Institutional and funding constrains

Antidepressant-like effects of sildenafil to its ability to modulate transduction pathways responsible for neuroplasticity. Treatment with sildenafil was shown to be PKG-dependent and lead to increased expression of cGMP, pCREB, BDNF and VGF in the hippocampus and prefrontal cortex (PFC), brain areas relevant to mood disorders pathophysiology. Sildenafil produces antidepressant-like effects by inhibiting oxidative stress in the hippocampus and by decreasing the levels of IL-1β in the hippocampus and striatum.

Inclusion Criteria:

• Eighty adult outpatients with the Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) diagnosis of MDD based on a MINI Neuropsychiatric Interview (MINI) (American Psychiatric Association., 2000; Sheehan et al., 1998), without psychotic features and a total 17 item HAM-D score of at least 18 with item 1 (depressed mood) scored 2 or greater were eligible (Hamilton, 1960).
• Patients were requested to be free of all the psychotropic and anti-inflammatory medications for at least 4 weeks before participating in the study.

Exclusion Criteria:

• Patients with bipolar I or bipolar II disorder
• Patients with personality disorders
• Patients with eating disorders
• Patients with substance dependence or abuse
• Patients with concurrent active medical condition
• Patients with history of seizures
• Patients with history of receiving Electroconvulsive therapy (ECT)
• Patients with inflammatory disorders
• Patients with allergy or contraindications to the used medications
• Patients with finally pregnant or lactating females
• Cardiovascular disorders
• Severe renal impairment: creatinine clearance of ≤ 25 ml/min
• Moderate or severe hepatic impairment