RU58841 – Research and Study Results for Hair Growth

  • Medically reviewed by: Debra Rose Wilson, PhD MSN RN IBCLC AHN-BC CHT
  • Written by: William Slator
  • Last updated: 18/01/2024

In this article you’re going to learn about RU58841. You’ll learn what it is, how effective it is at reversing hair loss, how to use it, how to make it, and associated side effects. You’ll see (from scientific studies) just how effectively this chemical can re-grow your hair.

If you have tried all sorts of drugs for hair loss, only to see disappointing results, you are definitely not alone. In fact, this is a common experience for many suffering from male pattern baldness or androgenetic alopecia.

Despite extensive research and eager patrons, there are still limited pharmaceutical options. Furthermore, many of these drugs are either ineffective or gradually lose their effectiveness over time.

There is one other option that has long existed but managed to slip under the radar: RU58841.

If you are an active member of the hair loss community, you have probably heard of this obscure chemical. Otherwise, you might be wondering if this is an ingredient in some brand of lotion.

RU58841 (also known as RU-58841, PSK-3841, or HMR-3841) is a compound that has been garnering attention for its effects on hair growth, even for individuals who have exhausted all other methods.

Many claimed that this “magic pill” has helped grow back stubborn hairs in areas considered irreversibly damaged. Some even claim to have regained a full head of hair.

However, the FDA has not approved the use of RU58841. No regulatory agency has even approved it for use in humans. Your doctor cannot prescribe it, and your pharmacy will not sell it to you. You can only obtain it for “research purposes”.

The Story of RU58841

RU58841 is not a recent invention. French scientists first developed it in the 1970s. They were looking into treatments for prostate cancer.

They synthesized RU58841 as a non-steroidal, antiandrogenic compound for topical use. This way there would be fewer systemic side effects.

After testing in on rats, they discovered it promoted hair growth.

The researchers concluded that RU58841 might be useful for the topical treatment of androgen-dependent skin disorders, like acne and alopecia.

But before they could make any additional plans for research or production, their company went through a merger with two other companies. Eventually, for reasons that are still unclear, the project was dropped.

A few years later, a company called ProStrakan acquired the rights to RU58841. ProStrakan renamed the drug to PSK3841.

In 2005, the company announced plans to run a Phase II trial. They planned for a full launch in 2010. The company ran  Phase I and II trials, but never started Phase III research.

Nowadays, there is no further research into RU58841. Unless there is a dramatic development, this drug will never come to market. As of today, it is not only unlicensed for hair loss but not even approved for use in humans.

The Science Behind Hair Loss

Androgens are the male hormones in charge of sexually related development, both anatomically and physiologically. They are predominantly produced in the adrenal glands and testes.

The most well-known androgen is testosterone. Another androgen is dihydrotestosterone (DHT), which is the byproduct of testosterone (1).

Testosterone converts to DHT via 5-alpha-reductase.

Androgens have an important role in controlling the maturation and maintenance of sexual characteristics. For men, both testosterone and DHT are pivotal to the formation and growth of the penis, scrotum, and prostate. In addition, they are necessary for the process of spermatogenesis, or sperm production.

They also control many secondary male characteristics. For example, the increase in muscle mass, deepening of the voice, and growth of body hair.

Around 5% of the free testosterone in the serum is transformed to DHT by enzymes called 5-alpha reductase. There are two forms of 5-alpha reductase: Type I and Type II.

Type I is expressed in the liver and sebaceous glands of the dermis. In the dermis, it is largely responsible for producing sebum. This is necessary for lubricating and protecting the skin from losing moisture.

Type II, on the other hand, is expressed in areas such as the prostate and dermal papilla cells of the skin. It contributes to the stimulation of the prostate and the hair follicles.

Together, these two enzymes convert testosterone to the more potent DHT. As essential as DHT is for human functioning, in adulthood, it can cause problems for some sensitive men. In the scalp, it has been shown to be the culprit for pattern hair loss.

Why is DHT so Influential in Hair Loss?                         

There are currently no clear explanations for the link between DHT and alopecia (2).

When testosterone is converted to DHT, some of it reaches the hair follicles. Once there, it binds to the androgen receptors located on the dermal papilla cells.

Once it binds to these receptors, it triggers a cascade of events inside the cell’s cytoplasm. Some of these changes involve the modification of certain gene functions. It is not yet clear exactly which of these biochemical pathways affected by DHT impede hair growth.

The compromised follicular cells will begin altering the growth cycle, most notably by reducing the duration of the anagen phase. When this happens, the cells that are rapidly dividing and forming the new hair will stop prematurely.

