Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.4.1 (phosphodiesterase)
18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In recent years, the better understanding of the pathobiology and pathogenesis of pulmonary arterial hypertension (PAH) has led to the development of new drugs for its treatment. Epoprostenol, which was the first drug approved for PAH, has shown an improvement in the survival at 3 years in patients with primary pulmonary hypertension. Recently, the Food and Drug Administration has approved two new compounds, Bosentan (an oral, non-selective endothelin receptor blocker) and Treprostinil (a subcutaneous prostacyclin analog). At least three multicenter, international studies are currently in progress. These studies include the use of a diet supplement rich in arginine (nitric oxide precursor), the evaluation of an endothelin A-receptor blocker (Sitaxsentan), and the evaluation of Sildenafil (a 5-phosphodiesterase inhibitor). As long as research continues to scrutinize the pathogenesis of this disease, clues to possible new therapies are warranted.
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PMID:[What is new in the treatment of pulmonary artery hypertension?]. 1296 61

New drugs for pulmonary arterial hypertension have shown efficacy in randomized controlled trials. Endothelin receptor antagonists (ERA) and prostanoids are most important for clinical practice. Bosentan represents the first approved orally active therapy for PAH. Besides its hepatotoxicity it is mostly well tolerated. The first approved prostanoid, epoprostenol, is currently first choice only for decompensated right heart failure in PAH. It has to be delivered continuously intravenously and is prone to complications, side effects and very high costs. Alternatively, subcutaneous treprostinil can be applied. It is less risky and expensive but may cause local pain at the infusion site. Inhaled iloprost combines the features of a prostanoid with pulmonary and intrapulmonary selectivity. Alternatively, iloprost is being used as continuous intravenous infusion. The phosphodiesterase-5 inhibitor sildenafil was effective in two randomized controlled trials but has not been approved for PAH therapy.
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PMID:[Therapy of pulmonary arterial hypertension]. 1570 89

Pulmonary arterial hypertension (PAH) is characterized by vasoconstriction, in situ thrombosis, and vascular remodeling of small pulmonary arteries. It induces a fixed pulmonary arterial obstruction, persistent elevation of pulmonary arterial resistance, and eventually right heart failure. Conventional therapy is based on simple measures (exercise limitation) and nonspecific treatments (warfarin, diuretics, and oxygen). Pure vasodilators, such as calcium channel blockers, are effective only in a minority of patients who have an acute response to vasodilator testing. Intravenous prostacyclin (epoprostenol) and endothelin receptor blockers have vasodilator and antiproliferative properties. Epoprostenol therapy has significantly improved PAH prognosis and remains the first-line treatment for patients with the most severe disease. Bosentan is an interesting first-line treatment for NYHA functional class III patients. Availability of novel specific drugs (endothelin receptor type A antagonists, prostacyclin analogues, type 5 phosphodiesterase inhibitors) is opening new perspectives in PAH treatment. The long-term benefit of these drugs remains to be evaluated and their respective place in treatment of these patients is still uncertain. The evolution of therapy from vasodilators to antiproliferative agents reflects the advancement in our understanding of the mechanisms mediating pulmonary arterial hypertension.
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PMID:[Treatment of pulmonary arterial hypertension]. 1630 76

The dual endothelin receptor antagonist, bosentan, and the phosphodiesterase inhibitor, sildenafil, are efficacious in experimental and clinical pulmonary hypertension (PHT). The effects of bosentan, sildenafil, and their combination were evaluated in rats with monocrotaline (MCT)-induced PHT. A first group consisted of control rats with no MCT injection. Four other groups of rats received MCT subcutaneously and were assigned to receive no treatment, 300 mg/kg/day bosentan as food admix, 100 mg/kg/day sildenafil in drinking water, or their combination for 4 weeks. The doses of bosentan and sildenafil were the maximally effective doses based on a dose-range-finding study. Mortality was 0%, 53%, 11%, 11%, and 0%, respectively, in the five different groups. Bosentan and sildenafil significantly attenuated the increase in mean pulmonary arterial pressure, and the combination had an additional effect. Similarly, bosentan, sildenafil, and, to a greater extent, their combination significantly reduced right ventricular (RV) hypertrophy. Bosentan, but not sildenafil, decreased norepinephrine and BNP plasma concentrations, reduced kidney weight, and normalized systemic hemodynamics. In conclusion, bosentan and sildenafil are efficacious in rats with chronic PHT, and their combination shows an additional effect for decreasing pulmonary arterial pressure, reducing plasma catecholamines, maintaining body weight, and reducing mortality.
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PMID:Bosentan, sildenafil, and their combination in the monocrotaline model of pulmonary hypertension in rats. 1674 Oct 32

