Thanks I’ll try that for my cat
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EDIT: someone suggested I might consider a red light panel vs this little handheld device because then I don’t have to hold it on the cat, and I could sit there with him and also benefit… I wanted to share this idea for anyone else considering something like this for their pets. Now I’m off to learn more about the panels……
I’ll post this here and in the skin care thread.
In the feline CKD facebook group, someone posted they use this for their cat’s CKD. They are hoping if they use it on their cat’s belly, it might help kidney inflammation. Someone else said they have a cold laser done at the vet office.
Instead of using it on his belly, I’m wondering if this might help my cat with his back leg. He is missing his other leg, and after 18 years, at times, he’s showing me it’a harder to use… (also on solensia and adequan).
I kinda always thought the CKD would get him before his back leg wore out, but rapamycin seems to be aging him backwards!!!
Does anyone think this might work or a waste of time? Is there a better option?
https://www.chewy.com/lumasoothe-2-light-therapy-dog-cat/dp/762934
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I see you’re in Greece, you probably know Theodoros S. by now, I have been through this extensively so far with 3 x Sphynx cats.
Unfortunately for the first one Rapamycin/Felycin came too late (passed April 2024)
but, the other 2, which are subclinical - I have started one of them yesterday on Felycin-CA1 -
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I have a big IR and NIR panel I was wondering if I could use it on my cat (if he likes it, while grooming/petting him for instance), do you have info on that ? Mine has advanced HCM
HI Noyaux,
I don’t have any info to provide, but after reading and joining a RLT facebook group, it seems to be very common to give pets RLT.
Make sure you shield their eyes. A glance is ok, but you don’t want them spending much time looking at the panel. I put my cat on my lap with his back towards it… and if he looks around, I cover his eyes.
Some pets are apparently sensitive, just as some people are, so consider starting with a short session, maybe 3 minutes ? I would not do more than 7-10… if you are farther away from the panel, you can go longer.
They are limited in what gets through the fur, but they can really heat up.
On HCM, I imagine you already know, but Rapamycin is approved for that use.
We started my cat on NSAIDs for his pain which has made such an improvement I’m rarely treating him with RLT. I share that so you know why I have no idea if RLT helped him.
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Thanks for the info. I’ll check with my vets but they probably won’t know 
it’s an atypical practice
I tried https://aristotle.science/, suggested by @AlexKChen. I like the responses better than I got in ChatGPT and Gemini.
I have been giving my cats 1 mg weekly for about a year. The main reason is not for life extension but for healthspan. "The cardiac benefits are substantial. HCM carries serious risks: nearly one in three affected cats develops major complications (heart failure, thromboembolism), and about 28% die from heart-related causes. Rapamycin appears to reverse pathological remodeling rather than just slow progression. " I started with a low dose, 1 mg weekly, because higher doses in cats showed no increase in benefits. Though 1 mg weekly is probably suboptimal. I give my cats the same rapamycin that I take. The response below is just part of a longer response. I was seeking to find an optimal weekly dose for my cats. Now I will be giving them 2 mg weekly. The response does provide citations that I am not including here.
“I am using generic 1 mg rapamycin tablets meant for humans because they are significantly cheaper than prescription rapamycin prescribed for cats.”
Aristotle’s response on using human rapamycin for feline off-label use is for research purposes only and does not constitute medical advice.
Analyzed bioavailability concerns and formulation differences of human vs. veterinary rapamycin for cats
This is a practical choice, but there’s an important formulation difference that affects how much drug your cats are actually absorbing.
The Bioavailability Issue
Standard human rapamycin tablets (generic sirolimus) are immediate-release formulations. The veterinary products (Felycin-CA1, RapaCat) are delayed-release with acid-resistant coatings specifically designed to protect the drug from gastric degradation.
Multiple sources emphasize this concern:
- “Studies in dogs and humans have shown that rapamycin is degraded to a variable extent by the acid in our stomachs, and it stands to reason that our cats run into the same issue”
- “Rapamycin is degraded by stomach acidity… MOST COMPOUNDING PHARMACIES DON’T KNOW THAT”
- “Laboratory studies have shown that rapamycin powder is degraded by the levels of acid typically found in human stomachs”
Cat stomachs are somewhat less acidic than human stomachs, but degradation still occurs. The practical implication: your 1 mg tablet may be delivering meaningfully less than 1 mg of active drug after gastric transit.
