sildenafil-citrate and Arterial-Occlusive-Diseases

The FDA approval of Viagra (sildenafil) for the on demand treatment of erectile dysfunction (ED) through relaxation of the corporal and cavernosal vascular smooth muscle that results in an increase in blood flow to the corporal tissues stemmed from 2 decades of research, mainly at academic centers. This culminated in the finding of the nitric oxide/cGMP pathway as the mediator of penile erection, followed by some years of basic studies and clinical validation at Pfizer. Further on, new translational laboratory and animal research from our group initiated a second phase when we proposed an alternative therapeutic schedule and mechanism of action for PDE5 inhibitors (PDE5i) in both corporal veno-occlusive dysfunction (CVOD) and Peyronie's disease (PD), specifically, continuous long-term administration (CLTA) to achieve sustained levels of cGMP within the penis. Due to the extended half-life of the long-acting PDE5i, tadalafil, this new alternative encompasses preferentially daily administration, although shorter half-life PDE5i, like sildenafil and vardenafil work too, depending on the duration, dose, and frequency of their administration This novel use was initially supported by showing the antifibrotic/antioxidant effects of nitric oxide and cGMP, produced by the induction of iNOS, as a mechanism of defense against collagen deposition in the localized fibrotic plaque of PD in an avascular tissue, the tunica albuginea. Our studies on iNOS and the progressive diffuse fibrosis occurring in the smooth muscle in CVOD, led to proposing the CLTA of PDE5i for maintaining sustained cGMP levels both in PD and in CVOD in order to halt or regress the penile fibrosis. In CVOD, we showed that PDE5i protect the corporal smooth muscle and reduce myofibroblast activation and number, counteracting the underlying corporal tissue pathology that causes CVOD, and potentially ameliorating long-term CVOD or even curing it. This review is focused on this novel PDE5i anti-fibrotic therapeutic concept.

Topics: Animals; Arterial Occlusive Diseases; Cyclic GMP; Disease Models, Animal; Drug Evaluation, Preclinical; Erectile Dysfunction; Humans; Male; Muscle, Smooth; Nitric Oxide Synthase Type II; Penile Induration; Phosphodiesterase 5 Inhibitors; Sildenafil Citrate; Translational Research, Biomedical

In this study, we tested whether the phosphodiesterase-5 inhibitor sildenafil protects against neurodegeneration and facilitates recovery from learning deficits examined long after chronic cerebral hypoperfusion (CCH) induced by the 4-vessel occlusion/internal carotid artery (4-VO/ICA) model in middle-aged rats. Male Wistar rats (12-15 months of age) were subjected to permanent 3-stage 4-VO/ICA with an interstage interval of 4 days. Sildenafil (3 mg/kg, p.o.) was administered at one dose per day for 10 days, beginning soon after the first occlusion stage. Three months later, learning in a non-food-rewarded, eight-arm radial maze task was tested. Learning performance is expressed as the latency to find a goal box and the number of reference or working memory errors. Histological examination was performed 1-3 days after behavioral testing. In the vehicle-treated group, permanent 4-VO/ICA markedly disrupted learning performance and caused moderate-to-severe neurodegeneration in the CA1-CA4 subfields of the hippocampus (56.2%), dentate gyrus (DG; 19.2%), retrosplenial cortex (RS cortex; 47.4%), and parietal association cortex (PtA cortex; 38.2%). Sildenafil treatment did not prevent 4-VO/ICA-induced learning deficits, whereas neurodegeneration was significantly reduced in the CA1-CA4 subfields (30.5%), DG (7.2%), RS cortex (11.8%), and PtA cortex (6.5%). Advancing previous findings from our laboratory, this study suggests that while sildenafil can provide important neuroprotection in different brain regions of middle-aged rats subjected to CCH, such histological effect does not translate into cognitive recovery.

Topics: Animals; Arterial Occlusive Diseases; Brain; Carotid Artery, Internal; Cell Count; Disease Models, Animal; Learning Disabilities; Male; Maze Learning; Neuroprotective Agents; Piperazines; Purines; Rats; Rats, Wistar; Reaction Time; Sildenafil Citrate; Sulfones; Time Factors

Selective right pulmonary arteriography and 3-dimensional computed tomography revealed multiple severe stenoses of the peripheral pulmonary artery associated with poststenotic aneurysms in a 65-year-old woman. She was referred to the hospital for evaluation of dry cough, gradually increasing dyspnea and multiple nodular shadows on a chest radiograph. Echocardiography and cardiac catheterization showed severe pulmonary hypertension, though other structural heart diseases or well-characterized congenital syndromes were ruled out. She was diagnosed as isolated peripheral pulmonary artery branch stenosis. Recent advances in CT technology enable a less-invasive assessment of pulmonary artery, and can be useful in the management of pulmonary arterial hypertension.

Topics: Aged; Aneurysm; Arterial Occlusive Diseases; Cardiac Catheterization; Constriction, Pathologic; Cough; Dyspnea; Epoprostenol; Female; Humans; Hypertension, Pulmonary; Imaging, Three-Dimensional; Oxygen Inhalation Therapy; Piperazines; Pulmonary Artery; Purines; Sildenafil Citrate; Sulfones; Tomography, X-Ray Computed; Ultrasonography; Vasodilator Agents; Warfarin

To evaluate whether the response to sildenafil administration in patients with arterial erectile dysfunction (ED) was related to their peak systolic velocity (PSV), peripheral atherosclerosis, cardiovascular risk factors (RF) and/or comorbidities at low cardiovascular risk.. We enrolled 97 patients with 1-2 RF and comorbidities, combined with arterial ED alone (group A, n = 27), ED plus atherosclerotic carotid artery (group B, n = 23), ED plus lower limb artery abnormalities (group C, n = 25), and ED plus carotid and lower limb artery abnormalities (group D, n = 22). Sildenafil efficacy (100 mg twice a week for 12 weeks) was also examined in patients with =or>3 RF, peripheral atherosclerosis and no cardiovascular comorbidities (group E, n = 20).. Median PSV was 24.1, 21.0, 19.3, 14.5 and 17.5 cm/s in groups A, B, C, D and E, respectively. Sildenafil response was higher in group A patients (77.8%), intermediate in groups B and C (65.2% and 56%) and lowest in groups D (45.4%) and E (50%), and the response in latter two groups was significantly lower than in the other three groups. In addition, sildenafil response was negatively influenced by: =or>3 RF, peripheral atherosclerosis and no systemic comorbidity, or presence of 1-2 RF associated with extended atherosclerosis and comorbidities. The number of comorbidities was positively related to atherosclerosis localization or extension (25, 35, 38 and 47 in groups A, B, C and D, respectively).. Low sildenafil efficacy in patients with arterial ED was associated with extended atherosclerosis. These patients should undergo extensive ultrasonography and a full cardiovascular examination.

Topics: Aged; Arterial Occlusive Diseases; Atherosclerosis; Cardiovascular Diseases; Erectile Dysfunction; Humans; Lower Extremity; Male; Middle Aged; Physical Examination; Piperazines; Purines; Regional Blood Flow; Retrospective Studies; Risk Factors; Sildenafil Citrate; Sulfones; Treatment Outcome; Vasodilator Agents