Hemodynamic effects of sildenafil citrate (Viagra) on segmental branches of bilateral renal arteries

Erectile dysfunction in renal failure and transplant patients

Erectile dysfunction (ED) is a prevalent and pertinent condition in the chronic kidney disease (CKD) population. It has a multifactorial etiology, including disruptions of the hypothalamic-pituitary-gonadal axis, the endothelial paracrine signaling system, calcium and vitamin D homeostasis, along with several other factors. Efficacy of treatment of ED in the CKD population is comparable to non-CKD patients across multiple modalities, including PDE5 inhibitors, vacuum erectile devices, intracavernosal injections and penile prostheses. Renal transplant improves the contributing comorbid conditions that lead to ED in CKD patients; thus rates of ED are improved post-transplant. It is important to note that there is a small percentage of patients with persistent ED after renal transplantation.

Phosphodiesterase type 5 inhibitors and kidney disease

Chronic kidney disease (CKD) represents a worldwide health problem. Traditionally, the nephroprotective treatment for CKD aims to slow progression to end-stage renal disease and includes dietary protein restriction, correction of metabolic acidosis, and renin-angiotensin system blockers. However, current standard therapeutic options may not be enough for preventing CKD progression in a subset of patients making necessary to develop novel therapeutic options to further slow renal function loss. Phosphodiesterase type 5 (PDE5) inhibitors represent a class of drugs traditionally used to treat erectile dysfunction and pulmonary hypertension. However, recent evidence suggests that PDE5 inhibitors may have additional therapeutic effects, such as cardioprotection and cerebrovascular protection. In the current review, we summarize PDE5 inhibitors' utility in disease states and clinical conditions related to kidney disease such as systemic hypertension and acute and chronic kidney injury and discuss the mechanisms explaining possible kidney protective roles of PDE5 inhibitors. A recently completed phase 2 trials demonstrated that the long-acting PDE5 inhibitor PF-00489791 decreased albuminuria in patients with overt diabetic nephropathy when added on top of renin-angiotensin system blockade.