Photosensitivity

Question 1

Drug Induced Photosensitivity

Answer 1

A skin reaction caused by exposure to sunlight. It is caused most often by the interaction of a drug and exposure to:

• ultraviolet A (UVA) light which can cause cellular damage.

However ultraviolet B (UVB) light may also contribute to drug Induced Photosensitivity reactions.

Question 2

Two types of Photosensitivity reactions:

Answer 2

-Photoallergic reaction(caused by previous exposure or sensitization, to the offending agent) -occurs when a drug (ex: sulfonamide) undergoes activation in the skin by ultraviolet light to a compound that is more allergenic than the parent compound.

-Phototoxic reactions-(result of a drug dose)-a photosensitive drug undergoes photochemical reactionswithin the skin to cause damage. This reaction is not immune mediated.

The onset of a photo toxic reaction with erythema can be rapid, occurring within 2 to 6 hours of sunlight exposure.

Question 3

How Photosensitivity reactions can be avoided:

Answer 3

-Uding sunscreen with a sun protection factor (SPF) greater than 15.
-Avoiding excessive sunlight (especially in the height of daylight hours)
-wearing protective clothing