Comparison
Rapamycin vs Thymosin Alpha-1
Side-by-side of Rapamycin and Thymosin Alpha-1. 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.
Rapamycin
Rapamycin for longevity: sirolimus, an mTOR inhibitor with ITP mouse lifespan data. Off-label geroprotective dosing remains investigational.
Thymosin Alpha-1
Thymosin alpha-1 peptide (Zadaxin, thymalfasin): 28-amino-acid TA1 immunomodulator. Dosing, T-cell effects, hepatitis B and HCV adjunct evidence.
Effects at a glance
Rapamycin
- •Inhibits mTORC1 signaling by binding FKBP12, reducing protein synthesis and relieving autophagy suppression
- •ITP mouse program reproduced lifespan extension of ~10 to 25% across multiple genetic backgrounds and sexes
- •Mannick trials showed improved influenza vaccine response in elderly adults using analogs of rapamycin
- •PEARL human trial reported acceptable safety at 5 to 10 mg weekly with some functional and lean-mass signals
- •Common dose-limiting adverse effects include stomatitis, acne-like rash, and mildly elevated lipid markers
- •CYP3A4 substrate: grapefruit, ketoconazole, and clarithromycin substantially raise rapamycin exposure
Thymosin Alpha-1
- •28-amino-acid synthetic peptide identical to thymic-derived immunomodulator
- •Approved in over 35 countries as Zadaxin for hepatitis B, hepatitis C adjunct, and immune support
- •Not FDA approved in US; compounded by 503A/503B pharmacies for off-label immune support
- •Modulates T-cell maturation, NK activity, and Th1 polarization in immunocompromised states
- •Standard label dose: 1.6 mg subcutaneously twice weekly
- •Cleanest safety profile in the peptide class with hundreds of regulated trials behind it
Side-by-side
| Attribute | Rapamycin | Thymosin Alpha-1 |
|---|---|---|
| Category | pharmaceutical | peptide |
| Also known as | Sirolimus, Rapamune | Talpha1, Ta1, Zadaxin, Thymalfasin |
| Half-life (hr) ↗ | 62 | 2 |
| Typical dose (mg) ↗ | 6 | 1.6 |
| Dosing frequency | weekly (longevity protocols); daily for transplant indication | 2x weekly |
| Routes | oral | subcutaneous, intramuscular |
| Onset (hr) | 1 | 24 |
| Peak (hr) | 2 | 168 |
| Molecular weight | 914.17 | 3108.32 |
| Molecular formula | C51H79NO13 | C129H215N33O55 |
| Mechanism | Binds FKBP12, and the resulting complex inhibits mTORC1, reducing protein synthesis and autophagy suppression downstream of nutrient and growth-factor signaling. | Synthetic peptide modulator of innate and adaptive immunity. Promotes T-cell maturation and CD4/CD8 production, modulates Th1/Th2 balance, stimulates NK cell activity, and modulates TLR2/TLR9 signaling in dendritic cells. |
| Legal status | Prescription only (off-label for longevity) | Approved in 35+ countries as Zadaxin (hepatitis B, hepatitis C adjunct, immune support); not FDA approved in US; compounded by 503A/503B pharmacies for off-label use; not on WADA Prohibited List |
| WADA status | allowed | unknown |
| DEA / Rx | Rx only (not a controlled substance) | Rx only via international approval or US compounding (no controlled-substance schedule) |
| Pregnancy | Not recommended | Not recommended; insufficient data |
| CAS | 53123-88-9 | 62304-98-7 |
| PubChem CID | 5284616 | 16130571 |
| Wikidata | Q410174 | Q913854 |
Safety profile
Rapamycin
Common side effects
- mouth ulcers (stomatitis)
- acne-like rash
- GI upset
- altered lipid panel
- delayed wound healing
Contraindications
- active infection
- severe hepatic impairment
- planned surgery (delayed wound healing)
- pregnancy
- live vaccines within dosing window
Interactions
- strong CYP3A4 inhibitors (ketoconazole, clarithromycin, grapefruit): substantially raises rapamycin levels, toxicity risk(major)
- strong CYP3A4 inducers (rifampin, St John's wort): lowers rapamycin levels, reduced effect(major)
- ACE inhibitors: increased risk of angioedema(moderate)
- live vaccines: reduced vaccine efficacy due to immunosuppression(major)
Thymosin Alpha-1
Common side effects
- mild injection-site irritation (rare)
- transient mild fatigue (rare)
- occasional headache (rare)
Contraindications
- pregnancy
- lactation
- active organ transplant rejection therapy
- systemic immunosuppression for autoimmune disease (relative)
- severe active autoimmune disease (caution)
Interactions
- interferon-alpha: additive immune effect; used clinically in approved combination protocols(minor)
- calcineurin inhibitors (cyclosporine, tacrolimus): theoretical destabilization of immunosuppression; avoid(major)
- antimetabolites (azathioprine, mycophenolate): theoretical destabilization of immunosuppression; avoid(major)
- vaccine administration: may augment vaccine response in elderly or immunocompromised; coordinate with clinician(minor)
Which Should You Take?
Rapamycin and Thymosin Alpha-1 score evenly on the criteria we weight (goal breadth, legal accessibility, evidence depth). The conditionals below should drive the decision more than any aggregate score.
- → If your priority is healthspan extension, pick Rapamycin.
- → If your priority is post-training recovery, pick Thymosin Alpha-1.
- → If your priority is antiviral action, pick Thymosin Alpha-1.
Edge case: If you cannot self-administer injections, Rapamycin is the only oral option in this pair.
Default choice: either is defensible. Rapamycin edges out on goal breadth + legal accessibility; Thymosin Alpha-1 is the right call if your priority sits in the goals listed 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 Rapamycin and Thymosin Alpha-1?
Rapamycin and Thymosin Alpha-1 differ in category (pharmaceutical vs peptide), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, Rapamycin or Thymosin Alpha-1?
Rapamycin half-life is 62 hours; Thymosin Alpha-1 half-life is 2 hours.
Can you stack Rapamycin with Thymosin Alpha-1?
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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