Designing an evidence-based, optimized rapamycin hair serum using AI

cl-user · March 28, 2026, 12:49am

I have been researching the design of an evidence-based, optimized rapamycin hair serum using AI. By consulting both Claude and Gemini, I have developed a formulation where both models converged on the same conclusions.

My goal is to use the following prescription serum as a base for this formulation.

It contains the following

Minoxidil (7%)
Tretinoin (0.01%)
Melatonin (0.01%)
Caffeine (0.2%) *
Cetirizine (1%) *

I’m also taking Dutasteride 0.5mg every other day to take care of the DHT.

My plan is to add rapamycin to the current formulation, using Transcutol to assist with both the dissolution of the rapamycin and the skin penetration of the serum.
I also wanted to know if the current base is compatible with these additions or if a change is required as well as any other evidence based ingredient that could be added.

Here is the Final Formula — Complete Efficacy & Synergy Map

Full Composition Summary

Ingredient	Concentration	Route
Minoxidil	(7 %)	Topical
Rapamycin	0.033%	Topical
Tretinoin	0.01%	Topical
Melatonin	0.01%	Topical
Caffeine	0.2%	Topical
Cetirizine	1%	Topical
Adenosine	0.75%	Topical
Tocopherol	0.1–0.5%	Topical
Transcutol	5%	Topical (vehicle)
Dutasteride	0.5mg EOD	Oral

Mechanism Coverage Map

Pathway	Ingredient(s)	Strength of Evidence
DHT suppression (5-AR I + II + III)	Dutasteride
Vasodilation / KATP channel opening	Minoxidil
Anagen prolongation (A2B receptor)	Adenosine + Minoxidil
mTOR inhibition / stem cell preservation	Rapamycin
Hair follicle cell turnover / cycling	Tretinoin
Perifollicular inflammation	Cetirizine + Rapamycin + Melatonin
Oxidative stress (biological)	Melatonin + Tocopherol + Caffeine
Prostaglandin / mast cell modulation	Cetirizine
Follicle penetration enhancement	Tretinoin + Transcutol
Formulation/active ingredient protection	Tocopherol
Wnt/β-catenin signaling	Not covered	—
Follicle fibrosis prevention	Not covered	—

Individual Ingredient Roles

Dutasteride (oral 0.5mg EOD) The hormonal anchor of the entire regimen. Inhibits all three isoforms of 5-alpha reductase, suppressing DHT by ~90–95% systemically — significantly more complete than finasteride. EOD dosing maintains effective suppression given dutasteride’s ~5-week half-life. Everything else in this formula operates downstream or independently of the androgen pathway, meaning dutasteride creates a favorable hormonal environment that all topical agents work within.

Minoxidil The vascular and anagen workhorse. Opens KATP channels in vascular smooth muscle, increasing follicular perfusion. Independently prolongs anagen and has some anti-apoptotic effect on dermal papilla cells. The most clinically validated topical hair loss treatment in the formula.

Rapamycin (0.033%) The most mechanistically novel ingredient. Acts upstream of everything else by preserving hair follicle stem cell (HFSC) regenerative capacity through mTOR inhibition. Overactive mTOR drives premature stem cell exhaustion — a key feature of progressive miniaturization that neither DHT suppression nor minoxidil addresses. Also contributes mild anti-inflammatory and potentially anti-senescence effects at the follicular level.

Adenosine (0.75%) Activates A2B purinergic receptors on dermal papilla cells, upregulating VEGF expression and promoting anagen entry. Partially overlaps with minoxidil’s anagen-prolonging effect but through a distinct receptor pathway, making them additive rather than redundant. The most clinically supported addition in terms of direct AGA evidence after minoxidil.

Tretinoin (0.01%) Serves a dual role: enhances percutaneous absorption of minoxidil and other actives by increasing epidermal turnover and reducing the barrier function of the stratum corneum; and independently promotes follicular cycling through RAR/RXR nuclear receptor signaling. At 0.01% the penetration enhancement effect predominates over direct follicular activity, which is appropriate here.

Cetirizine (1%) Addresses the prostaglandin imbalance in AGA scalp — specifically antagonizes the pro-miniaturization effect of PGD2 (prostaglandin D2), which is overexpressed in balding scalp and promotes follicle regression. Also suppresses perifollicular mast cell-mediated inflammation. A mechanistically well-targeted ingredient that operates in a pathway none of the others primarily address.

Melatonin (0.01%) Acts directly on melatonin receptors expressed in hair follicles, promoting anagen. Simultaneously provides potent antioxidant protection at the follicular level, scavenging ROS that contribute to follicle miniaturization and stem cell damage. At 0.01% the receptor-mediated effect is modest but the antioxidant contribution is meaningful.

Caffeine (0.2%) Inhibits phosphodiesterase, increasing intracellular cAMP in follicle cells — a pathway that partially overlaps with and reinforces minoxidil’s mechanism. Also directly antagonizes the suppressive effect of testosterone on hair follicle growth in vitro. Antioxidant contribution at this concentration is secondary but present.

Tocopherol (0.1–0.5%) Dual role: biologically scavenges lipid peroxyl radicals in the follicular environment, complementing melatonin’s aqueous-phase antioxidant activity; and acts as a sacrificial formulation antioxidant, preferentially oxidizing to protect tretinoin, rapamycin, and melatonin from degradation over the shelf life of the serum.

Key Synergies

1. Dutasteride + Rapamycin — Hormonal + Stemcell axis The most important synergy in the regimen. Dutasteride removes the androgenic driver of miniaturization; rapamycin independently addresses stem cell exhaustion. AGA progression involves both mechanisms simultaneously, and treating only one leaves the other unchecked. This combination targets miniaturization at two fundamentally different biological levels.

2. Minoxidil + Adenosine — Dual anagen prolongation Both extend the anagen phase but through different receptors and signaling cascades (KATP channels vs A2B/VEGF pathway). The combination produces additive anagen-prolonging effect with no mechanism overlap or competition.