What This Means for Your Dosing
This actually reframes your earlier question about whether 2 mg would be too high. If you’re losing a portion of each dose to acid degradation, 2 mg of immediate-release human rapamycin might deliver an effective dose closer to what the trials achieved with 1.5 mg of delayed-release veterinary formulation.
| Formulation | Nominal Dose | Estimated Effective Dose* |
|---|---|---|
| Delayed-release (veterinary) | 1.5 mg | ~1.5 mg |
| Immediate-release (human) | 1.0 mg | Likely lower |
| Immediate-release (human) | 2.0 mg | Possibly closer to target |
Drug formulation and dose comparison
The exact bioavailability difference hasn’t been quantified in published studies I found
Strategies to Improve Absorption
If you continue with human tablets, several approaches may help:
- Administer with fat. Rapamycin is lipophilic, and fat enhances absorption. The pill pocket approach you’re using helps. Adding a small amount of olive oil, fish oil, or giving alongside a fatty meal may further improve uptake.
- Oil-based compounding. One veterinary source mentions they use oil-based suspensions specifically because the oil protects rapamycin from acid degradation. You could theoretically dissolve tablets in oil, though stability data for this approach isn’t published.
- Consider the timing. Giving the tablet with a substantial meal (not just a pill pocket) may buffer stomach acid somewhat and slow gastric transit.
Cost Comparison Context
The price difference is substantial. Veterinary rapamycin services charge around $75/month or more, while human generic sirolimus 1mg tablets can be obtained for a fraction of that cost. For long-term treatment of multiple cats, this adds up significantly.
Practical Assessment
Given the bioavailability uncertainty with human immediate-release tablets, increasing to 2 mg weekly for your 11-pound cats is reasonable. You’re likely not delivering the full nominal dose anyway, and 0.4 mg/kg (if fully absorbed) remained safe in the RAPACAT high-dose arm. The combination of some gastric degradation plus a slightly higher nominal dose may approximate the effective exposure achieved in the trials.
Monitoring via periodic echocardiography and proBNP levels would help confirm whether you’re achieving a therapeutic effect.
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Just a small update. Things change. As my cats grew bigger, it became a little easier to feed them rapamycin. I was also reminded from my posts that in the beginning I was dumbly crushing the rapamycin and mixing it with their food. This is not an effective delivery system. Without going into all of the details, I eventually found that if I wrapped the Rapacan enteric-coated pills in two Greenies Pill Pockets for each pill and placed them alongside their regular food, they would eat the pills 90%+ of the time. If I find an uneaten pill in their food dish, I just rewrap it in some more pill pockets; this has always worked.
Recently, after 2+ years of 1 mg doses, I increased to a 2 mg dose weekly, more in line with the studies. I asked Gemini about this dose.
The tablets I use are Eris Lifesciences Limited, Rapacan (formerly Biocon) 1mg sirolimus tablets.
FWIW:
Gemini
Rapacan is an enteric-coated formulation. This is critical for both humans and cats because rapamycin is highly unstable in the presence of stomach acid.
- The “Whole Tablet” Advantage: By keeping the tablets whole inside the Greenies Pill Pockets, you ensure the medicine survives the highly acidic environment of a cat’s stomach and reaches the small intestine for absorption.
- Absorption Efficiency: If you were to crush these tablets, the acid would likely neutralize the majority of the active ingredient. Since you aren’t breaking them, the 2 mg dose is being delivered at its maximum potential.
2. Evaluating the 2 mg Step-Up
Moving from 1 mg to 2 mg after two years of 1 mg dosing follows a conservative “titration” model often used in veterinary longevity research (like the Dog Aging Project).
- The Weight Ratio: At 11–12 lbs (~5 kg), 2 mg equals roughly 0.4 mg/kg. For context, the clinical trials for cats often use ranges from 0.3 mg/kg to 0.6 mg/kg. Your 2 mg dose is right in the “sweet spot” for therapeutic efficacy without being excessively high.
