Comparison
Selank vs Vitamin D3 + K2
Side-by-side of Selank 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.
Selank
Selank peptide benefits: tuftsin analog heptapeptide, intranasal anxiolytic and nootropic. Russian clinical data, dosing, half-life, safety.
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
Selank
- •Synthetic heptapeptide analog of tuftsin developed in Russia in the 1990s
- •Approved in Russia for generalized anxiety disorder and asthenic conditions
- •Russian RCTs report anxiolytic effects comparable to medazepam without sedation or dependence
- •Modulates GABAergic and serotonergic signaling and BDNF expression in preclinical models
- •Most commonly administered intranasally; subcutaneous use is anecdotal
- •No Western-validated trials; 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 | Selank | Vitamin D3 + K2 |
|---|---|---|
| Category | peptide | supplement |
| Also known as | TP-7, Tuftsin analog | cholecalciferol + menaquinone, D3/K2, vitamin D3 with MK-7 |
| Half-life (hr) ↗ | 0.5 | 360 |
| Typical dose (mg) ↗ | 0.4 | 0.05 |
| Dosing frequency | 2-3x daily (intranasal) | daily with a fat-containing meal |
| Routes | intranasal, subcutaneous | oral |
| Onset (hr) | 0.25 | 24 |
| Peak (hr) | 1 | 168 |
| Molecular weight | 751.85 | 384.64 |
| Molecular formula | C33H57N11O9 | C27H44O (D3); C46H64O2 (MK-7) |
| Mechanism | Modulates GABAergic, serotonergic, and dopaminergic signaling. Increases BDNF expression in hippocampal neurons in preclinical models. Modulates enkephalin levels and immune cytokine signaling via tuftsin-like activity. | 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 as a prescription anxiolytic in Russia; not FDA approved; research-use-only grey market in most other jurisdictions | 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 | 129954-34-3 | 67-97-0 |
| PubChem CID | 11765600 | 5280795 |
| Wikidata | Q4416793 | Q139347 |
Safety profile
Selank
Common side effects
- mild nasal irritation (intranasal)
- transient drowsiness (uncommon)
- mild headache
Contraindications
- pregnancy
- lactation
- severe psychiatric disorder (insufficient data)
Interactions
- benzodiazepines: additive anxiolytic effect; potential for over-sedation when stacked(moderate)
- SSRIs: no documented adverse interaction; co-administration described in Russian protocols(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. Selank is the right call when one of the conditionals below applies.
- → If your priority is focus or working memory, pick Selank.
- → If your priority is anxiety reduction, pick Selank.
- → 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 Selank 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 Selank and Vitamin D3 + K2?
Selank 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, Selank or Vitamin D3 + K2?
Selank half-life is 0.5 hours; Vitamin D3 + K2 half-life is 360 hours.
Can you stack Selank 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.
Go deeper