Measurement of croton oil induced rabbit ear swelling and evaluation of anti-inflammatory agents with a standard low pressure caliper

Background/aims: Carbobenzoxy-phenylalanyl-methionine (CBZ-Phe-Met), a known inhibitor of the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP) in vitro, has not been evaluated as a topical anti-inflammatory agent in vivo. In order to measure the effect of CBZ-phe-met, one needs a repeat-able, quantitative, easily obtainable standard measurement of the edema formation. In this study, a caliper designed for measuring soft materials was used to evaluate the edema, induced by croton oil on rabbit ears, as well as the effects of CBZ-phe-met.
Methods: The model used in this study was croton-induced inflammation on rabbit ears. A caliper for measuring soft materials (European standard DIN 863 part 3, manufactured by TESA Ltd., Renens, Switzerland) was used to evaluate the edema, which is part of the inflammatory effect. The action of CBZ-phe-met and two other anti-inflammatory agents; hydrocortisone and Na-ibuprofen, were compared.
Results: CBZ-phe-met 1-5% was found to reduce the edema on rabbit ears induced by croton oil by 15 to 93%. 5% CBZ-phe-met was found to be as effective as 5% Na-ibuprofen and 0.1% hydrocortisone.
Conclusion: The caliper for soft materials was found to be suitable for measuring the edema induced by croton-oil, as well as the reducing edema due to anti-inflammatory treatment. It was also found that CBZ-phe-met is a potent topical anti-inflammatory agent in the croton-oil-induced inflammatory model. This may indicate a new approach in the treatment of inflammation.