Hi,
MT-II will not reverse the greying of hair. The greying of hair occurs because the melanocyte stem cells (McSCs) in hair follicles stop functioning as we age. This leads to the loss of melanin producing melanocytes that give pigmentation to our hair.
The mechanism by which MT-II darkens hair is by stimulating melanocytes to produce more melanin. The grey in your hair is a sign that the McSCs in your hair follicle have stopped functioning and there are no longer any melanocytes for MT-II to stimulate.
You may be able to darken the pigmentation of "peppered" hair, as there are still some functioning McSCs. How ever, the hair that is grey, will stay grey.
I think the risk profile of MT-II and potential increased risk of Melanoma is not worth it in your scenario. Using some hair dye will get the job done just fine .
Sources:
FitzGerald, Liesel M., et al. "Effect of MELANOTAN®,[Nle4, D-Phe7]-α-MSH, on melanin synthesis in humans with MC1R variant alleles."
Peptides 27.2 (2006): 388-394.
The stem cells responsible for hair color switch between stem cell and maturing states, but with age can get stuck and become unable to perform either function.
www.nih.gov