Background: St John s wort (SJW) is widely used as a treatment for depression. A phototoxic reaction, due to its content of hypericin, can occur in animals and in cell culture, and has been reported in humans. Hyper...Background: St John s wort (SJW) is widely used as a treatment for depression. A phototoxic reaction, due to its content of hypericin, can occur in animals and in cell culture, and has been reported in humans. Hypericin displays absorption within the ultraviolet (UV) A1 spectrum and there may therefore be a potential for phototoxicity if taken during high-dose UVA1 therapy. Objectives: To assess the phototoxicity risk of SJW ingestion. Methods: Eleven adult volunteers of skin types I and II were exposed to a geometric dose series of UVA1 irradiation from a high-output source (Dermalight Ultra 1; Dr H nle, Martinsreid, Germany; irradiance 70- 77 mW cm- 2) on the photoprotected lower back skin at eight 1.5-cm2 test areas. Irradiation was carried out at baseline and after 10 days of SJW extract 1020 mg (equivalent to 3000 μ g of hypericin) daily. Four, 8, 24 and 48 h after each exposure, the minimal erythema dose (MED) and the presence or absence of pigmentation were recorded visually and erythema was assessed objectively with an erythema meter. Results: The median MED and D0.025, an objective measure of MED, were lower at all time-points after SJW ingestion. The visual erythemal peak (lowest median MED), which was seen at 8 h postirradiation, was lower after SJW (median 14 J cm- 2, range 10- 56) than at baseline (median 20 J cm- 2, range 14- 56) (P = 0.047). Similarly, the median D0.025 at 8 h postirradiation was lower after SJW(median 22.0 J cm- 2, range 15.2- 53.9) than at baseline (median 33.7 J cm - 2, range 22.9- 136.0) (P = 0.014). The MED and D0.025 were also significantly different at the 48-h and 4-h time-points, respectively. Significance was not reached at the 24-h time-point. Median intensity of postirradiation erythema increased at all time-points after ingestion of SJW. Despite these differences, the maximum slope of the dose-response curve was not increased after SJW ingestion. Conclusions: These data suggest that SJW extract has the potential to lower the erythemal threshold to UVA1 irradiation in a significant proportion of individuals and highlight the importance of ascertaining a full drug history, including herbal remedies, before initiating UVA1 phototherapy.展开更多
Photopatch test (PhPT) interpretation is difficult and clinical relevance is n ot always apparent. A positive PhPT may reflect photocontact allergy or phototox icity. We hypothesized that it may also reflect the addit...Photopatch test (PhPT) interpretation is difficult and clinical relevance is n ot always apparent. A positive PhPT may reflect photocontact allergy or phototox icity. We hypothesized that it may also reflect the additive or synergistic effe cts of a suberythemal reaction to a contact irritant [e.g. sodium lauryl sulfat e (SLS)] or allergen (e.g. nickel) and suberythemal UV exposure. 10 nickel aller g ic volunteers had duplicate SLS and nickel series applied on either side of the back for 24 h and 48 h, respectively. After removal, one side was irradiated wit h 5J/cm2 UVA or the dose below the minimal erythema dose for solar-simulated ra diation (SSR). The minimal irritancy dose (MID) for SLS and the minimal allergen ic dose (MAD) for nickel were determined visually and objectively by erythema me ter. While photoaugmentation of subclinical contact allergy or irritancy occurre d in some subjects, photosuppression occurred in roughly an equal number. UVA ch anged the nickel MAD at 48 h in 2 of 5 volunteers but not the SLS MID. SSR chang ed the nickel MAD in 4 of 5 and the SLS MID in 3 of 5. 2 subjects (none after UV A) showed erythema only in the irradiated set of p atches, which could have been interpreted as a positive PhPT. We have demonstrat ed photoaugmentation and photosuppression of contact allergy and irritancy, whic h could result in false-positive or false-negative interpretation of PhPTs.展开更多
文摘Background: St John s wort (SJW) is widely used as a treatment for depression. A phototoxic reaction, due to its content of hypericin, can occur in animals and in cell culture, and has been reported in humans. Hypericin displays absorption within the ultraviolet (UV) A1 spectrum and there may therefore be a potential for phototoxicity if taken during high-dose UVA1 therapy. Objectives: To assess the phototoxicity risk of SJW ingestion. Methods: Eleven adult volunteers of skin types I and II were exposed to a geometric dose series of UVA1 irradiation from a high-output source (Dermalight Ultra 1; Dr H nle, Martinsreid, Germany; irradiance 70- 77 mW cm- 2) on the photoprotected lower back skin at eight 1.5-cm2 test areas. Irradiation was carried out at baseline and after 10 days of SJW extract 1020 mg (equivalent to 3000 μ g of hypericin) daily. Four, 8, 24 and 48 h after each exposure, the minimal erythema dose (MED) and the presence or absence of pigmentation were recorded visually and erythema was assessed objectively with an erythema meter. Results: The median MED and D0.025, an objective measure of MED, were lower at all time-points after SJW ingestion. The visual erythemal peak (lowest median MED), which was seen at 8 h postirradiation, was lower after SJW (median 14 J cm- 2, range 10- 56) than at baseline (median 20 J cm- 2, range 14- 56) (P = 0.047). Similarly, the median D0.025 at 8 h postirradiation was lower after SJW(median 22.0 J cm- 2, range 15.2- 53.9) than at baseline (median 33.7 J cm - 2, range 22.9- 136.0) (P = 0.014). The MED and D0.025 were also significantly different at the 48-h and 4-h time-points, respectively. Significance was not reached at the 24-h time-point. Median intensity of postirradiation erythema increased at all time-points after ingestion of SJW. Despite these differences, the maximum slope of the dose-response curve was not increased after SJW ingestion. Conclusions: These data suggest that SJW extract has the potential to lower the erythemal threshold to UVA1 irradiation in a significant proportion of individuals and highlight the importance of ascertaining a full drug history, including herbal remedies, before initiating UVA1 phototherapy.
文摘Photopatch test (PhPT) interpretation is difficult and clinical relevance is n ot always apparent. A positive PhPT may reflect photocontact allergy or phototox icity. We hypothesized that it may also reflect the additive or synergistic effe cts of a suberythemal reaction to a contact irritant [e.g. sodium lauryl sulfat e (SLS)] or allergen (e.g. nickel) and suberythemal UV exposure. 10 nickel aller g ic volunteers had duplicate SLS and nickel series applied on either side of the back for 24 h and 48 h, respectively. After removal, one side was irradiated wit h 5J/cm2 UVA or the dose below the minimal erythema dose for solar-simulated ra diation (SSR). The minimal irritancy dose (MID) for SLS and the minimal allergen ic dose (MAD) for nickel were determined visually and objectively by erythema me ter. While photoaugmentation of subclinical contact allergy or irritancy occurre d in some subjects, photosuppression occurred in roughly an equal number. UVA ch anged the nickel MAD at 48 h in 2 of 5 volunteers but not the SLS MID. SSR chang ed the nickel MAD in 4 of 5 and the SLS MID in 3 of 5. 2 subjects (none after UV A) showed erythema only in the irradiated set of p atches, which could have been interpreted as a positive PhPT. We have demonstrat ed photoaugmentation and photosuppression of contact allergy and irritancy, whic h could result in false-positive or false-negative interpretation of PhPTs.
