Kinetics of photosensitivity in bath-PUVA photochemotherapy.
BACKGROUND
Bath-PUVA is used to treat a variety of dermatoses. However, the kinetics of 8-methoxypsoralen during treatment are not completely clarified.


OBJECTIVE
The purpose of this study was to investigate the intensity of the phototoxic response and the persistence of phototoxicity after bath-PUVA.


METHODS
Twelve volunteers were exposed to UVA doses ranging from 0.5 to 40 J/cm2 from 10 to 240 minutes after bath-PUVA treatment. The resulting phototoxic response of the skin was determined.


RESULTS
Irradiation 10 minutes after the psoralen bath led to the lowest assessed minimal phototoxic dose (MPD) of 1.42 J/cm2 (mean, SD +/- 0.29). Thereafter, the MPD increased significantly and sharply every hour. At 4 hours after the psoralen bath, UVA doses up to 40 J/cm2 failed to induce any phototoxic erythema (MPD).


CONCLUSIONS
For optimal effects, UVA irradiation has to be administered immediately after the psoralen bath; no restrictive behavior is necessary after bath-PUVA treatment.
Gruss
C
C
Department of Dermatology, Ruhr-University Bochum, Germany.
Behrens
S
S
Reuther
T
T
Husebo
L
L
Neumann
N
N
Altmeyer
P
P
Lehmann
P
P
Kerscher
M
M
D000328:Adult; D001494:Baths; D017484:Dermatitis, Phototoxic / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008730:Methoxsalen / Q000008:administration & dosage / Q000009:adverse effects; D011701:PUVA Therapy / Q000009:adverse effects* / Q000379:methods; D017319:Photosensitizing Agents / Q000008:administration & dosage / Q000009:adverse effects; D013997:Time Factors
D017319:Photosensitizing Agents; D008730:Methoxsalen