PP405

What it is

PP405 is a topical small molecule from Pelage Pharmaceuticals, used as a 0.05% gel in its trials. It targets the energy metabolism of hair follicle stem cells by blocking the mitochondrial pyruvate carrier. The underlying "lactate wakes up follicle stem cells" biology comes from mouse work on UK-5099; we could not verify a published link between that paper and this company's compound beyond the shared mechanism. It is not approved in any country.

How it works

Follicle stem cells rely on glycolysis. Making them produce more lactate, by deleting the pyruvate carrier gene or blocking the carrier chemically, triggered activation and sped up the hair cycle in mice (Flores 2017). The mechanism does not depend on androgens, so in principle it could add to finasteride or minoxidil. Whether it does has not been tested.

What the studies show

• A phase 2a trial of 78 adults aged 18 to 55 used 0.05% gel once daily for 28 days, followed to week 12. The safety endpoint was met and no PP405 was detectable in blood. Adverse events were 22% versus 10% on vehicle, with no serious events on drug. The company reported hair density rising over 20% at week 8 in 31% of men with more advanced loss versus 0% on vehicle (trial record).
• That efficacy figure comes from press coverage of the company's announcement. The subgroup was reported after the fact, treatment lasted only four weeks, and we found no peer-reviewed paper. Percentages circulating on social media could not be traced to a primary source.
• A phase 2/3 trial called AWAKEN (about 600 men aged 18 to 55 with Norwood IV to V loss) began enrolling in September 2026, with 24 weeks of treatment then an extension to week 52. It has no results yet (trial record).

How it's used in studies

• 0.05% gel on the scalp once daily, for 28 days in phase 2a and 24 weeks plus extension in phase 2/3.

Side effects and safety

• In phase 2a there were no serious adverse events on drug, nearly all participants had no local skin reaction, and no systemic exposure was detectable (trial record). Long-term safety is unknown.

Bottom line

PP405 is the most interesting new mechanism in topical hair growth and a possible add-on to existing treatments, but it is not yet proven. Nothing to buy: avoid sellers of "PP405" before approval. Discuss with a doctor.

Fun facts

• It began with a basic-biology finding in mice that hair follicle stem cells wake up when lactate rises (Flores 2017).