sildenafil-citrate and Kidney-Diseases

Kidney diseases are major health problem and understanding the underlined mechanisms that lead to kidney diseases are critical research points with a marked potential impact on health. Cadmium (Cd) is a heavy metal that occurs naturally and can be found in contaminated food. Kidneys are the most susceptible organ to heavy metal intoxication as it is the main route of waste excretion. The harmful effects of Cd were previously well proved. Cd induces inflammatory responses, oxidative injury, mitochondrial dysfunction and disturbs Ca

Topics: Acetylcysteine; Cadmium; Cytochalasin D; Cytokines; Humans; Inflammation; Kidney Diseases; NF-kappa B; Polysaccharides; Sildenafil Citrate; Telmisartan

To review special safety topics associated with sildenafil and to document the tolerability of 50- and 100-mg doses, overall and by age, in men with erectile dysfunction (ED).. Data were collated from 67 double-blind placebo-controlled (DBPC) trials (> 14,000 men) conducted by the manufacturer and from the manufacturer's postmarketing safety database (39,277 patients). The DBPC data were stratified by dose, starting dose and age (> or = 65 and > or = 75 years). Special safety topics included cardiovascular risk, priapism, non-arteritic anterior ischaemic optic neuropathy (NAION), impaired renal and hepatic function, drug interactions (i.e. nitrates, cytochrome P3A4 inhibitors, other ED therapies and alpha-blockers) and incorrect use.. Sildenafil was well tolerated at a dose of 50 or 100 mg in men with ED, overall, in those aged > or = 65 years, and in those aged > or = 75 years. Analyses of the databases did not reveal any causal link between sildenafil and cardiovascular events, or any new safety risks relating to cardiovascular events, priapism, NAION, hearing loss or drug interactions. In the small number of men with moderate impairment of renal function or hepatic function who were treated with sildenafil in DBPC trials, the safety profile was similar to that in men with no impairment of renal or hepatic function. Overdose with sildenafil was rare in the ED population. No new safety issues, emerging trends or adverse reactions were identified in conjunction with overdose, dependence, abuse or misuse.. This collated review confirms generally the good tolerability and established safety profile of sildenafil 50 and 100 mg in men with ED and reveals no new safety issues.

Topics: Aged; Cardiovascular Diseases; Dose-Response Relationship, Drug; Double-Blind Method; Drug Interactions; Drug Overdose; Erectile Dysfunction; Hearing Disorders; Humans; Kidney Diseases; Liver Diseases; Male; Middle Aged; Phosphodiesterase Inhibitors; Piperazines; Priapism; Product Surveillance, Postmarketing; Purines; Randomized Controlled Trials as Topic; Sildenafil Citrate; Sulfones; Treatment Outcome

Endocrine abnormalities are common in patients with chronic kidney disease (CKD) and lead to sexual dysfunction, anemia, hyperparathyroidism, and altered mineral metabolism. Common clinical problems include disturbances in menstruation in women, erectile dysfunction in men, and decreased libido and infertility in both sexes. Organic factors tend to be prominent and are related to uremia and other comorbid illnesses. Psychological factors and depression may exacerbate the primary problem. Alterations in the hypothalamic-pituitary axis are seen early in CKD and tend to worsen after patients start dialysis. Hypogonadism plays a dominant role in male sexual function, whereas changes in hypothalamic-pituitary function predominate in female sexual dysfunction. In patients on dialysis, treatment strategies include optimizing dose of dialysis, correction of anemia with erythropoietin, and correction of hyperparathyroidism. Successful kidney transplantation may restore normal sexual function, especially in younger patients.

