Central effects of Sildenafil Citrate (Viagra) on auditory selective attention and verbal recognition memory in humans: a study with event-related brain potentials.

The purpose of this study was to assess possible central side-effects of Sildenafil Citrate (Viagra) on attention and memory functions.Sildenafil Citrate (Viagra) and placebo were administered in young male subjects in a double-blind balanced cross-over design. Behavioral patterns and event-related brain potentials (ERP) were recorded in a spatial auditory attention and a visual word recognition task. While behavioral patterns did not reveal any overt effects of sildenafil, auditory ERPs were indicative of an enhanced ability to focus attention (amplitude enhancement of Nd-effect) and to select relevant target stimuli in theSildenafil Citrate (Viagra) condition (P3 component). In the memory task, CNS-effects ofSildenafil Citrate (Viagra) were evident in a reduction of a negativity in the 150-250 ms range. No overt effects on behavior were observed. Nevertheless, the data reveal CNS-effects ofSildenafil Citrate (Viagra) necessitating further studies

Influence ofSildenafil Citrate (Viagra) on central dopamine-mediated behaviour in male rats.

Two experiments were performed to evaluate the effects ofSildenafil Citrate (Viagra) on spontaneous or dopamine agonist-induced behaviour in male rats. Data obtained in experiment 1 show that oral administration of the drug, at 1 mg/kg, significantly increased the occurrence of penile erections, anogenital self-grooming and homosexual mounting in grouped sexually-experienced, but not inexperienced, animals. In experiment 2, pre-treatment withSildenafil Citrate (Viagra) (0.5, 1 or 10 mg/kg) dose-dependently modified several behavioural signs, centrally evoked by the D2/D3 dopamine agonists, 7-OH-DPAT or B-HT 920 (both at 0.1 mg/kg), in experimentally naive male rats. WhileSildenafil Citrate (Viagra) at 1 mg/kg significantly increased the number of penile erection and stretching-yawning episodes induced by 7-OH-DPAT or B-HT 920, at 10 mg/kg it elicited low stereotyped behaviour, antagonizing stretching-yawning and sedation in 7-OH-DPAT treated rats. Discussion centres on the modulatory activity ofSildenafil Citrate (Viagra) on central dopaminergic pathways and, possibly, on nitric oxide production

The effect ofSildenafil Citrate (Viagra) on electrostimulation-induced erection in the rat model.

This study was conducted to show the effect ofSildenafil Citrate (Viagra) on electrostimulation-induced erection in the rat model. Fifteen 12-week-old male Wistar Kyoto rats were used. The intracavernous pressure and arterial blood pressure were simultaneously monitored through electric cavernous nerve stimulation before and after the administration ofSildenafil Citrate (Viagra) (2 mg/kg). Statistical analysis was performed on maximal intracavernous pressure (MIP), mean arterial blood pressure (MAP), the MIP/MAP and detumescence time. MAP decreased significantly by about 20 mmHg afterSildenafil Citrate (Viagra) administration. The MIP/MAP increased significantly afterSildenafil Citrate (Viagra) administration. The effect ofSildenafil Citrate (Viagra) on the MIP/MAP was marked especially at lower (2-3 Hz) frequencies. The detumescence time significantly increased afterSildenafil Citrate (Viagra) administration. We have shown thatSildenafil Citrate (Viagra) is effective for enhancing erection at lower frequencies and prolonging penile erection in rats. After the administration of sildenafil, penile erection would be induced by weak stimuli that will not cause penile erection under normal conditions

Transient renal effects ofSildenafil Citrate (Viagra) in male kidney transplant recipients.

BACKGROUND: Sildenafil Citrate (Viagra) improves erection by sustaining Guanosine 3', 5'-cyclic monophosphate (cGMP)-mediated smooth muscle relaxation in the corpus cavernosum. It also induces systemic vasodilation, resulting in a minor decrease in blood pressure. We evaluated the effect of one dose ofSildenafil Citrate (Viagra) on graft function and hemodynamics in impotent male transplant recipients. METHODS: Two sets of combined lithium, inulin, and p-amino hippurate clearance studies were conducted, with and withoutSildenafil Citrate (Viagra) (100 mg orally) in 11 male kidney transplant recipients (KTRs). RESULTS:Sildenafil Citrate (Viagra) increased glomerular filtration rate by 14+/-4 from the baseline value of 55+/-7 ml x min(-1) x 1.73 m2(-1) (P<0.01), whereas calculated renal vascular resistances decreased by 40+/-18 from the baseline value of 247+/-29 mmHg/L x min(-1) x 1.73 m2-1 (P<0.05). CONCLUSIONS: The oral administration ofSildenafil Citrate (Viagra) in KTRs did not impair the function of the graft. In terms of renal physiology, the observed modifications did not warrant any specific precautions when offeringSildenafil Citrate (Viagra) to KTRs suffering from Erectile Dysfunction.

Management of Erectile Dysfunction by combination therapy with testosterone andSildenafil Citrate (Viagra) in recipients of high-dose therapy for haematological malignancies.

