Our library of drug research abstracts drawn from the medical literature is updated on a regular schedule, and you can be assured that new imdur research articles will be listed here shortly after becoming available to us.
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Medical research on imdur
J Headache Pain. 2008 Jun 3;
Christiansen I, Iversen HK, Olesen J, Tfelt-Hansen P
Long-term exposure to organic nitrates influences different sections of the vascular bed heterogeneously. Continuous dosage of nitrates leads to the development of tolerance both to the vascular effects and to the unwanted adverse effect, headache. Human data on the development of tolerance in different cranial arteries over more than 24 h are lacking. We compared the vascular changes of the middle cerebral, superficial temporal and radial arteries during oral administration of isosorbide-5-mononitrate (5-ISMN) 30 mg three times daily for 7 days in 11 healthy subjects in a double-blind, randomised, placebo controlled cross-over design. Blood velocity in the middle cerebral artery was measured with transcranial Doppler and the diameters of the temporal and radial arteries were measured with high frequency ultrasound. Headache recordings were compared to the observed vascular changes over time. Tolerance was complete within 24 h in the middle cerebral artery whilst in the superficial temporal and the radial arteries, tolerance was only partial and developed much more slowly, i.e. after 7 days correlating with the disappearance of NO-induced headache. The present study thus demonstrated the important differences in the time profiles of appearance of nitrate tolerance in arteries of different vascular beds in man. If vasodilatation is the cause of NO-induced headache the results point to extracerebral arteries as the locus of nociception. Due to a variety of other possible pain-inducing effects of nitric oxide our results do not exclude cerebral arteries.
Aliment Pharmacol Ther. 2008 May 2;
Garcia-Pagan JC, De Gottardi A, Bosch J
Background. Variceal bleeding is a life threatening complication of liver cirrhosis with a high probability of recurrence. Treatment to prevent first bleeding or rebleeding is mandatory. Aim. To provide an overview of the current knowledge on the best evidence-based therapeutic options to prevent first or recurrent bleeding from esophageal varices in patients with cirrhosis. Methods For the preparation of this narrative review, we sought to analyze RCTs that examined the efficacy and side effects of pharmacological or endoscopic therapy for the primary and secondary prophylaxis of esophageal variceal bleeding. Results Endoscopic band ligation (EBL) and non-selective beta-blockers are both effective in preventing first bleeding. Until more long-term data is available, non-selective beta-blockers should be the first treatment option due to less severe side effects. EBL is an alternative when beta-blockers are contraindicated or not tolerated. Patient preference may also be considered. For prevention of rebleeding, non-selective beta-blockers (preferably in association with isosorbide-5-mononitrate) or EBL are both effective and good alternative treatments. A combination of both treatments may be the best alternative. Conclusions A great improvement in the prevention of variceal bleeding has emerged over the last years. However, further therapeutic options that combine higher efficacy, better tolerance and fewer side effects are needed.
Drug Dev Ind Pharm. 2008 Apr; 34(4): 363-72
Xie H, Gan Y, Ma S, Gan L, Chen Q
The aim of this work was to optimize time-dependent tablets using artificial neural network (ANN). The time-dependent tablet consisted of a tablet core, which contained sustained release pellets (70% isosorbide-5-mononitrate [5-ISMN]), immediate release granules (30% 5-ISMN), superdisintegrating agent (sodium carboxymethylstarch, CMS-Na), and other excipients, surrounded by a coating layer composed of a water-insoluble ethylcellulose and a water-soluble channeling agent. The chosen independent variables, i.e., X(1) coating level of tablets, X(2) coating level of pellets, and X(3) CMS-Na level, were optimized with a three-factor, three-level Box-Behnken design. Data were analyzed for modeling and optimizing the release profile using ANN. Response surface plots were used to relate the dependent and the independent variables. The optimized values for the factors X(1)-X(3) were 4.1, 14.1, and 29.8%, respectively. Optimized formulations were prepared according to the factor combinations dictated by ANN. In each case, the observed drug release data of the optimized formulations were close to the predicted release pattern. An in vitro model for predicting the effect of food on release behavior of optimized products was used in this study. It was concluded that neural network technique could be particularly suitable in the pharmaceutical technology of time-dependent dosage forms where systems were complex and nonlinear relationships often existed between the independent and the dependent variables.
