THE UVR WAVELENGTH DEPENDENCE FOR LOMEFLOXACIN PHOTOSENSITIZATION OF HUMAN SKIN

Lomefloxacin is a new fluoroquinolone with effective broad-spectrum an timicrobial activity. However, in common with other structurally relat ed drugs, skin photosensitization reactions have been reported. The wa velength dependence for such photosensitization has been investigated on the previously unexposed buttock skin of 12 normal healthy human vo lunteers of skin types I and II. Using geometric root 2 dose increment s, baseline 24 h minimal erythema doses were assessed at 300, 320, 330 , 340, 350 and 360 nm, and with broad-band UVA. In addition, dose-resp onse curves were constructed for erythema as measured by a reflectance device. Subjects received single daily oral doses of 400 mg lomefloxa cin at specified times for 4 days. At 2 h after the final dose, new ar eas of buttock skin were irradiated to assess changes in minimal eryth ema dose and erythema dose-response. Convolution of the erythema actio n spectra obtained pre- and on-drug with a terrestrial solar spectrum showed that, although the UVA sensitivity on-drug was enhanced, most o f the erythemally effective solar energy was still in the UVB region. An action spectrum derived for lomefloxacin skin photosensitization sh owed peak activity at 320 nm, the same spectral region as that for max imal absorption of the drug. There was no evidence of skin photosensit ization at 300 nm.