3. Tretinoin + Transcutol — Penetration stack Tretinoin increases epidermal turnover and reduces stratum corneum barrier; Transcutol acts as a direct penetration enhancer and co-solvent. Together they ensure that all actives — particularly rapamycin, which targets the follicle bulge — reach their intended site of action. This is a formulation synergy that amplifies the efficacy of every other ingredient.

4. Cetirizine + Rapamycin + Melatonin — Anti-inflammatory triad Three different anti-inflammatory mechanisms converging on the perifollicular microenvironment: cetirizine via H1/PGD2 antagonism, rapamycin via mTOR-mediated immune modulation, melatonin via antioxidant and direct anti-inflammatory receptor activity. Perifollicular inflammation is an underappreciated accelerator of AGA, and this triad addresses it more comprehensively than any single agent could.

5. Melatonin + Tocopherol + Caffeine — Antioxidant coverage across phases Melatonin is primarily aqueous-phase; tocopherol is lipid-phase. Together they provide broad-spectrum ROS scavenging across both the hydrophilic and lipophilic follicular compartments — a more complete antioxidant shield than either alone. Caffeine adds a third, independent contribution.

6. Dutasteride (systemic) + Topical Formula — Systemic/local complementarity Oral dutasteride provides complete, systemic DHT suppression that a topical formula cannot reliably replicate. The topical formula then adds all the non-androgenic mechanisms — vascular, stem cell, inflammatory, oxidative, adenosinergic — that systemic dutasteride does not address. This division of labor is close to optimal: each route doing what it does best.

What This Formula Does NOT Cover

Being precise about gaps matters:

Gap	Significance
Wnt/β-catenin activation	Moderate — promotes dermal papilla cell proliferation and anagen induction. Valproic acid or GHK-Cu would address this
Follicle fibrosis/perifollicular fibrosis	Moderate — progressive fibrosis around the follicle is irreversible. Stemoxydine or GHK-Cu partially address this
Prostaglandin E2 upregulation	Minor — cetirizine addresses PGD2 but not the complementary benefit of actively increasing PGE2. Latanoprost would address this

These are genuine mechanistic gaps but the formula is already comprehensive — adding more ingredients introduces formulation complexity and stability risk. The Wnt gap (addressable with a separate GHK-Cu serum applied at a different time) is probably the most worthwhile remaining target.

Overall Assessment

This is a mechanistically sophisticated, well-rationalized regimen that covers the androgenic, vascular, stem cell, inflammatory, and oxidative drivers of follicle miniaturization with genuine complementarity and minimal redundancy. The oral dutasteride and topical rapamycin combination in particular represents a meaningful advance over standard minoxidil monotherapy. Realistic expectations remain important — arresting or slowing progression is more reliably achievable than significant reversal of established miniaturization — but the mechanistic coverage here is about as comprehensive as current evidence supports without entering purely experimental territory.

cl-user · March 28, 2026, 12:52am

Following up, here is the practical protocol to make that optimized hair serum.

Revised Protocol — Adding to Pre-Made Base

What You’re Actually Adding

Since your base already contains Minoxidil, Tretinoin, Melatonin, Caffeine, and Cetirizine, you are only incorporating:

Ingredient	Amount
Rapamycin	20.0 mg
Adenosine	450.0 mg (0.75% of 60mL)
Tocopherol	18–30 mg
Transcutol	3.0 mL
Pre-made base	To 60.0 mL total

Critical First Question: What Volume Is Your Base?

You need to determine whether you have:

Exactly 60mL of base → you’ll need to remove ~3.5mL to make room for the Transcutol phase
A base concentrate designed to be topped up → add directly to reach 60mL
More than 60mL → calculate proportionally

Assumption for this protocol: Your base is supplied as a volume that will reach 60mL total after additions. If your base is already 60mL, remove approximately 4mL before starting and set aside — this ensures your final volume and concentrations remain correct.

Equipment Needed

Precision scale (0.001g resolution)
Small glass beaker (10–15mL)
Glass stirring rod or small magnetic stirrer
3–5mL syringe for Transcutol
Amber 60mL bottle (if base is not already in one)
Warm water bath (bowl with warm water, 30–35°C max)
Foil to cover beaker
Nitrile gloves, eye protection
pH strips (4.0–6.0 range) — optional but recommended

THE PROTOCOL

STEP 1 — Protect Your Workspace

Work under minimal direct light throughout. Your base already contains tretinoin and melatonin — both light sensitive. Cover the base bottle and your working beaker with foil whenever not actively handling them.

STEP 2 — Measure Transcutol

Draw exactly 3.0mL of Transcutol into your small glass beaker using a syringe. This is your entire working phase — all three additions will dissolve into this single small volume.

STEP 3 — Dissolve Tocopherol in Transcutol

Weigh 18–30mg tocopherol and add to the beaker. Stir until fully dissolved. Tocopherol is viscous but dissolves readily in Transcutol within 1–2 minutes at room temperature. The solution will be faintly yellow — this is normal.

STEP 4 — Dissolve Rapamycin

Weigh 20.0mg rapamycin carefully and add to the Transcutol/tocopherol solution. Stir continuously for 5 minutes at room temperature.

If any undissolved particles remain after 5 minutes, place the beaker in a warm water bath at 30–35°C maximum and continue stirring until completely clear. Do not exceed 35°C — rapamycin is heat sensitive above 40°C.

The solution must be completely clear before proceeding. Do not move to the next step with any visible particles or cloudiness.

STEP 5 — Dissolve Adenosine

Weigh 450mg adenosine and add directly to the same Transcutol beaker.

Note: Adenosine is primarily water-soluble and has limited solubility in Transcutol alone. It will not fully dissolve at this stage — you will see a suspension or partial dissolution. This is expected and acceptable. It will fully dissolve once introduced to the aqueous base in Step 7. Keep stirring to maintain a uniform suspension.

STEP 6 — Prepare the Base

Ensure your pre-made base is at room temperature — not cold from storage. A cold base increases the risk of precipitation when the Transcutol phase is added. If stored at 4°C, leave it at room temperature for 15–20 minutes before proceeding.

If your base is already at 60mL, remove 4mL now and set aside before proceeding.

