At a Glance
| Parameter | Typical Range |
|---|---|
| Starting dose | 1 mg once/week |
| Maintenance dose | 2–6 mg once/week |
| Titration interval | Every 4–6 weeks |
| Monitoring labs | Fasting glucose, HbA1c, lipids, CBC q3 months |
| Key concern with daily dosing | mTORC2 suppression → insulin resistance, immune dysregulation |
| Grapefruit/Seville orange | Avoid (CYP3A4 inhibition raises levels 3–7×) |
Why Pulsed Rather Than Daily?
When rapamycin reached transplant medicine in 1999, immunosuppression demanded continuous daily dosing at trough levels of 4–20 ng/mL. Anti-aging researchers discovered, however, that the biological targets for longevity and immunosuppression are not identical — and that continuous exposure creates collateral problems the longevity dose should avoid.
The mechanistic explanation centres on two related but distinct enzyme complexes.
mTORC1 drives protein synthesis, cell growth, and autophagy suppression. It is acutely sensitive to rapamycin. Inhibiting mTORC1 — especially in intermittent, fasted states — activates autophagy, reduces senescent cell burden, and mirrors the benefits seen in caloric restriction models. Animal studies, including the landmark ITP (Interventions Testing Program) mouse trials, showed 10–25 % lifespan extension with late-life rapamycin, primarily attributed to mTORC1 inhibition.
mTORC2 regulates glucose uptake (via AKT/GLUT4 signalling), the actin cytoskeleton, and lymphocyte survival. mTORC2 is rapamycin-resistant acutely but becomes progressively suppressed with chronic daily dosing. This is the mechanistic origin of two of rapamycin’s most clinically significant daily-dose side effects: insulin resistance and secondary immunosuppression (specifically decreased regulatory T-cell populations that guard against autoimmune flare and opportunistic infections).
A pulsed protocol — taking the full weekly dose as a single bolus — produces a high peak concentration sufficient for robust mTORC1 inhibition, followed by a trough period lasting 4–6 days in which mTORC2 activity recovers. The net result is targeted mTORC1 suppression with mTORC2 largely intact.
The Biology: mTOR, Autophagy, and Longevity
mTOR (mechanistic target of rapamycin) functions as the cell’s nutrient sensor. When mTOR is active, the cell enters an anabolic, growth-oriented state: protein synthesis is upregulated, autophagy is suppressed, and senescent cell removal slows. This state is appropriate for growth and reproduction but unfavourable for long-term cellular maintenance in post-reproductive life.
From an evolutionary perspective, mTOR evolved to be highly active when food is abundant and growth is advantageous. In modern humans with constant caloric availability, mTOR remains chronically elevated. Rapamycin intervenes at this level, effectively mimicking periods of nutrient scarcity and triggering cellular cleanup programs.
Key downstream effects of controlled mTORC1 inhibition include:
- Autophagy induction: Clearance of damaged organelles, aggregated proteins, and early apoptotic cells. Particularly relevant to neurodegenerative disease prevention.
- Senescent cell modulation: mTORC1 promotes the senescence-associated secretory phenotype (SASP). Rapamycin blunts SASP production, reducing the pro-inflammatory microenvironment that drives inflammaging.
- Mitochondrial quality control: Via ULK1 activation, rapamycin promotes mitophagy — selective removal of dysfunctional mitochondria.
- Immune rejuvenation: Joan Mannick’s 2014 study in elderly subjects showed that 6 weeks of low-dose rapamycin (rapalog everolimus) improved responses to influenza vaccine, a functional marker of immune aging.
Common Pulsed Dosing Protocols
There is no single agreed longevity protocol; the field is still building evidence from prospective observational cohorts and small clinical trials. The following represent the regimens most commonly used by experienced longevity physicians, with rationale:
1 mg/week (Starter Protocol)
Appropriate for patients new to rapamycin, those over 65, or anyone with borderline fasting glucose. Provides measurable mTORC1 inhibition — plasma trough levels at 24 hours remain well above the IC50 for mTORC1 — while minimising metabolic impact. Most patients tolerate this dose without any noticeable side effects.
2–3 mg/week (Standard Maintenance)
The most commonly reported longevity maintenance dose in published self-experimentation cohorts (e.g., the Lifespan.io PEARL study). Provides more robust autophagy signalling. Oral bioavailability of the generic sirolimus tablet is approximately 15 % (FKBP12-independent absorption), making the actual delivered dose somewhat variable.
4–6 mg/week (Higher-Intensity Protocol)
Used in higher-risk patients (strong family history of neurodegenerative disease, prior cancer) or in combination with caloric restriction windows for additive mTOR inhibition. At these doses, more frequent glucose monitoring is prudent. Some practitioners combine these doses with metformin on non-rapamycin days; others deliberately avoid metformin co-administration due to overlapping AMPK/mTOR pathway effects that may theoretically blunt exercise adaptation.
Biweekly 6–8 mg (Intensive Pulse)
Occasionally used when patients cannot maintain a strict weekly schedule or when initial mTORC1 inhibition is a priority. Less data exist for this variant. Not recommended as a starting protocol.
Titration: How to Start and Adjust
Step 1: Establish Baseline Labs
Before initiation, obtain: fasting glucose, HbA1c, fasting lipid panel (total cholesterol, LDL, HDL, triglycerides), CBC with differential, CMP (to assess hepatic and renal function), and — optionally — a biomarker of biological age (epigenetic clock, GlycanAge, or similar).