Prevention of recurrent variceal bleeding.
Dig Liver Dis. 2008 May; 40(5): 337-42
Berzigotti A, García-Pagán JC
Patients surviving a first episode of variceal bleeding have a risk of over 60% of experiencing recurrent haemorrhages within 1 year from the index episode. Because of this, all patients surviving a variceal bleeding should receive active treatments for the prevention of rebleeding. beta-Blockers+/-isosorbide-5-mononitrate and band ligation are effective in preventing recurrent bleeding and both can be used. Combination of beta-blockers+/-isosorbide-5-mononitrate and band ligation may be the best treatment to prevent rebleeding but more studies are needed to confirm this issue. In patients with recurrent variceal bleeding despite appropriate medical and endoscopic treatment, transjugular intrahepatic porto-systemic shunt is highly effective in controlling bleeding. The efficacy is not significantly different from that of shunt surgery (distal splenorenal shunt or 8mm H-graft shunt), especially since the introduction of polytetrafluoroethylene-covered stents. Therefore, in this situation, transjugular intrahepatic porto-systemic shunt using polytetrafluoroethylene stents should be the treatment of choice.
Research and clinical value of antibacterial-application software.
Chin Med J (Engl). 2008 Jan 5; 121(1): 86-9
Liang YJ, Zhai XB, He LX, Guo ZL, Ren T, He ZG, Zhang L, Zheng YH
Prevention of recurrent esophageal variceal hemorrhage: review and current recommendations.
J Clin Gastroenterol. 2007 Nov-Dec; 41(10 Suppl 3): S318-22
Kravetz D
Variceal rebleeding is a very frequent and severe complication in cirrhotic patients; therefore, its prevention should be mandatory. Lately several studies demonstrated that the rate of rebleeding was decreased by 40% and overall survival is improved by 20% with beta-blockers. However, this treatment presents some problems, such as the number of nonresponders and contraindications for its use. Recent trials found that the combination of beta-blockers with mononitrate of isosorbide to be superior to beta-blockade alone. Furthermore, endoscopic band ligation also shown to decrease the frequency of rebleeding, complications, and death compared with sclerotherapy and should be the preferred endoscopic treatment. In addition, the comparison between combined pharmacologic treatment with endoscopic treatment present similar rebleeding and mortality rates. More recently, the addition of nadolol to endoscopic band ligation increased the efficacy of endoscopy alone in the prevention of variceal rebleeding. These studies suggest that banding plus drugs could be the treatment of choice for the prophylaxis of rebleeding. When these treatments fail, the recommendation is to use transjugular intrahepatic portosystemic shunt (TIPS) or surgical shunts. Both treatments are effective in preventing rebleeding; however, they are associated with a greater risk of encephalopathy. The comparison of portacaval shunts with TIPS demonstrated that TIPS patients presented higher rebleeding, treatment failure, and transplantation. Another randomized controlled trial comparing distal splenorenal shunt with TIPS shows that variceal rebleeding was similar in both groups without differences in encephalopathy and mortality. The only difference observed was the higher rate of reintervention observed in the TIPS group to maintain his patency.
Assessment of acute pulmonary vascular reactivity in portopulmonary hypertension.
