PDE5A and brain neoplasm: A study in a murine model treated with an oral dose of 10 mg/kg vardenafil in brain tumor metastatic mice, increased permeability of metastatic brain tumors, without significantly affecting tight junctions of the capillary endothelium of tumors, suggesting that PDE5 inhibitors should activate its effect through stimulation of caveolae-mediated endocytosis and micropinocytosis (86).