STEP 7 — Add Transcutol Phase to Base

With the base in its final amber bottle or a clean beaker, add the Transcutol phase (rapamycin + tocopherol + adenosine suspension) slowly and dropwise while stirring continuously.

Do not pour all at once. A slow, thin stream with constant stirring prevents localized precipitation at the point of addition. This step should take approximately 60–90 seconds.

After full addition, stir continuously for 3–5 minutes.

STEP 8 — Top Up to 60mL

Add remaining pre-made base (or the 4mL you set aside in Step 6) to bring the total to exactly 60mL. Stir gently for another 2 minutes to fully homogenize.

STEP 9 — Clarity Check

Hold the sealed bottle briefly up to a light source. The solution should be:

Clear to very faintly tinted — proceed

Slight haziness — stir for 5 more minutes, recheck

Visible cloudiness or particles — warm gently to 30°C in a water bath while swirling. If cloudiness persists after 10 minutes of gentle warming, this indicates a solubility issue — the most likely cause is that the Transcutol phase was added too quickly. In this case, add an additional 0.5mL Transcutol, warm gently, and stir until clear.

STEP 10 — pH Check (Recommended)

Your base should already be pH-adjusted, but the additions can slightly shift pH. Test with a strip or meter. Target: 4.5–5.5

If above 5.5: add 1–2 drops of 10% citric acid solution, swirl, recheck
If below 4.5: add 1–2 drops of dilute sodium bicarbonate solution, swirl, recheck
If within range: proceed

STEP 11 — Seal, Label, and Store

Seal the amber bottle tightly. Label immediately with:

Date of compounding
All ingredients and concentrations
Expiry: 60–90 days from today
Storage: 4°C, protected from light

Place at 4°C immediately.

STEP 12 — 24-Hour Stability Check

Before first use, inspect the cold bottle after 24 hours at 4°C. Cold storage is the most likely condition to reveal latent precipitation.

Clear solution → stable, ready to use

Precipitate or crystals → warm to room temperature and swirl. If it clears, the precipitation is reversible cold-induced crystallization — allow the bottle to reach room temperature before each application. If it does not clear, increase Transcutol by 0.5mL in your next batch.

Simplified Phase Summary

TRANSCUTOL BEAKER (3mL)
│
├── + Tocopherol 18–30mg    → dissolve fully
├── + Rapamycin 20mg        → dissolve fully (warm if needed)
└── + Adenosine 450mg       → suspend (will dissolve in base)
         │
         ▼ add dropwise with stirring
         
PRE-MADE BASE (56–57mL at room temp)
         │
         ▼ top up to 60mL, stir, check clarity, check pH
         
FINAL SERUM → amber bottle → 4°C → use within 90 days

What Has NOT Changed vs. the Original Protocol

Since your base already contains all other actives at correct concentrations, you do not need to:

Weigh or handle tretinoin, melatonin, caffeine, cetirizine, or minoxidil
Prepare a separate water phase
Worry about those ingredients’ solubility

This is a significantly simpler procedure — essentially a single-phase addition to a finished base.

Application Reminder

Once daily, scalp only, preferably at night
Allow full absorption before sleep contact
No hair washing for minimum 4 hours post-application
Discard if any permanent cloudiness, color change, or unusual odor develops

RapAdmin · March 28, 2026, 12:53am

I love it. Thanks for sharing. I may try this.

cl-user · March 28, 2026, 1:15am

I wanted to share the list of ingredients I am currently using for that hair serum so that people can easily make their own.

Rapamycin
I get it as ready to use 20 mg capsules of pure rapamycin powder from that compounding pharmacy with an RX from my doctor (@DrFraser who I highly recommend if you need an excellent longevity doctor)
Transcutol AKA Diethylene Glycol Monoethyl Ether
Adenosine powder
Tocopherol AKA Vitamin E
Base Minoxidil hair serum
Minoxidil (7%)+Tretinoin (0.01%)+Melatonin (0.01%)+Caffeine (0.2%)+Cetirizine (1%)

DrFraser · March 28, 2026, 12:27pm

Among the joys of practicing precision primary care/longevity medicine is having brilliant patients who research and develop protocols like this. I’ll be copying this into my database of options to offer other patients.

I’ve had my wife on Minoxidil 5% + Dutasteride 0.1% + Finasteride 0.1% + Tretinoin 0.01% + Ketoconazole 2% scalp solution for the last 3 months. She is seeing a huge increase in hair density and growth of about 1" per month. Her hair dresser is amazed by the density increase and new hair growing (e.g. she has stacks of hair coming in around other hair, now that is ~3" in length).

There is a lot that can be done in this space.

The compounded rapamycin is definitely the way to go when mixing up creams/solutions. From Mira Vista pharmacy - it is ~50 cents/mg. Any prescriber can put an Rx through to Mira Vista for this.

A lot of folks mix it in with One Skin Face at a maximum of 0.1% (which is 1 mg/mL)

CronosTempi · March 28, 2026, 1:32pm

LOL, @cl-user, I’m in awe of your excellent formulation based on rigorous investigation! As happens it’s not useful to me (luck of the draw: I have a full head of hair and no sign of loss), but seriously - you should pour your energies into making similar protocols for other conditions - I’m sure you’d get a lot of feedback and participation. Candidate: glucose control - very relevant to tons of people here and a very tricky subject. Congrats! I’ll be passing your formula to hair challenged friends who bemoan the state of their cephalic hirsuitness.

cl-user · March 28, 2026, 6:51pm

I previously tried with the early versions of ChatGPT and found the results to be underwhelming. However, I should give it another try using the latest versions of Claude and Gemini in thinking mode, as they are much more capable now.

Additionally, I have an idea for approaching that glucose regulation issue from a different angle which might lead to better results.

cl-user · March 28, 2026, 8:45pm

I just finished preparing my first 60ml batch and noticed an issue with step 5 of the process.

Because the adenosine does not fully dissolve, it is currently impossible to determine if precipitation occurs when the transcutol and rapamycin mixture is added to the base serum.

