Clinical pharmacokinetics of molsidomine

Overview of the effects and mechanisms of NO and its donors on biofilms

Microbial biofilm is undoubtedly a challenging problem in the food industry. It is closely associated with human health and life, being difficult to remove and antibiotic resistance. Therefore, an alternate method to solve these problems is needed. Nitric oxide (NO) as an antimicrobial agent, has shown great potential to disrupt biofilms. However, the extremely short half-life of NO in vivo (2 s) has facilitated the development of relatively more stable NO donors. Recent studies reported that NO could permeate biofilms, causing damage to cellular biomacromolecules, inducing biofilm dispersion by quorum sensing (QS) pathway and reducing intracellular bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) levels, and significantly improving the bactericidal effect without drug resistance. In this review, biofilm hazards and formation processes are presented, and the characteristics and inhibitory effects of NO donors are carefully discussed, with an emphasis on the possible mechanisms of NO resistance to biofilms and some advanced approaches concerning the remediation of NO donor deficiencies. Moreover, the future perspectives, challenges, and limitations of NO donors were summarized comprehensively. On the whole, this review aims to provide the application prospects of NO and its donors in the food industry and to make reliable choices based on these available research results.

Quantitative Translation of Substrate Intrinsic Clearance from Recombinant CYP1A1 to Humans

CYP1A1 is a cytochrome P450 family 1 enzyme that is mostly expressed in the extrahepatic tissues. To understand the CYP1A1 contribution to drug clearance in humans, we examined the in vitro-in vivo extrapolation (IVIVE) of intrinsic clearance (CLint) for a set of drugs that are in vitro CYP1A1 substrates. Despite being strong in vitro CYP1A1 substrates, 82% of drugs gave good IVIVE with predicted CLint within 2-3-fold of the observed values using human liver microsomes and hepatocytes, suggesting they were not in vivo CYP1A1 substrates due to the lack of extrahepatic contribution to CLint. Only three drugs (riluzole, melatonin and ramelteon) that are CYP1A2 substrates yielded significant underprediction of in vivo CLint up to 11-fold. The fold of CLint underprediction was linearly proportional to human recombinant CYP1A1 (rCYP1A1) CLint, indicating they were likely to be in vivo CYP1A1 substrates. Using these three substrates, a calibration curve can be developed to enable direct translation from in vitro rCYP1A1 CLint to in vivo extrahepatic contributions in humans. In vivo CYP1A1 substrates are planar and small, which is consistent with the structure of the active site. This is in contrast to the in vitro substrates, which include large and nonplanar molecules, suggesting rCYP1A1 is more accessible than what is in vivo. The impact of CYP1A1 on first-pass intestinal metabolism was also evaluated and shown to be minimal. This is the first study providing new insights on in vivo translation of CYP1A1 contributions to human clearance using in vitro rCYP1A1 data.

Pharmacotherapy in patients with vasomotor disorders

Background

Anginal symptoms in patients with non-obstructive coronary artery disease are frequently related to vasomotor disorders of the coronary circulation. Although frequently overlooked, a distinct diagnosis of different vasomotor disorders can be made by intracoronary function testing. Early detection and treatment seems beneficial, but little evidence is available for the medical treatment of these disorders. Nevertheless, there are several pharmacotherapeutic options available to treat these patients and improve quality of life.

Methods & findings

We performed an extensive yet non-systematic literature search to explore available pharmacotherapeutic strategies for addressing vasomotor disorders in individuals experiencing angina and non-obstructive coronary artery disease. This article presents a comprehensive overview of therapeutic possibilities for patients exhibiting abnormal vasoconstriction (such as spasm) and abnormal vasodilation (like coronary microvascular dysfunction).

Conclusion

Treatment of vasomotor disorders can be very challenging, but a general treatment algorithm based on the existing evidence and the best available current practice is feasible.

