Drug-Induced Photosensitivity: Clinical Types of Phototoxicity and Photoallergy and Pathogenetic Mechanisms

Abstract

Drug-induced photosensitivity (DIP) is a common cutaneous adverse drug reaction, resulting from the interaction of ultraviolet radiations, mostly ultraviolet A, with drugs. DIP includes phototoxicity and photoallergy. A phototoxic reaction is obtained when topical and systemic drugs or their metabolites absorb light inducing a direct cellular damage, while a photoallergic reaction takes place when the interaction between drugs and ultraviolet radiations causes an immune cutaneous response. Clinically, phototoxicity is immediate and appears as an exaggerated sunburn, whereas photoallergy is a delayed eczematous reaction. DIP may show several clinical subtypes. In this mini-review we report the pathogenetic mechanisms and causative drugs of DIP. We offer a detailed description of DIP clinical features in its classical and unusual subtypes, such as hyperpigmentation/dyschromia, pseudoporphyria, photo-onycolysis, eruptive teleangiectasia, pellagra-like reaction, lichenoid reaction, photodistributed erythema multiforme and subacute/chronic cutaneous lupus erythematosus. We described how physicians may early recognize and manage DIP, including diagnostic tests to rule out similar conditions. We made suggestions on how to improve sun exposure behaviors of patients at risk of DIP by means of an aware use of sunscreens, protective clothing and recent technologic tools. We highlighted the lack of sun safety programs addressed to patients at risk of DIP, who need a formal education about their condition.

Dronedarone‐induced phototoxic dermatitis

“…Dear Editor, Drug-induced photosensitivity (DIP) occurs when a medication causes an unexpected eruption on sun-exposed skin. [1][2][3] We present a case of a patient with severe dronedaroneinduced phototoxicity.…”

“…

Dronedarone-induced phototoxic dermatitisDear Editor, Drug-induced photosensitivity (DIP) occurs when a medication causes an unexpected eruption on sun-exposed skin. [1][2][3] We present a case of a patient with severe dronedaroneinduced phototoxicity.An 85-year-old woman, with a past medical history of atrial fibrillation, chronic kidney disease, hypertension, and hyperlipid-

…”

“…There is often an overlap between the two patterns. 1,3 Phototoxicity is mediated by direct tissue and oxygen-mediated cell damage caused by a photoproduct. It is dose-dependent and manifests as a severe sunburn with erythema, edema, vesicles, and bullae, followed by hyperpigmentation.…”

“…In contrast, photoallergy requires prior sensitization; it is caused by a photoproduct leading to a type IV hypersensitivity reaction and occurs at least 24 hours following sun exposure. 3,4 Photoallergy symptoms are similar to acute allergic contact dermatitis with vesicles and scaling that may develop on unexposed skin with no chronic phase. 1,3 Histologically, acute phototoxic dermatitis results in apoptotic keratinocytes with dermal edema and secondary infiltrate of neutrophils and lymphocytes, while photoallergic drug reactions are characterized by spongiosis, vesiculation, exocytosis of lymphocytes into the epidermis, and perivascular inflammation with or without eosinophils.…”

Photodistributed eruptive telangiectasias: an uncommon adverse drug reaction. A retrospective case series

“…Although the efficacy of photoprotection in preventing drug-induced PT is not demonstrated in the literature, it is known that sun-protection measures may help patients to avoid discontinuing photosensitive drugs. 15 For that reason, we always recommend sunscreen use to patients with a history of drug-induced PT, especially in those who cannot discontinue or change the culprit drug. Systemic photoprotection with oral nicotinamide may also be useful in patients with drug-induced PT.…”