Setipiprant for Hair Loss: Reduce Scalp PGD2 Receptor Activity -

Setipiprant for Hair Loss: Reduce Scalp PGD2 Receptor Activity

Setipiprant is another example of an anti-allergy medication which was discovered to reduce hair loss. It does this by decreasing scalp PGD2, which is key to stopping hair loss.

Setipiprant is a drug that was initially tested for the treatment of allergic rhinitis (hay fever) and asthma.

While the drug proved to be effective in treating allergies, the final results of the clinical trials showed no superior efficacy compared to existing drugs, thus stopping its development by some companies; however, newer antagonists have progressed to major phase II studies, and other companies are entering the field.

Through the clinical trials performed to see the efficacy of Setipiprant on asthma and allergic rhinitis, positive effects for treating androgenic alopecia (male pattern baldness) were noted.

This is believed to be mediated by inhibiting Prostaglandin D2 receptor 2 (DP2), which is responsive to the action of Prostaglandin D2 (PGD2).

Research and results

Setipiprant has passed phases I and II of the clinical studies for the treatment of androgenetic alopecia (AA), which means it will now move on to phase III before applying for FDA approval.

In phase I, the drug was tested for possible adverse effects and Setipiprant showed few side effects; however, these findings were established in the clinical trials aimed at treating allergic rhinitis and not androgenetic alopecia.

In the fall of 2019, Setipiprant successfully completed phase II with 169 participants (age 18-49) with AA.

Currently, the drug is undergoing phase III of the clinical trials that involve more participants to evaluate the actual effectiveness of this drug, as well as the possible side effects.
Once Setipiprant completes this phase, the FDA will decide whether to approve it or not for commercial use.

Phase III may take months to years before it is completed, so Setipiprant is not expected to be commercially available any time soon.

How it works

Reduce scalp PGD2

Prostaglandin D2 is produced by an enzyme called Prostaglandin D2 synthase, the latter is upregulated in patients with androgenetic alopecia; this is theorized to be influenced by the action of Dihydrotestosterone (DHT), which is substantially elevated in this group of patients since it is the cornerstone of AA pathophysiology.

To summarize, high DHT leads to elevated levels of the Prostaglandin D2 synthase, which in turn increases PGD2.

By inhibiting the major enzyme of this metabolic pathway –Prostaglandin D2 synthase–, Setipiprant may reverse the hair loss seen in AA.


Setipiprant is a new drug with promising preliminary results in the treatment of androgenetic alopecia, and while this drug was not initially designed to treat hair loss, it just shows how fascinating medicine is when researchers are on the look for one thing and end up finding a whole new thing.

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Estimates say that Setipiprant will take a few years before it gets released in the market, and it will probably be a prescription drug only.

While some physicians and patients are excited about these findings and believe it is the ultimate breakthrough that they have been waiting for, it still too early to judge, and we have to wait until phase III is complete before coming up with any conclusions.