Pulmonary arterial hypertension (PAH) is a severe vasculopathy, which is characterised by progressive narrowing and obliteration of the pulmonary arterioles and increased endothelin-1 levels. The increase of vascular resistance in the lung vessels leads to chronic pressure overload and to right heart failure, if untreated. PAH often occurs in association with rheumatic-inflammatory diseases (e.g., in 15% of patients with systemic sclerosis (SSc), especially in the limited form or in CREST patients) and determines their prognosis: in advanced stages, untreated patients die within a short period. Therefore all SSc patients, particularly the newly diagnosed ones, should be screened for PAH with echocardiography. If PAH is suspected, a right heart catheter should be performed, and if PAH is confirmed, adequate treatment should be initiated. While few years ago lung transplantation was the only option for patients with severe PAH, in recent years enormous progress was seen in drug treatment. Today prostanoids (Ventavis) and the endothelin receptor antagonist bosentan (Tracleer) are available for patients with PAH in WHO/NYHA stage III: they have substantially improved the prognosis of PAH in the last years. Since few months, also the phosphodiesterase inhibitor sildenafil (Revatio) is available. The combination of drugs with different mode of action will likely further improve the prognosis of PAH patients.
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PMID:[Pulmonary arterial hypertension in collagenoses: clinical features, epidemiology, pathogenesis, diagnosis and treatment]. 1680 98

Pulmonary arterial hypertension (PAH) is a serious complication of systemic sclerosis (SSc) and a leading cause of death in patients with it. Recent publications suggest that a prevalence of 10-15% is likely. The prognosis remains poor compared to that of idiopathic PAH. WHO recommends annual echocardiography for PAH screening of patients with SSc. Right heart catheterization is necessary to confirm the diagnosis. Nevertheless, more than half of all SSc patients have symptoms classified as WHO functional class III or IV at diagnosis. Prostacyclin therapy, delivered via continuous intravenous infusion (epoprostenol), has been demonstrated to be effective in patients with severe PAH (both idiopathic and scleroderma-related). Prostacyclin analogs (such as treprostinil and iloprost) are other options. Bosentan is the first endothelin receptor antagonist approved in the EU for the treatment of PAH, both idiopathic and related to connective tissue diseases such as scleroderma, in patients in WHO functional class III. Sildenafil by its selective inhibition of phosphodiesterase type 5 is also effective against both types of PAH. It too is now approved in the EU for this purpose in patients in WHO functional class III, but we do not yet have any information about its long-term effects in scleroderma.
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PMID:[Pulmonary arterial hypertension and systemic sclerosis]. 1715 19

Acral manifestations of systemic sclerosis include Raynaud's phenomenon, calcinosis cutis, and sclerodactyly. In the later stages of the disease, contractures of the skin and joints as well as obliterative vasculopathy leading to digital ulcers and necrotic lesions may occur. Patients with acral manifestations of systemic sclerosis are ideally treated by a team that includes a rheumatologist, dermatologist, hand surgeon, physiotherapist, and, eventually, a psychologist. Calcium channel antagonists, alpha(1)-adrenergic blockade with prazosin, and prostacyclin analogs were proven to be effective in the treatment of scleroderma-related Raynaud's phenomenon. Losartan, an angiotensin II receptor inhibitor, and fluoxetine, a selective serotonin reuptake inhibitor, have been beneficial for systemic sclerosis-associated Raynaud's phenomenon in pilot studies. Parenteral prostacyclin analogs, e. g., iloprost, can be recommended as first-line treatment of ischemic digital ulcers. When prostacyclin analogs fail, the phosphodiesterase type 5 inhibitor sildenafil can be tried to improve ulcer healing. Bosentan, an endothelin receptor antagonist, may prevent new digital ulcers. At present, there are no medical agents agreed to be generally effective in the reduction of calcinotic deposits or cutaneous fibrosis, although some drugs have been identified as potentially beneficial. Surgical treatment of acral manifestations consists of excision or curettage of symptomatic calcific deposits, digital sympathectomy, arterial reconstruction, and amputation in rare cases. Flexion contractures of the proximal interphalangeal joints, with secondary hyperextension of the metacarpophalangeal joints, can be treated by arthrodesis of the proximal interphalangeal joints and resection arthroplasty or prostheses at the metacarpophalangeal joints to improve hand function.
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PMID:[Therapeutic management of acral manifestations of systemic sclerosis]. 1734 17