Erectile Dysfunction (ED) is a well recognised complication of bone marrow transplantation, which affects quality of life in adult patients. Although the major contributory factors include hypogonadism and psychogenic factors, the best treatment still remains to be established due to the complex aetiopathology of the condition. Here, we report our preliminary results in eight patients treated with testosterone replacement therapy and sildenafil. We studied eight male recipients of BMT aged 22-58 years, presenting with clinical features of hypogonadism, ED, diminished libido and ejaculatory disorders. ED was assessed clinically and by colour flow Doppler studies of the cavernosal vessels. Testicular function was assessed by testicular volume, FSH, LH and testosterone (T) measurements. Erectile performance, libido and ejaculatory function were determined by a structured interview. Patients had severe primary hypogonadism as evidenced by low mean testicular volume, elevated gonadotrophins and low normal mean testosterone levels compared with controls. All had Leydig cell insufficiency (LCI) with or without frank serum testosterone insufficiency. All except one had cavernosal arterial insufficiency. All patients received intramuscular injections of testosterone cypionate (250 mg 4 weekly) for 6 months and 50-100 mg ofSildenafil Citrate (Viagra) orally, one to two times per week. All patients responded favourably as substantiated from the NIH consensus criteria. Our preliminary results suggest that this combined therapy is a safe and effective therapeutic approach in recipients of high-dose therapy presenting with ED after transplant

Effects of phosphodiesterase 3,4,5 inhibitors on hepatocyte cAMP levels, glycogenolysis, gluconeogenesis and susceptibility to a mitochondrial toxin.

Various phosphodiesterase (PDE) 3,4 and 5 inhibitors have been compared with glucagon for their effectiveness at increasing hepatocyte cAMP, glycogenolysis and gluconeogenesis. Preincubation of isolated hepatocytes with PDE 3 and 4 inhibitors (50 microM) for 2 h induced significant increases in cellular cAMP level. The order of effectiveness was: glucagon (78%), V11294A (42%), rolipram (40%), milrinone (36%), CDP-840 (33%), R(0) 20-1724 (31%), papaverine (27%), isobutylmethylxanthine (28%), isoliquiritigenin (25%), theophylline (22%), and amrinone (22%). The PDE 5 inhibitors dipyridamol andSildenafil Citrate (Viagra) had only a slight effect on cAMP levels. Glucose formation was increased as a result of increased glycogenolysis in the following order of effectiveness: glucagon (89%), V11294A (63%), rolipram (61%), milrinone (50%), CDP-840 (46%), R(0) 20-1724 (45%),Sildenafil Citrate (Viagra) (34%), dipyridamol (31%), papaverine (30%), isobutylmethylxanthine (29%), theophylline (20%), amrinone (20%), and isoliquiritigenin (20%). Rolipram and milrinone, selective PDE 4 and PDE 3 inhibitors respectively, stimulated the gluconeogenesis of alanine, lactate + pyruvate, or fructose in hepatocytes isolated from fasted rats. On the other hand, selective cGMP specific phospodiesterase inhibitors,Sildenafil Citrate (Viagra) and dipyridamol inhibited alanine-induced gluconeogenesis. All PDE inhibitors increased hepatocyte susceptibility to cyanide toxicity (3-4 fold) which was prevented by fructose whereas PDE 5 inhibitors did not significantly increase hepatocyte susceptibility

Assessment of the efficacy and safety of Viagra (Sildenafil Citrate (Viagra)) in men with Erectile Dysfunction during long-term treatment.

Long-term efficacy and safety ofSildenafil Citrate (Viagra) was assessed in 1008 patients with Erectile Dysfunction (ED) enrolled in four flexible-dose (25 - 100 mg), open-label, 36- or 52-week extension studies. After 36 and 52 weeks, 92% and 89% of patients felt that treatment withSildenafil Citrate (Viagra) had improved their erections. Responses to a Sexual Function Questionnaire indicated that 52 weeks ofSildenafil Citrate (Viagra) treatment resulted in clinically significant improvements in the duration and firmness of erections, overall satisfaction with sex life, and the frequency of stimulated erections. Commonly reported adverse events (AEs) were headache, flushing, dyspepsia, and rhinitis, which were generally mild to moderate. Reports of abnormal vision were consistent with previous clinical trials. The occurrence of treatment-related cardiovascular AEs, such as hypertension, tachycardia, and palpitation, was <1%. Discontinuations due to treatment-related AEs were low (2%). Long-term therapy does not diminish the efficacy ofSildenafil Citrate (Viagra) in patients with ED and remains well tolerated

Effect of Sildenafil Citrate (Viagra) on penile erection of rhesus macaques.

AIM: To examine the effect of Sildenafil Citrate (Viagra) on penile erection of male rhesus macaque. METHODS: Twenty Macaca mulatta were divided into theSildenafil Citrate (Viagra) treated and the control groups of 10 animals each. The penile size, the corpus cavernosal electromyogram (EMG) and the intra-corpus cavernosal pressure (ICP) were determined. RESULTS: The diameter of penis and the ICP were significantly increased and the corpus cavernosal EMG significantly reduced in theSildenafil Citrate (Viagra) group. CONCLUSION: Sildenafil Citrate (Viagra) increases the penile size and ICP and reduces the corpus cavernosal EMG in male rhesus macaque