Rapamycin is currently one of the hottest drugs in the anti-aging and longevity community. Prominent figures such as Peter Attia and Bryan Johnson are using this drug for its potential anti-aging benefits. Tech moguls like Vinod Khosla have called Rapamycin as a “no-brainer.”

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Originally developed as an immunosuppressant for organ transplant patients, Rapamycin has shown promise as a potential anti-aging drug. It works by inhibiting mTOR (mechanistic target of rapamycin), a key regulator of the aging process. mTOR is a protein complex that promotes cellular growth which is essential during youth. However, continuous activation of this pathway with age may lead to excessive growth or “hyperfunction” as Mikhail V. Blagosklonny, a cancer and aging scientist, calls it. Hyperfunction may be a major driver of aging eventually leading to many of the age-related diseases we know.

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Blagosklonny uses an analogy to explain this idea: imagine a car driving at 65 miles per hour (mph) on a highway with a 65 mph speed limit. If the car exits the highway onto low-speed streets without slowing down - a stuck accelerator for example - driving at 65 mph becomes over-speeding or hyperfunction.

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Rapamycin may act as a brake to slow down the aging process by inhibiting mTOR. Though it is licensed as an immunosuppressant for organ transplant patients, different dosing and frequency could offer geroprotective effects. This practice, known as off-label prescribing, involves using a medication for an unapproved purpose. While not uncommon, off-label prescribing is regulated and comes with certain restrictions.

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The safety of off-label rapamycin use

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Currently, there are no standardized protocols for using Rapamycin for its anti-aging effects. A weekly dose of up to 6 mg is a commonly used approach. A recent study by Matt Kaeberlein, a prominent researcher in this space, found that this dosage is relatively safe based on survey data from 333 adults using Rapamycin for this purpose.

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If we know it’s safe, why don’t we use it more?

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The problem with Rapamycin is the lack of reliable ways to measure its effectiveness in humans. In animal studies, particularly with mice and flies, Rapamycin has consistently shown lifespan benefits, such as lower cancer rates, enhanced cognitive abilities, and improved immune function. In fact, treatment starting in middle age has been sufficient to significantly extend lifespan in mice, indicating that starting late in life may be enough to reap the benefits.

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So why don’t we have similar data for humans? Demonstrating efficacy in clinical trials requires large cohort sizes and long time horizons, making it particularly challenging from both policy and recruitment perspectives.

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Given its safety profile within certain limits and the well-understood side effects from its use in organ transplant patients, should you take Rapamycin in the hope of benefit? This is a complex question that should be addressed between a patient and their doctor, weighing the risks, benefits, and unknowns. Personally, I plan to consider Rapamycin later in life due to concerns about potential effects on fertility. This may not be an issue for those who have completed their families or do not want children. For younger people, I would advise to wait for more data, as there are multiple trials currently underway which will give us more certainty in the future.

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I wrote more about Rapamycin in a previous post for those interested. You can subscribe to our email list for more articles like this one. 

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Adam Bataineh MD

Medical Director, Numenor

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