RU58841 For Hair Loss | Safe Finasteride Alternative? A Chemist's View



Some people believe it (or RU-58841, or RU) is a safe alternative to finasteride. But is it really true? Are there any better options available if someone does not want to use finasteride? What is the verdict on how often RU should be used? What are the caveats when one tries to concoct their own solution? This blog will try to answer all of these and many other commonly asked questions about this treatment from a chemist's perspective.


Table of Content
What is RU58841?
How does it work, and how is it different from finasteride?
Performance & Evidence
How to use and get the best result?
RU4881 before and after Results
How to make your own RU solution?
How stable is it, two years or two weeks?
What are the Side effects?
Alternatives to RU
RU-58841 price, where to buy
RU58841 vs Minoxidil vs Finasteride


So what is it?

RU58841, also known as PSK-3841 or HMR-3841,  is a nonsteroidal anti-androgen (NSAA). Its structure is shown below. It is nonsteroidal because it does not have the steroidal skeleton structure. It was investigated and developed by ProStrakan (a Scottish based specialty pharmaceutical company) for its potential therapeutic applications in conditions that were driven by androgens, such as acne, hirsutism (excessive hair growth), and androgenetic alopecia (male-pattern baldness). ProStrakan conducted phase I and II clinical studies and the results of 5% RU-58841, when applied twice daily, were reported to be similar to that of finasteride. However, no further clinical studies were performed after. Thus, this product was never officially approved as a hair loss treatment.


How does it work?

As a non-steroidal anti-androgen, RU 58841 binds itself to androgen receptors and directly inhibits the effects of endogenous (from our own body) androgens such as testosterone and dihydrotestosterone (DHT). As a first generation non-steroidal anti-androgen, it selectively competes for the androgen receptors. This effectively attenuates the activity of testosterone and DHT, leading to an overall anti-androgen effect. 

The way it works is similar to that of spironolactone, and ketoconazone, a key ingredients used in hair loss shampoo.

It is different from finasteride, which works by inhibiting the activity of 5α-Reductase, an enzyme that converts testosterone into dihydrotestosterone (DHT). DHT is the primary hormone that causes hair loss in men.

Topical RU solution has a rather short half life (1 hour) in comparison to Finasteride (6 hrs) and minoxidil (4 hrs).


Performance & Evidence

There have been several studies on the performance, efficacy and safety of RU5881 since 1994 when it was first developed by French researchers. In the original study by Battmann et al. (1994), it was found to display a high and extremely specific binding to androgen receptors in mice. Compared to other non-steroidal anti-androgens such as flutamide, RU had a staggering 30-fold higher affinity for the androgen receptors. Importantly, Battmann and his fellow researchers found that the local activity of RU-58841 was significant at an extremely low dose (1µg/animal), but was limited to the site of application. This meant that the anti-androgenic effects of it were limited to the target area where it was applied. Indeed, the researchers found that RU- 58841 did not exert any anti-androgenic effects on deep accessory sex organs as well as the serum (blood) testosterone level.

Four years later, American researchers tested RU-58841 in macaques (a type of monkey) [2]. They found that the topical application of this substance resulted in a significant increase in density, thickening and length of hair in macaques with androgenetic alopecia. Similar to the 1994 study, they did not observe any adverse systemic effects and concluded that RU was a promising therapeutic modality for patients with androgen driven conditions such as acne, hirsutism and androgenetic alopecia. These findings echoed observations made by Japanese researchers in a similar study – 20 bald scalps of macaques were subjected to Finasteride as well as RU[3].

Another group of researchers examined 20 scalp grafts from men with androgenetic alopecia; these were grafted onto mice and monitored every month for six months [4]. Ten scalp grafts were each subjected to the RU-588 41 topical solution and ethanol (as a control) respectively. Although both groups had similar (28 vs 29) active follicles which appeared in total, the RU-58841 group demonstrated a second growth cycle more so than the ethanol group (8 vs 2). This led the researchers to conclude that RU- 58841 led to a higher linear hair growth rate and had therapeutic potential for androgenetic alopecia [4].