Topics: Androgens; Chronic Disease; Erythropoietin; Female; Hormone Replacement Therapy; Humans; Hypogonadism; Kidney Diseases; Kidney Transplantation; Male; Phosphodiesterase Inhibitors; Piperazines; Purines; Recombinant Proteins; Sexual Dysfunction, Physiological; Sildenafil Citrate; Sulfones; Testosterone

To investigate the effects of age and renal and hepatic impairment on the pharmacokinetics, tolerability and safety of sildenafil (single 50-mg oral dose) and its major circulating N-desmethyl metabolite, UK-103,320.. Three open-label, parallel-group studies were conducted. The first study compared sildenafil pharmacokinetics, safety and toleration in 15 healthy young male subjects (mean age 30 years; range 19--45 years) to 15 healthy elderly male subjects (mean age 70 years; range 65--81 years). The second study included eight male volunteers with normal renal function and 16 male volunteers with varying degrees of renal impairment as assessed by measurement of creatinine clearance (CLcr). The third study included 12 male volunteers with normal hepatic function and 12 male volunteers with chronic stable hepatic cirrhosis (Child-Pugh A and B). For all three studies, blood and urine samples were collected predose and at specified intervals up to 48 h postdose for assays of sildenafil and UK-103,320, and measurements of protein binding.. Significant differences in Cmax and AUC were observed between the young and the elderly subjects for both the parent drug and the metabolite. In the elderly, AUC values were approximately twice as high and Cmax values 60--70% higher than those for young men, while t1/2 values were approximately 1 h longer for sildenafil and 2 h longer for UK-103,320. Due to a significantly smaller unbound fraction of drug in the elderly, free drug concentrations were only approximately 40% higher in the elderly group compared to the young group. In the renal impairment study, significant correlations with CLcr were demonstrated for sildenafil oral clearance (CL/F) and Cmax and UK-103,320 Cmax and AUC. Pairwise comparisons between subjects with normal renal function and those with severe renal impairment (CLcr<30 ml min-1) supported these findings, showing significant increases in Cmax and AUC for both the parent drug and the metabolite in the severely impaired subjects. The hepatic impairment study demonstrated that the pharmacokinetics of sildenafil were altered in subjects with chronic stable cirrhosis, as shown by a 46% reduction in CL/F and a 47% increase in Cmax compared with subjects with normal hepatic function, suggesting a reduction in first-pass metabolism as well as systemic clearance. The increase in systemic exposure for UK-103,320 was approximately twice that seen for the parent drug. In all three studies, sildenafil was well tolerated, most adverse events were mild and no subjects discontinued treatment.. Sildenafil pharmacokinetics were affected by age and by renal and hepatic impairment, suggesting that a lower starting dose of 25 mg should be considered for patients with severely compromised renal or hepatic function.

Topics: Administration, Oral; Adult; Age Factors; Aged; Aged, 80 and over; Area Under Curve; Humans; Kidney; Kidney Diseases; Liver; Liver Diseases; Male; Metabolic Clearance Rate; Middle Aged; Phosphodiesterase Inhibitors; Piperazines; Purines; Pyrimidinones; Sildenafil Citrate; Sulfones

The aim of the study was to evaluate the potential protective role of sildenafil and tadalafil in contrast-induced nephropathy (CIN) by modulating oxidative stress. Thirty Wistar male rats were equally assigned into five groups: sham, CIN, CIN + sildenafil (10 mg/kg bw/day), CIN + tadalafil (5 mg/kg bw/day) and CIN + N-Acetyl Cysteine (NAC) (100 mg/kg bw/day) as a positive control. CIN was induced by 12 h dehydration and administration of indomethacin (10 mg/kg bw), N-ω- nitro-L-arginine methyl ester (10 mg/kg bw), and iopromide (3 g/kg bw iodine). Blood was drawn prior to and 24 h after CIN induction for evaluating renal function and oxidative stress. In the CIN group, total antioxidant capacity (TAC), reduced glutathione (GSH) and catalase (CAT) levels were significantly decreased; and protein carbonyl (PROTC) and thiobarbituric reactive species (TBARS) were significantly increased compared to the sham group. Pre- Sildenafil and tadalafil pre-treatment reduced CIN risk and reversed oxidative stress almost to the sham group levels. These results suggest that PDE5Is can be good candidates for preventing CIN based on their ability to modulate the oxidant/antioxidant balance.

