RU58841: Stability and Storage

RU58841 can be purchased from various sources as a powder, and the user then has to dissolve the compound before use. Some sources have started offering ready-made RU58841 solutions, advertising them as more convenient and easier to use. However, the conventional wisdom is that once dissolved, RU58841 has a very limited shelf-life. Therefore, it is possible that pre-made RU58841 solutions may contain little to no active ingredient by the time the user receives them.

What to Dissolve RU58841 in?

RU58841, a semi-polar compound, will not dissolve in plain water and will not allow it to enter deep into the scalp to reach the targeted level. Many users dissolve it in a mixture of water, ethanol, and propylene glycol as cosolvency. Others swear by a solvent called K&B Solution, claiming it enhances the absorption of the compound through the scalp. K&B Solution consists of about 60% ethanol and 5% K&B emulsifiers in water. Emulsifiers are compounds that help keep non-water-soluble compounds dissolved in water-containing solutions; in the K&B Solution, the emulsifiers are taking the place of propylene glycol in helping the RU58841 to dissolve. Users who plan to use RU58841 in conjunction with minoxidil often simply dissolve it in the minoxidil, which is sold already dissolved in a mixture of water, alcohol, and propylene glycol.

Shelf-life of RU58841 SolutionsRU58841 solution

Most users of RU58841 are convinced it is not very stable once dissolved. They state it needs to be protected from light and oxygen, and should be stored in the refrigerator. A few individuals that dissolve their RU58841 in K&B Solution claim it is stable at room temperature for weeks to months, but they don’t seem to have any solid data to back up their claims. Anageninc (a chinese webshop, so they have financial interest to sell solutions) states they have tested a solution of RU58841 and found it to be stable at room temperature for at least a month (1). However, the test they are using is not a test of the activity of the solution and therefore doesn’t truly demonstrate the compound is stable. Also, it is not quite clear what they have dissolved the compound in for their test. They state it is dissolved in ethanol, which suggests they used pure ethanol rather than any of the common solvents used to prepare RU58841 for use.

Studies on the Stability of RU58841 Solutions

RU58841 stabilityThere do not appear to be any published studies on the stability of this compound. However, nilutamide, a compound with a similar chemical structure, has been evaluated (2). Nilutamide is stable in acidic solutions and is fairly heat-stable. However, it breaks down rapidly when exposed to light, and when dissolved in a solution containing water, it is subjected to hydrolysis and breaks down fairly quickly. Extrapolating these results to RU58841, if the compound is dissolved in pure ethanol (and keeped in the dark) it is probably stable at room temperature, as reported by Anageninc. However, applying a solution of RU58841 dissolved in pure ethanol to the scalp will cause significant irritation and damage to the skin, hair, and hair follicles. It is also possible that very little of the RU58841 will be absorbed unless it is dissolved in a solution containing water and some type of polar compound or polar carrier, such as the emulsifiers in K&B Solution. All of the clinical studies of RU58841 demonstrating it is active topically use a semi-polar carrier, such as propylene glycol (3) or special lipid-based carriers (4).

Therefore, based on the currently available evidence, we suggest storing your self-made RU58841 solutions in the dark for only a few days. Preparing a week’s worth of solution at a time, no more, is a prudent precaution. Moreover, especially with chinese company, the consumer has almost no guarantee at all that the RU58841 solution was prepared, and stored in a dark room, prior to the bottling for usual batches. It is unlikely that the commercially available pre-made solutions contain significant amounts of active ingredient unless the company can guarantee the solution was custom-prepared immediately before shipping and made fully in the dark. Ideally, the dry powder is best stored sealed against light and oxygen in the freezer (-20°C), where it should remain stable for months to years.

Many of these points may explain why some users do not have the expected result. We highly recommand to only use the powder form and only from a company which can ensure the full process and quality control. You can read our RU58841 guide to make your own solution.


(2) Biomed Chromatogr. 2014 Jun;28(6):788-93. Liquid chromatography electrospray ionization tandem mass spectrometry study of nilutamide and its stress degradation products: in silico toxicity prediction of degradation products.
(3) Skin Pharmacol. 1997;10(5-6):288-97. Effects of topical antiandrogen and 5-alpha-reductase inhibitors on sebaceous glands in male fuzzy rats.
(4) Expert Opin Drug Deliv. 2008 Jun;5(6):665-79. Novel vesicular and particulate drug delivery systems for topical treatment of acne.

2 Comments on RU58841: Stability and Storage

  1. First of all, thanks for creating this excellent site. However, there seems to be some conflicting advice given. On this page you say a RU58841 solution is only stable for a few days – a week at most. But over on the “RU58841 Guide” page (which you’ve also referenced here), the advice is that “solutions are generally stable for about 6 months”. Which figure is correct?

  2. Hi Andrew,

    thank you to point this. As we are learning deeper and deeper into RU58841, we learn all the time and make progress. The guide was written about a year ago now and we will update the full article soon. The solution is not stable for a long time, and most lab that offer it do not comply any stability test and do not own any ISO or GMP certification. They are also aware its hard to control what is the RU58841 amount in their solution… So you have also 0% quality control there. They just spam and offer free powder to famous forum member to speak good about their brand like is doing Anageninc unfortunately. So for now reduce the chance to get bad result by buying only the raw powder


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