The Nitric Oxide (NO) Donor Molsidomine Attenuates Memory Impairments Induced by the D1/D2 Dopaminergic Receptor Agonist Apomorphine in the Rat

Several lines of evidence suggest that scarcity of the gaseous molecule nitric oxide (NO) is associated with the pathogenesis of schizophrenia. Therefore, compounds, such as NO donors, that can normalize NO levels might be of utility for the treatment of this pathology. It has been previously shown that the NO donor molsidomine attenuated schizophrenia-like behavioral deficits caused by glutamate hypofunction in rats. The aim of the current study was to investigate the efficacy of molsidomine and that of the joint administration of this NO donor with sub-effective doses of the non-typical antipsychotics clozapine and risperidone to counteract memory deficits associated with dysregulation of the brain dopaminergic system in rats. Molsidomine (2 and 4 mg/kg) attenuated spatial recognition and emotional memory deficits induced by the mixed dopamine (DA) D1/D2 receptor agonist apomorphine (0.5 mg/kg). Further, the joint administration of sub-effective doses of molsidomine (1 mg/kg) with those of clozapine (0.1 mg/kg) or risperidone (0.03 mg/kg) counteracted non-spatial recognition memory impairments caused by apomorphine. The present findings propose that molsidomine is sensitive to DA dysregulation since it attenuates memory deficits induced by apomorphine. Further, the current findings reinforce the potential of molsidomine as a complementary molecule for the treatment of schizophrenia.

The Nitric Oxide (NO) Donor Molsidomine Counteract Social Withdrawal and Cognition Deficits Induced by Blockade of the NMDA Receptor in the Rat

The deficiency of the gaseous molecule nitric oxide (NO) seems to be critically involved in the pathogenesis of schizophrenia. Thus, molecules that can normalize NO levels, as are NO donors, might be of utility for the medication of this psychiatric disease. The aim of the present study was to detect the ability of the NO donor molsidomine to reduce schizophrenia-like impairments produced by the blockade of the N-methyl-D-aspartate (NMDA) receptor in rats. Molsidomine's ability to attenuate social withdrawal and spatial recognition memory deficits induced by the NMDA receptor antagonist ketamine were assessed using the social interaction and the object location test, respectively. Further, the efficacy of the combination of sub-effective doses of molsidomine with sub-effective doses of the atypical antipsychotic clozapine in alleviating non-spatial recognition memory deficits was evaluated utilizing the object recognition task. Molsidomine (2 and 4 mg/kg) attenuated social withdrawal and spatial recognition memory deficits induced by ketamine. Co-administration of inactive doses of molsidomine (1 mg/kg) and clozapine (0.1 mg/kg) counteracted delay-dependent and ketamine-induced non-spatial recognition memory deficits. The current findings suggest that molsidomine is sensitive to glutamate hypofunction since it attenuated behavioral impairments in animal models mimicking the negative symptoms and cognitive deficits of schizophrenia. Additionally, the present results support the potential of molsidomine as an adjunctive drug for the therapy of schizophrenia.

Impact of endothelial nitric oxide synthase activation on accelerated liver regeneration in a rat ALPPS model

BACKGROUND

Although the associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) induces more rapid liver regeneration than portal vein embolization, the mechanism remains unclear.

AIM

To assess the influence of inflammatory cytokines and endothelial nitric oxide synthase (eNOS) activation on liver regeneration in ALPPS.

METHODS

The future liver remnant/body weight (FLR/BW) ratio, hepatocyte proliferation, inflammatory cytokine expression, and activation of the Akt-eNOS pathway were evaluated in rat ALPPS and portal vein ligation (PVL) models. Hepatocyte proliferation was assessed based on Ki-67 expression, which was confirmed using immunohistochemistry. The serum concentrations of inflammatory cytokines were measured using enzyme linked immune-solvent assays. The Akt-eNOS pathway was assessed using western blotting. To explore the role of inflammatory cytokines and NO, Kupffer cell inhibitor gadolinium chloride (GdCl₃), NOS inhibitor N-nitro-arginine methyl ester (L-NAME), and NO enhancer molsidomine were administered intraperitoneally.

RESULTS

The ALPPS group showed significant FLR regeneration (FLR/BW: 1.60% ± 0.08%, P < 0.05) compared with that observed in the PVL group (1.33% ± 0.11%) 48 h after surgery. In the ALPPS group, serum interleukin-6 expression was suppressed using GdCl₃ to the same extent as that in the PVL group. However, the FLR/BW ratio and Ki-67 labeling index were significantly higher in the ALPPS group administered GdCl₃ (1.72% ± 0.19%, P < 0.05; 22.25% ± 1.30%, P < 0.05) than in the PVL group (1.33% ± 0.11% and 12.78% ± 1.55%, respectively). Phospho-Akt Ser⁴⁷³ and phospho-eNOS Ser¹¹⁷⁷ levels were enhanced in the ALPPS group compared with those in the PVL group. There was no difference between the ALPPS group treated with L-NAME and the PVL group in the FLR/BW ratio and Ki-67 labeling index. In the PVL group treated with molsidomine, the FLR/BW ratio and Ki-67 labeling index increased to the same level as in the ALPPS group.

