Effect of drugs on the early and late phase UV erythema.

The inhibition of erythema by drugs applied topically after irradiation with 0.2-0.8 J of 313 nm has been studied in healthy volunteers. Indomethacin and piroxicam markedly inhibited the erythema at 6 to 24 h after irradiation but erythema reappeared at 45 h. The results reported suggest that the UVB response is biphasic with an early phase responsive to nonsteroid anti-inflammatory drugs and a late phase which is not responsive. No effect on the intensity of the erythema was seen with betamethasone chloroquine and cetirizine. Oral intake of aspirin before and/or after irradiation did not influence the UV response.