Comparison
Semax vs Vitamin D3 + K2
Side-by-side of Semax and Vitamin D3 + K2. 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.
Semax
Semax peptide benefits: nootropic ACTH(4-10) analog without corticotropic activity. Cognitive enhancement, neuroprotection, intranasal dosing, Russian stroke.
Vitamin D3 + K2
Vitamin D3 K2 supplement profile: cholecalciferol at 1000-4000 IU/day corrects deficiency, MK-7 directs calcium to bone, away from arteries.
Effects at a glance
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
Vitamin D3 + K2
- •Reduces non-vertebral fractures 10-20% in older adults at 800 IU/day or above when combined with calcium
- •VITAL trial showed neutral results on primary CV and cancer endpoints at 2000 IU/day over 5 years
- •Vitamin D supplementation reduces respiratory infection incidence ~10-20% in deficient populations
- •K2 MK-7 has 72-hour plasma half-life vs 1-2 hours for MK-4; once-daily dosing is sufficient
- •Synergy hypothesis is largely preclinical; dedicated combination RCTs are limited
- •Daily dosing outperforms bolus dosing for immune and infection outcomes
Side-by-side
| Attribute | Semax | Vitamin D3 + K2 |
|---|---|---|
| Category | peptide | supplement |
| Also known as | Met-Glu-His-Phe-Pro-Gly-Pro, ACTH(4-10) Pro-Gly-Pro analog | cholecalciferol + menaquinone, D3/K2, vitamin D3 with MK-7 |
| Half-life (hr) ↗ | 0.5 | 360 |
| Typical dose (mg) ↗ | 0.6 | 0.05 |
| Dosing frequency | 2-3x daily (intranasal) | daily with a fat-containing meal |
| Routes | intranasal | oral |
| Onset (hr) | 0.5 | 24 |
| Peak (hr) | 2 | 168 |
| Molecular weight | 813.94 | 384.64 |
| Molecular formula | C37H51N9O10S | C27H44O (D3); C46H64O2 (MK-7) |
| Mechanism | 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. | D3 converts to calcidiol then calcitriol, activating the vitamin D receptor (VDR) to increase intestinal calcium absorption and modulate immune and bone gene transcription. K2 carboxylates osteocalcin and matrix Gla protein, directing calcium toward bone and inhibiting vascular calcification. |
| Legal status | Approved in Russia for stroke and cognitive disorders; not FDA approved; research-use-only grey market elsewhere | Dietary supplement (global) |
| WADA status | unknown | allowed |
| DEA / Rx | Not FDA approved; not scheduled; research-chemical status outside Russia | Not scheduled |
| Pregnancy | Not recommended; insufficient data | Recommended at standard doses for fetal bone development; consult clinician at higher doses |
| CAS | 80714-61-0 | 67-97-0 |
| PubChem CID | 9811102 | 5280795 |
| Wikidata | Q4413083 | Q139347 |
Safety profile
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)
Vitamin D3 + K2
Common side effects
- GI upset at high doses
- headache (rare)
- hypercalcemia (only at sustained very high D3 doses)
Contraindications
- hypercalcemia
- sarcoidosis
- active hyperparathyroidism
- warfarin therapy (K2 component requires stable intake)
Interactions
- warfarin: K2 component can affect anticoagulation; maintain stable intake and inform anticoagulation clinic(moderate)
- thiazide diuretics: additive calcium retention; hypercalcemia risk with high-dose D3(moderate)
- digoxin and calcium channel blockers: additive effects from D3-induced hypercalcemia(moderate)
- glucocorticoids: reduced vitamin D efficacy and bone effects(moderate)
- cholestyramine and orlistat: bind fat-soluble vitamins; separate dosing by 2 to 4 hours(moderate)
Which Should You Take?
Vitamin D3 + K2 comes out ahead for most readers on the criteria we weight: 3 catalogued goals, OTC dietary supplement, oral dosing, with a Tier-A outcome catalogued. Semax is the right call when one of the conditionals below applies.
- → If your priority is focus or working memory, pick Semax.
- → If your priority is long-term neuroprotection, pick Semax.
- → If your priority is bone density, pick Vitamin D3 + K2.
- → If your priority is healthspan extension, pick Vitamin D3 + K2.
Edge case: If you want to avoid research-only / gray-market sourcing, Vitamin D3 + K2 is the more accessible choice.
Default choice: Vitamin D3 + K2. Lower friction to source, 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 Semax and Vitamin D3 + K2?
Semax and Vitamin D3 + K2 differ in category (peptide vs supplement), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, Semax or Vitamin D3 + K2?
Semax half-life is 0.5 hours; Vitamin D3 + K2 half-life is 360 hours.
Can you stack Semax with Vitamin D3 + K2?
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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