Topics: Acetylcysteine; Animals; Antioxidants; Catalase; Contrast Media; Disease Models, Animal; Glutathione; Kidney Diseases; Male; Mice; Oxidants; Oxidative Stress; Phosphodiesterase 5 Inhibitors; Rats; Rats, Wistar; Sildenafil Citrate; Tadalafil; Thiobarbituric Acid Reactive Substances

Patients with heart failure with preserved ejection fraction (HFpEF) and chronic kidney disease (CKD) represent a high-risk phenotype. The Phosphodiesterase-5 Inhibition to Improve Clinical Status and Exercise Capacity in Heart Failure with Preserved Ejection Fraction (RELAX) trial enrolled a high proportion of CKD participants, allowing investigation into differences in HFpEF by CKD status.. Renal dysfunction in HFpEF is characterized by echocardiographic and biomarker profiles indicative of more advanced disease, and reduced hemoglobin is a strong mediator of the association between renal dysfunction and low exercise capacity. Sildenafil therapy was associated with worsening of renal function in RELAX.

Topics: Diastole; Heart Failure; Humans; Kidney Diseases; Sildenafil Citrate; Stroke Volume

Physiologically based pharmacokinetic (PBPK) modeling permits clinical scientists to reduce practical constraints for clinical trials on patients with special diseases. In this study, simulations were carried out to validate the pharmacokinetic parameters of clozapine and sildenafil using Simcyp. A full PBPK model was built in the simulator for clozapine and sildenafil based on physicochemical properties and observed clinical results. The model used was Advanced, Dissolution, Absorption and Metabolism (ADAM) for both drugs.. The PBPK model adequately predicted the pharmacokinetic parameters of clozapine and sildenafil for the healthy adult population. In the simulation results, the bioavailability of both drugs was remarkably raised in both renal and hepatic impairment in young and elderly populations.. PBPK modeling could be helpful in the investigation and comparison of the pharmacokinetics in populations with specific disease conditions.

Topics: Adult; Clozapine; Humans; Kidney Diseases; Liver Diseases; Male; Middle Aged; Models, Biological; Sildenafil Citrate; Young Adult

The aim of the study was to investigate the potential of sildenafil and tadalafil to ameliorate structural kidney damage in contrast-induced nephropathy (CIN). A rat model of CIN was developed by dehydration, administration of a nitric oxide inhibitor and a prostaglandin synthesis inhibitor (L-NAME/indomethacin) and contrast media exposure to iopromide. The effect of pre-treatment with sildenafil, tadalafil or N-acetyl cysteine (NAC) for 7 days prior to CIN induction was investigated. All animals were sacrificed at 24 h after CIN induction and both kidneys were collected. Histopathological examination was performed under light microscopy in serial tissue sections stained with hematoxylin and eosin. CIN group showed hydropic changes of the renal tubules (proximal and distal convoluted tubules and Henle's loop), an increased Bowman space with lobulated glomerulus and alteration of macula densa region of distal convolute tubules. The groups pretreated with sildenafil and tadalafil showed nearly normal histological aspects of renal tissue. The group pretreated with NAC showed similar but less intense histopathologic changes compared to CIN group. Sildenafil and tadalafil pre-treatment ameliorates CIN-related structural kidney damage and the protective potential of these agents is superior to NAC.

Topics: Animals; Contrast Media; Kidney Diseases; Kidney Tubules; Male; Phosphodiesterase 5 Inhibitors; Rats; Rats, Wistar; Sildenafil Citrate; Tadalafil

Topics: Acetylcysteine; Animals; Contrast Media; Disease Models, Animal; Female; Hypoxia-Inducible Factor 1, alpha Subunit; Kidney Diseases; Phosphodiesterase 5 Inhibitors; Rats; Rats, Wistar; Sildenafil Citrate

Topics: Drug Monitoring; Glomerular Filtration Rate; Humans; Injections, Intravenous; Kidney; Kidney Diseases; Liver Cirrhosis; Male; Middle Aged; Phosphodiesterase 5 Inhibitors; Severity of Illness Index; Sildenafil Citrate; Treatment Outcome

