Primary Photosensitization or Type I
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PRIMARY PHOTOSENSITIZATION OR TYPE I
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Primary photosensitization occurs when the photodynamic agent is absorbed either through the skin or from the GI tract unchanged, reaching the skin in its native form.
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Examples of primary photosensitizers are hypericin (from Hypericum perforatum [St. John’s wort]).
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Plants in the families Umbelliferae and Rutaceae contain photoactive furocoumarins, which cause photosensitization in livestock and poultry.
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Ammi majus (Bishop’s weed) and Cymopterus watsonii (spring parsley) have produced photosensitization in cattle and sheep, respectively.
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Species of Trifolium , Medicago (clovers and alfalfa), Erodium , Polygonum , and Brassica have been incriminated as primary photosensitizers.
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Many other plants have been suspected, but the toxins responsible have not been identified.
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Additionally, some coal tar derivatives, phenothiazine, sulfonamides and tetracyclines have induced primary photosensitivity.
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Last modified: Sunday, 18 December 2011, 12:05 AM