The invention relates to a pharmaceutical composition comprising: a tyrosine hydroxylase inhibitor； and melanin, a melanin promoter, or a combination thereof. The invention also relates to a tyrosine hydroxylase inhibitor that is a-methyl-DL-tyrosine for use in treating cancer. Pharmaceutical compositions and kits including a tyrosine hydroxylase inhibitor； melanin, a melanin promoter, or a combination thereof； a p450 3A4 promoter； and a leucine aminopeptidase inhibitor are also provided. Also provided is the treatment of cancer in a subject, comprising administering an effective amount of a tyrosine hydroxylase inhibitor, a melanin promoter, a p450 3A4 promoter, and a leucine aminopeptidase inhibitor to the subject in need thereof. Also provided are means of reducing cell proliferation in a subject comprising administering an effective amount of a tyrosine hydroxylase inhibitor, a melanin promoter, a p450 3A4 promoter, and a leucine aminopeptidase inhibitor to the subject in need thereof.
