Forsøksdyr: Pilot study with substance X

Godkjenningsdato 16.01.2018

NoMA has assessed the reports from previous safety trials with the substance X, and asked for additional documentation in larger fish (>800 grams).
New substances for treatment of Atlantic salmon for sea lice, Lepeophtheirus salmonis are crucial important for the aquaculture industry.

Efficacy studies have shown that target dose (mg active/ litre) gives > 90 % effect on mobile sea lice. Earlier safety studies have also shown that this dose gives gill damage in fish (average weight: 395 g), investigated by gill histology. Substance X will be recommended for Atlantic salmon > 800 g in the field. The use of smaller fish in previous studies, was due to laboratory practical limitations (no availability of larger fish).

We will use Atlantic salmon (> 800 g) well adapted to sea water in this test. Only 3 fish will be used in each group, totally 18 fish. This is the lowes acceptable number to avoid errors due to single abnormal sensitive fish. Mortality is not expected to occur, and the regimes With highest doses will be moderately stressful.

The pilot test is designed as a conditional test, i.e. the results from the first step defines / decides the next steps. The criteria for deciding next step, i.e. higher or lower temperature and higher or lower concentration, will be:

2. Gill damage based on fast analyzed histological samples – 48 hours
3. Adverse behavior

The conditional test design is further explained by an example in the attached document.

The result from this safety study will decide the doses used in the GLP safety test with substance X. The safety test will be designed with a target dose (mg active/ L), i.e the highest dose with no significant gill damage in the pilot study.