Photoallergic reaction

The drug is effective against all four types of malaria with the exception of chloroquine-resistant P. falciparum Chloroquine destroys the blood stages of the infection and therefore ameliorates the clinical symptoms seen in P. malariae, P. vivax, P. ovale, and sensitive P. falciparum forms of malaria. The disease will return in P. vivax and P. ovale malaria, however, unless the liver stages are sequentially treated with primaquine after the administration of chloroquine. Chloroquine also can be used prophylactically in areas where resistance does not exist. In addition to its use as an antimalarial, chloroquine has been used in the treatment of rheumatoid arthritis and lupus erythematosus (see Chapter 36), extraintestinal amebiasis, and photoallergic reactions. 

There is also a case report of photoallergic reactions to intravenous pyridoxine hydrochloride.122... 

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

Chlorpromazine [2-chloro-A-(3-dimethylaminopropyl)phenothiazine] is a frequently prescribed antipsychotic drug which causes both phototoxic and photoallergic reactions [49,50], UV irradiation of chlorpromazine (C1PZ) in solution is known to produce the chlorpromazine cation radical [51], as well as other photoproducts, which may go through radical intermediates [52], Under UV irradiation, the aryl radical resulting from dechlorination of chlorpromazine has been trapped using 2-methyl-2-nitrosopropane (MNP),... 

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. 

Photosensitivity after administration of ribavirin has been described (20). A well-documented photoallergic reaction in a woman who was taking both ribavirin and interferon alfa provided evidence that ribavirin is a potential photosensitizer for UVB, a problem that may become increasingly relevant in patients with chronic hepatitis C taking combination therapy for 6-12 months with interferon alfa and ribavirin (20). 

With photoallergic reactions, cytopathologic events are believed to be even more complex than with direct phototoxicity. Although many mechanistic features remain obscure, fundamental concepts include the photoactivation of endogenous or xeno-biotic haptens so that they combine with cellular proteins and form a complete antigen. Subsequent immunologic reactions, especially cell-mediated hypersensitivity, complete the sensitivity process. 

In the case of photoallergic reactions, the formation of heteroadducts plays an important role. It comprises the combination of exogenous molecules... 

Usually, but not invariably, dermatologic lesions are restricted to light-exposed areas. Changes may vary from urticaria to papular and eczematous eruptions with subsequent exfoliation and lichenification. Microscopically, it is very difficult to distinguish photoallergic reactions from nummular eczema, atop dermatitis, eczematous drug eruptions, and, especially, allergic contact dermatitis. 

Simoneaux PW, Curr Concept Skin Dis Winter, 15 (1980) Koranda FC, ] Am Acad Dermatol 4, 650 (passim) Lymphoproliferative disease (1980) Schechter SL+, Arthritis Rheum 23, 256 Photoallergic reaction... 

There are two main types of photosensitive reactions the phototoxic and the photoallergic reaction. 

Photoallergic reactions may occur as a result of exposure to systemically administered drugs such as griseofulvin, NSAIDs, phenothiazines, quinidine, sulfonamides, sulfonylureas, and thiazide diuretics as well as to external agents such as para-aminobenzoic acid (found in sunscreens), bithionol (used in soaps and cosmetics), paraphenylenediamine, and others. 

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. 

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