Phototoxicity and photoallergy.
ABSTRACT Photosensitivity may be phototoxic or photoallergic. Phototoxicity is much more common. There are 2 types of phototoxicity: photodynamic, which requires oxygen, and nonphotodynamic, which does not. Reactions induced by porphyrin molecules, coal tar derivatives, and many drugs are photodynamic. The reaction induced by psoralens, for the most part, is nonphotodynamic. Acute phototoxic reactions are characterized by erythema and edema followed by hyperpigmentation. Long-term ultraviolet phototoxicity results in chronic sun damage and skin cancer formation. Also, certain chemicals such as psoralen molecules and coal tar are photocarcinogenic. Phototoxic reactions to certain drugs produce unusual clinical patterns, that is lichenoid eruptions, dyschromia, photo-onycholysis, and pseudoporphyria. Photoallergy is an uncommon acquired altered reactivity dependent on an immediate antibody or a delayed cell mediated reaction. Solar urticaria is an example of the former, whereas photoallergy to exogenous chemicals is an example of the latter. Photoallergy to systemic drugs does occur but is difficult to characterize. The action spectrum for photoreactions to exogenous agents usually at least includes the ultraviolet A rays for both phototoxicity and photoallergy.
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ABSTRACT: Background Voriconazole, a broad-spectrum triazole antifungal agent increasingly used to treat aspergillosis, has been linked with acute photosensitivity and skin carcinogenesis. The action spectrum of the photosensitivity is unknown, whilst an indirect retinol effect secondary to the anti-fungal's impact on CYP450 enzymes has been proposed to contribute to the underlying mechanism. Objectives To perform a detailed photobiological assessment of the photosensitivity presenting in a series of 12 voriconazole treated patients. Results Patients (8 male, 4 female; median age 54y, range 40-63y) experienced moderate-severe cutaneous erythema (n=12), burning pain (n=5), itching (n=3), scaling (n=5), vesiculation (n=5) and oedema (n=1) following sunlight exposure; increased lentigines (n=5) and actinic cheilitis (n=3) were also observed. While the majority (n=8) of patients showed normal minimal erythemal (MED) thresholds to monochromator phototesting to UVB, UVA and visible light, a low MED to UVA was observed in 4 patients. Repeated provocation testing with broadband UVA and solar simulated radiation (SSR) provoked an abnormal erythema in 8 and 10 patients, respectively. Serum retinol levels were mildly elevated in 2 patients but normal in the majority Conclusion UVA sensitivity is the predominant finding in acute voriconazole induced photosensitivity. We found little evidence of elevated circulating retinol as the causal factor. Patients with voriconazole-induced photosensitivity require education in appropriate UVA protective measures in addition to consideration of skin surveillance for malignant sequelae.British Journal of Dermatology 08/2012; · 3.76 Impact Factor
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ABSTRACT: BACKGROUND In screening pharmaceuticals for possible carcinogenic effects we noted an association between lip cancer risk and the photosensitizing antihypertensive drugs hydrochlorothiazide and nifedipine. In this study, we further characterized the risk of lip cancer associated with these and other commonly used antihypertensive drugs. METHODS In a comprehensive medical care program, we evaluated prescriptions dispensed and cancer occurrence from August 1, 1994, to February 29, 2008. We identified 712 patients with lip cancer (cases) and 22 904 comparison individuals (controls) matched for age, sex, and cohort year of entry in the susceptible group, non-Hispanic whites. We determined use, at least 2 years before diagnosis or control index date, of the commonly prescribed diuretics hydrochlorothiazide and hydrochlorothiazide combined with triamterene, the angiotensin-converting enzyme inhibitor lisinopril, the calcium channel blocker nifedipine, and the β-adrenergic blocker atenolol, the only nonphotosensitizer agent studied. We analyzed the use of each drug exclusively and regardless of use of the others, and focused on duration of use. Conditional logistic regression was used for analysis of matched case-control sets, with control for cigarette smoking. RESULTS At least a 5-year supply of a drug yielded the following odds ratios (95% CIs), respectively, compared with no use: hydrochlorothiazide, 4.22 (2.82-6.31); hydrochlorothiazide-triamterene, 2.82 (1.74-4.55); lisinopril, 1.42 (0.95-2.13); nifedipine, 2.50 (1.29-4.84); and atenolol, 1.93 (1.29-2.91). When the other drugs were excluded, the odds ratio for atenolol was reduced to 0.54 (0.07-4.08). CONCLUSION These data support an increased risk of lip cancer in non-Hispanic whites receiving treatment for hypertension with long-term use of photosensitizing drugs.Archives of internal medicine 08/2012; 172(16):1246-51. · 11.46 Impact Factor
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ABSTRACT: Although there have been recent advances in the development of photoprotective clothing and broad-spectrum sunscreens, few peer-reviewed publications have focused on photoprotection recommendations for travelers. In order to describe the adverse health effects of excessive ultraviolet (UV) radiation exposures; review recent studies of public perceptions regarding photoprotection and sun exposure behaviors; identify special populations at increased risks of drug-induced photosensitivity reactions and UV-induced skin cancers; and recommend several effective photoprotection strategies for travelers, Internet search engines were queried with the key words as search terms to examine the latest references on photoprotection and the epidemiology of UV-associated skin cancers. Observational studies have demonstrated that the public knows little about proper sunscreen protection, selection, and use, and often abuses sunscreens for intentional UV overexposures. Cohort studies have identified special populations at increased risks of UV-associated skin cancers without the proper use of sunscreens and photoprotective clothing including children, fair-skinned persons, patients taking photosensitizing drugs, and organ transplant recipients (OTRs). Clinical investigations support the regular use of broad-spectrum sunscreens to prevent the development of premalignant actinic keratoses (AK) in all sun-exposed subjects, especially OTRs; to prevent the development of squamous cell carcinomas from new AK in sun-exposed subjects, especially OTRs; to possibly prevent the development of cutaneous malignant melanomas in children and adults; and to possibly prevent the development of basal cell carcinomas in OTRs. Recommended photoprotection strategies for travelers should include avoiding intense sunlight, wearing photoprotective clothing, wearing sunglasses, and selecting the right sunscreen for their skin type. Travel medicine practitioners should counsel travelers about photoprotection and encourage travelers to take advantage of recent advances in the development of more effective broad-spectrum sunscreens and photoprotective clothing for themselves and their children.Journal of Travel Medicine 03/2013; 20(2):108-18. · 1.68 Impact Factor