Comparison
PT-141 vs Semax
Side-by-side of PT-141 and Semax. Every row below is pulled from the compound schema and will update as our data grows. For deeper reads, follow through to each compound page.
PT-141
PT-141 peptide (bremelanotide, Vyleesi): MC4R agonist for libido and erectile dysfunction. 1.75 mg subcutaneous, 30 to 60 min onset, 2 to 4 h half-life.
Semax
Semax peptide benefits: nootropic ACTH(4-10) analog without corticotropic activity. Cognitive enhancement, neuroprotection, intranasal dosing, Russian stroke.
Effects at a glance
PT-141
- •Cyclic 7-amino-acid synthetic peptide and melanocortin receptor agonist (MC4R-preferring)
- •FDA approved in 2019 as Vyleesi for hypoactive sexual desire disorder in pre-menopausal women
- •Acts centrally on hypothalamic sexual-desire circuits rather than peripherally on vasculature
- •On-demand dosing: subcutaneous 1.75 mg approximately 45 minutes before sexual activity
- •Common adverse effects: nausea (~40%), flushing, headache, injection-site reactions, hyperpigmentation
- •Off-label male ED use is documented but not FDA approved; mechanism is distinct from PDE5 inhibitors
Semax
- •Synthetic heptapeptide analog of ACTH(4-10) developed in Russia in the 1980s
- •Approved in Russia for ischemic stroke, cognitive impairment, and cerebrovascular disorders
- •Lacks the corticotropic activity of native ACTH due to the Pro-Gly-Pro stabilizing tail
- •Russian RCTs report improved cognitive recovery in acute ischemic stroke versus standard care
- •Modulates BDNF and NGF expression and dopaminergic signaling in preclinical models
- •Standard route is intranasal; not FDA approved; research-use-only outside Russia
Side-by-side
| Attribute | PT-141 | Semax |
|---|---|---|
| Category | peptide | peptide |
| Also known as | Bremelanotide, Vyleesi | Met-Glu-His-Phe-Pro-Gly-Pro, ACTH(4-10) Pro-Gly-Pro analog |
| Half-life (hr) ↗ | 2.7 | 0.5 |
| Typical dose (mg) ↗ | 1.75 | 0.6 |
| Dosing frequency | as needed (max once per 24 hours, max 8 per month) | 2-3x daily (intranasal) |
| Routes | subcutaneous | intranasal |
| Onset (hr) | 0.75 | 0.5 |
| Peak (hr) | 1.5 | 2 |
| Molecular weight | 1025.18 | 813.94 |
| Molecular formula | C50H68N14O10 | C37H51N9O10S |
| Mechanism | Synthetic agonist of melanocortin receptors with preference for MC4R, expressed in hypothalamic and limbic circuits regulating sexual motivation. Engages central pathways distinct from peripheral PDE5-mediated vasodilation. | Modulates BDNF and NGF expression in hippocampus and cortex, enhances dopaminergic and serotonergic signaling, and reduces oxidative stress markers in preclinical ischemia models. Lacks corticotropic activity of native ACTH. |
| Legal status | Prescription only as Vyleesi; FDA-approved 2019 for HSDD in pre-menopausal women. Compounded versions sold off-label for male sexual function are research-use-only grey market. | Approved in Russia for stroke and cognitive disorders; not FDA approved; research-use-only grey market elsewhere |
| WADA status | allowed | unknown |
| DEA / Rx | Rx only (not a controlled substance) for the FDA-approved Vyleesi formulation | Not FDA approved; not scheduled; research-chemical status outside Russia |
| Pregnancy | Not recommended; contraindicated during pregnancy per Vyleesi label | Not recommended; insufficient data |
| CAS | 189691-06-3 | 80714-61-0 |
| PubChem CID | 9941379 | 9811102 |
| Wikidata | Q422059 | Q4413083 |
Safety profile
PT-141
Common side effects
- nausea (~40%)
- flushing
- headache
- injection-site reactions
- hyperpigmentation (focal, gums, face, breasts)
- transient blood pressure increase (~6 mmHg systolic)
Contraindications
- uncontrolled hypertension
- established cardiovascular disease
- pregnancy
- naltrexone co-administration (reduces opioid efficacy due to MC receptor crosstalk)
Interactions
- naltrexone (oral): bremelanotide reduces oral naltrexone exposure significantly; avoid co-administration(major)
- antihypertensives: transient BP rise after bremelanotide can offset BP control(moderate)
- PDE5 inhibitors (sildenafil, tadalafil): no documented adverse interaction; mechanisms are non-overlapping(minor)
Semax
Common side effects
- mild nasal irritation
- transient mild headache
- rare mild euphoria or activation
Contraindications
- pregnancy
- lactation
- acute psychotic disorder
- severe hypertension (caution due to mild activating effect)
Interactions
- stimulants (caffeine, amphetamines): potential additive activation; monitor for overstimulation(minor)
- antipsychotics: theoretical antagonism via dopaminergic modulation(minor)
Which Should You Take?
PT-141 comes out ahead for most readers on the criteria we weight: 2 catalogued goals, research-only / gray-market sourcing, with a Tier-A outcome catalogued. Semax is the right call when one of the conditionals below applies.
- → If your priority is sexual function, pick PT-141.
- → If your priority is libido, pick PT-141.
- → If your priority is focus or working memory, pick Semax.
- → If your priority is long-term neuroprotection, pick Semax.
Edge case: PT-141 is contraindicated in pregnancy; Semax is the safer pick if that applies.
Default choice: PT-141. Wider use case, a Tier-A evidence outcome catalogued, and broader goal coverage. Reach for Semax only if your priority sits squarely in the goals it owns above.
This verdict is generated from each compound's schema (goals, legal status, evidence outcomes, dosing route). It updates automatically as our compound data evolves; the deeper read sits on each individual compound page.
Common questions
What is the difference between PT-141 and Semax?
PT-141 and Semax differ in category (peptide vs peptide), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, PT-141 or Semax?
PT-141 half-life is 2.7 hours; Semax half-life is 0.5 hours.
Can you stack PT-141 with Semax?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
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