Our previous studies support the protective effect of cGMP and cGMP-dependent protein kinase I (PKG-I) pathway on the development of renal fibrosis. Therefore, in the present studies, we determined whether pharmacologically or genetically increased PKG activity attenuates renal fibrosis in a unilateral ureteral obstruction (UUO) model and also examined the mechanisms involved. To increase PKG activity, we used the phosphodiesterase 5 inhibitor sildenafil and PKG transgenic mice. UUO model was induced in wild-type or PKG-I transgenic mice by ligating the left lateral ureteral and the renal fibrosis was observed after 14 days of ligation. Sildenafil was administered into wild-type UUO mice for 14 days. In vitro, macrophage and proximal tubular cell function was also analyzed. We found that sildenafil treatment or PKG transgenic mice had significantly reduced UUO-induced renal fibrosis, which was associated with reduced TGF-β signaling and reduced macrophage infiltration into kidney interstitial. In vitro data further demonstrated that both macrophages and proximal tubular cells were important sources of UUO-induced renal TGF-β levels. The interaction between macrophages and tubular cells contributes to TGF-β-induced renal fibrosis. Taken together, these data suggest that increasing PKG activity ameliorates renal fibrosis in part through regulation of macrophage and tubular cell function, leading to reduced TGF-β-induced fibrosis.

Topics: Actins; Angiotensin II; Animals; Cadherins; Cells, Cultured; Culture Media, Conditioned; Cyclic GMP-Dependent Protein Kinase Type I; Cytokines; Disease Models, Animal; Fibrosis; Inflammation Mediators; Kidney Diseases; Kidney Tubules, Proximal; Macrophages; Male; Mice; Mice, Transgenic; Phosphodiesterase 5 Inhibitors; Phosphorylation; Piperazines; Purines; Signal Transduction; Sildenafil Citrate; Smad2 Protein; Sulfones; Time Factors; Transforming Growth Factor beta1; Up-Regulation; Ureteral Obstruction

Cyclosporine A (CsA) is the most widely used immunosuppressant in organ transplant surgery and in treatment of autoimmune disease. Nevertheless, animal and clinical studies have demonstrated that nephrotoxicity is the major adverse effect limiting the prolonged CsA therapeutic use. The present study aimed to investigate possible protective effect of sildenafil, a phoshodiestrase-5 inhibitor, on CsA-induced nephrotoxicity and various mechanism(s) underlies this effect. Male Wistar rats were administered CsA (20 mg/kg/day, s.c.) for 21 days alone or in combination with sildenafil (5 mg/kg/day, p.o.). Sildenafil exhibited nephroprotective effects as evidenced by significant decrease in serum creatinine and urea levels, spot urine albumin-creatinine ratio, as well as renal level of malondialdehyde, with a concurrent increase in renal levels of reduced glutathione and nitric oxide along with catalase activity compared to CsA-treated rats. [corrected]. Additionally, immunohistochemical analysis demonstrated that sildenafil treatment markedly reduced inducible nitric oxide synthase, tumor necrosis factor-alpha, and caspase-3 expressions, while expression of endothelial nitric oxide synthase was prominently enhanced. The protective effects of sildenafil were confirmed by renal histopathological examination. Pretreatment with l-nitro-arginine methyl ester (10 mg/kg/day, i.p.), a non-selective nitric oxide synthase inhibitor, reversed the protection afforded by sildenafil. Taken together, the current study highlighted the renoprotective effects of sildenafil against CsA-induced nephrotoxicity in rats, which might be mediated, in part, through nitric oxide pathway as well as antioxidant, anti-inflammatory, and anti-apoptotic activities.

Topics: Albuminuria; Animals; Catalase; Creatinine; Cyclosporine; Glutathione; Immunosuppressive Agents; Kidney Diseases; Male; Malondialdehyde; Nitrates; Nitric Oxide; Nitrites; Phosphodiesterase 5 Inhibitors; Piperazines; Protective Agents; Purines; Rats; Rats, Wistar; Sildenafil Citrate; Sulfones; Urea

Chronic kidney disease, or renal impairment (RI) can increase plasma levels for drugs that are primarily renally cleared and for some drugs whose renal elimination is not a major pathway. We constructed physiologically based pharmacokinetic (PBPK) models for 3 nonrenally eliminated drugs (sildenafil, repaglinide, and telithromycin). These models integrate drug-dependent parameters derived from in vitro, in silico, and in vivo data, and system-dependent parameters that are independent of the test drugs. Plasma pharmacokinetic profiles of test drugs were simulated in subjects with severe RI and normal renal function, respectively. The simulated versus observed areas under the concentration versus time curve changes (AUCR, severe RI/normal) were comparable for sildenafil (2.2 vs 2.0) and telithromycin (1.6 vs 1.9). For repaglinide, the initial, simulated AUCR was lower than that observed (1.2 vs 3.0). The underestimation was corrected once the estimated changes in transporter activity were incorporated into the model. The simulated AUCR values were confirmed using a static, clearance concept model. The PBPK models were further used to evaluate the changes in pharmacokinetic profiles of sildenafil metabolite by RI and of telithromycin by RI and co-administration with ketoconazole. The simulations demonstrate the utility and challenges of the PBPK approach in evaluating the pharmacokinetics of nonrenally cleared drugs in subjects with RI.