The elimination process of the endothelin receptor antagonist bosentan (Tracleer) in humans is entirely dependent on metabolism mediated by two cytochrome P450 (P450) enzymes, i.e., CYP3A4 and CYP2C9. Most interactions with concomitantly administered drugs can be rationalized in terms of inhibition of these P450 enzymes. The increased bosentan concentrations observed in the presence of cyclosporin A, rifampicin, or sildenafil, however, are incompatible with this paradigm and prompted the search for alternative mechanisms governing these interactions. In the present article, we identify bosentan and its active plasma metabolite, Ro 48-5033 (4-(2-hydroxy-1,1-dimethyl-ethyl)-N-[6-(2-hydroxy-ethoxy)-5-(2-methoxy-phenoxy)-[2,2']bipyrimidinyl-4-yl]-benzenesulfonamide), as substrates of the human organic anion transporting polypeptides (OATP) OATP1B1 and OATP1B3. Bosentan uptake into Chinese hamster ovary cells expressing these OATP transporters was efficiently inhibited by cyclosporin A and rifampicin with IC(50) values significantly below their effective plasma concentrations in humans. The phosphodiesterase-5 inhibitor sildenafil was also shown to interfere with OATP-mediated transport, however, at concentrations above those achieved in therapeutic use. Therefore, inhibition of bosentan hepatic uptake may represent an alternative/complementary mechanism to rationalize some of the pharmacokinetic interactions seen in therapeutic use. A similar picture has been drawn for drugs like pitavastatin and fexofenadine, drugs that are mainly excreted in unchanged form. Bosentan elimination, in contrast, is entirely dependent on metabolism. Therefore, the described interactions with rifampicin, cyclosporin A, and, to a lesser extent, sildenafil represent evidence that inhibition of hepatic uptake may become the rate-limiting step in the overall elimination process even for drugs whose elimination is entirely dependent on metabolism.
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PMID:Bosentan is a substrate of human OATP1B1 and OATP1B3: inhibition of hepatic uptake as the common mechanism of its interactions with cyclosporin A, rifampicin, and sildenafil. 1749 8

Hepatopulmonary syndrome (HPS) is found in 4-47% of patients with cirrhosis and is characterized by intrapulmonary vascular dilatations especially in the basal parts of the lung. Liver injury and/or portal hypertension trigger the release of endothelin-l, TNF-alpha, cytokines and mediate vascular shear stress and release of nitric oxide and carbon monoxide, all contributing to intrapulmonary vasodilation. Severe HPS increases mortality (30%) after liver transplantation, especially if Pa O2 is below 50 mmHg. The diagnosis is made by calculating the alveolar-arterial oxygen gradient and by performing a contrast echocardiography. Medical therapy fails and the only long-term treatment available is liver transplantation. More than 85% experience significant improvement or complete resolution in hypoxaemia, but this may take more than 1 year. Portopulmonary hypertension (PPHT) occurs in 2-8% of the patients with cirrhosis. Imbalance between vasodilating (decreased pulmonary expression of eNOS and prostacyclin I2) and vasoconstrictive agents (increased expression of ET-1 and angiotensin 1) may be responsible for misguided angiogenesis and pulmonary hypertension. The diagnosis is made by performing an echocardiography and a right heart catheterisation when systolic pulmonary artery pressure is higher than 30 mmHg on echocardiography. Although prostacyclin analogues are efficacious, adverse effects in terms of safety, tolerability and drug delivery occur. Bosentan is probably the therapy of choice for patients with PPHT because it decreases pulmonary but can also diminish portal hypertension. Sildenafil, a phosphodiesterase-5 inhibitor is used for idiopathic pulmonary hypertension, however, it should be used cautiously in patients with portal hypertension as it may increase portal hypertension by splanchnic vasodilation.
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PMID:Hepatopulmonary syndrome and portopulmonary hypertension: what's new? 1771 35

Pulmonary arterial hypertension (PAH) is an important cause of death in systemic sclerosis (SSc), despite the improvement of therapies. An early diagnosis and the use of drugs interfering with the main pathogenic pathways of PAH is pivotal for the improvement of prognosis in primary PAH and PAH secondary to autoimmune rheumatic diseases, mainly SSc. Lately, new specific therapies have been developed targeting prostacyclin, endothelin, and nitric oxide pathways, the major pathogenic pathways leading to endothelial dysfunction in PAH. Epoprostenol improved life expectancy of patients with primary and secondary PAH, but its continuous intravenous administration requires experienced centers. More stable analogues of prostacyclin, administrated by intravenous (iloprost, treprostinil), subcutaneous, inhalatory (treprostinil, iloprost), and oral route (Beraprost) have shown efficacy in PAH. Bosentan, the first oral endothelin receptor antagonist (with affinity for endothelin A and B receptors) improves exercise function and survival in PAH, both primary and secondary to autoimmune rheumatic diseases. This is confirmed also for Sitaxsentan and Ambrisentan, selective A receptor antagonists. Because of its short half-life and systemic side effects, short-term NO inhalation is used only in short-term management of PAH in critically ill adults. Inhibitors of NO degradation, such as sildenafil, a phosphodiesterase (PDE) type 5 inhibitor, improved functional and hemodynamic parameters without significant side effects. Vardenafil and taladafil, longer-acting PDE inhibitors, also have vascular pulmonary selectivity. All these drugs may be used in combination, to maximize their clinical benefit not only in patients unresponsive to single drugs, but also potentially as initial therapy of PAH.
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PMID:Therapeutic challenges for systemic sclerosis: facts and future targets. 1791 60


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