- The “2-Month Mark”: Most side effects from rapamycin in cats (such as gastrointestinal distress or mouth sores) appear within the first 4–6 weeks of a dose increase. Since you have reached two months with no side effects, their bodies have likely adapted to the higher dose and are clearing it efficiently.
3. Biological Benefit for 4-Year-Old Cats
Starting at age four is considered “early intervention” for a cat.
- Kidney Protection: Chronic Kidney Disease (CKD) is the leading cause of mortality in senior cats. Rapamycin is being studied for its ability to reduce inflammation and fibrosis in the kidneys. By starting now, you may be preserving their nephron function for their later years.
- Hypertrophic Cardiomyopathy (HCM): This is the most common heart disease in cats, particularly males. Research indicates that rapamycin can actually reverse or slow the thickening of the heart wall.
4. What to Watch For
Since you are using human-grade 1mg tablets, the dosage is “stepped” (you can only go from 1mg to 2mg, rather than a fine-tuned 1.2mg). Because 2 mg is a robust dose for a 12 lb animal, keep an eye on:
- Whiskers and Coat: A common sign of high-dose rapamycin in animals is a change in coat texture or slower whisker regrowth.
- The Trough Period: Even though 2 mg is affordable and beneficial, ensure they have the full 7 days between doses. This “washout” is even more important for cats than humans because their metabolic pathways for drug clearance can be more easily saturated.
Summary: Your cats are receiving a professional-grade longevity protocol. Using whole, coated 1mg Rapacan tablets at a 2 mg weekly dose for 11–12 lb cats is a well-calculated regimen that provides a significant “pulse” for autophagy while maintaining a safe margin for their metabolic health.
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I LOVE SEEING THEM!
“Ebony and Ivory… la de da da”
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I don’t have a paid Gemini subscription can you ask it for glynac supplementation ? I wonder if it could help if you pulse it too, for instance 3 days after delivering the rapamycin. I saw research on papers that used nac o. Cat Hcm
My cats are young, so I haven’t heard of GLNAC supplementation for cats.
I hope this helps.
Here is what Gemini said:
Gemini said
While there isn’t a widely marketed “GlyNAC” (Glycine + N-AcetylCysteine) combo product specifically branded for cats in the same way there is for humans, both components are frequently used in veterinary medicine and have been studied for feline longevity.
Does someone make it for cats?
There is no single “GlyNAC” brand for pets at this time. Instead, owners and veterinarians typically use separate high-quality pet supplements or compounded versions.
- NAC: Brands like Thorne Vet and Nutramax produce NAC or liver-support blends (like Denamarin) that contain glutathione precursors.
- Glycine: Usually found in collagen supplements or as a standalone powder.
- Combined Research: Recent studies (such as those published in The British Journal of Nutrition in 2024) have specifically looked at feeding senior cats a diet supplemented with 1.5% Glycine to restore age-associated glutathione deficiency.
Dosage and Frequency
Because “GlyNAC” for wellness is still relatively new in the veterinary world, most dosages come from clinical studies rather than a standard label.
| Supplement | Studied Dosage (Approximate) | Common Frequency |
|---|---|---|
| Glycine | 100 mg per kg of body weight (or ~1.5% of their total daily food intake) | Once daily |
| NAC | 100 mg per kg of body weight for “longevity” protocols; clinical doses for liver issues are often lower (approx. 125–250 mg total per cat). | Once or twice daily |
[!IMPORTANT]
The “Terrible Taste” Factor: Pure NAC has a very strong sulfurous (rotten egg) smell and a bitter taste. Most cats will flatly refuse food if it’s mixed in. If your friend proceeds, they should look for enteric-coated capsules or a flavored suspension from a compounding pharmacy to avoid a battle at mealtime.
Key Considerations
- Senior Support: Most research suggests these supplements are most beneficial for cats 7 years or older, as younger cats generally maintain healthy glutathione levels on their own.
