ABSTRACT; Ten healthy volunteers were studied to find out whether tachyphyiaxis occurs on repeated application of topical steroids. The Singh and Singh modification of the Reddy and Singh (1976) technique was used. Fluocinolone acetonide cream (O. 1%) under occlusion was applied daily for 14 days on the flexor aspect of the forearms. The wheal was induced by pricking with histamine acid phosphate solution and the volume of the wheal produced was calculated. The test was repeated on the same sites on alternate days for 14 days. The maximum wheal suppression, which gradually diminished, was observed on the 8th day. By the 14th day, there was practically total tolerance to topical steroid, which showed minimal suppression of histamine wheal formation. This confirms the occurrence of the phenomenon of tachyphylaxis by different experimental techniques.

The role of topical steroids in the management of noninfective inflammatory and allergic dermatoses is well established. Soon after the success of hydrocortisone as a topical remedy in these disorders, a number of potent, synthetic, topical steroids were synthesized. In clinical practice, patients sometimes complain about the reduced effectiveness of steroids on repeated and continuous applications. The occurrence of acute tolerance to repeatedly administered or topically applied drug is known as tachyphylaxis. This concept is relatively new as far as topical steroids are concerned. It was first reported by du-Vivier and Stoughton1) in 1975 by using the McKenzie and Stoughton2) technique. The Reddy and Singh technique3) of assessing the potency of topical steroids was considered to be closer to clinical practice and to match more sophisticated methods. 4) We have, however, improvised the technique by measuring the volume of the wheal, which is a more sensitive indicator5) of histamine response. This technique has been used to study the efficacy of repeatedly applied steroid under occlusion.

Methods

Ten healthy volunteers aged 15 to 30 years were selected for the study. None of them had used systemic or topical steroids or antihistaminies for at least 56 days prior to the study.