Source comparison
Melanocortin Peptides Melanotan PT-141 MCR System: Dosing and Kinetics Comparison
Melanotan I (afamelanotide) MC1R (high), MC4R/MC5R (moderate) 33 minutes (subcutaneous implant extends to weeks) 0.25–1.0 mg subcutaneous daily Visible tanning in 5–7 days Linear structure; FDA-approved for EPP; minimal CNS effects Melanotan II MC1R, MC3R, MC4
This comparison does not assign a generated winner or score.
- Melanotan I (afamelanotide)
- MC1R (high), MC4R/MC5R (moderate)
- 33 minutes (subcutaneous implant extends to weeks)
- 0.25–1.0 mg subcutaneous daily
- Visible tanning in 5–7 days
- Linear structure; FDA-approved for EPP; minimal CNS effects
- Melanotan II
- MC1R, MC3R, MC4R, MC5R (non-selective)
- 33–60 minutes
- 0.25–1.0 mg subcutaneous 2–3×/week
- Tanning in 7–10 days; arousal within 1–4 hours
- Cyclized structure; broad receptor activation; significant nausea risk
- PT-141 (bremelanotide)
- MC3R, MC4R (preferential); MC1R (reduced)
- 2.7 hours
- 1.75 mg subcutaneous as needed
- Arousal effects peak at 2–3 hours
- Des-acetyl modification; FDA-approved for HSDD; minimal tanning
- Professional Assessment
- Receptor selectivity determines both efficacy and side effect profile. Melanotan I is pigmentation-focused with minimal systemic effects. Melanotan II is non-selective—expect tanning, appetite suppression, arousal, and GI distress. PT-141 isolates CNS arousal/appetite effects while reducing pigmentation. Choose based on primary research outcome, not marketing claims.