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Author: Admin | 2025-04-28
On the alternating days of saline injection. Because of the prolonged (Grade 2) somnolence and fatigue experienced by one subject at the 0.03 mg/kg dose, the next-lower dose of 0.025 mg/kg was determined to be the maximally-tolerated dose for a single subcutaneous injection of MT-II. With 6 months of follow-up, none of the subjects have reported any adverse symptoms related to this MT-II administration.DiscussionThis pilot trial shows that MT -II can increase human skin pigmentation at cumulative doses much lower than with the linear, 13-amino acid homolog, Nle4-Phe7-a-MSH (MT-I) (7). The cumulative dose of MT-1 which produced a similar degree of tanning was 0.8 mg/kg (ten SC doses of 0.08 mg/kg, each) (7). This compares with a cumulative MT-II dose of 0.10 mg/kg (and only 5 active injections) in the current study. MT-IIwas also more potent in terms of side effects, particularly nausea, which was seen in a mild form at all dose levels in one or more subjects. However, Grade 2 fatigue and somnolence were the overall acute dose-limiting toxicities of MT-II. Whether these effects would be increased with more frequent drug administration, is not known. These effects have not been reported with MT-I or with natural a-MSH, although formal Phase I dose-escalation studies with these melanotropins have not been performed. The alternate day administration schedule for MT-II was used both to observe for toxicities over a longer time period after dosing, and also to estimate the background incidence of “side effects” such as penile erections on the day of saline injection. There were no prolonged side effects of MT-II, and no side effects were reported on the alternating saline treatment days. To prevent moderate toxicity, further Phase I/H studies with MT-II should limit single SC doses to 0.025 mg/kg.Alternatively, Melanotan-I may be the preferred agent for tanning since
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