Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0018681 (headache)
 56,091 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

There are no published controlled clinical trials of regular phosphodiesterase type 5 inhibitor therapy as a long-term treatment of hypertension. In a randomized, double-blind, 2-way crossover study, 25 otherwise untreated hypertensive subjects were administered 50 mg of sildenafil or matched placebo 3 times daily for 16 days, and the effects on ambulatory blood pressure (BP), clinic BP, arterial wave reflection, carotid-femoral pulse wave velocity, and brachial artery flow-mediated dilatation were assessed. Three subjects were withdrawn because of adverse effects, and the data from the remaining 22 subjects were analyzed. Sildenafil reduced ambulatory BP (mean [SE] change from baseline for average daytime BP: systolic -8 [2] mm Hg versus 2 [2] mm Hg with placebo, P<0.01; diastolic -6 [1] mm Hg versus 0 [1] mm Hg, P<0.01) and clinic BP (change from baseline to 1 hour after drug administration on day 16: systolic -5 [2] mm Hg versus 4 [2] mm Hg, P<0.01; diastolic -5 [1] mm Hg versus 2 [2] mm Hg, P<0.01). Compared with baseline, sildenafil, but not placebo, reduced arterial wave reflection both acutely and after chronic treatment, but the chronic change in arterial wave reflection was not statistically different from the chronic change with placebo. Sildenafil did not affect pulse wave velocity or flow-mediated dilatation. The main adverse effects of sildenafil, which were generally transient and rated as mild or moderate in severity, were dyspepsia, headache, and myalgia. In conclusion, regular sildenafil constitutes effective antihypertensive therapy. Further studies are warranted to evaluate the role of longer-acting phosphodiesterase type 5 inhibitors as antihypertensive agents in clinical practice.
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PMID:Effect of regular phosphodiesterase type 5 inhibition in hypertension. 1744 22

Within 6 months of approval by the U.S. Food and Drug Administration (FDA), 5.3 million prescriptions were written for sildenafil citrate. It represented the first clearly effective and FDA-approved oral therapy for the treatment of ED. The chemical structure of sildenafil is very similar to the cyclic guanosine monophosphate molecule with which it competes, in the enzyme phosphodiesterase type-5. Sildenafil binds to the phosphodiesterase-5 enzyme, preventing the breakdown of cyclic guanosine monophosphate through competitive inhibition. The onset of action for sildenafil can be as short as 20 minutes and the duration of action may be as long as three half-lives (18 hours). Anecdotal evidence suggests that many men describe an erectogenic effect for almost 24 hours. The safety of sildenafil has been established in many pre- and postapproval studies at doses as high as eight times the maximum recommended dose. It is likely that the rare instance of myocardial infarction after taking sildenafil as directed, is due more to the activity of sexual intercourse rather than the medication itself. Efficacy have been established in patients with diabetes, parkinsonism, spinal cord injury, and those on antihypertensive (single- and multiple-therapy) agents. It has also been shown to be effective in reversing selective serotonin reuptake inhibitor-induced sexual side effects. Initial concerns about sildenafil with respect to ocular safety were based on misinterpretation of the FDA submission data. The two most common side effects are headache and flushing, both of which are short-lived and easily treated.
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PMID:Four-year review of sildenafil citrate. 1698 12

