Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.4.1 (phosphodiesterase)
 18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although intraportal infusion of adenosine suppressed the oxidative stress caused by activated neutrophils and attenuated ischemia-reperfusion injury of canine liver, high doses of adenosine elicit systemic hypotension. The present work demonstrates that combined use of low doses of adenosine and amrinone, a phosphodiesterase inhibitor, strongly inhibited reperfusion injury of the liver without eliciting hypotension. After 45 min ischemia followed by 60 min reperfusion of rat liver, low doses of adenosine and amrinone were administrated intraportally, resulting in significantly increased hepatic levels of cGMP, cAMP, nitrite plus nitrate in plasma, and decreased alanine aminotransferase in plasma without changing hemodynamics. Thus, intraportal administration of low doses of adenosine and amrinone increased the cyclic nucleotides, thereby improved microcirculation and attenuated reperfusion injury of the liver.
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PMID:Combined use of adenosine and amrinone inhibits reperfusion injury of rat liver. 1147 70

Erectile dysfunction (ED) (impotence) is a widespread, age-related problem, which affects 52% of men between 40 and 70 years of age. It is classified as psychogenic, organic, or mixed psychogenic and organic. ED is not a problem only of men, because the relationship between partners can also be disturbed. Therefore, adequate treatment of ED is needed and the most convenient and simplest way is oral drug therapy. Sildenafil, phosphodiesterase-(PDE)-5-selective inhibitor has been the drug of choice for patients with ED since it has been launched in March 1998. The results of various studies have confirmed the efficacy of the drug in men with ED of various etiologies, as well as the positive effect of sildenafil on the quality of a partnership. The most frequent adverse effects documented with sildenafil usage are headache, flushes, dyspepsia, visual disturbances and nasal congestion/rhinitis. These adverse effects are dose-related, usually transient and mild, with low withdrawal rate. Several studies performed recently have shown that sildenafil is a safe and effective treatment of ED in patients with cardiovascular disease, who do not take nitrates or nitrate donors concomitantly. Other oral medications for ED include apomorphine, phentolamine, yohimbine, trazodone, testosterone and new PDE-5 inhibitors in Phase III clinical trials, such as vardenafil and tadalafil. It is obvious, according to recent data, that the concept of PDE-5 inhibition has a central position in oral pharmacotherapy of ED. However, larger clinical studies of efficacy and safety should be carried out using most of the other above-mentioned oral agents and these may also gain a place in the therapy of ED. There are no studies directly comparing sildenafil and other treatments of ED or assessing its role in combination with other therapies. According to the present knowledge, the quality of life, not only of patients but also of their sexual partners, will be improved significantly with sildenafil usage and this is an important precondition for overall health ofboth. Sildenafil is thus a highly effective peroral treatment for ED in patients without contraindications for its use, which can be considered as the firstline therapy with an acceptable risk-benefit ratio.
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PMID:Erectile dysfunction: oral pharmacotherapy options. 1235 56

Erectile dysfunction (ED) and cardiovascular disease share many of the same risk factors and have some common elements of pathophysiology. Clinically, they often coexist. Another link between the two conditions is that sildenafil, the first oral therapeutic agent effective in treating ED, has been shown to potentiate the hypotensive effects of nitrates, a potentially serious side effect. Nitrates are commonly used in the treatment of coronary artery disease. As such, sildenafil (and, likely, other new phosphodiesterase type 5 [PDE5] inhibitors) is contraindicated in men who use nitrate medications. This article will examine the risk of an acute coronary event during sexual activity, and review an algorithm for evaluating the cardiac risk of a patient with ED. The interaction between PDE5 inhibitors and cardiac medications will be discussed, along with guidelines for using sildenafil in men with cardiac disease.
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PMID:Cardiovascular safety of PDE5 inhibitors. 1262 47

