Pyrilutamide

Pyrilutamide
Clinical data
Other names	KX-826
Routes of; administration	Topical
Drug class	Nonsteroidal antiandrogen
ATC code	None;
Identifiers
	IUPAC name 4-(3-(4-cyano-2-fluoro-3-(trifluoromethyl)phenyl)-5,5-dimethyl-4-oxo-2-thioxoimidazolidin-1-yl)-2-fluoro-N-methylbenzamide;
PubChem CID	50940514;
Chemical and physical data
Formula	C21H15F5N4O2S
Molar mass	482.43 g·mol−1
3D model (JSmol)	Interactive image;
	SMILES CNC(=O)C1=C(F)C=C(C=C1)N1C(=S)N(C(=O)C1(C)C)C1=C(F)C(=C(C=C1)C#N)C(F)(F)F;
	InChI InChI=1S/C21H15F5N4O2S/c1-20(2)18(32)29(14-7-4-10(9-27)15(16(14)23)21(24,25)26)19(33)30(20)11-5-6-12(13(22)8-11)17(31)28-3/h4-8H,1-3H3,(H,28,31); Key:CGRMNGGGSWLDDC-UHFFFAOYSA-N;

Pyrilutamide (developmental code name KX-826) is a nonsteroidal antiandrogen (NSAA) – specifically, a selective high-affinity silent antagonist of the androgen receptor (AR) – which is under development by Suzhou Kintor Pharmaceuticals, inc., a subsidiary of Kintor Pharmaceutical Limited, for the potential treatment of androgenic alopecia (androgen-dependent scalp hair loss)^[1]^[2]^[3] As of October 2022, it is in phase 3 clinical trials for androgenic alopecia and phase 2 trials for acne.^[2]

Development

The primary endpoint is the change from baseline in non-vellus target area hair count (TAHC) at the end of week 24. The drug will be dosed at 10 mg (0.5% BID) per patient per day in the trial.^[4]

Adverse effects

Pyrilutamide is generally well-tolerated. The most common adverse event is contact dermatitis.^[5]

Pharmacology

Plasma concentration of pyrilutamide and metabolite KX-982 in different dose groups in phase Ib clinical trials in China

Pharmacodynamics

Pyrilutamide binds to the androgen receptor with a very high affinity with an IC₅₀ of 0.28 nM. ^[3] Reference drug bicalutamide had an IC₅₀ of 3.1 nM. ^[3]