With each successive hair growth cycle, the hair strands will become shorter and thinner. This is called miniaturization.

Another frequent problem with a balding scalp is poor blood circulation. This can stop essential vitamins, minerals, antioxidants, and proteins from nourishing the cells. This will also reduce the average growth span of the follicles, further exacerbating development problems.

The adverse effects of DHT on hair growth will not be immediately obvious. Male pattern baldness is a slow, gradual process.

The Science Behind RU58841

Many commercial drugs for hair loss, such as finasteride (Propecia), work by specifically inhibiting 5-alpha reductase, the enzyme that converts testosterone into DHT (3).

However, reducing DHT on a systemic level affects all tissues in the body, not just the hair follicles. This can hurt parts of the body that rely on DHT to function properly.

As mentioned before, RU58841 is a topical anti-androgenic. This means it counteracts the effects of DHT by binding to the androgen receptors at the hair follicles. This then prevents DHT from binding to these receptors. The result is that the process of miniaturization never initiates, and the hair undergoes its normal growth cycle.

RU58841 also aids in cellular recovery by allowing time for damaged follicles to transition back to a normal anagen phase.

Since RU58841 is topical and does not block the production of DHT in the body, the levels of DHT in the blood are presumably not affected.

The Available Research

There are some favorable studies indicating RU58841’s hair growth properties. However, since the rights for RU58841 were transferred, there have been no new studies published.

Furthermore, none of the existing studies have studied the side effects of long-term, extended use of RU58841.

Study #1. Follicular regrowth with 5 alpha-reductase inhibitors (finasteride) or androgen receptor blocker (RU58841)

An article from the Journal of Dermatology by researchers Uno et al examined the effects of two different antiandrogens on follicular growth and serum levels of testosterone and DHT: oral finasteride and topical RU58841 (4).

The researchers chose to use the bald scalps of 20 macaques (monkeys). These are bald in a similar pattern to men. This makes them an excellent animal model to study hair loss.

The researchers gave finasteride (1mg/kg/day) and placebo to 10 macaques, while they applied RU58841 topically applied to 10 other macaques.

They also collect skin biopsies for the hair follicles at various times. For the finasteride, they collected results at zero and six months, while for RU58841 they took them at zero and four months.

Hair growth after 4 months using ru58841

First, they looked at the population of anagen follicles to vellus follicles. This is a measure of how many healthy hairs are growing.

In the finasteride group, they observed an average of 88% increase. RU58841, on the other hand, showed a staggering 103% percent increase. Out of all the treatment groups, RU58841 induced the most growth after only two months.

The researchers also tested the levels of serum testosterone and DHT. The finasteride group showed a decrease in DHT and an increase in testosterone levels. Consistent with expectations, the RU58841 exhibited no significant changes in DHT and testosterone levels.

The researchers concluded that blocking androgen receptors is more effective than systemically targeting the enzyme 5-alpha reductase.

Study #2. Dose-dependent and long-term effects of RU58841 on hair regrowth

After the promising results of the first study, Uno et al. decided to further test the effectiveness of RU58841, but this time in different dosages (5).

They split 20 macaques into five different groups: four experimental groups with RU58841 in 5, 3, 1, and 0.5 percent dosages and one placebo group. They applied the solutions topically once per day for 6 months.

The scientists also wanted to test the long-term effects of RU58841. For this reason, three monkeys from each of the 5 percent, 0.5 percent, and placebo groups continued treatment for 12 to 24 months.

The results revealed that the group with 5 percent RU58841 showed a marked increase on all measures. These include density, thickness, and length of hair. The researchers could measure the differences as early as three months into treatment.

After 5 months, in addition to an average of two- to three-fold increase in the number of scalp follicles, the macaques also had more follicles in the anagen growth phase.

There was also noticeable growth in other groups. Yet none showed results nearly as promising as the 5% group. The 1% and 0.5% were the weakest.

The macaques in the 5 percent group that continued the long-term treatment also showed progressive hair growth. This occurred continuously for 3-7 months. In all cases, the macaques started to lose their hair again approximately three months after stopping treatment.

The 0.5 percent group did not appear to have any noticeable progression after the initial minimal effects.

The researchers conclude that 5 percent of topical RU58841 induced remarkable effects on hair and follicular regrowth in a short amount of time. Continued use of the chemical maintained these gains.

