Phototoxicity, drug-induced

Morliere, P. (1986) Drug-induced photosensitivity phototoxic and photoallergic reactions-a few molecular aspects, Biochemie 68, 849-855. 

Drug-induced photosensitivity reactions are divided into phototoxicity (a nonimmunologic reaction) and photoallergic reactions (an immunologic reaction). The latter form is far less common. Medications associated with photosensitivity reactions include fluoroquinolones, nonsteroidal antiinflammatory drugs, phenothiazines, antihistamines, estrogens, progestins, sulfonamides, sulfonylureas, thiazide diuretics, and tricyclic antidepressants. 

Precautionary measmes on melasma-inducing factors such as OCPS, scented cosmetics, phototoxic drugs, and pregnancy. 

Harber LC, Bickers DR (1989) Drug induced photosensitivity (phototoxic and photoallergic drug reactions). In Photosensitivity diseases principles of diagnosis and treatment, 2nd edn. Decker, Toronto, pp 160-202 Hare PJ (1951) A case of occupational iron pigmentation of the skin. Br J Dermatol 63 63-66... 

Selvaag, E., Anholt, H., Moan, J., and Thune, R, Inhibiting effects of antioxidants on drug-induced phototoxicity in ceU cultures. Investigation with sulphonamide-derived oral antidiabetics and diuretics,/. Photochem. Photobiol B Biol, 38, 88,1997. 

Figure 19.1 Mechanisms involved in sunlight-induced phototoxicity of drugs. Type 1 photosensitization (electron transfer) mainly generates singlet oxygen Oj", whereas type 2 reaction (energy transfer) leads to adduct formation or singlet oxygen...

K. Shimoda, M. Nomura, and M. Kato, Effect of antioxidants, antiinflammatory drugs, and histamine antagonists on sparfloxacin induced phototoxicity in mice. Fundam. Appl. Toxicol. 31 133-140, 1996. 

Photodynamic ACT (PACT), similar to photodynamic therapy (PDT) described in Chapter 17, utilizes photosensitizers and visible or UV light in order to induce a phototoxic response, usually via oxidative damage. For some time the disinfection of blood products, particularly for viral inactivation, has been the major use of PACT, although more and more clinically based protocols are being developed, eg in the treatment of oral infections. The technique has been shown to be effective in vitro against bacteria (including drug resistance strains), yeasts, viruses, and parasites. 

Some of the dyes that are photolabile have been reported to cause phototoxic effects. For example, curcumin has demonstrated phototoxicity to mammalian cells (20). Methylene blue in eye solutions was reported to induce toxic effects (21). It is important, therefore, that drugs and excipients used in product formulations be screened for their photostability as well as photosensitizing effects. 

UV exposure is known to induce photosensitive responses in humans. Photosensitivity is an adverse reaction that occurs when a chemical or drug is applied to the skin or taken internally at the same time that one is exposed to UV. Not all people are photosensitive to the same agents. Two distinct responses are observed phototoxic and photoallergic reactions. 

For example, tetracycline (506), a broad-spectrum antibiotic, and its derivatives are known to induce phototoxic or photoallergic reactions that involve photosensitization of biomolecules by the drug or the formation of one or more photoproducts and their subsequent photoreactions.1383 Singlet oxygen is probably involved. 

Harber, L. C., Bickers, D. R., Dmg Induced Photosensitivity (Phototoxic and Photoallergic Drug Reactions). In Harber, L. C., Bickers, D. R. (eds), Photosensitivity Diseases. Principles of Diagnosis and Treatment, 2nd edn, Marcel Decker, Toronto, 1986, pp. 160 202. 

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