Comparison
ISRIB vs Rapamycin
Acute memory potentiation vs. proven lifespan extension — two distinct plays.
ISRIB
eIF2B Activator / ISR Inhibitor
Rapamycin
mTOR Inhibitor
Effectiveness Profile
At a Glance
| ISRIB | Rapamycin | |
|---|---|---|
| Type | Nootropic | Longevity |
| Legal status | Research | Rx-Only |
| Half-life | ~8 hours | ~62 hours (range 46–78h) |
| Preferred route | Sublingual | Oral |
| Dose frequency | once-daily | weekly |
| Beginner dose | 2–5 mg | 2–3 mg |
| Intermediate dose | 5–7.5 mg | 4–6 mg |
| Advanced dose | 7.5–10 mg | 6–8 mg |
| Cycle length | 1–3 wks | 8–52 wks |
| Bioavailability | — | 15% |
| Time to peak | — | 1.5h |
| Active duration | 12h | 168h |
| Storage | Store powder desiccated at -20°C; reconstituted solutions at 2–8°C, protected from light | Room temperature (15–25°C); protect from light |
| PCT required | No | No |
| Ancillaries required | No | No |
| Safe for women | Yes | Yes |
Verdict
ISRIB wins for rapid and durable enhancement of memory consolidation, reversal of cognitive deficits post-injury, and minimal metabolic side effects due to its pulsed protocol and self-limiting mechanism. Its effects persist after dosing and avoid major downstream pathway suppression.
Rapamycin wins for clinically validated longevity benefits, robust enhancement of autophagy and immune function, and the sheer volume of mammalian data supporting lifespan increase. Its weekly protocol is better-studied in primates, and it delivers system-level aging interventions ISRIB simply cannot touch.
Pick A or B?
Pick ISRIB if:
- The protocol targets acute rescue of cognitive performance after stress or injury (e.g., TBI, age-related decline models).
- Durable increases in memory, LTP, or dendritic spine density are desired from short pulsed courses.
- The research requires minimal interference with whole-body metabolic signaling (mTOR, glucose, insulin).
- The goal is combinatorial synergy with racetams or other nootropics without broad growth pathway inhibition.
- Side effect mitigation is a top priority and pulsed administration fits the model.
Pick Rapamycin if:
- The protocol aims for whole-organism lifespan or healthspan extension, especially in aging models.
- Induction of autophagy, mTORC1 inhibition, or immune system rejuvenation is the primary driver.
- Weekly, intermittent dosing is compatible with the design and chronic daily suppression is not desirable.
- The stack includes other longevity agents (metformin, GLP-1s, low-dose tadalafil) targeting systemic aging.
- There is interest in lean mass retention data in aging or post-menopausal models as seen in the PEARL trial.