Topics: Area Under Curve; Carbamates; Chronic Disease; Computer Simulation; Drug Interactions; Humans; Ketolides; Kidney Diseases; Models, Biological; Piperazines; Piperidines; Purines; Sildenafil Citrate; Sulfones

Erectile dysfunction (ED) is common in men with systemic sclerosis (SSc) but the demographics, risk factors and treatment coverage for ED are not well known.. This study was carried out prospectively in the multinational EULAR Scleroderma Trial and Research database by amending the electronic data-entry system with the International Index of Erectile Function-5 and items related to ED risk factors and treatment. Centres participating in this EULAR Scleroderma Trial and Research substudy were asked to recruit patients consecutively.. Of the 130 men studied, only 23 (17.7%) had a normal International Index of Erectile Function-5 score. Thirty-eight per cent of all participants had severe ED (International Index of Erectile Function-5 score ≤ 7). Men with ED were significantly older than subjects without ED (54.8 years vs. 43.3 years, P < 0.001) and more frequently had simultaneous non-SSc-related risk factors such as alcohol consumption. In 82% of SSc patients, the onset of ED was after the manifestation of the first non-Raynaud's symptom (median delay 4.1 years). ED was associated with severe cutaneous, muscular or renal involvement of SSc, elevated pulmonary pressures and restrictive lung disease. ED was treated in only 27.8% of men. The most common treatment was sildenafil, whose efficacy is not established in ED of SSc patients.. Severe ED is a common and early problem in men with SSc. Physicians should address modifiable risk factors actively. More research into the pathophysiology, longitudinal development, treatment and psychosocial impact of ED is needed.

Topics: Adult; Databases, Factual; Erectile Dysfunction; Humans; Kidney Diseases; Male; Middle Aged; Muscular Diseases; Piperazines; Prospective Studies; Purines; Scleroderma, Systemic; Severity of Illness Index; Sildenafil Citrate; Skin Diseases; Sulfones; Surveys and Questionnaires; Treatment Outcome; Vasodilator Agents

Sildenafil, the first selective phosphodiesterase-5 (PDE5) inhibitor to be widely used for treating erectile dysfunction, has been investigated with regard to its cardioand renoprotective effects in animal models. This study further investigated the renoprotective effects of sildenafil and their molecular mechanisms in deoxycorticosterone acetate (DOCA)-salt hypertensive (DSH) rats.. DOCA strips (200 mg/kg) were implanted in rats 1 week after unilateral nephrectomy. These rats were fed on a control diet, with or without sildenafil (50 mg·kg(-1)day(-1)), for 2 weeks. Systolic blood pressure (SBP) was measured by the tail cuff method, and the urinary albumin-to-creatinine ratio (ACR) was calculated. The extent of glomerulosclerosis and tubulointerstitial fibrosis was determined by Masson's trichrome stain. Renal expression of ED-1, transforming growth factor-β1 (TGF-β1), Bax, and Bcl-2 were determined by semiquantitative immunoblotting, polymerase chain reaction (PCR), and immunohistochemistry. TUNEL staining was used for detecting apoptotic cells.. The increased SBP in DSH rats was not attenuated by sildenafil treatment. The decreased creatinine clearance and increased ACR in DSH rats, compared with control animals, were attenuated by sildenafil treatment. Further, sildenafil treatment attenuated glomerulosclerosis and tubulointerstitial fibrosis in DSH rats and counteracted the increased expression of ED-1, TGF-β1, and Bax and the decreased expression of Bcl-2 in the kidneys of these rats. The increase in the number of apoptotic cells in DSH rats was attenuated by sildenafil treatment.. Sildenafil effectively prevented the progression of renal injury in DSH rats via its anti-inflammatory, antifibrotic, and antiapoptotic effects.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; Blood Pressure; Desoxycorticosterone; Disease Models, Animal; Disease Progression; Hypertension; Kidney; Kidney Diseases; Male; Phosphodiesterase 5 Inhibitors; Piperazines; Proto-Oncogene Proteins c-bcl-2; Purines; Rats; Rats, Sprague-Dawley; Sildenafil Citrate; Sulfones; Transforming Growth Factor beta1

