FDA Drug Approval Stages: From Discovery Through Clinical Trials to Market 2023 FDA approvals: unprecedented volume at moderate value Did you know some preclinical studies report Dihexa showing neurotrophic activity far exceeding BDNF in laboratory assays? Research links its mechanism to HGF c Met signaling and synaptic plasticity in animal models. Human data The FDA's Category 2 list restricted 19 peptides from compounding. Now, approximately 14 of them may be coming back. HHS has signaled that peptides previously barred from compounding spanning categories like Dihexa in Clinical Trials: What We've Learned So Far