Liver Transpl. 2007 Nov; 13(11): 1506-14
Ricci GL, Melgosa MT, Burgos F, Valera JL, Pizarro S, Roca J, Rodriguez-Roisin R, Barberà JA
The role of acute pulmonary vasodilator testing in portopulmonary hypertension (PoPH), a current contraindication for orthotopic liver transplantation (OLT), has not been thoroughly elucidated. The purpose of this work was to analyze the results of acute vasodilator testing with inhaled nitric oxide (NO), to compare them with intravenous epoprostenol (PGI(2)), and to investigate the acute effects of the oral vasodilator isosorbide-5-mononitrate (Is-5-MN), in patients with PoPH. A total of 19 patients with PoPH (male/female = 9/10) were studied. Pulmonary hemodynamic measurements were performed at baseline and during NO inhalation (40 ppm); additionally, 15 patients were tested with PGI(2) (2-12 mug/kg/minute) and 8 were tested with Is-5-MN (20-40 mg). Inhaled NO reduced pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR) by 5.7% and 11.0%, respectively. PGI(2) elicited greater reductions in PAP (11.8%) and PVR (-24.0%), and produced a 28% drop in systemic vascular resistance (SVR) and a 17% increase in the cardiac index (CI). Is-5-MN reduced PAP by 25.6% and PVR by 21.5%, without systemic changes. There was good agreement between the response to PGI(2) and Is-5-MN: 6 patients of the whole series (32%) decreased PAP >20% from baseline, reaching a final value < or = 35 mmHg, the current limit for OLT. In conclusion, acute vasodilator testing has a relevant role in PoPH, as it identifies one-third of patients able to reach a more favorable hemodynamic situation, which can be determinant for their management. For vasodilator testing, PGI(2) is more suitable than NO in PoPH. Is-5-MN exerts a selective effect on pulmonary circulation in patients who had already responded to PGI(2).
Transplant Proc. 2007 Oct; 39(8): 2501-6
Reis F, Teixeira de Lemos E, Almeida L, Parada B, Garrido AP, Rocha-Pereira P, Santos-Silva A, Santos-Dias J, Dinis A, Figueiredo A, Costa-Almeida C, Mota A, Teixeira F
The present study sought to evaluate the prevention and reversion effects of isosorbide-5-mononitrate (Is-5-Mn) on the development of hypertension (HT) and on the underlying vascular and platelet morphofunctional disturbances, using an animal model of cyclosporine (CsA)-induced HT. The following rat groups (n = 8) were tested: (1) a control group (orange juice, for 7 weeks); (2) the CsA group (5 mg/kg/d for 7 weeks); (3) the Is-5-Mn group (150 mg/kg/d, twice a day for 7 weeks); (4) the prevention group (Is-5-Mn + CsA) treated for 2 weeks with Is-5-Mn only and thereafter with both drugs for 7 weeks; (5) the curative group (CsA + Is-5-Mn) beginning 7 weeks after CsA and following thereafter with both drugs for 5 weeks. Blood pressure, lipid profile, vascular lesion, platelet aggregation and morphology, and platelet thromboxane A(2)/vascular prostacyclin equilibrium were evaluated. Is-5-Mn + CsA therapy prevented (systolic blood pressure [SBP]: 114.3 +/- 1.9 mm Hg, P < .001; diastolic blood pressure [DBP]: 97.0 +/- 3.3 mm Hg, P < .001) the CsA-induced HT (SBP: 146.2 +/- 4.5 mm Hg, P < .001; DBP: 124.9 +/- 4.5 mm Hg, P < .001 vs control: SBP: 111.6 +/- 0.7 mm Hg; DBP: 94.6 +/- 1.0 mm Hg), as well as the vascular lesion and the platelet morphofunctional disturbances. The curative group did not show attenuated CsA-induced BP increase; it showed further enhancement of the HT effect (SBP: 159.7 +/- 5.5 mm Hg, P < .05; DBP: 132.8 +/- 2.8 mm Hg), as well as worsened vascular lesions and platelet function, namely a disruption in the TXA(2)/PGI(2) equilibrium. Our data suggested that Is-5-Mn therapy may be a valid choice to prevent the morphofunctional changes associated with CsA-induced HT, when used as a preventive therapy. A careful evaluation of the impact of nitrate therapy should be considered, particularly the negative effect on cardiovascular hemodynamics, when considering its use after previous CsA disturbances have been established.
