PP405 is not a peptide, and it does not block DHT — here is what it actually is

For many people, hair loss isn't just a cosmetic concern: it can be the visible sign of a hormonal process. While it's normal to shed between 50 and 100 hairs a day, if your overall volume is decreasing, your scalp is becoming more visible, or bald patches are forming, it's worth investigating.

How can you tell if you're experiencing hormone-related hair loss? The first step is to observe the pattern: Is the hair falling out more on the top of the head? Are you developing receding temples or thinning at the hairline? Is there thinning at the crown or all over the scalp?

DHT: the silent culprit

One of the main hormonal factors behind hair loss is dihydrotestosterone, or DHT. This hormone is a byproduct of testosterone, and while it's completely normal to have DHT in the body, some people are genetically sensitive to it.

That sensitivity causes DHT to bind to receptors in hair follicles, gradually miniaturizing them and making it harder for new hair to grow. This type of hair loss is called androgenetic alopecia, and it can occur in both men and women, though it follows different patterns.

In men, the typical pattern starts with a receding hairline and thinning at the crown. In women, it usually presents as diffuse thinning across the top of the scalp, without necessarily leading to complete bald patches.

What about people in transition?

Those undergoing gender transition may also experience significant changes in hair health due to hormonal shifts. Reviews of gender-affirming hormone therapy report that transmasculine individuals (assigned female at birth) who begin testosterone therapy can develop androgenetic alopecia if they are genetically susceptible (Ginsberg, 2018; Tang et al., 2023).

Conversely, transfeminine individuals whose testosterone levels are lowered are reported to see a slowdown in scalp hair loss, with some regrowth described in the same reviews. However, these changes depend on multiple factors: genetic predisposition, age, duration of DHT exposure, and individual scalp characteristics.

So... What is PP405, and why is everyone talking about it?

Here is the correction this article exists to make. PP405 is not a peptide, and it is not designed to protect follicles from DHT. It is an experimental topical gel from Pelage Pharmaceuticals containing a small molecule that inhibits the mitochondrial pyruvate carrier (MPC) — a transporter that controls how a cell fuels itself.

The rationale comes from University of California, Los Angeles work on follicle metabolism. A 2017 paper in Nature Cell Biology reported that hair follicle stem cells depend on glycolysis and lactate production, and that pushing their metabolism that way activated dormant follicle stem cells in mice (Flores et al., 2017). Blocking the MPC forces that metabolic shift. PP405 is the attempt to make a topical drug out of that finding.

So PP405 does not sit anywhere on the DHT axis. It is not a hormone blocker, and it is not a follicle "shield" against DHT either — it is aimed at waking dormant follicles, whatever put them to sleep.

PP405 is not approved for commercial use and is not for sale. It is in clinical trials. No published trial has shown that it grows hair in people.

What if it reaches the market? How would it compare to other treatments?

Because PP405 is not a hormonal drug, it is often discussed as a possible option for people who cannot or do not want to take 5-alpha-reductase inhibitors such as finasteride or dutasteride, which reduce DHT production and are associated in some users with sexual dysfunction or mood changes.

That comparison is speculation, not a finding. A drug that does not touch DHT is also a drug that does not address the cause of pattern hair loss, so if PP405 ever reaches the market it is more likely to be discussed alongside existing treatments than as a replacement for them. Until trials are conclusive and a regulator such as the FDA approves it, all of this is hypothetical.

Why is it important to know your hair loss pattern?

Understanding your hair loss pattern matters for choosing the right treatment. Someone with diffuse shedding may be experiencing telogen effluvium — a temporary condition related to stress, illness or hormonal changes — which is approached differently from androgenetic alopecia. The pattern can also indicate whether an autoimmune factor (like alopecia areata) is involved, or whether the cause is traction from tight hairstyles.

Correctly identifying the pattern also saves time: it lets a clinician focus on the right tests (such as hormone panels or a scalp biopsy) and rule out reversible causes. Treatments such as minoxidil are generally described as working better in earlier stages, while the follicle is still capable of producing hair.

What does science actually say about PP405?

The evidence base is preclinical plus early-phase safety work.

The preclinical basis is the 2017 Nature Cell Biology paper above: mouse hair follicle stem cells, metabolic manipulation, follicle activation. Study critique: it is mouse work on stem cell metabolism, not a hair-loss treatment trial. Mouse hair cycling differs substantially from human hair cycling, and a mechanism that activates follicles in a mouse has repeatedly failed to translate.

The clinical work on record is a registered Phase 2 trial, NCT06393452, sponsored by Pelage Pharmaceuticals. It enrolled 78 adults with androgenetic alopecia, who applied a 0.05% PP405 topical gel or a matching vehicle gel once daily. Part 1 was a randomized, quadruple-masked 28-day period; Part 2 was an open-label extension of about three months. Its listed primary outcomes were treatment-related adverse events and local skin tolerability — that is, safety, not regrowth. The registry lists it as completed in October 2025.

There is no published in-vitro dermal-papilla study of PP405 against DHT, and no percentage reduction in DHT-induced inflammation has been reported for it.

Conclusion

Can PP405 protect your follicles from DHT? No — that is not what it does, and the claim comes from a mix-up rather than from any study. What PP405 is, is an experimental MPC-inhibitor gel that has finished an early safety trial in pattern hair loss and has no published efficacy result.

In the meantime, know your pattern of hair loss and get it assessed. Talk to a doctor or pharmacist before starting, stopping or combining any hair-loss treatment, including finasteride and dutasteride — and treat anything sold online as "PP405" as not being the trial drug, because the trial drug is not for sale.

References

Flores, A., Schell, J., Krall, A. S., Jelinek, D., Miranda, M., et al. (2017). Lactate dehydrogenase activity drives hair follicle stem cell activation. Nature Cell Biology, 19(9), 1017–1026. https://pubmed.ncbi.nlm.nih.gov/28812580/

ClinicalTrials.gov. Safety, Pharmacokinetics and Efficacy of PP405 in Adults With AGA. NCT06393452. https://clinicaltrials.gov/study/NCT06393452

Ginsberg, B. A. (2018). Understanding and addressing hair disorders in transgender individuals. American Journal of Clinical Dermatology, 19(4), 517–527. https://pubmed.ncbi.nlm.nih.gov/29352423/

Tang, G. T., Zwickl, S., Sinclair, R., Zajac, J. D., & Cheung, A. S. (2023). Effect of gender-affirming hormone therapy on hair growth: a systematic review of the literature. Clinical and Experimental Dermatology, 48(10), 1117–1127. https://pubmed.ncbi.nlm.nih.gov/37311161/