test item liquid, calculated to produce the target concentration, was injected into the air filled gas bag with a gas tight syringe and allowed to evaporate completely.

TEST ATMOSPHERE
- Brief description of analytical method used: The samples of test atmosphere were injected directly into a gas chromatograph calibrated using vapour standards prepared in gas bags.
- Samples taken from breathing zone: yes, A sample of the test atmosphere was drawn into a 20 mL polypropylene syringe from a sampling port on the gas bag.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The achieved concentration were close to the target concentrations

Dose / conc.:

0.1 other: % v/v air

Dose / conc.:

0.2 other: % v/v air

Dose / conc.:

0.5 other: % v/v air

Control animals:

yes, concurrent vehicle

Details on study design:

The study was performed in 2 stages:
- STAGE 1:
In this stage an individual response to adrenaline alone was selected for each of the dogs using a range of adrenaline doses.

- STAGE 2:
The dogs were to be exposed according to following schedule:
Exposure session/ Target test gas concentration (v/v% in air): 1/air only; 2/0.1; 3/0.2; 4/0.5; 5/1; 6/2; 7/5.
Following the results obtained from exposure up to 0.5 % v/v and in order to establish a NoAEL, dogs were exposed to 0.05 % v/v during Exposure Session 5. There were no further exposures.
At least one calendar day was allowed between each exposure session.

Examinations:

- Measurement of electrocardiogram (ECG):
The standard lead II electrocardiograph was used throughout the study.
Appropriate areas on the dog's limbs were shaved and electrode gel applied. Standard ECG limb leads were then connected to the prepared areas on the dog with blunt clips. The electrocardiograph (Lectromed Multitrace 2, two channel chart recorder) was calibrated with 1mV peaks. The electrocardiogram was then checked for clarity before dosing commenced.

Positive control:

Not performed

Details on results:

- STAGE 1- challenges with adrenaline alone:
Dogs 1373 and 1379 responded strongly with several ectopic beats following administration of adrenaline at 1 μg/kg.
Dogs 1367, 1347, 1375 and 1377 were moderately responsive to administration of adrenaline with a few ectopic beats at 4, 8 or 12 μg/kg.
Dog 1371 was unresponsive following adrenaline administration at 12 μg/kg.
Dog 1363 produced spontaneous ectopic beats in the absence of exogenous adrenaline and was rejected from the Stage 2 of the study.
On the basis of these results the dose of adrenaline selected for each dog was:
1 μg/kg: Dogs 1373 and 1379
4 μg/kg: Dogs 1367
8 μg/kg: Dogs 1375
12 μg/kg: Dogs 1347, 1371 and 1377

- STAGE 2 - exposure to test item:
Six dogs were selected from the 8 available: Dogs 1347, 1371 and 1377 (week responders); Dogs 1375 (moderate responder); Dogs 1373 and 1379 (strong responders).

0.1 % v/v test item in air:
Six dogs were tested. One dog struggled against restraint such that it was not possible to administer the adrenaline challenges. Of the remaining 5 animals 2 gave a positive response and 3 a negative response. There were no clinical signs attributed to exposure to test item.

0.2 % v/v test item in air:
The three dogs which gave a negative response at 0.1% v/v were tested, one of which gave a positive response. There were no clinical signs attributed to exposure to test item.

0.5 % v/v test item in air:
The two dogs which gave a negative response at 0.2% v/v were tested, there were no positive responses. However, there were marked clinical signs evident at this level. The signs included, restlessness, hind limb tremors, rocking of the head from side to side in a rhythmic fashion, apparent drowsiness, lack of response to external stimuli and collapse of hind limbs. The clinical signs seen at 0.5 % v/v were such that exposures at higher levels could not be carried out.

0.05 % v/v test item in air:
The two dogs which gave a positive response at 0.1% v/v were tested.
One dog gave a negative response, the remaining dog struggled against restraint to a degree such that it was impossible to administer the second adrenaline challenge. A second attempt was made to expose this animal a few days later without success. It was considered that further attempts to expose this animal would be unsuccessful. There were no clinical signs attributed to exposure to test item.

Conclusions:

The results of this study show that the test item has potential to cause cardiac sensitisation in beagle dogs.
The no adverse effect level for this study was 0.05% v/v test item in air (equivalent to 538 ppm or 4.3 mg/L).
The low adverse effect level for this study was 0.1% v/v test item in air (equivalent to 1074 ppm or 8.6 mg/L).
The calculated EC50 concentration for this study was 0.24% v/v test item in air (equivalent to 2400 ppm or 19.2 mg/L).

Executive summary:

This study was designed to assess the cardiac sensitisation potential of test item in beagle dogs.

Adrenaline was administered by intravenous injection before and during inhalation of test substance. The effect of the adrenaline on the ECG pattern was examined. Positive evidence of cardiac sensitisation would be observed as the presence of multiple multifocal ectopic beats or ventricular fibrillation following adrenaline administration during inhalation of the test substance. No such effect should be observed in the absence of the test substance.

The dogs was exposed to 1074, 1968, 4824 and 538 ppm test item in air , levels equivalent to 0.1, 0.2, 0.5, 0.05 % v/v and 8.6, 15.8, 38.7 and 4.3 mg test item / L air, respevtively.

 

At 0.1 % v/v test item in air, six dogs were tested. One dog struggled against restraint such that it was not possible to administer the adrenaline challenges. Of the remaining 5 animals 2 gave a positive response and 3 a negative response. There were no clinical signs.

At 0.2 % v/v test item in air, three dogs were tested, of which 1 gave a positive response. There were no clinical signs.

At 0.5 % v/v test item in air, two dogs were tested, there were no positive responses. However, there were marked clinical signs evident at this level. The signs included, restlessness, hind limb tremors, rocking of the head from side to side in a rhythmic fashion, apparent drowsiness, lack of response to external stimuli and collapse of hind limbs. The clinical signs seen at 0.5 % v/v were such that exposures at higher levels could not be carried out.

The two dogs which gave a positive response at 0.1% v/v were exposed to a level of 0.05 % v/v test item in air. One dog gave a negative response, the remaining dog struggled against restraint to a degree such that it was impossible to administer the second adrenaline challenge. A second attempt was made to expose this animal a few days later without success. It was considered that further attempts to expose this animal would be unsuccessful.

The results of this study show that the test item has potential to cause cardiac sensitisation in beagle dogs. The no adverse effect level for this study was 0.05% v/v test item in air (equivalent to 538 ppm or 4.3 mg/L). The low adverse effect level for this study was 0.1% v/v test item in air (equivalent to 1074 ppm or 8.6 mg/L). The calculated EC50 concentration for this study was 0.24% v/v test item in air (equivalent to 2400 ppm or 19.2 mg/L).

Description of key information

This study was designed to assess the cardiac sensitisation potential of test item in beagle dogs.

The results of this study show that the test item has potential to cause cardiac sensitisation in beagle dogs. The no adverse effect level for this study was 0.05% v/v test item in air (equivalent to 538 ppm or 4.3 mg/L). The low adverse effect level for this study was 0.1% v/v test item in air (equivalent to 1074 ppm or 8.6 mg/L). The calculated EC50 concentration for this study was 0.24% v/v test item in air (equivalent to 2400 ppm or 19.2 mg/L).