Studies to date have been limited to studies performed on cultured cell lines in Petri dishes and animal studies. ProStrakan did perform phase I (5% topical solution administered twice daily over 4 weeks to a total of 30 people.and phase II clinical trials (5% and a 2.5% topical solutionadministered once a day over six months in 120 people.) of the drug on humans to evaluate its safety in 2002 and 2003.  The results of those trials were not published.

The information from animal studies indicates that the action of RU should be localized to where it is applied. A great deal of caution should be exercised when considering this substance.  Not only was the official efficacy study never performed, but also short-term and long-term safety data are missing for the human use.  


How to use?

Should RU-58841 be used once or twice a day?

There seems to be no clear consensus on this. While most users apply it once a day (1 ml per application), it appears that using it twice a day with half of the dosage (0.5 ml) per application should provide better results given the short half life of this substance ( 1 hour).

You apply the topical solution to the scalp just like you would with a minoxidil solution. Be careful to apply the solution directly on the scalp instead of the hair by parting your hair with one hand. Any product applied on the hair will not be absorbed.

Should RU-58841 be used with minoxidil?

Minoxidil works by stimulating hair growth via mechanisms that are still not fully known. RU is believed to work by preventing premature hair falling by binding to androgen receptors and directly inhibiting the effects of androgens such as testosterone and dihydrotestosterone (DHT). It makes sense to use both minoxidil and RU to maximize hair regrowth.

When using both products, one can use the RU in the morning and minoxidil product in the evening. Alternatively, one can apply RU first and wait for 20 to 30 mins before applying minoxidil solution.

Yet the most convenient way is to dissolve RU in a minoxidil solution. That way, both products are applied at the same time.


RU 58841 before and after results

The before and after photos from use of RU-58841 is of great scarcity. They are not readily available like minoxidil and finasteride as shown here.


ru58841 before and after

ru58841 results


How to make your own RU58841 solution?

Premixed and ready-to-use RU solution appears to be available for purchase through a few outlets.

To save money, some people make their own by purchasing the raw materials. Here are a few important things to keep in mind if you want to your own.

1. RU-58841 Dosage: the most common concentration is 5%. Have you ever wondered why a lot of hair growth products have a concentration at 5%? ( e.g. 5% minoxidil, 5% stemoxydine (by  L'Oreal ), 5% azelaic acid, 5% Spironolactone)? If a topical product is 5%, it suggests that higher potency can be achieved with higher concentration. However, companies generally like to keep it at 5% for the convenience of formulation, because it adds challenge to dissolve more material and keep the product stable.  Higher concentration also requires longer absorption times when applied to the skin, making it less favorable from the user's point of view. 

2. If you are not allergic to propylene glycol, you can use a PG based solvent as the one we offer.

3. If you have a sensitive scalp and are allergic to PG, you can use a PG free vehicle which we offer at our store. Or you can add it our product Essengen-5 NO PG Fast Dry to make a minoxidil-RU solution.

4. If you want to verify the purity of your purchased RU-58841. You can send a sample (1 gram powder or 10 ml solution) to S&N Labs ( testing.  This is the lab where most RU5881 and SARM providers send their materials for testing.

5. Store the solution in use at room temperature, and store RU powder and the solution that is not currently used in a freezer. RU may precipitate out of the solution when stored in the freezer. If that happens, you can simply bring it room temperature and shake the bottle for a few mins before use. Powder is stable for at least two years when stored in an airtight container in a freezer. 

6. You can see the comment at the end of the blog for details on how to make a PG-based solution. 


How stable is it?

Stability of RU48851 solution:   There is conflicting information about the stability of the RU-58841 solution. Some say it is stable for years even when it is stored at room temperature, while others say it is only stable for up to 2 weeks. The truth probably lies somewhere in between.

If the solution was stable for only two weeks, it is unlikely that ProStrakan would conduct the phase I and II clinical trials. The project must have been killed long before that. 

Also the product does not seem to be that unstable based on the structure of this material (see the main image of the blog). There is no particular bond that appears unstable. It is interesting to note that the solutions used in ProStrakan's clinical studies did not contain any water. It only contained ethanol and propylene glycol. Water-ethanol-propylene is a very common vehicle for topical solution (e.g. topical minoxidil). The fact that there was no water present in the delivery vehicle suggests that the stability of the solution may be an issue. That is reason why neither PG Solvent nor PG Free Solvent we offer has water. 