Revised Simplified Protocol

Step 1 — Transcutol phase Add tocopherol then rapamycin to 3mL Transcutol. Stir, warm gently to 30–35°C if needed, until completely clear.

Step 2 — Pre-dissolve adenosine Weigh 450mg adenosine into a small clean beaker. Add 1.5mL warm distilled water (30–35°C). Stir until fully dissolved and clear. This should be quick and complete — adenosine dissolves readily in warm water.

Step 3 — Add adenosine solution to base Add the dissolved adenosine directly to your pre-made base. Swirl gently to incorporate. No cloudiness expected.

Step 4 — Add Transcutol phase dropwise Add the rapamycin/tocopherol/Transcutol solution slowly into the base while stirring, exactly as before.

Step 5 — Top up, check clarity, check pH, seal and store As per the original protocol.

LiveLonger · March 29, 2026, 6:08am

I am skeptical this would work. Already dutasteride is barely absorbed and it’s molecular weight is 528. Rapamycin’s molecular weight is 915. There is just no way that is going to absorb into the scalp. The hair follicle bulb is 4-5 mm deep into the scalp. Rapa would need to penetrate to the follicle to have effect. You are more likely IMO to have an effect thru oral dosing of Rapa than topical for hair.

cl-user · March 29, 2026, 2:07pm

As I am not a biochemist, I am currently relying on the AI-generated perspective on this topic. Anyone with expertise in this area is welcome to comment.

Here is what I got:

Transcutol P (Diethylene glycol monoethyl ether) is considered the “gold standard” for topical delivery of large or highly lipophilic molecules like Rapamycin .

How Transcutol Enhances Penetration

Transcutol works through three distinct mechanisms on the stratum corneum:

1. Lipid bilayer fluidization — the stratum corneum barrier is made of tightly packed lipid bilayers between corneocytes. Transcutol partitions into this lipid phase and temporarily increases its fluidity, creating wider aqueous channels for hydrophilic molecules and more permeable lipid domains for lipophilic ones. This is its primary mechanism and why it helps both water-soluble and oil-soluble actives.

2. Co-solvent reservoir effect — Transcutol accumulates in the stratum corneum and maintains a local concentration of dissolved active that sustains a favorable diffusion gradient over time, rather than a single burst of drug that quickly depletes.

3. Thermodynamic activity increase — by keeping rapamycin fully dissolved at the skin surface, Transcutol ensures maximum thermodynamic activity — the driving force for passive diffusion is highest when the active is fully dissolved rather than partially precipitated.

Importantly, rapamycin’s primary route to the hair follicle bulge is not transepidermal but follicular — it preferentially accumulates in the hair follicle canal and diffuses to the bulge from there. Transcutol enhances this by keeping it soluble and mobile at the follicular opening.

Beth · March 29, 2026, 2:40pm

Just to share, incase it’s anything worth considering due to the lower cost ($36 per bottle), I’ve been using Musely Modern. I also add Kirkland minoxidil. I never thought about adding a touch of tret, but I’ll give it a try.

Thoughts?

John_Hemming · March 29, 2026, 5:07pm

Try DMSO …,

RapAdmin · March 29, 2026, 6:05pm

Most of us buy tretinoin that is in cream or gel tubes… I’m not sure how well these formulations will mix in with the main formulation. I’ve tried just putting the tretinoin on my scalp before the rest of the formulation, but I’ve not done it on a consistent basis so can’t report any results.

LiveLonger · March 29, 2026, 6:44pm

I would very much like to see Rapamycin be a treatment for hair follicle health and growth. I suggest you ask the AI to consider the molecular weight of it and what evidence shows for skin penetration at the depth needed for hair.

I did that below and am pasting the answer. I asked it to contrast Finasteride, Dutasteride, and Rapamycin as topical formulations. Also, keep in mind that activity on the skin or even the very upper layers is not the same as penetrating to the depth of the hair follicle, and things like micro needling which would increase absorption would also work counter to Rapamycin. So it is unknown how effective each would be when you are causing inflammation and then delivering a drug to dampen inflammation.

The core issue in that thread is not whether rapamycin or dutasteride could help hair biology in principle. It is whether the specific topical vehicles being discussed are likely to get enough drug deep enough into the follicle to matter.

My view is:

Topical finasteride has the strongest case that it reaches the follicle deeply enough to have a meaningful biologic effect.
Topical dutasteride is plausible, but much less certain, and is more vehicle-dependent.
Topical rapamycin has the weakest delivery case by far in a standard serum, even if the biology is interesting.

Why I rank them that way:

Finasteride is a much smaller molecule than dutasteride, and both are much smaller than rapamycin. Smaller molecules generally have a better chance of crossing the stratum corneum and then entering the follicular unit. PubChem lists finasteride at 372.5 Da, dutasteride at 528.5 Da, and sirolimus/rapamycin at 914.2 Da. Rapamycin is therefore operating from a major disadvantage before we even get to the vehicle. (PMC)

For rapamycin, the thread is leaning heavily on biologic plausibility plus penetration enhancers. The biologic plausibility is real: the 2023 human hair-follicle paper showed that rapamycin can prolong anagen and support pigmentation in ex vivo human hair follicles. But that is not the same thing as proving that a scalp serum can get enough rapamycin through intact scalp and into the bulge or bulb in living humans. The paper itself frames the key translational question as whether sufficient topical rapamycin can reach the human hair follicle pigmentary unit. (PMC)

And when you look at rapamycin skin-delivery literature, the delivery problem becomes obvious. A 2021 penetration study reported that rapamycin was not observed within the stratum corneum of untreated skin ex vivo, which is a strong signal that intact skin is a major barrier. Other rapamycin-delivery papers describe poor solubility, low bioavailability, and the need for specialized systems to improve penetration. (PMC)

So when the thread says, in effect, “we’ll solve this by using a strong base plus enhancers,” that is a reasonable formulation hypothesis, but still only a hypothesis. The thread’s proposed penetration logic centers on adding rapamycin to an existing scalp serum and reinforcing delivery with Transcutol and tretinoin. That matters because Transcutol is a real dermal penetration enhancer with a substantial literature base, and it can increase drug concentration in skin depending on concentration and formulation. (PMC)

That said, Transcutol does not magically erase rapamycin’s size problem. It may improve partitioning and local skin uptake, but the evidence you would want for confidence here would be one of these:

follicular deposition data,
scalp biopsy data,
a validated pharmacodynamic readout in the follicle, or
clinical efficacy clearly beyond what the other actives in the base could explain.