Sildenafil, the first drug for erectile dysfunction, has cardiopulmonary protective actions. A recent study has reported that sildenafil given intraperitoneally (i.p.) attenuated cisplatin (CP)-induced nephrotoxicity. Here, we evaluated whether sildenafil, given by two different routes and at two different doses, can attenuate CP-induced nephrotoxicity and would also affect renal haemodynamics in CP-treated rats. Six groups of rats were treated with saline (controls), CP [5 mg/kg, intraperitoneally (i.p.) once], sildenafil (0.4 mg/kg/day, i.p. for 5 days), sildenafil (0.4 mg/kg/day i.p. for 5 days) plus CP (5 mg/kg, i.p., once), sildenafil [10 mg/kg/day, subcutaneous (s.c.) for 5 days] or sildenafil (10 mg/kg/day, s.c. for 5 days) plus CP (5 mg/kg, i.p. once). Five days after the end of the treatments, urine was collected from all rats, which were then anaesthetized for blood pressure and renal blood flow monitoring. This was followed by intravenous (i.v.) injection of norepinephrine for the measurement of renal vasoconstrictor responses. Thereafter, blood and kidneys were collected for measurement of several biochemical, functional and structural parameters. CP reduced body-weight and renal blood flow but did not affect norepinephrine-induced renal vasoconstriction. It increased the plasma concentrations of urea and creatinine, and reduced creatinine clearance. CP caused extensive renal tubular necrosis, increased urine volume and N-acetyl-β-D-glucosaminidase activity. When sildenafil (0.4 mg/kg/day, i.p. for 5 days) was combined with cisplatin, there was a dramatic improvement in renal histopathology, reduction in N-acetyl-β-D-glucosaminidase and increase in renal blood flow. However, sildenafil (10 mg/kg/day, s.c. for 5 days) did not affect CP nephrotoxicity, suggesting the importance of dose and route selection of sildenafil as a nephroprotectant.

Topics: Animals; Antineoplastic Agents; Cisplatin; Disease Models, Animal; Hemodynamics; Injections, Subcutaneous; Kidney; Kidney Diseases; Kidney Tubules; Male; Necrosis; Piperazines; Purines; Rats; Rats, Wistar; Renal Circulation; Sildenafil Citrate; Sulfones; Vasoconstriction; Vasodilator Agents

Sildenafil is the first commercially available selective inhibitor of phosphodiesterase-5 (PDE5) and is widely used for the treatment of erectile dysfunction. In recent years, investigations of the role of sildenafil in cardioprotection in animal models have received considerable interest. We evaluated whether sildenafil can attenuate cisplatin-induced nephrotoxicity in a rat experimental model. Male Sprague-Dawley rats were divided into five groups: control rats, sildenafil-control rats, cisplatin-injected rats (5 mg kg(-1) IP, single dose), sildenafil-treated cisplatin-injected rats (0.4 mg kg(-1), daily), and sildenafil+NG-nitro-l-arginine methyl ester hydrochloride (l-NAME)-treated rats. The molecular, functional, and structural parameters of the kidney were measured. At 96 h after cisplatin injection, serum levels of creatinine were lower in rats treated with both sildenafil+cisplatin compared with rats treated with cisplatin alone, and renal iNOS and eNOS expression was significantly higher in sildenafil+cisplatin-treated rats compared with rats treated with cisplatin alone (all P<0.05). Renal Bax gene and protein expression was significantly higher in cisplatin-treated rats compared with control rats, and sildenafil treatment significantly reduced the levels of Bax and increased the renal Bax/Bcl-2 ratio (P<0.05). Sildenafil treatment also reduced renal caspase-3 activation and TUNEL-positive apoptotic cells. These data suggest that sildenafil attenuates experimental cisplatin-induced nephrotoxicity by preventing apoptosis.