- Safety: NAC is extremely safe but can cause nausea or vomiting if given on an empty stomach. It is always best to give it with a small amount of food.
- Consult a Vet: Since NAC is “off-label” for general wellness and can interact with certain medications (like nitroglycerin or activated charcoal), you should run the specific plan by a vet first.
About pulse dosing:
This is for informational purposes only. For medical advice or diagnosis, consult a professional.
Gemini said
The short answer is that pulse dosing is generally not recommended for GlyNAC, and the biological logic behind it is very different from that of rapamycin.
While pulsing rapamycin is a strategy to balance mTOR inhibition with immune function and glucose metabolism, GlyNAC serves a fundamentally different purpose: replenishing a constant metabolic drain.
Why Rapamycin is Pulsed vs. Why GlyNAC is Daily
| Feature | Rapamycin (Sirolimus) | GlyNAC (Glycine + NAC) |
|---|---|---|
| Primary Goal | Modulation: Periodically inhibiting the mTOR pathway to trigger “cleanup” (autophagy). | Supply: Providing the raw materials for the body to synthesize Glutathione (the master antioxidant). |
| Metabolic Life | Long half-life; stays in the system for days. | Very short half-life; precursors are used or excreted within hours. |
| The “Why” for Pulsing | To avoid chronic side effects like immune suppression or insulin resistance. | N/A; these are amino acids/precursors that the body uses constantly. |
| The “Why” for Daily | N/A (usually weekly or bi-weekly). | Glutathione levels drop quickly once the “raw materials” (Glycine/NAC) are gone. |
The Argument Against Pulsing GlyNAC for Cats
- Rapid Turnover: Glutathione is the body’s primary defense against oxidative stress, and it is consumed rapidly, especially in older cats or those with chronic inflammation. In human trials (such as those by Dr. Rajagopal Sekhar), glutathione levels returned to “baseline” (deficient) levels fairly quickly once supplementation stopped.
- No “Break” Required: Unlike rapamycin, which is a powerful drug that can “clog” certain pathways if taken daily, GlyNAC consists of a semi-essential amino acid (Glycine) and a modified amino acid (NAC). There is no evidence that “pulsing” provides a recovery period for the liver or kidneys; in fact, daily support is often what helps those organs stay healthy.
- Feline Metabolism: Cats have a unique liver metabolism (they are “glucuronidation deficient”), meaning they process many compounds differently than humans or dogs. Maintaining a steady, low-dose supply of glutathione precursors is generally safer and more effective than “bombing” the system with high doses on a pulsed schedule.
Is there any reason to pulse?
The only reason a forum member might consider pulsing would be cost or compliance (the “battle” of getting a cat to take a pill). However, from a biological standpoint, a cat would likely benefit more from a smaller daily dose hidden in food than a large “pulse” dose once a week.
[!TIP]
The 24-Hour Rule: If your friend is worried about over-supplementation, a “5 days on, 2 days off” schedule is a common middle ground in bio-hacking circles. This allows for a metabolic “reset” without letting glutathione levels crash completely.
Thanks a lot for the reply !
It’s an odd response because Glycine glycine stimulates the mechanistic target of rapamycin so that’s why I’m not giving both at the same time for my cat, I thought gemini would catch that but maybe it’s not true or too specific
Gemini said
Your friend is absolutely correct and has highlighted a high-level geroscience detail that many people (and often standard AI responses) miss: Glycine is indeed an mTORC1 activator.
Specifically, glycine promotes the translocation of mTORC1 to the lysosome via the Rag GTPase pathway (specifically RagB). While it is a “gentle” activator compared to the heavy-hitting branched-chain amino acids like Leucine, it is a signal for growth nonetheless.
The mTOR Paradox: Why Both Are Pro-Longevity
This creates what looks like a contradiction:
- Rapamycin extends lifespan by inhibiting mTOR.
- Glycine extends lifespan (proven in the NIA Interventions Testing Program) by activating mTOR (among other mechanisms).
The current thinking in the longevity community is that the benefits of Glycine—such as mimicking methionine restriction, clearing toxic metabolites, and providing the backbone for Glutathione—outweigh the “noise” it adds to the mTOR signal. However, for a “purist” protocol, your friend’s instinct is scientifically sound.