It is wise to store the solution in a fridge although some providers claim that the solution is stable for over 12 months at room temperature (We are going to conduct a stability study on this and will provide an update with the results. Stay tuned). 


Stability of powder:  RU powder is stable for at least two years when stored in a airtight container in a freezer. 




Unfortunately, there has not been phase III clinical trials for this material. Hence, there is no publicly available longitudinal data concerning its side-effect and safety profile in humans. Indeed, the last known study to have verified its efficacy and performance was published in 2005 [5]. No studies in the literature have been scoped to identify and risk and side-effects of this product. However, the side-effects can be extrapolated based on its classification as a non-steroidal anti-androgenic compound. Testosterone is typically converted to DHT by an enzyme known as 5α-Reductase. An excess of DHT is implicated in androgenetic alopecia; RU directly competes for androgen receptors with testosterone and DHT, thereby limiting the effects of these androgens at the target site. 


Alternatives to RU58 841

Most people consider RU because they are concerned about the possible side effects of oral Finasteride. However, one shouldn't so quick to consider it since there are better alternatives to consider before trying this less-studied substance.

1. Topical finasteride: If one tried oral fin and did not like it, one should definitely consider topical finasteride before trying something else. Topical finasteride is directly applied to the scalp; it greatly minimizes its systemic effect while working as effectively as oral fin.

2. Topical spironolactone:. Spironolactone works the same way as RU. It is an androgen receptor, preventing DHT from binding to the DHT receptors of hair follicles and thus avoiding the damage. In addition, it also lowers the concentration of testosterone which is believed to suppress hair growth. In addition, it does not have any systemic effect as it is completely metabolized in the scalp (read more about topical spironolactone here).

3. Keotoconazole:  Ketoconazole shampoo is a widely recognized treatment for androgenetic alopecia. One landmark study in 1998 showed that 2% ketoconazole shampoo was equivalent to a topical minoxidil treatment in promoting the density, size and proportion of hair follicles in patients with male pattern baldness [6]. Ketoconazole shampoo which was only used two to four times weekly by participants over 21 months performed just as well as with the participants who used once-daily minoxidil lotion for the same duration.

Ketoconazole shampoo with biotin, saw palmetto, niacin, black castor oil, caffeine and argon oil is available at:


Price; Where to buy

Minoxidilmax offer 5% RU 58841 in plant based solvent (PG free). The product is for research only. The prices are: $50 for 2 oz, and $130 for 6 oz.


RU58841 vs Minoxidil vs Finasteride

RU: It is believed to work by binding to DHT receptors thus attenuating DHT's effect. It was never approved for hair loss treatment. Short and long term safety data are NOT available.


Minoxidil: It works by improving blood flow to hair follicles. It has been used for hair loss treatment for over 3 decades since1988. Short and long term safety data are well-known.

Finasteride: It works by blocking 5-alpha-reductase activity thus less DHT is formed.  It has been used to treat hair loss for over 2 decades since1997. Short and long term safety data are well-known.



Although RU58841 has been shown to affect hair growth in androgenetic alopecia, the evidence for this is outdated and extremely sparse. Indeed, most of the studies in the late 90s concerning RU were cell and animal-based studies. There has not been no clinical study on its safety and long-term effects. Its long term safety was not established like finasteride. If one hesitates to use oral finasteride, topical finasteridetopical spironolactone or ketoconazole shampoo can be a good option. 



1.            Battmann, T., et al., RU-58841, a new specific topical antiandrogen: a candidate of choice for the treatment of acne, androgenetic alopecia and hirsutism. J Steroid Biochem Mol Biol, 1994. 48(1): p. 55-60.


2.            Pan, H.J., et al., Evaluation of RU5884 1 as an anti-androgen in prostate PC3 cells and a topical anti-alopecia agent in the bald scalp of stumptailed macaques. Endocrine, 1998. 9(1): p. 39-43.


3.            Obana, N., C. Chang, and H. Uno, Inhibition of Hair Growth by Testosterone in the Presence of Dermal Papilla Cells from the Frontal Bald Scalp of the Postpubertal Stumptailed Macaque1. Endocrinology, 1997. 138(1): p. 356-361.


