Pyrazole is an organic compound with the formula C₃H₃N₂H. It is a heterocycle characterized by a 5-membered ring of three carbon atoms and two adjacent nitrogen atoms, which are in ortho-substitution. Pyrazole is a weak base, with pKb 11.5 (pKa of the conjugate acid 2.49 at 25 °C). Pyrazoles are also a class of compounds that have the ring C₃N₂ with adjacent nitrogen atoms.[3] Notable drugs containing a pyrazole ring are celecoxib (celebrex) and the anabolic steroid stanozolol.