The purpose of this study is three-fold. First, researchers will assess whether subjects who have clinically abnormal reactions to sunlight (photosensitivity) have increased levels of microvesicle particles (MVP) following ultraviolet B (UVB) treatment to localized area of skin. Second, researchers will assess if topical application of the medicine imipramine will block UVB-induced MVP release. Third, researchers will assess if the topical cream will block UVB-induced increased erythema reactions (reddening of the skin).

Inclusion Criteria:

• Female and Male adult subjects age 18 to 50
• Must be able to give informed consent
• Have access to stable transportation
• All skin types on Fitzpatrick Scale (Type I-VI)
• Self-Identified photosensitivity
• Able to provide medical history and list of medications-control subjects will not be allowed to be taking a medication that is known to be photosensitizer.

Exclusion Criteria:

• Underlying diseases that could affect wound healing (e.g., uncontrolled diabetes mellitus)
• Taking medications that are known photosensitizers (e.g., doxycycline) or anti-inflammatories (e.g., NSAIDS [except for low-dose aspirin] or steroids)
• Utilizing imipramine or any other tricyclic antidepressant (oral or cream)
• Utilizing topical anti-inflammatory or systemic agents (e.g., prednisone)
• Large tattoos in the designated testing areas
• Tanning bed use within last 3 months
• Photodynamic Therapy or UVB treatments in past 3 months
• Female Subjects: pregnant or nursing
• History of abnormal scarring (i.e., keloids)