The discovery that inhibition of phosphodiesterase-5 (PDE5) reduces the degradation of cGMP, allowing erectile function to occur by relaxation of penile smooth muscle, represents a revolutionary approach or the treatment of erectile dysfunction (ED). Three PDE5 inhibitors (sildenafil, tadalafil, and vardenafil) are clinically available at this time, and extensive drug design efforts are registered for finding agents with a better activity, enhanced selectivity and reduced side effects. Many classes of such compounds have been reported, belonging to diverse chemical entities. The drug design has been very much facilitated after the report of the X-ray crystal structure of the PDE5 catalytic domain in complex with the three clinically used derivatives. PDE5 inhibitor therapy, has been found to be effective in special clinical populations, such as those with prostate cancer, diabetes, and cardiovascular disease. The duration of action of sildenafil and vardenafil is of about 4 hours, whereas that of tadalafil is of about 36 hours, and the overall safety of the treatments is good. There is a risk of hypotension if nitrates are given concurrently with the PDE5 inhibitors. Common side-effects include headache, facial flushing, nasal congestion, dyspepsia and transient visual impairment. There are pharmacological interactions between these drugs and other medications metabolized by the cytochrome P450 (P3A4 isoform), such as the azole antifungals, erythromycin and the HIV protease inhibitors.
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PMID:Phosphodiesterase 5 inhibitors--drug design and differentiation based on selectivity, pharmacokinetic and efficacy profiles. 1701 39

Raynaud's phenomenon is a common disorder with vasospasm of the digital arteries causing pallor with cyanosis and/or rubor. It can be primary (idiopathic), where it is not associated with other diseases, or secondary to several diseases or conditions, including connective tissue diseases, such as scleroderma and systemic lupus erythematosus. Raynaud's is often mild enough to not require treatment; however, with secondary Raynaud's there is not only vasospasm but also fixed blood vessel defects so the ischaemia can be more severe. Complications can include digital ulcers and could, rarely, lead to amputation. Treatment is often non-pharmacological including avoiding cold and smoking cessation. Calcium channel antagonists, such as nifedipine, are often considered when treatment is needed; however, adverse effects of these drugs can include hypotension, vasodilatation, peripheral oedema and headaches. Other treatments have been studied in randomised, controlled trials including classes of drugs, such as angiotensin II inhibitors, selective serotonin reuptake inhibitors, phosphodiesterase-5 inhibitors (e.g. sildenafil), nitrates (topical or oral; the latter can be limited by adverse effects, such as flushing, headache and hypotension), and for more serious Raynaud's or its complications prostacyclin agonists may be used. There are two large studies that demonstrate that endothelin receptor blockade with bosentan can reduce the number of new digital ulcers in scleroderma patients. However, it does not affect the healing period. Thus, Raynaud's is common and often requires non-pharmacological treatment. When secondary Raynaud's is suspected, such as Raynaud's with an older age at onset or other features of connective tissue disease, then an appropriate history, physical examination and laboratory tests may be indicated to reach an appropriate diagnosis. There have been advances in pharmacological treatment, but some of the treatments are limited by adverse effects.
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PMID:The diagnosis and treatment of Raynaud's phenomenon: a practical approach. 1735 12

Vardenafil is a selective phosphodiesterase-5 inhibitor approved for the treatment of erectile dysfunction. It was found to be effective in a high percentage of patients and a broad spectrum of underlying conditions. It potentiates the increase in intracellular cGMP in the corpora cavernosa in response to sexual stimuli, resulting in enhanced and prolonged erections. The overall tolerability and safety profile is acceptable, with headache, flushing, rhinitis and dyspepsia being the major reported side effects. Importantly, tolerability and safety in cardiovascular patients seems to be good with no significant increase in cardiovascular events that could be directly attributed to the pharmacologic agent. Only mild blood-pressure lowering effects were observed in healthy individuals, as well as hypertensive patients on multiple antihypertensive agents. However, special caution is mandatory if vardenafil is administered in combination with alpha-blockers, as significant hypotension might occur. Importantly, any drug serving as a nitric oxide donor is contraindicated in combination with vardenafil.
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PMID:Vardenafil: a selective inhibitor of phosphodiesterase-5 for the treatment of erectile dysfunction. 1747 42

