15-Ketoprostaglandin E2 (15-keto PGE2) is a metabolite of prostaglandin E2 (PGE2) with reduced biological activity, which then by the action of prostaglandin reductase 2 (PTGR2) transforms into 13,14-dihydro-15-keto-PGE2, s a secondary metabolite without biological activity. Some experiments have shown that exists the therapeutic potential by targeting PTGR2/15-keto-PGE2 in pancreatic cancer. Besides, it is known, that 15-keto-PGE2 has higher affinity to the prostaglandin EP2 receptor than to the EP4 receptor. Some experiments also have revealed the key signaling cascade: 15-Hydroxyprostaglandin dehydrogenase (15-PGDH)/15-keto-PGE2-mediated activation of PPARγ and p21(WAF1/Cip1) in the regulation of the hepatocarcinogenesis and tumor progression.

Norcyclobenzaprine (aka desmethylcyclobenzaprine) is one of the major metabolites of cyclobenzaprine which is a muscle relaxant marketed under the brand name Flexeril. Both cyclobenzaprine and norcyclobenzaprine are known to be potent antagonists of the serotonin 2a receptor.

4-Nitro-3-trifluoromethylaniline is one of the two main products of flutamide metabolism in human liver microsomes. Also, it is a major urinary metabolite of S-1 [3-(4-fluorophenoxy)-2-hydroxy-2-methyl-N-[4-nitro-3-(trifluoromethyl)phenyl]-propanamide] - a member of a series of potent selective androgen receptor modulators.