1. Field of the Invention
This invention is directed to methods and compositions for the oral administration of niacin for the prevention of photocarcinogenesis and photoimmunosuppression.
2. Description of the Background
Nonmelanoma skin cancers are the most frequent of human cancers, approximating 62.5% of the expected incidence for all non-skin cancers combined (Parker, S L et al., CA Cancer J Clin 47, 5-27, 1997). Nonmelanoma skin cancers have been increasing in incidence at an annual rate of 3-6% (Gallagher, R P et al., J Am Acad Dermatol 23, 413-421, 1990). The increase in nonmelanoma skin cancer rate is likely due to an increase in lifetime exposure to UV radiation caused by a longer life expectancy and ozone depletion (Moseley, H, and Mackie, R M, Brit J Dermatol 137, 101-103, 1997). Nonmelanoma skin cancers represent considerable morbidity (Johnson M L et al., J Am Acad Dermatol 11: 930-936, 1984). Both squamous cell carcinoma and basal cell carcinoma can be invasive and tend to present as multiple primary tumors on visible areas of the body (Kwa, R E, et al., J Am Acad Dermatol 26, 1-26, 1992; Miller, S J, J Am Acad Dermatol 24, 1-13, 1991; Miller, S J, J Am Acad Dermatol 24, 161-175, 1991; Schreiber, M M, J Am Acad Dermatol 23, 1114-1118, 1990). The use of sunscreens alone may not be sufficient protection against skin cancer development (Naylor, M F et al., Arch Dermatol 131, 170-175, 1995). These observations indicate an increasing need for novel skin cancer prevention strategies.
It is an object of the invention to suppress or reverse photoimmunosuppression and photocarcinogenesis in a subject.
One embodiment of the invention is directed to a method for reducing photocarcinogenesis or photoimmunosuppression in a subject. In the method, one or more oral administration of a pharmaceutical composition is given to the subject. The pharmaceutical composition comprises niacin in an amount effective to reduce photocarcinogenesis or photoimmunosuppression. The pharmaceutical composition may optionally comprise a pharmaceutically acceptable carrier. The method may be used to reduce, eliminate, prevent or reverse photocarcinogenesis. Further, the method may be used to reduce, eliminate, prevent or reverse photoimmunosuppression.
The subject to be treated may be any animal. Thus, the subject may be a mammal, such as, for example, a human.
The pharmaceutical composition may contain niacin in an amount such that the dosage to be administered orally is between 1 mg niacin per kilogram of subject weight to about 100 mg per kilogram of subject weight. Preferably, the dosage is between 10 mg niacin per kilogram of subject weight to about 40 mg per kilogram of subject weight.
The photoimmunusuppression and photocarcinogenesis referred to in this application may be caused by natural or artificial means. Natural means include direct or reflected sunlight. Artificial means include all man made ultraviolet light sources such as UV lamps, residue UV from lighting fixtures, and ultraviolet light emitted from industrial processes and methods of manufacture.