Rapamycin vs RTB101
Written by Aaron CuhaReviewed Sep 2026
The short answer
An mTOR blocker used off label, against the mTOR pathway drug that was properly tested and failed. RTB101 looked good in two early trials and did nothing in a 1,024 person large final stage trial, even though the blood marker it aimed at still moved in both.
- Rapamycin people
- 25
- Rapamycin nulls
- 0
- RTB101 people
- 1,024
- RTB101 nulls
- 0
Dose
Approved medicine. No human dose established for unlabelled uses
Labeled amounts sit on the prescribing information. This page records what trials measured, not a personal dose.
FDA-approved (Rapamune); use for longevity is off-label (not what it is approved for) and investigational
Dose
No human dose established
Amounts that were given in studies sit in Human evidence on this page. None of them is a personal dose.
1 completed trial, 1,024 people given it
First-hand reports are counted on each profile and never added together. This page sets two published records side by side. It does not pick a winner.
Column A
RapamycinRapamycin (Sirolimus, mTOR inhibitor)
An approved drug that blocks mTOR, a growth switch in cells. It makes many kinds of animals live longer. Some people take low, spaced-out doses for ageing, off-label. Studies in people are small.
Column B
RTB101RTB101 (dactolisib, BEZ235), low-dose TORC1 inhibitor
The most important failed trial in ageing research. It looked good in two mid-stage trials, then did nothing in a 1,024 person final-stage trial. The lab marker it targeted still moved in both of the later trials.
Side by side, on the facts we can check
| What we compare | Rapamycin | RTB101 |
|---|---|---|
| Category | Longevity | Longevity |
| FDA status | FDA-approved (Rapamune); use for longevity is off-label (not what it is approved for) and investigational | Never approved. The final-stage studies missed their main goal, and work on it for this use stopped. |
| Half-life | ~60 hours | Not asserted. No reliable half-life figure at the low geroscience doses was resolved in the sources loaded. |
| Molecular weight | 914.2 Da | 469.5 Da for dactolisib. A small molecule, not a peptide. |
| How it works | It blocks the mTOR pathway. That copies part of what eating less does to cells, and it boosts cell clean-up and upkeep. | It blocks TORC1 at a low dose. At the higher doses first developed for cancer, dactolisib blocks two things, an enzyme called PI3K and mTOR. The ageing programme used much lower doses meant to block only TORC1. The thinking was that the immune benefits of blocking mTOR show up at doses well below those that weaken the immune system. The goal was to switch on genes triggered by interferon, the body's antiviral alarm, so older adults would be readier to fight viruses. The trials confirmed that effect. |
| Studies in people | 3 | 3 |
| Evidence | Limited: 2 completed trials, 25 people given it | Moderate: 1 completed trial, 1,024 people given it |
| Legal status, US | FDA-approved (for its labeled use), prescription only | Not approved; research use only |
Frequently asked questions
What is the difference between Rapamycin and RTB101?
Rapamycin: An approved drug that blocks mTOR, a growth switch in cells. It makes many kinds of animals live longer. Some people take low, spaced-out doses for ageing, off-label. Studies in people are small. RTB101: The most important failed trial in ageing research. It looked good in two mid-stage trials, then did nothing in a 1,024 person final-stage trial. The lab marker it targeted still moved in both of the later trials.
Which has stronger research evidence, Rapamycin or RTB101?
Each compound gets a band worked out from facts we counted, with the math shown. Rapamycin is Limited (2 completed trials, 25 people given it). RTB101 is Moderate (1 completed trial, 1,024 people given it). That counts how much has been done in people. It does not rate whether either one works, and neither one is called the winner.
Are Rapamycin and RTB101 FDA-approved?
Rapamycin: FDA-approved (Rapamune); use for longevity is off-label (not what it is approved for) and investigational. RTB101: Never approved. The final-stage studies missed their main goal, and work on it for this use stopped..
Related posts
Blog articles that cover Rapamycin or RTB101, newest first.
- Longevity / Sep 27, 2026 / 12 minPeptides for Longevity: What the Evidence Actually Shows in 2026
- Longevity / Sep 27, 2026 / 9 minSenolytics in 2026: Dasatinib plus Quercetin, Fisetin, and What Human Trials Have Shown
- Longevity / Sep 27, 2026 / 9 minThe Rapamycin Dosing Debate: What PEARL Tested, the Bioavailability Problem, and What Is Unproven
Reviewed Sep 2026. This page puts two published records side by side. It is for learning, and it is not medical advice. When this site shows a dose, it is the dose a trial or a clinic actually used, or what people say they did, with the source attached. None of it tells you what to take.