Effects of a superpotent melanotropic peptide in combination with solar UV radiation on tanning of the skin in human volunteers.
OBJECTIVE
Three phase 1 clinical trials of a superpotent melanotropic peptide, melanotan-1 (MT-1, or [Nle(4)-D-Phe(7)]alpha-melanocyte-stimulating hormone) were performed to demonstrate safety for MT-1 therapy combined with UV-B light or sunlight.


METHODS
Open-label studies at 2 dose levels of MT-1 combined with small doses of UV-B to the neck or buttock or full sunlight to half of the back.


METHODS
Dermatology clinics at the Arizona Health Sciences Center, Tucson.


METHODS
The first study randomized 4 subjects to MT-1 (0.08 mg/kg per day subcutaneously) and 4 subjects to injections of isotonic sodium chloride (9%) solution for 10 days, followed by neck irradiation with 3 times the minimal erythema dose (MED) of UV-B light. In the next study (n = 12), the MT-1 dosage was increased to 0.16 mg/kg per day for 10 days, with UV-B radiation (0.25-0.75 MED) given to a buttock site for 5 days during (n = 7) or after (n = 5) MT-1 administration. A final study randomized 8 subjects to 3 to 5 days of sunlight to half of the back or to sunlight plus 0.16 mg/kg of MT-1 for 5 days per week for 4 weeks.


RESULTS
Tanning in the first study was achieved in 3 of 4 subjects receiving MT-1, and these subjects also had 47% fewer sunburn cells at the irradiated neck site. More skin sites darkened with the higher dose of MT-1 in the second study. In the third study, there was significantly enhanced tanning of the back in the MT-1 group, and this was maintained at least 3 weeks longer than the tanning in the sunlight-only controls, who required 50% more sun-exposure time for equivalent tanning.


METHODS
There were no pathologic findings at any UV-B or sun-exposed sites in any subject. Toxic effects due to MT-1 were minor, consisting of nausea and transient facial flushing.


CONCLUSIONS
Melanotan-1 can be safely combined with UV-B light or sunlight and appears to act synergistically in the tanning response to light.
Dorr
Robert T
RT
Department of Medicine, Cancer Center Division, University of Arizona, Tucson, AZ, USA. bdorr@azcc.arizona.edu
Ertl
Gregory
G
Levine
Norman
N
Brooks
Chris
C
Bangert
Jerry L
JL
Powell
Marianne Broome
MB
Humphrey
Stuart
S
Alberts
David S
DS
D000328:Adult; D016588:Anticarcinogenic Agents / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007279:Injections, Subcutaneous; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D012016:Reference Values; D012880:Skin Pigmentation / Q000187:drug effects* / Q000528:radiation effects*; D013471:Sunburn / Q000473:pathology / Q000517:prevention & control*; D016896:Treatment Outcome; D014466:Ultraviolet Rays; D000521:alpha-MSH / Q000008:administration & dosage* / Q000031:analogs & derivatives*
D016588:Anticarcinogenic Agents; D000521:alpha-MSH; C027756:MSH, 4-Nle-7-Phe-alpha-