title: Differences in phototoxic potency should be considered when tetracyclines are prescribed during summer-time. A study on doxycycline and lymecycline in human volunteers, using an objective method for recording erythema.
abstract: In order to test the phototoxic potency of the two tetracyclines most frequently prescribed in Sweden, a double-blind cross-over study using a double-dummy technique with doxycycline 0.1 g twice daily, lymecycline 0.6 g twice daily, and placebo, was performed in 15 healthy volunteers. Drugs were given for 3 consecutive days, and on the third day volunteers were tested with 25, 50, 75 and 100 J/cm2 of artificial long-wave ultraviolet radiation (UVA), and assessed 6 h later for erythematous photoreactions. Objective readings were made using skin reflectance spectrophotometry. All three substances were tested in each individual at weekly intervals. Within 50, 75 and 100 J/cm2 of UVA, lymecycline showed a slight increase in erythema compared with placebo, but this was not significant (50 and 100 J/cm2), or was of low significance (75 J/cm2). However, with the same doses, doxycycline showed a substantial increase in erythema compared with placebo, which was highly significant. We conclude that doxycycline has a higher phototoxic potency than lymecycline, and this is in agreement with earlier in vitro experimental data. We recommend that therapy with doxycycline is avoided during summer-time, and during holidays in a sunny climate.
authors.affiliation: Department of Dermatology, Lund University, General Hospital, Malmö, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Bjellerup
authors.forename: B
authors.initials: B
authors.lastname: Ljunggren
mesh_terms: D000328:Adult; D017484:Dermatitis, Phototoxic / Q000209:etiology*; D004311:Double-Blind Method; D004318:Doxycycline / Q000009:adverse effects*; D004890:Erythema / Q000209:etiology; D005260:Female; D006801:Humans; D008194:Lymecycline / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D012621:Seasons; D014466:Ultraviolet Rays
chemical_list: D008194:Lymecycline; D004318:Doxycycline