The Phosphodiesterase 4 Inhibitor Roflumilast as an Adjunct to Antidepressants in Major Depressive Disorder Patients. Proof-of-Concept, Randomized, Double-Blind, Placebo-Controlled Trial

Phosphodiesterase-4 (PDE4), an important member of the PDE superfamily, is a key regulator of intracellular cyclic AMP (cAMP) level. As the second messenger, cAMP activates protein kinase A, which phosphorylates the subsequent downstream cAMP-response element binding (CREB) protein. In the central nervous system, this signaling cascade exerts both pre- and post-synaptic effects and is essential for a variety of cellular functions, including neurotransmitter release and neuroprotection. Inhibition of PDE4 prevents cAMP breakdown, which is well recognized as the mechanism by which PDE4 inhibitors can treat impaired memory linked to several brain disorders. In pre-clinical studies and early-stage clinical trials, PDE4 inhibitors such as rolipram have been shown to enhance memory. They also improve depressive-like behaviors induced by chronic unpredictable mild stress, lipopolysaccharide, or ethanol abstinence . Consequently, it is reasonable to believe that PDE4 is a potential target for treatment of the comorbidity of depression and AD.

The aim of the current study is to evaluate the potential adjunct antidepressant effect of Roflumilast in adult patients with MDD. Furthermore, we will assess the relationship between HAM-D score and BDNF as well as their role as a therapeutic targets of MDD.