The efficacy and safety of low-dose diclofenac sodium 0.1% gel for the symptomatic relief of pain and erythema associated with superficial natural sunburn.

A randomised, double-blind, single-centre, vehicle-controlled clinical trial was conducted to assess the efficacy and tolerability of diclofenac-Na 0.1% gel in 172 subjects suffering from acute first-degree natural sunburn. Overall 172 subjects with skin phototypes II-IV were randomised in a ratio of 2:1 to receive two applications of either diclofenac-Na 0.1% Emulgel gel or its vehicle Emulgel gel, 6 and 10 hours after the end of sun exposure. Subjects were drawn from a target population of healthy volunteers and well outdoor sunbathers with normal tolerance to ultraviolet light and the sun. Previously untanned areas were exposed to carefully determined standardised doses of sun (2.8 individual minimal erythema doses) on 15% body surface area to induce first-degree sunburn. After administration of diclofenac-Na 0.1% gel, subjects reported a significant reduction in spontaneous pain intensity compared with those on vehicle. Pain relief was rapid with a reduction in erythema, which was apparent within the first few hours after the first application of the trial medication with a maximum effect observed up to 30 hours after sun exposure. A good', very good', or excellent' cooling effect was recorded by 85% of subjects after treatment. Reported treatment-emergent adverse effects were infrequent, generally mild and none were considered to be related to the trial medication. Only one severe treatment emergent adverse event (abdominal pain) was recorded in the active group, and another (burning sensation) with vehicle.

Standardized protocols for photocarcinogenesis safety testing.

Solar ultraviolet radiation (UVR) is recognized as a major cause of non-melanoma skin cancer in man. Skin cancer occurs most frequently in the most heavily exposed areas and correlates with degree of outdoor exposure. The incidence of skin cancer is also increased by contact with photosensitizing drugs and chemicals such as psoralens, coal tars and petroleum stocks. Other substances which do not act as photosensitizers, such as immunosuppressants taken by organ transplant recipients, also increase the risk of skin cancer. The U.S. Food and Drug Administration requests, on a case-by-case basis, that risk of enhanced photocarcinogenesis is assessed for many classes of drugs. Health Canada's Therapeutic Products Programme has issued a Notice of Intent to regulate pharmaceutical products which may enhance carcinogenicity of the skin induced by ultraviolet radiation. Other national regulatory agencies review such data when they exist, but their own requirements emphasize batteries of short-term in vitro and in vivo tests. While they may support drug development strategies, short-term tests have yet to be validated as predictors of the ability of drugs or chemicals to enhance photocarcinogenesis. Published protocols now describe study designs and procedures capable of determining whether test agents enhance the rate of formation of UVR-induced skin tumors.

Activities of CIE DIV-6 (photobiology and photochemistry) in UV protection and clothing.

Clothing can provide substantial protection against solar ultraviolet radiation (UVR). A technical committee (TC6-29), formed by experts in the field of UVR and photoprotection, was raised and, after extensive exchanges of information on the various existing test methods, prepared a technical report. The report is circulating within the CIE national committees for approval which is expected before the end of 2001. P. Gies (Australia) was in charge of collecting all information and prepared the final document. In the report, various test methods for measurement of UVR transmittance through fabrics are discussed. The measured transmittances can be used to calculate the erythemally weighted UVR transmitted by the fabric and thus the amount of protection provided. Factors affecting the UVR transmission of fabric, i.e. the characteristics of the radiometer, weave, color, weight, stretch, water, quality (holes) and eventual UV-absorbers are also detailed. In vivo and in vitro tests were found to be in broad agreement, particularly when the test method detailed in the AS/NZS 2604 "Sunscreen products--evaluation and classification", with the fabric substituted for the sunscreen, was used. The report concludes: "The UVR transmission of fabrics depends on too many factors to be predicted and must be measured. Particular attention must be paid to sampling to account for variations due to weave and non-uniformity of the product. Accurate and reliable assessment of the protection factors requires spectral measurements of the total (ie. direct and scattered) UVR transmission. A detection system, which closely matches human skin response, can be used to determine protection factors, but should always be checked against the spectral transmission measurement."