photosensitization

n.
The act or process of inducing photosensitivity.

(fō'tō-sĕn'sĭ-tĭ-zā'shən)
n.

The act or process of inducing photosensitivity.

The development of abnormally heightened reactivity of the skin to sunlight. In food animals the principal photodynamic agents are porphyrins and phylloerythrin. The principal clinical manifestations are as dermatitis and conjunctivitis. There may be an accompanying hepatic insufficiency or porphyrinuria. See liver dysfunction, photosensitive dermatitis. Called also light sensitization.
There is a long list of drugs that can cause photosensitization reactions. Antineoplastics, antimicrobials, diuretics, hypoglycemic agents, and even antihistamines are capable of triggering photosensitivity reactions in certain individuals.

• inherited p. — in Corriedale and Southdown sheep is caused by an inherited liver transport defect. The liver is histologically normal but phylloerythrin excretion is impeded. Photosensitive dermatitis appears as soon as the lambs begin to eat grass.
• primary p. — caused by the ingestion of exogenous photosensitizing agents such as dianthrone derivatives (e.g. hypericin, fagopyrin), furanocoumarins, perloline, phenothiazine, rose bengal.
• secondary p. — secondary to hepatic cell damage, biliary obstruction leading to the accumulation in the body of phylloerythrin, a metabolic end-product of chlorophyll.