Step 2: Start at 1 mg/week
Take rapamycin on the same day each week, ideally in the morning on an empty stomach or with a low-fat meal (high-fat meals increase bioavailability unpredictably due to lymphatic absorption). Consistency in food context matters more than any specific timing.
Step 3: Reassess at 4–6 Weeks
Before any dose increase, recheck fasting glucose (critical), triglycerides, and LDL. Rapamycin can raise LDL and triglycerides in susceptible individuals, particularly at higher doses, through mTORC1-mediated effects on hepatic lipid metabolism. A fasting glucose increase of more than 10 mg/dL warrants a pause before escalation.
Step 4: Titrate Based on Tolerance and Goals
Increase by 0.5–1 mg increments every 4–6 weeks. Most longevity-oriented patients find their dose ceiling between 2–4 mg/week. Dose-limiting factors are usually metabolic (glucose/lipid changes) rather than symptomatic — mouth sores (aphthous stomatitis), which are more common in transplant patients on continuous daily dosing, are uncommon at these once-weekly doses.
Step 5: Steady-State Monitoring
Once at stable maintenance dose, check fasting glucose, lipids, and CBC every 3 months for the first year, then every 6 months if stable. Wound healing impairment is a theoretical concern at longevity doses; clinical significance at 1–6 mg/week appears low, but elective surgeries warrant a 1–2 week hold as a precaution.
Drug and Supplement Interactions
Critical (CYP3A4 Pathway)
Rapamycin is metabolised by CYP3A4 and is a substrate of P-glycoprotein. Agents that inhibit this pathway dramatically increase plasma concentrations:
- Grapefruit and Seville orange juice: Contain furanocoumarins that irreversibly inhibit intestinal CYP3A4. Even one glass can increase rapamycin exposure 3–7-fold. This is a hard contraindication during treatment.
- Ketoconazole, itraconazole, voriconazole: Potent CYP3A4 inhibitors. Requires dose reduction or suspension.
- Clarithromycin and erythromycin: Clinically significant inhibitors. Use azithromycin for short-course antibiotic needs.
- Diltiazem, verapamil: Moderate inhibitors. Monitor closely; may require dose reduction.
- St. John’s Wort: CYP3A4 inducer — decreases rapamycin levels and undermines efficacy.
Common Longevity Stack Interactions
- Metformin: Complex interaction. Both inhibit mTOR via complementary pathways; combination may be additive for longevity endpoints but potentially blunts mitochondrial hormesis from exercise. Current evidence is insufficient to recommend or contra-indicate co-use.
- NMN/NR: No pharmacokinetic interaction expected. Mechanistically complementary — NAD⁺ precursors support sirtuin activity while rapamycin addresses the mTOR axis.
- Berberine: Mild CYP3A4 modulation; monitor glucose more closely given additive glucose-lowering potential.
- Statins: No direct interaction. May be beneficial in patients where rapamycin raises LDL.
Who Should Avoid or Defer Rapamycin
The full contraindications list is covered in detail in a separate article on rapamycin contraindications; key exclusions for the longevity population include:
- Active infection (rapamycin blunts innate immune responses acutely)
- Planned major surgery within 2 weeks
- Poorly controlled type 2 diabetes (HbA1c > 8 %)
- Active or recent malignancy where mTOR inhibition is not part of the treatment plan
- Pregnancy or active fertility treatment
- Concurrent use of potent CYP3A4 inhibitors without dose adjustment
Monitoring and Red Flags
| Finding | Action |
|---|---|
| Fasting glucose rises > 10 mg/dL | Pause dose increase; re-check diet and co-medications |
| LDL rises > 30 mg/dL above baseline | Consider statin or dose reduction |
| Triglycerides > 300 mg/dL | Reduce dose; add omega-3 fatty acids |
| Mouth sores (stomatitis) | Usually resolves with mouth rinse; consider dose reduction if persistent |
| New or recurrent infection | Suspend rapamycin until infection resolves |
| Unexplained fatigue or myopathy | Check CK; review drug interactions |
Related Articles
- Rapamycin for Longevity: The Evidence
- Rapamycin Dosage Guide
- Rapamycin Side Effects
- Rapamycin Contraindications
- Rapamycin vs Metformin for Longevity
References
- Harrison DE, et al. “Rapamycin fed late in life extends lifespan in genetically heterogeneous mice.” Nature. 2009;460(7253):392-395. https://doi.org/10.1038/nature08221
- Mannick JB, et al. “mTOR inhibition improves immune function in the elderly.” Science Translational Medicine. 2014;6(268):268ra179. https://doi.org/10.1126/scitranslmed.3009892
- Saxton RA, Sabatini DM. “mTOR Signaling in Growth, Metabolism, and Disease.” Cell. 2017;168(6):960-976. https://doi.org/10.1016/j.cell.2017.02.004
- Lamming DW, et al. “Rapamycin-induced insulin resistance is mediated by mTORC2 loss and uncoupled from longevity.” Science. 2012;335(6076):1638-1643. https://doi.org/10.1126/science.1215135
- Bitto A, et al. “Transient rapamycin treatment can increase lifespan and healthspan in middle-aged mice.” eLife. 2016;5:e16351. https://doi.org/10.7554/eLife.16351
- Mannick JB, et al. “TORC1 inhibition enhances immune function and reduces infections in the elderly.” Science Translational Medicine. 2018;10(449):eaaq1564. https://doi.org/10.1126/scitranslmed.aaq1564
- Attia P. “Rapamycin: The Drug That Could Help Us Live Longer.” Peter Attia MD blog. 2022. [Available at peterattiamd.com]