The “Pro-Level” Strategy: Cyclic Timing
If your friend wants to ensure the cat gets the maximum “cleanup” (autophagy) benefit from Rapamycin without Glycine blunting that effect, the best approach is Cyclic Dosing rather than pulsing the GlyNAC itself.
| Phase | Timing (Example) | Action |
|---|---|---|
| The “Inhibit” Phase | Day 1 (Rapamycin Day) | Give the Rapamycin. Withhold GlyNAC (and perhaps avoid high-protein treats) for 24–48 hours to ensure mTOR is deeply suppressed. |
| The “Rebuild” Phase | Days 3–7 | Resume daily GlyNAC. This provides the glycine needed for glutathione and the “building blocks” for muscle maintenance once the Rapamycin has cleared its peak levels. |
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I love these AIs. Yeah normally Glycine should be fine to take with rapamycin because the lowering of methionine would counteract the mtorc activation but since we don’t really know I’d rather be safe with my cat
NEVER trust AI. Normally I use several models for anything critical, and then I still double check. Though I think that they have made great advancements in the past year, especially when it comes to hallucinating or downright lying.
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It is with immeasurable grief, that I must report that our beloved white cat, Austin, has passed away, 16 years old. He was battling a severe case of squamous cell carcinoma since 2021, that started on the lower eyelid of his left eye. For awhile he did very much better on rapamycin, which stopped the spread to the rest of his body, but despite our escalating the dose, it never arrested the original site. It kept getting worse.
Eventually, the cancer ate away all around the eye, burned through to his nasal passages and gangrene set in despite the use of antibiotics. His quality of life got to the point where we felt it was bordering on cruelty to subject him to daily pill stuffing, injections and pain killers. We made the difficult decision to put him down and a special service vet came over to administer the drugs.
We tried to make his last weeks the best we knew how to, he had the full run of the house with zero restrictions, plenty of love and treats. He used to walk on a leash around the garden and a short distance beyond the gate, and on the last day, just hours before the vet came, he took a long, long walk off leash where he smelled all his usual places, branches, bushes and grass. It was as if he was saying goodbye to the world. He finally stopped and as we sat on the grass in the garden, he crawled into my lap, then my wife’s lap looking up at our faces as if he knew… he was such a wise cat. This behavior was different from his usual. He talked to us looking at us - gentle sounds. I cannot express to you how I felt, knowing that he trusted us and we had to do this horrifyingly difficult thing. It felt like a knife stabbing me in the heart. He acted very calm when the stranger came - the vet - to the garden and sat down. My wife dealt with all the paperwork, and Austin just sat there looking at us. We all decided that it would happen right there, in his favorite sunning spot in the garden. And so it did. He didn’t even flinch with the injections. He went to sleep and then the final doses were delivered, we gently stroked him throughout.
I can’t help going over in my mind what I could have done better, despite my wife’s protests that we did all we could. It seems like we moved mountains, chasing down every study that would be remotely relevant, flying out to meet researchers of a paper who had access to drugs used in that paper that were not commercially available. I picked up the drugs and consulted far and wide. But nothing helped. The decline was extremely fast. The cancer seemed to grow literally every hour as we examined it minutely. Within a few weeks it went from just bleeding to severe tissue loss. We did all we could and knew, we stayed up nights just watching him rest, treasuring every minute of life spent together.
And now he’s gone. Everything reminds us of him, his routines, how he greeted us every morning, and now just emptiness.
Love your little furry friend, because one day he’ll be gone.
Goodbye Austin 
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I’m so sorry to hear that. You did everything you could.
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Yeah, good job. Most people don’t get such care.
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I’m so sorry for your loss. I have been in similar impossible situations and my heart goes out to you and your wife.
As much as we can do for our beloveds, it is not enough, it never is – we are so very limited. You moved mountains, as you say. It is human to wonder what else you could have done, but…if we had the power to save their lives and health, we would have. If only we did. We don’t.
I have every faith that you did everything that was possible, and loved with great heart.
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Happy cat - he had you!
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