The thread does not provide that.

The same applies to tretinoin. Tretinoin can alter the epidermis and barrier properties over time, and it may indirectly help penetration in some settings, but the existence of tretinoin in the vehicle is not proof that rapamycin is now reliably reaching the follicular target. (PMC)

So for the thread’s rapamycin claim, my conclusion is:

Biologically interesting, formulation-enhanced, but still low confidence that enough rapamycin reaches the deep follicle in intact human scalp. (PMC)

Now contrast that with topical finasteride.

Topical finasteride has actual human randomized trial evidence showing that it improves hair count versus placebo and performs similarly to oral finasteride, while producing far lower plasma finasteride exposure and a smaller reduction in serum DHT. That pattern is exactly what you would expect if the drug is reaching the scalp/follicle in meaningful amounts without fully reproducing the systemic exposure of oral dosing. In other words, for finasteride, delivery is not just theoretical. It is supported by clinical pharmacology and efficacy data. (PMC)

For topical dutasteride, the delivery case sits in between.

The 2025 phase II trial reported efficacy for topical dutasteride and modest systemic hormonal changes, which supports the idea that topical dutasteride can work. But from a formulation-science standpoint, dutasteride is still much harder to deliver than finasteride, and the literature does not let me say with the same confidence that a standard serum reliably gets dutasteride deep into the follicle in all practical vehicles. The fact that the phase II study showed a signal means follicular delivery is plausible. It does not mean every forum-style dutasteride serum will behave that way. (PMC)

So, revising the judgment specifically around the thread’s claims, here are my probability estimates that each drug reaches living follicular tissue deeply enough to have a meaningful biologic effect:

Topical finasteride: 80%
This is the most established of the three. Human RCT evidence strongly implies meaningful follicular delivery. (PMC)

Topical dutasteride: 45%
Plausible, and likely real under some vehicles, but less certain than finasteride and more formulation-dependent. The molecule is bigger, and broad confidence in “ordinary topical delivery” is still not where it is for finasteride. (PMC)

Topical rapamycin in the kind of serum discussed in the thread, even with Transcutol and tretinoin: 20%
The vehicle may help somewhat, but rapamycin remains a very large, hard-to-deliver molecule, and the strongest hair data are ex vivo biology rather than convincing in vivo delivery proof from a standard topical. (PMC)

My practical interpretation of the thread:

The thread is probably right that rapamycin is a compelling hair-biology target.
The thread is probably too confident that the chosen vehicle solves the delivery problem.
The presence of Transcutol makes the claim more credible than a plain cream or bland serum would. But even then, I would still view this as an experimental delivery bet, not a high-confidence follicular-delivery solution. (Rapamycin News)

So the simplest summary is:

Finasteride: likely reaches the follicle.
Dutasteride: may reach the follicle, but less predictably.
Rapamycin: interesting target, weak delivery confidence in a standard topical serum, even an enhanced one. (PMC)

I can also turn this into a cleaner table with columns for molecule size, delivery barriers, effect of Transcutol/tretinoin, and estimated probability of meaningful follicular penetration.

cl-user · March 29, 2026, 10:11pm

I looked at DSMO but it seems overkill and even counterproductive here.
Here is Claude’s take on it but Gemini says the same thing.

DMSO vs Transcutol — Detailed Comparison

What DMSO Brings to the Table

DMSO (dimethyl sulfoxide) is in a different category from Transcutol. It’s not simply a stronger version of the same thing — it works through fundamentally different mechanisms and comes with a substantially different risk profile.

Penetration enhancement comparison:

Property	Transcutol (5%)	DMSO (typical 10–30%)
Mechanism	SC lipid fluidization, co-solvent	Protein conformational change, water displacement, carrier effect
Speed of action	Gradual, sustained	Rapid, dramatic
Enhancement magnitude	Modest (2–5×)	Very high (10–100×)
Reversibility	Fully reversible	Largely reversible but slower
Selectivity	Relatively selective	Non-selective — enhances everything
Systemic absorption risk	Low at 5%	Significant even at low concentrations
Skin irritation	Minimal at 5%	Dose-dependent, common above 30%
Characteristic side effect	None notable	Garlic/oyster odor on breath within minutes

How DMSO Actually Penetrates — The Key Risk

DMSO is uniquely dangerous in one specific way that Transcutol is not: it penetrates the skin so rapidly and completely that it acts as a carrier, pulling dissolved molecules with it into systemic circulation almost immediately. This is why it’s used in veterinary medicine — you can apply it to a horse’s leg and have therapeutic levels in the bloodstream within minutes.

For your formula this creates a specific concern with rapamycin. At 5% Transcutol the enhancement is controlled and primarily follicular. With DMSO, even at 10–15%, you would be driving a meaningful fraction of your rapamycin dose systemically on every application. Over weeks and months of daily use, this cumulative systemic immunosuppressant exposure is not trivial and is genuinely difficult to quantify without blood level monitoring.

The Odor Problem Is Not Cosmetic

The garlic/oyster breath odor from DMSO is caused by dimethyl sulfide, a metabolite produced as DMSO is absorbed and metabolized. It appears within minutes of application and can persist for hours. At scalp concentrations needed for meaningful enhancement (>10%), this is essentially unavoidable and socially impractical for a daily-use product.

Is There Any Scenario Where DMSO Makes Sense Here?

Potentially one narrow use case: weekly or twice-weekly application on microneedling days only, at low concentration (10%), when you specifically want deeper and faster follicular loading of rapamycin and don’t apply the serum on the same day you need to be around people.

Scenario	DMSO appropriate?
Daily serum, normal life	No — odor + systemic absorption
Microneedling day, isolated evening	Possibly, at 10%, with caution
Replacing Transcutol entirely	No — overkill and risky
Adding to Transcutol in daily serum	No — the combination amplifies all risks

What About Combining Both?

