Contact dermatitis (CD) refers to localized skin inflammation elicited by an exogenous substance. It is characterized by blistering, redness, burning and itching. The two subtypes are irritant contact dermatitis (ICD) and allergic contact dermatitis (ACD). ICD accounts for about 80% of patients and occurs when the offending substance has direct cytotoxic effects leading to activation of the innate immune system. Conversely, ACD is a delayed-type hypersensitivity reaction that is stimulated when skin comes into contact with a substance to which it was previously exposed. While there are no FDA-approved treatments for CD, calcineurin inhibitors and corticosteroids are used, the latter of which can cause ACD in some individuals.
It has been estimated that up to 20% of the population is affected by CD; furthermore, it is a common occupation-related illness. In the United States if has been estimated to cost in excess of $1 billion annually due to reduced productivity, lost work, medical costs and disability payments.
Hemorrhoids are a very common anorectal condition with estimates that up to 75% of people will experience them during their lifetime. Currently, the National Institute of Diabetes and Digestive Kidney Diseases estimates the prevalence to be 12.5 million adults in the United States. Hemorrhoids are characterized by degradation of the connective tissue within the anal canal concomitant with inflammation and swelling of the veins around the lower rectum and anus. The most common complications of hemorrhoids include pain, itching, bleeding, and difficulty defecating. Although no FDA-approved prescription treatment exists for hemorrhoids, both suppository and topical formulations of corticosteroids and vasoconstrictors are widely used to treat the symptoms associated with hemorrhoids. According to IMS there are over 3 million prescriptions written each year for hemorrhoids, in addition to 22 million over the counter units.
An anal fissure (AF) is a tear in the anal canal causing bleeding and severe pain during bowel movements. AFs are relatively common with an estimated lifetime incidence of 11% and greater than 4 million people currently afflicted in the USA. Anal fissures can be acute and heal over a few weeks or they can become chronic and require treatment. Increased resting sphincter muscle tone and decreased blood flow are hypothesized to contribute to the pathogenesis of AFs with current off-label treatments seeking to address these contributing factors. Currently the only approved treatment for AFs is a nitroglycerin ointment.