Repeated dose 28 days oral toxicity study in rodents - OECD 407: 2008
Test with the Certificate of Good Laboratory Practices (GLPs)
The objective of the test according to the OECD 407 guideline is the study of the effects on a wide variety of possible toxicity targets, providing information on possible health hazards that may arise from repeated exposure during a relatively limited period of time, including effects on the nervous, immune and endocrine systems. The data derived from this study allow the characterization of the toxicity of the test substance, indicate the dose response relationship and determine the dose level without observable adverse effect (NOAEL: No-Observed Adverse Effect Level).
The preferred rodent species for this test is the rat, although other species of rodents can be used whenever the choice is justified. The study should be done in young adult animals. The test substance is administered orally (by tube or by incorporation into the diet and drinking water) daily in graduated doses to several groups of experimental animals, using one dose per group for a period of 28 days. At least 3 dose levels and one control should be used. Each group must consist of at least 10 animals (5 males and 5 females). The highest dose level should be chosen with the aim of inducing toxic effects, but not the death or suffering of the animals. Subsequently, a descending sequence of dose levels should be selected, generally reductions between 2 to 4 times are appropriate for these tests. In addition, an additional satellite group of 10 animals (5 per sex) can be included in the control and the upper dose level, to study the reversibility or persistence of the observed toxic effects at least 14 days after treatment. The guideline also contemplates that, if from other data no toxic effects are expected at a dose of 1.000 mg/kg per day, a complete study may not be considered necessary, and a limit test may be performed.
During the administration period, animals are observed daily for signs of toxicity. In the fourth week of exposure, sensory reactivity to stimuli of different types, grip strength and motor activity should be evaluated. At the end of the test period, hematological, clinical biochemical, necropsy exam and histopathology tests should be performed.