4.            De Brouwer, B., et al., A controlled study of the effects of RU58 841, a non-steroidal antiandrogen, on human hair production by balding scalp grafts maintained on testosterone-conditioned nude mice. Br J Dermatol, 1997. 137(5): p. 699-702.


5.            Munster, U., et al., RU5-8841-myristate--prodrug development for topical treatment of acne and androgenetic alopecia. Pharmazie, 2005. 60(1): p. 8-12.


6.            Draelos, Z.D., et al., A pilot study evaluating the efficacy of topically applied niacin derivatives for treatment of female pattern alopecia. J Cosmet Dermatol, 2005. 4(4): p. 258-61.


7.            Mysore, V. and B.M. Shashikumar, Guidelines on the use of finasteride in androgenetic alopecia. Indian J Dermatol Venereol Leprol, 2016. 82(2): p. 128-34.


8.            Blume-Peytavi, U., et al., Efficacy and safety of a new 5% minoxidil formulation in male androgenetic alopecia: A randomized, placebo-controlled, double-blind, noninferiority study. J Cosmet Dermatol, 2019. 18(1): p. 215-220.


Submit Your Own Feedback

Bryant's picture


  April 23, 2020 Author

Step by Step how to make 5% RU58841 solution consisting of 70% ethanol and 30% propylene glycol.

Prior to preparing 5% RU, we need the following materials and devices:

  • Raw RU58841 powder
  • Digital Scale for measurement (accurate to 0.1gram)
  • 100ml graduated glass cylinder
  • Plastic stirrer
  • Measuring spoon
  • Glass bottle
  • Propylene Glycol
  • Alcohol

The steps to preparing RU are as follows:

  1. Place the glass bottle upon the digital scale and tare it. This ensures that the subsequent measurements are only for the Ru bottle and do not include the bottle’s weight.
  2. Scoop out 5.0 grams of RU powder into the glass bottle.
  3. Using the 100 ml graduated cylinder , measure 70 mL of alcohol and dispense it into the glass bottle.
  4. Using the 100 ml graduated cylinder , measure 30 mL of propylene glycol and dispense it into the glass bottle.
  5. Using the plastic stirrer, stir the mixture until the resulting mixture appears clear.
  6. For the next 15 minutes, occasionally stir the mixture using the plastic stirrer
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Dudebroham's picture


  November 17, 2020

Is there a way to get the contact for a confirmed, legit chinese supplier of the raw RU/58841 powder? Going with MiC is sort of hit and miss...

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Bryant's picture


  November 23, 2020 Author

We purchased a sample from one supplier. The quality seems to be good. Please send us a message if you need the info.

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Deemo's picture


  December 14, 2020

Hi there, please I will be interested in knowing the details of a legit RU raw materials supplier. I am here in UK. You can find my email here too

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Has's picture


  April 10, 2020

Dear Dr Hair

I am currently using your product called maxogen-x for 3 months now and I've started to see some nice results.
I might add RU58841 in the future to my regime maybe in the next 6 months.
Is it possible to add RU55841 to maxogen-x, will it dissolve and have the same effect as an KB solution/stemoxydine?

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Bryant's picture


  April 14, 2020 Author

We didn't test it. But I believe Ru-58841 should be soluble in Maxogen-x.

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Moen's picture


  January 17, 2020

Is there any minoxidilmax product that can be used to dissolve RU58841?

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Bryant's picture


  January 17, 2020 Author

Both Dualgen-5 NO PG and Dualgen-5 With PG are good options for that purpose.

Also we have two solvents that can be used to dissove RU, one is called PG Solvent, the other one called PG Free Solvent

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Usman's picture


  February 8, 2020

So how to make Dualgen-5 NO PG to make 5% RU-58841 solution?

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Matthiew's picture


  January 15, 2020

Do you know any place to test RU58841 raw material? Thank You!

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Bryant's picture


  January 15, 2020 Author

You can contact to see if they can do it. 

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Ali Raza's picture

Ali Raza

  May 11, 2021

Hi Bryant,    I would heartly appreciate if you can mention me few legit ru58841 suppliers from china. As it is very very difficult to find genuine one who can also supply in Pakistan :(