Erectile dysfunction is a medical condition that influences the sexual life of millions of men and women worldwide. Due to a large number of currently available drugs, the therapy of erectile dysfunction has changed profoundly during the last decades. The pharmacologic options are divided into initiators versus conditioners and central- or peripheral-acting drugs. Besides intraurethral and intracavernous application of prostaglandin E(1) (PGE(1), peripheral initiator)--a transdermal application is still in clinical testing--there are drugs for oral application. PGE(1), the vasoactive drug mainly used, was replaced by sildenafil in first-line-therapy. PGE(1), administered intracavernosally or intraurethrally, is highly effective with success rates up to 90%, but the attrition rate due to personal inconvenience remains significant. Yohimbine is known as a central amplifier of erection and is useful in psychogenic and mild organic erectile dysfunction. Apomorphine, a central initiator of erection, amplifies erectile response as a central dopamine agonist in mild and moderate erectile dysfunction and starts acting 15-20 min after sublingual application. The phosphodiesterase type 5 (PDE-5) inhibitors sildenafil, vardenafil, and taldalafil are peripheral conditioners. Sildenafil, the most distributed oral agent worldwide, should be taken orally 60 min before sexual intercourse in combination with sexual stimulation. Sildenafil shows a high efficacy-safety profile with success rates for all etiologies between 50-80%. Paralleling nitrate-containing medication is an absolute contraindication. Vardenafil, another selective PDE-5 inhibitor with potentially higher selectivity and efficacy compared to sildenafil was just approved. The data from the clinical trials show the same adverse events and success rates as sildenafil. Tadalafil, just launched as well, amplifies erectile function for up to 24 h, allowing the patient to engage in sexual activity for this period. Adverse events and success rates resemble those of the other two substances. If medical treatment fails, there are nonpharmacologic options such as the vacuum constriction device and penile implants. The vacuum device is a safe and effective option for well-selected patients. Penile implants, especially the inflatable ones, completely imitate the physiologic erection. Due to recent research, infection rates and mechanical failures were minimized. Therefore penile implant surgery is well accepted by the patients and their partners. Despite this wide variety of options, therapy of erectile dysfunction should be performed in an individually adapted way. The patient's exact history, physical examination, collaboration of medical disciplines and choice of therapy will offer all patients the possibility to achieve or regain a satisfying sexual life.
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PMID:[New treatment options for erectile dysfunction. Pharmacologic and nonpharmacologic options]. 1282 47

Hospital admissions for acute decompensated heart failure (ADHF) have increased precipitously during the past few decades and are projected to continue to increase in the future. To optimize patient outcomes and reduce the costs associated with this disorder, evidenced-based pharmacotherapy is essential. Continuous infusions of loop diuretic therapy rather than bolus dosing may enhance efficacy and reduce the extent of diuretic resistance. Nesiritide is a pharmacologically novel preload and afterload reducer but based on clinical trial evidence should be reserved for those unable to take or with resistance to intravenous nitrate therapy. Catecholamine- and phosphodiesterase-based inotropic therapies are efficacious, but the increased risk of arrhythmogenesis and the potential for negative survival effects limit their use. The experimental agent levosimendan is a positive inotropic agent but does not increase myocyte calcium concentrations as do catecholamines or phosphodiesterase inhibitors. Clinical trial evidence demonstrates a positive survival benefit for levosimendan versus dobutamine.
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PMID:Acute decompensated heart failure: a contemporary approach to pharmacotherapeutic management. 1292 Dec 47

Sildenafil citrate, the first internationally approved and widely used oral agent for the treatment of erectile dysfunction (ED), has revolutionized the treatment of ED throughout the past 5 years. This phosphodiesterase type-5 (PDE-5) inhibitor is selective for corpus cavernosum smooth muscle tissue and produces excellent erectile function. Its efficacy and safety over a wide variety of etiologies of ED and severities of ED demonstrates its usefulness in the clinical treatment of these patients. More than 20 million men have been treated worldwide with sildenafil with excellent results. ED caused by difficult-to-treat etiologies such as radical prostatectomy, severe diabetes, and spinal cord injury have demonstrated efficacy. Although sildenafil citrate, like all PDE-5 inhibitors, is contraindicated in patients taking nitrate medications for cardiac disease, it is effective and safe for those cardiovascular patients who are not taking nitrate medications. The incidence of adverse cardiovascular events in patients taking sildenafil does not differ from those of the general population. Investigations into the pharmacologic effect of sildenafil on coronary myocardial tissue further supports the safety of this medication. Sildenafil has been safe and effective in patients taking various medications including multiple antihypertensive drugs, selective serotonin reuptake inhibitors, cardiac, and diabetic medications.
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PMID:Sildenafil: a 4-year update in the treatment of 20 million erectile dysfunction patients. 1462 3

(1) The standard oral treatment for erectile dysfunction is sildenafil, a type 5 phosphodiesterase inhibitor, whether the underlying problem is organic (for example, post prostatectomy or spinal cord damage) or psychological. (2) Another inhibitor of the same type, tadalafil, has been available in France since early 2003. (3) At 10 mg to 20 mg, tadalafil is more effective than placebo, including in diabetic patients. But placebo-controlled trials have included few patients with a history of total prostatectomy, spinal cord damage, or sildenafil failure. One trial, which was not published in detail, reported that the effects last more than 12 hours. But the European Medicines Evaluation Agency considered that the reported data did not support this conclusion. There was no significant difference between active treatment and placebo groups after 12 hours. The risk-benefit ratio of long term treatment with tadalafil is unknown. (4) The two available comparative trials do not rule out the possibility that tadalafil is less effective than sildenafil. (5) Known adverse effects and drug interactions are similar in both tadalafil and sildenafil. Both drugs are contraindicated in patients using nitrate derivatives, because of a risk of abrupt hypotension. (6) Unlike sildenafil, administration of tadalafil does not retard its action. (7) In practice, sildenafil remains the first line option for treating erectile dysfunction with an organic cause. Tadalafil is slightly easier to use.
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PMID:Tadalafil: new preparation. Slightly more convenient, but poorly assessed in organic disorders. 1498 90

