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Protocol no. 2
RABBIT ISOLATED TERMINAL ILEUM

This test is designed to detect damage to the eye after application of test substance to the conjunctiva.

CONTACT

Dr. B. Northover
Department of Pharmacology School of Pharmacy
Leicester Polytechnic Leicester, LE1 9BH UK
Tel: England - 533 551551 ext 2271

RATIONALE

Terminal segments of rabbit ileum retain spontaneous contractile activity when isolated and maintained in physiological solution. It has been suggested that the ability of compounds to inhibit this spontaneous activity may be related to their irritant effect, thus the preparation may provide an alternative means of assessing likely potency of irritants in the eye in the in vivo situation.

BASIC PROCEDURE

Sections of terminal rabbit ileum are removed, suspended in an organ bath and the spontaneous contractile activity monitored. The test substance is added to the organ bath in a cumulative manner until spontaneous contractions are inhibited by more than 50% of original activity.

CRITICAL ASSESSMENT

It would seem that the test is sensitive to mild irritants, although the authors stress that it has not been thoroughly tested and validated against the in vivo situation at this point and is currently regarded by them as a workable idea. General advantages include an accurate quantifiable endpoint, relatively simple technique to implement, one animal provides several preparations, technique is inexpensive. The main disadvantage of this technique is that, at this moment, only water soluble compounds can easily be tested. Comparisons to other tests The in vivo Draize test involves a more subjective measurement of damage and cannot be as readily quantified. The same argument applies to the fertilized egg chorio-allantoic membrane test. Cell culture cytotoxicity tests, e.g. cultured corneal cells, fail to imitate the multilayered structure of the cornea. This system maintains an intact multicellular layered structure and, therefore, the measured toxicity of a compound will reflect both its ability to penetrate the tissue and its direct toxic effect, thus making it more representative of the in vivo situation. Other tests such as the intact eye preparations require a higher degree of operator proficiency and may not provide as precise a measurement of damage or as sensitive a test as this system.

TEST STATUS

Undergoing in-house development.

CHEMICALS TESTED

Anionic Surfactants:

  • triethanolamine decyl sulphate
  • triethanolamine lauryl sulphate
  • triethanolamine myristyl sulphate
  • sodium decyl sulphate
  • sodium lauryl sulphate

Cationic Surfactants:

  • cetyltrimethylammonium bromide
  • myristyltrimethylammonium bromide
  • lauryltrimethylammonium bromide

Miscellaneous and Industrial chemicals:

  • acetone
  • acetophenone
  • allyl alcohol
  • n-butanol
  • Carbitol  ™
  • dioxane
  • ethanol
  • formaldehyde
  • iso-propanol
  • mercaptoethanol
  • methanol
  • propylene glycol

Shampoos:

  • Antidandruff shampoo (for normal hair)
  • Antidandruff shampoo, Boots Co. Ltd
  • ZPII formula treatment shampoo, Revlon
  • Head and Shoulders, Proctor and Gamble
  • All Clear, A and F Pears Ltd
  • Adult shampoos (all non-cream shampoo for normal hair)
  • Country Born sunflower shampoo, Boots Co. Ltd
  • Sunsilk, Elida
  • Bristows Deep Shine, T.F. Bristow and Co.
  • Pears, A and F Pears Ltd
  • Baby Shampoos
  • Boots baby shampoo, Boots and Co Ltd
  • New Matey mild and gentle, Nicholas Laboratories Ltd
  • Milton Infa Soft baby shampoo, Richardson-Vicks Ltd
  • Johnson's Baby shampoo, Johnson and Johnson Ltd

REFERENCES

  1. Muir, C.K.; Flower, C. & Van Abbé, N.J. (1983). A novel approach to the search for in vitro alternatives to in vivo eye irritancy testing. Toxicol. Lett., 18, 1-5.
  2. Muir, C.K. (1983). The toxic effect of some industrial chemicals on rabbit ileum in vitro compared with eye irritancy in vivo. Toxicol. Lett., 19, 309-312.
  3. Muir, C.K. (1983). The comparative effects of proprietary antidandruff, adult and baby shampoos on the rabbit ileum. Toxicol. Lett., 18, 227-230.
  4. Muir, C.K. (1984). Further investigations on the ileum model as a possible alternative to in vivo eye irritancy testing. ATLA, 11, 129-134.

IP-2 © June 1989