Nitrates are potent venous dilators and anti-ischemic agents. They are widely used for the relief of chest pain and pulmonary congestion in patients with acute coronary syndromes and heart failure. Nitrates, however, do not reduce mortality in patients with acute coronary syndromes. Combination of nitrates and hydralazine when given in addition to beta-blockers and angiotensin-converting enzyme (ACE) inhibitors reduce mortality and heart failure hospitalizations in patients with heart failure due to left ventricular systolic dysfunction who are of African-American origin. Side effects during nitrate therapy are common but are less well described in the literature compared with the reported side effects in patients with stable angina pectoris. The reported incidence of side effects varies highly among different studies and among various disease states. Headache is the most commonly reported side effect with an incidence of 12% in acute heart failure, 41-73% in chronic heart failure, 3-19% in unstable angina and 2-26% in acute myocardial infarction. The reported incidence of hypotension also differs: 5-10% in acute heart failure, 20% in chronic heart failure, 9% in unstable angina and < 1-48% in acute myocardial infarction, with the incidence being much higher with concomitant nitrate therapy plus angiotensin-converting enzyme inhibitors. Reported incidence of dizziness is as low as 1% in patients with acute myocardial infarction to as high as 29% in patients with heart failure. Severe headaches and/or symptomatic hypotension may necessitate discontinuation of nitrate therapy. Severe life threatening hypotension or even death may occur when nitrates are used in patients with acute inferior myocardial infarction associated with right ventricular dysfunction or infarction, or with concomitant use of phosphodiesterase-5 inhibitors or N-acetylcysteine. Despite the disturbing observational reports in the literature that continuous and prolonged use of nitrates may lead to increased mortality and recurrent myocardial infarction in patients with stable coronary artery disease, no such adverse effects of nitrates have been reported in the large randomized trials in patients with acute myocardial infarction or chronic heart failure.
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PMID:Side effects of using nitrates to treat heart failure and the acute coronary syndromes, unstable angina and acute myocardial infarction. 1768 82

Sildenafil (Viagra) is a selective phosphodiesterase type 5 inhibitor (PDE5-I) approved for treatment of erectile dysfunction. Although relatively well-tolerated, sildenafil is associated with undesired effects including headache, flushing, dyspepsia, nasal congestion, and visual disturbances. In the present study we explored the impact of sildenafil on nasal airway parameters in young potent men. Eleven men (age 26.0 +/- 1.8 years) with normal BMI (25.7 +/- 0.5) and without nasal respiratory disorders were enrolled in a double-blind, crossover study. All men underwent evaluation of systolic (SBP) and diastolic blood pressure (DBP), heart rate (HR), SpO2%, acoustic rhinometry, and nasal endoscopy before and after placebo or sildenafil (50 mg) plus visual sexual stimulation (VSS). Nasal examination was performed using 0 degrees rigid telescopes, 4 mm in diameter. A Student's t test was used for direct comparisons, while the Kruskal-Wallis test (K-W) was utilized for multiple comparisons. After administration of sildenafil plus VSS, the minimum cross sectional area (MCA) was significantly lower that observed with either placebo (P = 0.03) or sildenafil alone (P = 0.003). However, the post-stimulation values did not demonstrate any significant differences among the different treatment arms (P = 0.48; DF = 2; K-W test). In contrast, endonasal volume (VOL) was significantly lower after sildenafil + VSS (P = 0.01), but not after placebo + VSS (P = 0.18). None of the other parameters monitored showed any significant variations. Rhinoscopy showed a characteristic increase of the volume of the inferior turbinates, with subjective differences between placebo and sildenafil. These preliminary results suggest that sildenafil reduces nasal volume, and that sexual stimulation may decrease nasal airflow by itself.
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PMID:Nasal congestion after visual sexual stimulation with and without sildenafil (Viagra): a randomized placebo-controlled study. 1790 71