Study 3#. Controlled study of the effects of RU58841 on human hair production by balding scalp grafts maintained on testosterone-conditioned nude mice

Researchers Brouwer et al took 20 productive scalp grafts from middle-aged, balding men. They then grafted them onto nude mice, where they were studied for 8 months. Remarkably, if treated appropriately, this grafted scalp skin can survive after it is transplanted onto mice. This makes it a very convenient way of using mice to potentially examine effects on humans (6).

All mice in the study were conditioned by the topical application of testosterone on the non-grafted flank. The researchers exposed the mice to testosterone because previous research showed this inhibits the growth of the transplanted human grafts. They wanted to see if RU58841 would be able to overcome this testosterone-induced inhibition.

The twenty mice were randomly assigned to one of two different groups: the RU58841 experimental group and the control group.

In the experimental group, the grafted mice were topically applied with a 1 percent RU58841 solution. The control group only received a topical application of ethanol solution.

The solutions were applied five days per week, for a total of six months. The researchers then recorded the results.

On the control grafts, 28 active follicles appeared in total. Among them, only two follicles (7%) initiated a second hair cycle. On the RU-58841 grafts, 29 active follicles appeared in total. However, eight of them showed a second growth cycle.

This means that while RU58841 did not lead to more new active follicles, those that did appear were more likely to function normally over several hair growth cycles.

The researchers concluded that RU58841 may be useful in the treatment of androgen-dependent alopecia in humans.

Studies on Humans

Prostrakan, the company that eventually acquired the rights to the drug, ran two clinical trials with humans in the early 2000s.

The first was a phase I study in France to assess safety. Thirty men with male pattern baldness applied 5% solution on their head twice a day, for 4 weeks. The results of this study were never published. All indications are they were positive because the company then ran a phase II trial.

The phase 2 trial compared placebo to two solutions of RU58841: a 2.5% and a 5% strength. The total sample size was 120 balding men. They were treated for over 6 months.

Again, this study was never published, so we don’t have the full results. According to leaks, the results were comparable to finasteride, if not better.

After these successful trials, the company planned to go ahead with a phase III trial. For reasons that are not clear, this never happened. Some say it is because the drug is too unstable, and has a limited shelf life. Another possibility is that Prostrakan simply decided the compound would not be sufficiently profitable.

RU58851 Side Effects

There are no longitudinal studies that measured the side effects of RU58441. This means we do not know what these are with certainty.

Any information about side effects is extracted from online testimonials and existing knowledge on physiological processes. Like all drugs, each user may react differently.

Unfortunately, some users who experimented with the chemical report systemic effects. Some have been serious enough to warrant discontinuation.

Given that RU58841 has only been available (for research purposes) in the last few years, it is not possible to know for certain the side effects after chronic use.

It is important to remember this drug not only blocks DHT and testosterone but all androgens. If even small traces of it reach the blood supply, it will find and attach to any androgen receptors. Users should therefore proceed with extreme caution.

Some reported side effects include the following:

  • Erectile dysfunction
  • Low libido
  • Chest pain
  • Irregular heartbeat
  • Low mood
  • Fatigue
  • Irregular sleep
  • Skin irritation

Where to Purchase It

Currently, RU58841 is available for purchase online, with Kane and Anagen Inc as the most popular suppliers. You can only purchase it for research and laboratory experimentation purposes.

If you have thought it through and decided to try this out, then make sure to choose at least a 99% pure grade. Also, read the label carefully to make sure that nothing appears out of place.

Keep in mind that because it is not FDA-regulated the powder may not be as advertised.

Kane and Anagen Inc offers the product pre-made for your convenience, but there is no guarantee on the concentration, quality, and purity of the pre-made mixtures.

One advantage of trying a pre-made mixture first is to see how your body reacts. If you see troubling side effects and your body reacts poorly, you will know RU58841 is not for you before committing to expensive ingredients and equipment.

How to Make RU58851

You will need two basic components: RU58841, which comes in a bag of white powder, and a vehicle. The RU58841 will go into the vehicle, which you then apply directly to the hair.

The vehicle helps dissolve the powdered RU58841 into a liquid infusion. This allows it to penetrate past the skin barrier and reach the hair follicles.

Depending on your preference, there are several options for the vehicle.  Many choose the KB solution, available in the Kane Shop.

KB Solution Carrier is a pre-mixed vehicle that claims the ability to lower side effects by reducing the rate of absorption. This encourages the drug to stay locally on the scalp.

It also has the additional, but important, benefit of producing a protective film over the scalp after application. This will help prevent any undesirable transfers to others who may touch it by accident (such as expecting mothers).