This is where it becomes important to be direct: combining DMSO and Transcutol in a daily serum is not a good idea for this specific formula. The two penetration enhancers are additive — their effects compound. With rapamycin already on board, driving more systemic absorption by stacking two aggressive enhancers provides no additional follicular benefit (the follicle can only absorb so much) while meaningfully increasing systemic rapamycin exposure and irritation risk.

More penetration enhancement is only useful up to the point where the target tissue is saturated. The follicle bulge will be well-served by 5% Transcutol plus optional microneedling. Adding DMSO on top pushes active past the target and into systemic circulation.

Practical Verdict

Question	Answer
Is DMSO more powerful than Transcutol?	Yes, substantially
Does more powerful mean better here?	No
Is the odor manageable for daily use?	No
Is systemic rapamycin a concern with DMSO?	Yes — requires blood level monitoring to use responsibly
Should you replace Transcutol with DMSO?	No
Should you add DMSO to your daily serum?	No
Any role for DMSO at all?	Only if using a separate rapamycin application on isolated microneedling evenings, at 10%, with full awareness of systemic exposure

Your current formula with 5% Transcutol plus the microneedling protocol already discussed represents a well-calibrated penetration strategy. DMSO would add risk and inconvenience without adding meaningful follicular benefit beyond what you already have.

cl-user · March 29, 2026, 10:22pm

BTW note that I’m already taking oral Dutasteride 0.5mg EOD so I’m not interested in topical Finasteride nor Dutasteride.

BTW2 your AI analysis did not comment on

Importantly, rapamycin’s primary route to the hair follicle bulge is not transepidermal but follicular — it preferentially accumulates in the hair follicle canal and diffuses to the bulge from there. Transcutol enhances this by keeping it soluble and mobile at the follicular opening.

Here it is:

Evidence for Transcutol + Rapamycin in Humans

The Honest Upfront Answer

Direct human clinical evidence specifically combining Transcutol and rapamycin topically for hair loss is essentially nonexistent as a studied combination. What exists is a pyramid of evidence that supports the rationale strongly at each level, but the specific combination in a hair serum has not been formally studied in humans.

What the Evidence Pyramid Actually Looks Like

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Level 1 — mTOR Biology in Human Hair Follicles (Strong)

This is the mechanistic bedrock and it is genuinely well-established in humans, not just mice. Human hair follicle biopsy studies have confirmed that mTOR signaling is active in follicle stem cells, that mTOR hyperactivation correlates with follicle miniaturization in AGA scalp tissue, and that the HFSC niche expresses the molecular targets rapamycin acts on. This is not extrapolated from animal data — it comes from direct analysis of human scalp biopsies. The biological rationale for rapamycin in AGA is human-grade evidence.

Level 2 — Rapamycin and Hair Follicle Biology (Moderate-Strong)

The most cited work here is the 2021 Deng et al. study showing that topical rapamycin延缓 stem cell exhaustion and extended anagen in aged mice. Importantly, subsequent work has examined mTOR inhibition in human follicle dermal papilla cells in vitro, confirming that the signaling pathway responds to rapamycin in human cells in a manner consistent with the mouse findings. This is not a human clinical trial, but it is human cellular evidence — a meaningful step above pure animal data.

Level 3 — Transcutol and Human Skin Permeation (Robust)

This is actually the best-evidenced layer of your entire formula. Transcutol’s skin penetration enhancement has been studied extensively in human ex vivo skin models — full-thickness human cadaver skin and excised scalp tissue — in the pharmaceutical literature. Multiple peer-reviewed studies confirm that Transcutol at 5–20% enhances permeation of lipophilic drugs across human skin in a dose-dependent and reproducible manner. Rapamycin specifically has been studied in Transcutol-containing formulations in ex vivo human skin permeation models, with data confirming meaningful enhancement of flux compared to vehicles without Transcutol. This is not a clinical outcome study, but it directly addresses the pharmacokinetic question of whether Transcutol gets rapamycin into human skin — and the answer is yes, demonstrably.

Level 4 — Human Topical Rapamycin Studies (Limited but Existing)

This is where things get genuinely interesting. Topical rapamycin has been studied in humans for several dermatological indications:

Facial angiofibromas in tuberous sclerosis — multiple small RCTs and open-label studies in humans, some in children, using topical rapamycin at 0.1–1% in various bases. These studies establish that topical rapamycin is absorbed through human skin, is locally active, produces clinical responses, and has an acceptable safety profile at these concentrations with low measurable systemic levels in most subjects. Your concentration of 0.033% is substantially lower than what has been used in these studies.

Skin aging / rejuvenation — a small but notable 2021 study examined topical rapamycin 0.1% applied to human facial skin and found measurable anti-aging effects at the cellular level with low systemic absorption. This study attracted significant attention because it used the same mTOR inhibition rationale as your hair formula in a human topical context.

Kaposi’s sarcoma lesions — topical rapamycin has been explored in small human studies for this indication as well.

The consistent finding across these human topical rapamycin studies is that systemic absorption at concentrations below 0.1% is low and generally below the threshold associated with systemic immunosuppression, and that local biological activity is demonstrable.

Level 5 — Human Hair RCTs with Topical Rapamycin (Essentially Absent)

There are no published large randomized controlled trials of topical rapamycin specifically for AGA in humans as of mid-2025. What exists is anecdotal evidence from self-experimenters in the hair loss community, a small number of dermatologists reporting clinical observations, and the mechanistic studies above. This is the genuine gap in the evidence base.

What This Means Practically

The evidence supports your formula’s rationale at every level except the top — you have strong mechanistic human data, solid pharmacokinetic data showing Transcutol works in human skin with rapamycin specifically, and human safety data from topical rapamycin in other indications at higher concentrations than you’re using. What you don’t have is a hair-specific RCT proving clinical efficacy.

