The present invention generally relates to compositions and methods for the delivery of tetrahydrobiopterin and/or related compounds through the skin. In general, tetrahydrobiopterin may react with oxygen, and various formulations discussed herein may prevent or reduce the ability of tetrahydrobiopterin to react with oxygen. For example, in some aspects, the tetrahydrobiopterin may be contained with a composition comprising a lecithin, such as phosphatidylcholine. In certain embodiments, the lecithin is present in liposomes, micelles, liquid crystals, or other configurations. The composition can take the form of a gel, a cream, a lotion, an ointment, a solution, a solid “stick,” etc., that can be rubbed or sprayed onto the skin. Other aspects of the present invention are generally directed to methods of making or using such compositions, methods of promoting such compositions, kits including such compositions, or the like.
