Intracutaneous test

1. Biological Effect: Intracutaneous test
2. Turnaround time: 4 weeks (after approval from Local Ethics Committee)
3. Sample Requirements:

USP

to be individually determined;

4. Animal Quantity: 4 rabbits

USP <88>

This test is designed to evaluate local responses to the extracts of materials under test following intracutaneous injection into rabbits.

Test Animals

Select healthy, thin-skinned albino rabbits with fur that can be clipped closely and skin that is free from mechanical irritation or trauma. In handling the animals, avoid touching the injection sites during observation periods, except to discriminate between edema and an oil residue.

Procedure

On the day of the test, closely clip the fur on the animal’s back on both sides of the spinal column over a sufficiently large test area. Avoid mechanical irritation and trauma. Remove loose hair by means of vacuum. If necessary, swab the skin lightly with diluted alcohol and dry the skin prior to injection. More than one extract from a given material can be used per rabbit, if it is determined that the test results will not be affected. For each Sample use two animals and inject each intracutaneously using one side of the animal for the Sample and the other side for the Blank.

Observation

Examine injection sites for evidence of any tissue reaction such as erythema, edema, and necrosis. Swab the skin lightly, if necessary, with diluted alcohol to facilitate reading of injection sites. Observe all animals at 24, 48, and 72 h after injection. Rate the observations on a numerical scale for the extract of the Sample and for the Blank. Reclip the fur as necessary during the observation period. The average erythema and edema scores for Sample and Blank sites are determined at every scoring interval (24, 48, and 72 hours) for each rabbit. After the 72 hour scoring, all erythema scores plus edema scores are totalled separately for each Sample and Blank. Divide each of the totals by 12 (2 animals × 3 scoring periods × 2 scoring categories) to determine the overall mean score for each Sample vs each corresponding Blank. The requirements of the test are met if the difference between the Sample and the Blank mean score is 1.0 or less. If at any observation period the average reaction to the Sample is questionably greater than the average reaction to the Blank, repeat the test using 3 additional rabbits. The requirements of the test are met if the difference between the Sample and the Blank mean score is 1.0 or less.