Nitric oxide (NO), which is synthesized from the guanidino nitrogen of l-arginine by nitric oxide synthase (NOS), plays an important role in many physiological and pathological processes. Most of the effects of NO are mediated by cyclic guanosine 3'5 monophosphate (cGMP), which is synthesized by soluble guanylate cyclase (sGC) and degraded by phosphodiesterases (PDEs). Although the NO/cGMP pathway has been extensively studied, remarkably little is known about the regulation of NO release. Furthermore, controversial studies have indicated that intervention of the sGC/cGMP pathway modulates the release of NO. The purpose of this study was to evaluate the hypothesis that drugs that affect the sGC/cGMP pathway may modulate NO release and, if so, is there a correlation between NO levels and blood pressure effect? To this end, we investigated the effects of the PDE 5 inhibitor zaprinast on mean arterial pressure (MAP), nitrite/nitrate levels and cGMP in normotensive male Sprague Dawley rats. The results of the current study indicated that zaprinast dose-dependently increased plasma cGMP levels at 18, 24 and 36 mg/kg and decreased MAP at 24 and 36 mg/kg. However, zaprinast at 18, 24 and 36 mg/kg did not affect NO levels either in serum or aortic tissue. We have concluded that the PDE 5 inhibitor zaprinast has no regulatory effect on NO release in serum and aortic tissue, and NO was not involved in the hypotensive effect of zaprinast.
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PMID:Effect of zaprinast on nitric oxide levels in serum and aortic tissue. 1498 37

Impairment of erectile function compromises quality of life in millions of men and their partners, many of whom prefer to suffer in silence. It is important to maintain an elevated index of clinical suspicion in patients with erectile dysfunction (ED) risk factors (e.g. hypertension, diabetes, coronary heart disease). There remains a high rate of voluntary discontinuation of therapy associated with most treatment modalities. Since the introduction of sildenafil, a greater awareness and openness regarding the epidemiology and treatment of male erectile dysfunction has emerged. The development of newer and potentially more efficacious phosphodiesterase type 5 (PDE5) inhibitors will serve to treat an even greater number of patients, allowing once daily and more convenient dosing. An increased understanding of the physiological principles of penile erection has allowed the development of novel oral pharmacological therapies. The new agents offer a potential benefit in a broader range of patients and clinical situations. They may provide a more acceptable alternative than other more invasive options (intracavernosal/urethral injection, implant surgery). The dopamine agonist apomorphine acts on the central control of penile erection to allow a sublingual preparation to produce a prompt response. It is not contraindicated in patients on nitrate medication for coronary artery disease, or in patients with depression or on antidepressants. As with any other treatment, the clinician's responsibility in the care of ED patients does not end with the writing of a prescription. Adequate education and follow-up are needed to optimize the efficacy and safety of oral ED therapy. Furthermore, patients and their partners need to be advised that the agents are not effective in the absence of sexual stimulation. Communicating with both the patient and his partner in a discreet, non-judgmental manner that fosters the physician-patient alliance can facilitate the recognition and treatment of ED.
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PMID:Update on oral treatments for male erectile dysfunction. 1509 34

Erectile dysfunction (ED) is often a marker for serious underlying cardiovascular disease (CVD), and cardiologists are increasingly involved in the care of men with ED. It is important to ask specifically about ED when evaluating men with CVD, since they may be embarrassed to volunteer this information. During the clinical workup, it is also important to check for contributing factors to ED such as diabetes, depression, stress, alcohol abuse, and cardiovascular risk factors. Patients should be advised that many treatment options are available for ED, including the phosphodiesterase type 5 (PDE5) inhibitors. The PDE5 inhibitors are safe and effective in most patients with CVD, including those taking multiple antihypertensive drugs. Furthermore, they have no deleterious effect on exercise capacity, heart rate, or extent of exercise-induced ischemia. In the future, the PDE5 inhibitors may have a role in reducing pulmonary hypertension in persons with primary pulmonary arterial hypertension (PAH) or congestive heart failure. The one major precaution for men taking PDE5 inhibitors is to avoid concomitant administration of therapeutic and recreational nitrate preparations. Patients with chest pain suggestive of a heart attack need to inform emergency room (ER) personnel if they are taking a PDE5 inhibitor. Similarly, before giving nitrates, ER personnel need to ask patients if they have used PDE5 inhibitors. Nitrates should not be given for at least 24 h after a patient uses sildenafil or vardenafil and at least 48 h after a patient uses tadalafil.
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PMID:Role of the cardiologist: clinical aspects of managing erectile dysfunction. 1511 89


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