Photosensitivity associated with systemic triflusal therapy

Abstract

To the Editor, Triflusal (2-acetyloxy-4-trifluoromethylbenzoic acid) is a fluorinated acetylsalicylic acid analogue used as an antiplatelet drug for prophylaxis of thromboembolic disease. Its main side effects are those concerning the gastrointestinal system. We report a systemic photosensitivity and a solar urticaria in a patient under triflusal therapy. A 72-year-old man, with Fitzpatrick skin phototype II and medical history of hypertension undergoing treatment with olmesartan since 2005, was diagnosed with a carotid stenosis in September 2011; therefore, triflusal (300 mg/12 h) was prescribed. Two years later, he was sent to our Photobiology Unit because of outbreaks of eczematous lesions involving the photoexposed areas of his face, neck and hands (Fig. 1a). Those lesions had appeared 1 month after the introduction of triflusal, and persisted despite the use of topical corticosteroids and oral antihistamines. He was taking no other medication. In order to rule out a systemic photosensitivity, phototesting was performed on the skin of his lower back, using a solar simulator to test UVB and UVA (Xenon arc 16S; Solar Light Co., Philadelphia, PA, USA) and a slide projector to test visible light (GAF 502 Autofocus slide projector lamp). The doses we used were from 3.7 to 24.7 mJ/cm for UVB and from 0.5 to 10 J/cm for UVA. An urticarial reaction was observed 15 min after UVB irradiation (>3.7 mJ/cm) (Fig. 1b) and UVA irradiation (>0.5 J/cm) (Fig. 1c), whereas visible light showed a negative response. These lesions were highly pruritic and cleared after 30 min. Moreover, the minimal erythema dose to UVB (UVB-MED) was 10 mJ/cm (normal value 28 4 mJ/cm, pathologic value <19 mJ/cm) (1) and response to UVA was abnormal (erythema after a single dose of 10 J/cm) (Fig. 1d). He was asked to discontinue triflusal, which was replaced by acetylsalicylic acid (ASA), with a subsequent improvement of his lesions. One week after this switch, the patient was almost asymptomatic, the UVB-MUD had risen to 13.5 mJ/cm and there was no urticarial response to UVA (up to 10 J/cm). A new phototest was performed 2 months later, showing a negative response to UVA and a UVB-MED of 24.7 mJ/cm (an increase above 70% of the previous one). Photopatch tests were also performed with the baseline series of the Spanish Group of Photobiology (MartiTor, Barcelona, Spain) being applied in duplicate to the skin of the upper back, extended with triflusal, 2-hydroxy-4-trifluoromethylbenzoic acid (HTB, the triflusal active metabolite) and ASA. All of them were prepared by the hospital pharmacy at 1% in petrolatum and were applied in triplicate to the skin of the upper back. After 2 days, one set was removed and irradiated with 5 J/cm UVA, and the set of triflusal, HTB and ASA was also removed and irradiated with a sub-UVB-MED dose (17.3 mJ/cm). Readings were done immediately, at 30 min, 60 min, days 1, 2 and 3 postirradiation. Immediate reading was negative, whereas a palpable erythemato-edematous reaction was observed at day 1 postirradiation only in triflusal and HTB UVB photopatches. A weak non-palpable erythema was also noticed in the same patches irradiated with UVA (Fig. 2). Laboratory tests were also performed in