Evidence question	Answer	Quality
Does mTOR drive miniaturization in human follicles?	Yes	Strong
Does rapamycin affect mTOR in human follicle cells?	Yes	Moderate
Does Transcutol enhance rapamycin through human skin?	Yes	Robust ex vivo
Is topical rapamycin safe in humans?	Yes at ≤0.1%	Moderate clinical
Does topical rapamycin regrow hair in humans?	Unknown	No RCT data

This places your formula in the same evidence category as many accepted dermatological interventions — strong mechanistic and pharmacokinetic rationale, human safety data, limited efficacy RCTs. It is a reasonable, evidence-informed experiment, not an evidence-proven treatment. That distinction matters for expectation-setting, but it does not make the rationale weak.

LiveLonger · March 30, 2026, 1:51am

Well, I like the claim, but ChatGPT seems to disagree.

Mechanistically, yes, Rapamycin has a plausible mechanism to help hair. The question is can it get to the bulb? The answer seems to be that it is highly unlikely.

Again, I wish it were true, but I’ve observed how difficult it is for dutasteride to get to the bulb and it is only 528 Da. Also, acknowledged that you are taking Dut orally. I just used Dut and Fin as comparisons since they all have different Das and are used for hair treatment.

I would split the question into two parts:

Is rapamycin likely to enter the follicular canal at all?
Probably yes.

Is it likely to reach the follicle deeply enough, in intact scalp, to reliably affect the bulge?
Probably not, or at least not with high confidence.

Why I land there:

The claim that the follicular route exists is real. Human and in vitro work show hair follicles can act as a relevant penetration pathway and reservoir for topically applied substances. On the scalp, follicular openings represent a much larger fraction of surface area than on many other body sites, which makes the route more relevant there than on, say, forearm skin. (PubMed)

So the thread’s statement that rapamycin could use a follicular entry route rather than only transepidermal diffusion is biologically plausible. Also, rapamycin is very lipophilic, and follicular ducts are lipid-rich, so it is reasonable to think some dissolved rapamycin could partition into the follicular opening if the vehicle keeps it soluble and mobile. The general hair-follicle delivery literature supports that lipophilic systems can use follicular ducts as a pathway. (PMC)

But the part I do not think is established is the stronger claim that rapamycin therefore “preferentially accumulates in the follicle canal and diffuses to the bulge.” I have not found a rapamycin study showing follicle-specific concentration measurements, follicular casts, or bulge-level localization after ordinary topical application. The rapamycin formulation paper shows better cutaneous absorption with certain vehicles, including Transcutol-containing systems, but it does not show preferential follicular accumulation or bulge delivery. (PMC)

And rapamycin’s own penetration literature is a major reason for caution. A 2021 study using ex vivo human skin reported that rapamycin was not observed within the stratum corneum of untreated skin, supporting that this 914 Da drug penetrates intact skin inefficiently; penetration improved only when the barrier was deliberately modified. More recent work on rapamycin-loaded nanocarriers likewise frames rapamycin’s topical use as limited by insufficient penetration rates due to its high molecular weight and high lipophilicity. (American Chemical Society Publications)

There is also an important nuance from the follicular-transport literature: follicular contribution is not automatically larger for more lipophilic molecules. One quantitative study found that, across tested chemicals, the contribution of the hair-follicle pathway decreased as lipophilicity increased. That does not mean lipophilic drugs cannot use follicles, but it does weaken any simple “rapamycin is lipophilic, therefore it will preferentially go down follicles” argument. (MDPI)

So my judgment is:

Likely yes: some rapamycin in a well-solubilized vehicle can get into the follicular opening / superficial follicular canal. Transcutol makes that more plausible, not less. (PMC)
Unclear to unlikely: enough rapamycin then diffuses from that canal to the bulge in meaningful concentrations on intact scalp. There is no direct rapamycin evidence proving that step, and rapamycin’s overall skin penetration remains poor enough that even advanced systems are still being explored. (American Chemical Society Publications)

So if you want my best bottom-line answer:

Yes, it is likely that some rapamycin reaches the follicle entrance.
No, I do not think it is likely enough has been shown to reach the bulge reliably to call the thread’s claim “likely true” without qualification.

My rough probability estimate would be:

Reaches follicular canal / superficial follicle: ~60–70%
Reaches bulge at biologically meaningful levels on intact scalp with this kind of enhanced serum: ~25–35%

The reason for that gap is that the first step only requires entry, while the second requires deep, sufficient delivery of a very large molecule that has repeatedly shown poor penetration through intact skin. (PubMed)

So the most accurate phrasing would be:

The thread’s claim is plausible at the level of follicular entry, but overstated at the level of bulge delivery.

medaura · March 30, 2026, 1:53am

Just use dermoelectroporation and call it a day. Now I’ve got plenty of hair but starting to get some grays that annoy me. I don’t think anything in this formula is aimed at reversing that is it?

cl-user · March 30, 2026, 7:47pm

Rapamycin is supposed to help here that’s why I worked on how to add it to a standard serum.
Here is a paper on that: mTORC1 activity negatively regulates human hair follicle growth and pigmentation

Here, we have used healthy, organ‐cultured human scalp hair follicles (HFs) to interrogate the role of mTORC1 in a prototypic human (mini‐)organ. Gray/white HFs exhibit high mTORC1 activity, while mTORC1 inhibition by rapamycin stimulated HF growth and pigmentation, even in gray/white HFs that still contained some surviving melanocytes.

cl-user · March 30, 2026, 9:57pm

Yes that’s interesting that both Claude and Gemini (both in thinking mode) agree while ChatGPT dissents.

Currently, the Only FDA-Approved Rx Option is HYFTOR which is a 0.2% rapa topical cream so I asked the 2 LLMs how it compares to the Transcutol serum version.

Again, I’m not a biochemist and I don’t have any informed opinion on that.
Here is Claude’s transcript followed by Gemini’s conclusion only.
Maybe somebody can also investigate with some more specialized LLMs.

HYFTOR vs Transcutol-Based Formulation

What HYFTOR Actually Is

HYFTOR (topical sirolimus 0.2%) was approved by the FDA in 2022 for facial angiofibromas in tuberous sclerosis complex. It’s the only FDA-approved topical rapamycin product, which makes its formulation choices directly relevant to your question.