Transplant Proc. 2007 Oct; 39(8): 2494-500
Reis F, Rocha-Pereira P, Teixeira de Lemos E, Parada B, Baptista S, Figueiredo A, Santos-Silva A, Costa-Almeida C, Mota A, Teixeira F
The aim of this study was to evaluate the effect of cyclosporine (CsA) on oxidative stress as well as the use of a nitric oxide (NO) donor, the organic nitrate isosorbide-5-mononitrate (Is-5-Mn), to prevent or reverse CsA-induced toxicity, namely on the vascular NO-cGMP pathway or on oxidative equilibrium. The following rat groups (n = 8) were tested: (1) a control group; (2) the CsA group (5 mg/kg/d for 7 weeks); (3) the Is-5-Mn group (150 mg/kg/d, twice a day for 7 weeks); (4) the preventive group (Is-5-Mn + CsA) treated for 2 weeks with Is-5-Mn only, and thereafter with both drugs for 7 weeks; (5) the curative group (CsA + Is-5-Mn) beginning 7 weeks after CsA, and following thereafter with both drugs for 5 weeks. The following parameters were evaluated: aortic cNOS activity and cGMP content; plasma levels of lipid peroxidation (malondialdehyde [MDA] levels); antioxidant capacity (glutathione peroxidase [GPx] and superoxide dismutase [SOD] activities, total antioxidant status, and vitamins A, C, and E); and peroxynitrite formation (3-nitrotyrosine [3-NT] content). Is-5-Mn + CsA therapy showed, when compared with the CsA group, total prevention of CsA-induced NO and cGMP attenuation, and no relevant influence on antioxidant indices, as well as on MDA and 3-NT levels. However, when compared with this CsA group, the curative group (CsA + Is-5-Mn) showed NO-cGMP values only partially reversed, and an enhancement in lipid peroxidation (5.6 +/- 1.4 vs 12.78 +/- 3.63 mumol/L; P < .05) and in peroxynitrite formation (16.7% incidence of positives vs 83.3% incidence of positives). Our data suggested that nitrate therapy may provide a valid choice to prevent CsA-induced NO-cGMP decrease, without a negative influence on the oxidative equilibrium. However, when the local environment is adverse, as occurs after CsA therapy, Is-5-Mn seemed to enhance the CsA-induced oxidative stress, promoting even worse deleterious effects, probably through the generation of the cytotoxic ROS peroxynitrite.
Yao Xue Xue Bao. 2007 Aug; 42(8): 833-7
Si WX, Lu HG, Ren LM
The aim of this study is to investigate the effect of isosorbide-5-mononitrate (ISMN) on the electric field stimulation induced sympathetic purinergic vasoconstriction of the rabbit saphenous arterial rings. Isometric vasoconstrictive responses to electric field stimulation and to exogenous noradrenaline and adenosine triphosphate were recorded. We found that the vasoconstrictive responses to electric field stimulation (15 V, 1 ms pulse duration, 2 - 16 Hz) were frequency-dependant in the rabbit saphenous arterial rings, and abolished by tetrodotoxin (0.1 micromol x L(-1)). The alpha1-adrenoceptor antagonist prazosin (1 micromol x L(-1)) did not affect the vascular responses to the electric field stimulation (2 -8 Hz). After a combination treatment with both alpha,beta-meATP (3 micromol x L(-1), desensitizing P2X1 receptors) and prazosin (1 micromol x L(-1)), the vasoconstrictive responses to electric field stimulation were abolished. When the arterial preparation was treated with ISMN (one preparation was exposed to only one concentration of ISMN), ISMN at 0.1 mmol x L(-1) significantly inhibited the vasoconstriction induced by electric stimulation at 8 Hz, 0.3 and 1.0 mmol x L(-1) significantly inhibited the vasoconstrictive responses to electric stimulation at 2 - 16 Hz. The highest concentration of ISMN (1.0 mmol x L(-1)) reduced the vasoconstrictive responses by 46% (2 Hz), 47% (4 Hz), 34% (8 Hz) and 22% (16 Hz), separately. ISMN (0.3 and 1.0 mmol x L(-1)) did not affect the vascular responses to exogenous noradrenaline (0.01-100 micromol x L(-1)) and adenosine triphosphate (1 mmol x L(-1)). It is reasonable to suggest that ISMN inhibits the purinergic vasoconstriction induced by sympathetic nerve stimulation via a prejunctional mechanism.