Topics: Animals; Antineoplastic Agents; bcl-2-Associated X Protein; Blood Urea Nitrogen; Blotting, Western; Caspase 3; Cisplatin; Creatinine; In Situ Nick-End Labeling; Kidney; Kidney Diseases; Kidney Function Tests; Male; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Phosphodiesterase Inhibitors; Piperazines; Purines; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; RNA; Sildenafil Citrate; Sulfones

Sildenafil was the first selective inhibitor of phosphodiesterase-5 (PDE5) to be widely used for treating erectile dysfunction. Many recent studies have investigated the cardioprotective role of sildenafil in animal models. We evaluated the protective effects of sildenafil in experimental renal ischemia-reperfusion (IR) injury in two studies. In study 1, male Sprague-Dawley rats were divided into four groups: sham, sildenafil-treated sham, vehicle-treated IR, and sildenafil-treated IR groups. In study 2, we divided the rats into two groups: sildenafil-treated IR rats and PD98059 (ERK inhibitor)+sildenafil-treated IR rats. Functional parameters of the kidney were evaluated at the molecular and structural levels. Blood urea nitrogen (BUN) and serum creatinine levels were lower in sildenafil-treated IR rats than in vehicle-treated IR rats. The expression of inducible (iNOS) and endothelial nitric oxide synthase (eNOS) proteins in sildenafil-treated IR rats was significantly higher than in vehicle-treated IR rats. Pretreatment with sildenafil in IR rats increased ERK phosphorylation and reduced the renal Bax/Bcl-2 ratio, renal caspase-3 activity, and terminal dUTP nick end-labeling-positive apoptotic cells. In contrast, PD98059 treatment increased BUN and serum creatinine levels and attenuated the sildenafil-induced expression of pERK, iNOS, eNOS, and Bcl-2. PD98059 also increased caspase-3 activity but did not decrease the sildenafil-induced accumulation of cGMP. In conclusion, this study suggests that sildenafil has antiapoptotic effects in experimental IR renal injury via ERK phosphorylation, induction of iNOS and eNOS production, and a decrease in the Bax/Bcl-2 ratio.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; Blood Urea Nitrogen; Caspase 3; Creatinine; Cyclic GMP; Cyclic Nucleotide Phosphodiesterases, Type 5; Disease Models, Animal; Drug Administration Schedule; Extracellular Signal-Regulated MAP Kinases; Flavonoids; Kidney Diseases; Male; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Phosphodiesterase 5 Inhibitors; Phosphodiesterase Inhibitors; Phosphorylation; Piperazines; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-bcl-2; Purines; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Sildenafil Citrate; Sulfones; Time Factors

The treatment of erectile dysfunction (ED) has been revolutionised by new agents to inhibit the enzyme PDE5. The scientific basis of this treatment of ED includes relaxation of the corpus cavernosum smooth muscle tissue by inhibition of PDE5 that breaks down cGMP, the key pathway for the production of erectile function in humans. Many clinical studies, both pre- and post-marketing, have demonstrated the clinical efficacy and safety of sildenafil (Viagra, Pfizer) - the first approved selective PDE inhibitor for the treatment of ED. Sildenafil is inhibitory of PDE5 at a rate tenfold higher than for the next PDE (PDE6), which produces visual changes through the retinal rods. Its clinical effectiveness has been well documented in the majority of men with ED irrespective of aetiology. The aetiology of ED, also, does not appear to effect the function of sildenafil in relaxing corpus cavernosum smooth muscle tissue. Adverse events are usually associated with the vascular changes from PDE5 inhibition. These include headache and flushing. Each of these adverse events, however, declines with medication use. With the use of sildenafil, it has been clearly, clinically demonstrated that the selective inhibition of PDE5 is an appropriate, effective, safe method for the treatment of ED of all aetiologies and severities.

Topics: Aged; Area Under Curve; Central Nervous System Diseases; Chemical and Drug Induced Liver Injury; Chronic Disease; Erectile Dysfunction; Humans; Kidney Diseases; Male; Phosphodiesterase Inhibitors; Piperazines; Product Surveillance, Postmarketing; Purines; Sildenafil Citrate; Sulfones