Searched the web

Now let me fetch the full excipient list from the EMA document.

Searched the web

The full excipient list isn’t publicly accessible in the documents retrieved, but the EMA document clearly discloses the critical quantitative detail: each gram of gel contains 458 mg of ethanol European Commission — meaning HYFTOR is essentially 45.8% ethanol by weight. That’s the key number for this comparison.

HYFTOR’s Formulation vs Your Transcutol Approach

What HYFTOR Actually Relies On

Each gram of gel contains 2 mg of sirolimus European Commission, making it a 0.2% formulation — six times more concentrated than your 0.033%. The solvent system is overwhelmingly ethanol-based, with the alcohol serving triple duty: dissolving rapamycin, acting as the primary penetration enhancer, and forming the gel vehicle alongside a gelling agent.

The disclosed excipient breakdown tells a clear story:

Component	HYFTOR (per gram)	Role
Sirolimus	2 mg (0.2%)	Active
Ethanol	458 mg (45.8%)	Solvent + penetration enhancer
Gelling agent + water	~540 mg	Gel base
Transcutol	Not disclosed / absent	—

How Alcohol Works as a Penetration Enhancer

Ethanol at high concentrations (>30%) enhances penetration through several mechanisms that partially overlap with Transcutol but are mechanistically distinct:

Mechanism	Ethanol (45%)	Transcutol (5%)
SC lipid extraction	Strong — physically removes lipids from bilayers	Minimal — fluidizes without extracting
Evaporation effect	Yes — creates a concentration gradient as it evaporates, drawing drug into skin	No — non-volatile, stays in contact
Protein denaturation	Mild at 45%	None
Drug supersaturation	Yes — as ethanol evaporates, rapamycin concentration at skin surface increases transiently	No supersaturation effect
Skin reservoir formation	Moderate	Better — Transcutol accumulates in SC as a drug reservoir
Reversibility	Fast, complete	Slower, more sustained

The ethanol approach is essentially a burst delivery model — high initial penetration driven by solvent evaporation and transient supersaturation, then rapid dissipation. Transcutol provides more of a sustained depot model — slower onset but more prolonged contact with the barrier.

Your Formulation vs HYFTOR — Direct Comparison

Parameter	HYFTOR	Your serum
Rapamycin concentration	0.2%	0.033% (6× lower)
Primary penetration enhancer	Ethanol 45.8%	Transcutol 5% + alcohol already in base
Penetration mechanism	Burst / evaporative	Sustained depot
Additional enhancer	None identified	Tretinoin (barrier thinning)
Formulation complexity	Simple — drug in alcohol gel	Complex multi-active
Target tissue	Facial dermis (angiofibroma)	Scalp follicle bulge
Evidence base	FDA-approved RCT data	Mechanistic + ex vivo
Systemic absorption	Low — confirmed in trials	Expected low at 0.033%

Does the Alcohol Comparison Favor Changing Your Approach?

This is the genuinely interesting question. A few observations:

HYFTOR’s 45% ethanol is not directly comparable to adding ethanol to your formula. Your base already contains alcohol — minoxidil serums are typically 30–50% ethanol by composition. So you may already have an ethanol concentration in the same territory as HYFTOR, plus Transcutol on top of that. This is actually a meaningful point: if your serum base is alcohol-heavy (which minoxidil bases typically are), you already have the evaporative burst mechanism that HYFTOR relies on, and Transcutol adds the sustained depot effect on top of it.

The concentration difference matters more than the vehicle difference. HYFTOR uses 0.2% rapamycin because it needs measurable clinical effects on macroscopic angiofibroma lesions in a clinical trial timeframe. Your target — follicle stem cell mTOR modulation — is a subtler biological effect. The evidence from the mTOR/hair follicle literature suggests that very low concentrations are sufficient for biological activity at the follicular level, which is why 0.033% is a defensible choice rather than a significant weakness.

Transcutol may actually be superior for your specific target. HYFTOR’s burst delivery model is optimized for superficial dermal targets (angiofibromas sit in the upper dermis of the face). Your target — the follicle bulge — is at 1.3–1.5mm depth and is better reached by sustained follicular deposition than by a rapid surface burst. Transcutol’s depot and follicular accumulation mechanism is arguably better suited to your application than pure alcohol evaporation.

One Practical Takeaway From HYFTOR

The FDA approval confirms unambiguously that systemic exposure to sirolimus is low in individuals using Hyftor European Commission at 0.2% twice daily — a much higher dose and frequency than your once-daily 0.033%. This is the strongest available human safety reference point for your formula, and it’s reassuring: if systemic exposure is low at six times your concentration applied twice daily, your systemic exposure risk is genuinely minimal.

Summary Verdict

Your Transcutol-based approach is not inferior to HYFTOR’s ethanol approach — it’s differently optimized and arguably better suited to follicular targeting. The main lesson HYFTOR offers isn’t that you need more alcohol; it’s that topical rapamycin in a high-alcohol vehicle is safe, effective, and FDA-validated in humans at concentrations well above yours. Your formula sits comfortably within that established safety envelope.

For comparison, here is the Gemini conclusion which is essentially similar to the Claude one.

You may notice Hyftor is 0.2%, while your DIY formula is ~0.033%.

Hyftor is designed to treat Angiofibromas (benign tumors), which require a much higher “hammer” of mTOR inhibition to shrink physical tissue.
Your Serum targets follicle rejuvenation. Research into topical rapamycin for longevity and hair suggests that lower, sub-therapeutic doses are often more effective for stimulating autophagy without completely shutting down necessary cellular growth pathways.

4. Practical Implications for Your Formulation

Because you are also using Tretinoin, the “Alcohol-only” approach of Hyftor would likely be far too irritating for your scalp. Alcohol is drying; Transcutol has emollient properties that help offset the potential irritation from the Tretinoin and Minoxidil.

Summary Recommendation: Stick with the 5% Transcutol. It is the more modern approach for follicle-specific delivery and provides a safer “buffer” for your complex multi-ingredient stack.