Overactive bladder (OAB) is a syndrome characterized by urinary urgency, with or without urgency urinary incontinence, usually with frequency and nocturia. OAB symptoms are often associated with detrusor overactivity (DO). Like OAB symptoms, the prevalence of DO increases with age and can have a neurogenic and/or myogenic aetiology. Bladder outlet obstruction can be a contributing factor in DO, possibly through cholinergic denervation of the detrusor and supersensitivity of muscarinic receptors to acetylcholine, although the prevalence of OAB is similar in men and women across age groups. Acetylcholine is the primary contractile neurotransmitter in the human detrusor, and antimuscarinics exert their effects on OAB/DO by inhibiting the binding of acetylcholine at muscarinic receptors M(2) and M(3) on detrusor smooth muscle cells and other structures within the bladder wall. Worldwide, there are six antimuscarinic drugs currently marketed for the treatment of OAB: oxybutynin, tolterodine, propiverine, trospium, darifenacin, and solifenacin. Each has demonstrated efficacy for the treatment of OAB symptoms, but their pharmacokinetic and adverse event profiles differ somewhat due to structural differences (tertiary vs quaternary amines), muscarinic receptor subtype selectivities, and organ selectivities. Antimuscarinics are generally well tolerated, even in special populations (e.g. men with bladder outlet obstruction, elderly patients, children). The most frequently reported adverse events in clinical studies of antimuscarinics are dry mouth, constipation, headache, and blurred vision; few patients withdraw from clinical trials because of adverse events. Development of an antimuscarinic with functional selectivity for the bladder would reduce the occurrence of antimuscarinic adverse events. The therapeutic potential of several other agents, such as alpha(3)-adrenoceptor agonists, purinergic receptor antagonists, phosphodiesterase inhibitors, neurokinin-1 receptor antagonists, opioids, and Rho-kinase inhibitors, is also under investigation for the treatment of OAB.
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PMID:Muscarinic receptor antagonists for overactive bladder. 1792 84

Erectile dysfunction is a common multifactorial complication of diabetes mellitus. In recent years, phosphodiesterase type 5 (PDE-5) inhibitors have been introduced in the management of erectile dysfunction. A recent Cochrane systematic review assessed the effects ofPDE-5 inhibitors in patients with diabetes mellitus and erectile dysfunction from 8 randomized placebo-controlled trials (a total of 1759 participants). The duration of therapy was mainly 12 weeks. The weighted mean difference (WMD) for the International Index of Erectile Function (erectile dysfunction domain) at the end of the study period was 6.6 in favour of the PDE-5 inhibitors arm. The relative risk for answering 'yes' to a global efficacy question ('did the treatment improve your erections?') was 3.8 in the PDE-5 inhibitors arm compared with the control arm. Headache and flushing were the most common adverse events, followed by flu-like symptoms, dyspepsia, myalgia, vision disorders and lower back pain. The overall risk ratio for developing any adverse reaction was 4.8 in the PDE-5 inhibitors arm as compared to the control arm. It was concluded that sufficient evidence exists that treatment with PDE-5 inhibitors can improve erectile dysfunction in diabetic men.
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PMID:[From the Cochrane Library: Phosphodiesterase inhibitors are effective in treating erectile dysfunction in diabetic men]. 1794 26

Prevalence and severity of erectile dysfunction (ED) increase with aging and are often associated with illnesses, like diabetes mellitus, heart disease, and hypertension, pathologically characterized by endothelial dysfunction and whose prevalence increases with age. The assumption that ED is mainly a neurovascular disease is supported by the evidence that specific phosphodiesterase type 5 (PDE5) inhibition produces an efficient erection in a wide range of ages and conditions. The availability of specific PDE5 inhibitors has enabled the development of effective treatment strategies, in this contest, tadalafil may be considered as the least "typical" PDE5 inhibitor. In clinical trials, tadalafil significantly enhanced, in patients of different ages, all efficacy outcomes across disease etiologies and severities. With an effectiveness lasting up to 36h, tadalafil allows patients to choose when to have sexual activities without the need to time it, showing positive feedback in terms of quality of life related to the treatment. Headache and dyspepsia were the most frequent side-effects of tadalafil, followed by back pain, nasal congestion, myalgia, and flushing, but the impact that long time action could have on effectiveness and safety is not yet entirely defined. The aim of this article is to critically review the available evidence from the tadalafil clinical research program and give the physician a rational approach for intervention in the treatment of ED and related diseases.
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PMID:Tadalafil in the treatment of erectile dysfunction; an overview of the clinical evidence. 1804 21


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