Another available vehicle to consider is minoxidil (Rogaine). You will need to wait around three to four months to start seeing results. You can mix the RU58841 powder directly into a liquid solution of minoxidil. Avoid minoxidil if it produces any unfavorable side effects.

If you want to cut costs and make your own mixture, below are the ingredients and recipes to assist you.

These instructions and measurements are tailored for those producing a fresh, daily batch. There are further instructions after if you want to produce larger batches.


  • Raw RU58841 powder. You can order it from Kane, Anagen Inc, or other reputable companies in packages of 5g, 10g, or 20g
  • Small, accurate digital scale (make sure it goes to the third decimal, 0.001)
  • 1 ml dropper
  • Small measuring spoon
  • 20 ml glass bottle (for mixing PG and Everclear together)

Vehicle (if foregoing pre-made solutions):

  • Propylene glycol
  • Everclear alcohol, 190 proof = 95%

Mixing Procedure:

  1. Take your glass bottle and place it on the digital scale. Press the TARE function so that the scale resets to 0. This is necessary to accurately weigh the powder and not the bottle.
  1. Take your RU58841 powder and scoop exactly 50 mg, or however much you would like to use. DO NOT recommend exceeding more than 100 mg. This is can be too potent and increases the chance of systemic absorption.
  1. Use your 1 ml dropper to extract 0.7 ml of Everclear alcohol. Place it in the bottle with the powder. Swirl or stir the mixture (be sure the stirring instrument is clean) until the powder has completely dissolved into the Everclear.
  1. Use your 1 ml dropper again to extract 0.3 ml of propylene glycol and mix it with the powder and Everclear. Wait for up to 10 minutes, occasionally swirling or stirring the mixture. Note: This recipe is using a 70/30 percent ratio of Everclear/propylene glycol. You are free to adjust the proportion as you see fit.

**If you want to make the solutions in larger batches, follow the instructions above, but take a 50 ml glass beaker and scoop ~2.5 grams of RU58841 instead. Dissolve the powder in 35 ml of Everclear and 15 ml of propylene glycol. This will result in a 5% RU58841 in 50 ml, or 50mg/ml.

When and How to Apply

It is best to apply the solution within 20 minutes after washing and drying your hair. The sebum in the skin will make your scalp oily, reducing the effectiveness of the RU58841 solution.

Exfoliating before showering may also help shed the scalp’s old, dead skin cells and uncover fresh, new cells below. However, try limiting the exfoliation to just once or twice a week. Over-exfoliating will leave the scalp red, tender, and sensitive.

Carefully apply the solution to affected areas of the scalp using the dropper. Make sure to also apply it in areas where you want to have hair maintained. Because the solution is very watery, you can use gloved hands to help spread it evenly around.

Use the mixture once every day or two. It may take up to four months before you see results.

How to Store It Properly

The manufacturers claim that you can store RU58841 at room temperature for up to two weeks. Many users, however, place the raw RU58841 in airtight bags and store it in the freezer to minimize degradation.

Make sure to keep it away from any light source, as this will accelerate its deterioration.

You can store any large batches or unused solution in the fridge for up to seven days. However, if you want to make the most of the RU58841’s effect, you can consider making a fresh mixture every day.


Overall, RU58841 may prove to be a useful asset in counteracting alopecia and promoting thick, healthy hair.

Because RU58841 was never given the proper scientific scrutiny it deserves, many aspects of this chemical are still obscure. Long-term side effects may not show until many years pass, when it may be too.

Without an understanding of long-term effects, consider other options first. One often-overlooked step involves lifestyle changes, for example, adopting a balanced diet or switching to a more natural shampoo.

Look at drugs that have well-studied safety and efficacy records. RU58841 is a last resort. There are safer options to address hair loss.

Consult with a healthcare provider to help make an informed decision.

Disclaimer: Given the lack of peer-reviewed studies, we are not endorsing the use of this chemical. Any medical information in this article is provided for information purposes only. Please do not use or rely on it for any diagnostic or treatment purposes. This article is not a substitute for proper professional treatment.

Please consult your healthcare provider for any medical advice or decisions before adopting RU58841 into your regimen. If you experience any symptoms, contact your healthcare provider right away. We are not responsible for any liability, damages, loss, or injury as a consequence of your reliance on the information contained on this site.

Information contained on this website has not been evaluated by any medical body such as the Food & Drug Administration. All information is for educational purposes only. We do not aim to diagnose, treat, cure or prevent any disease or illness. You must consult a medical professional before acting on any content on this website.