In this task, you are given a sentence. You are expected to recognize the name of any form of chemical substances. Although there might be several correct answers, you need to write one of them.

Effect of cyproheptadine on serum leptin levels.
cyproheptadine

Adapalene, a new chemical entity with retinoid activity.
retinoid

Study of the nematode putative GABA type-A receptor subunits: evidence for modulation by ivermectin.

GABA