Topical metronidazole does not abate UVB-induced erythema.

BACKGROUND: The capacity of topical metronidazole to reduce erythema severity scores in rosacea has been attributed to its anti-inflammatory activity. METHODS: Nine healthy subjects were irradiated on three 1-cm(2) areas on their volar forearm with 2 MEDs of UVB. Twenty-four hours later, one of the irradiated areas was treated daily with metronidazole 1% vanishing cream, one with the vehicle only and the third was left untreated (control). The intensity of erythema was measured, at 24, 48, 72 and 96 h after irradiation, by a Chromameter CR200 (Minolta, Japan) and expressed in the L*a*b* system. The a* parameter was taken as the measure of redness. RESULTS: Overall, redness diminished over time in a linear way, but treatments did not influence it significantly. CONCLUSION: In our vehicle, metronidazole 1% cream failed to abate the UVB-induced erythema. An activity other than the anti-inflammatory one should be suggested to explain the topical metronidazole efficacy in rosacea.

Persistent solar urticaria. A case report.

Solar urticaria is an uncommon dermatological disease characterized by wheals developing within a few minutes after sun exposure and lasting a few hours. We describe a man in whom wheals developed on his trunk and arms more than 30 min after sun exposure and lasted more than 24 h. High doses of UVA reproduced lesions with histological features typical of urticaria. After 7 years, urticaria began to develop even in winter and without sun exposure. Our patient is unusual in that his wheals were delayed in onset and longlasting. The later association of idiopathic urticaria is an additional unusual feature.