CONCLUSION

Early induction of inflammatory cytokines may not be pivotal for accelerated FLR regeneration after ALPPS, whereas Akt-eNOS pathway activation may contribute to accelerated regeneration of the FLR.

Dynamics of Irreversible NO Release from Photoexcited Molsidomine

Molsidomine (SIN-10), an orally administered NO-delivery drug for vasodilation, cannot be used to alleviate hypertensive crisis because it releases NO at a slow rate. SIN-10 may be used to treat sudden cardiac abnormalities if the rapid and immediate release of NO is achieved via photoactivation. The photodissociation dynamics associated with the NO release process from SIN-10 in CHCl₃ was investigated using time-resolved infrared spectroscopy. Approximately 41% of photoexcited SIN-10 at 360 nm decomposed into CO₂, CH₂CH₃ radical, and the remaining radical fragment [SIN-1A(-H)] with a time constant of 43 ps. All SIN-1A(-H) released NO spontaneously with a time constant of 68 ns, becoming N-morpholino-aminoacetonitrile, resulting in 41% for the quantum yield of immediate NO release from SIN-10. The results obtained can be used to realize the quantitative control of the NO administration at a specific time, and SIN-10 can be potentially used to address the phenomenon of hypertensive crisis.

Interactions between Nitric Oxide and Hyaluronan Implicate the Migration of Breast Cancer Cells

Nitric oxide (^•NO) is one of the prominent free radicals, playing a pivotal role in breast cancer progression. Hyaluronic acid (HA) plays an essential role in neutralizing free radicals in tumor tissues. However, its interactions with nitric oxide have not been thoroughly investigated. Hence, this study attempts to understand the mechanism of these interactions and the different effects on the intracellular ^•NO levels and migration of breast cancer cells. The affinity of HA to scavenge ^•NO was investigated alongside the accompanying changes in specific physico-chemical properties and the further effects on the ^•NO-induced attachment and migration of the breast cancer cell lines, MDA-MB-231 and HCC1806. The reaction of the nitrogen dioxide radical, formed via ^•NO/O₂ interactions, with HA initiated a series of oxidative reactions, which, in the presence of ^•NO, induce the fragmentation of the polymeric chains. Furthermore, these interactions were found to hinder the NO-induced migration of cancer cells. However, the NO-induced HA modification/fragmentation was inhibited in the presence of hemin, a NO-scavenging compound. Collectively, these results help toward understanding the involvement of HA in the ^•NO-induced cell migration and suggest the possible modification of HA, used as one of the main materials in different biomedical applications.

Nitrates vs. Other Types of Vasodilators and Clinical Outcomes in Patients with Vasospastic Angina: A Propensity Score-Matched Analysis

Although vasodilators are widely used in patients with vasospastic angina (VA), few studies have compared the long-term prognostic effects of different types of vasodilators. We investigated the long-term effects of vasodilators on clinical outcomes in VA patients according to the type of vasodilator used. Study data were obtained from a prospective multicenter registry that included patients who had symptoms suggestive of VA. Patients were classified into two groups according to use of nitrates (n = 239) or other vasodilators (n = 809) at discharge. The composite clinical events rate, including acute coronary syndrome (ACS), cardiac death, new-onset arrhythmia (including ventricular tachycardia and ventricular fibrillation), and atrioventricular block, was significantly higher in the nitrates group (5.3% vs. 2.2%, p = 0.026) during one year of follow-up. Specifically, the prevalence of ACS was significantly more frequent in the nitrates group (4.3% vs. 1.5%, p = 0.024). After propensity score matching, the adverse effects of nitrates remained. In addition, the use of nitrates at discharge was independently associated with a 2.69-fold increased risk of ACS in VA patients. In conclusion, using nitrates as a vasodilator at discharge can increase the adverse clinical outcomes in VA patients at one year of follow-up. Clinicians need to be aware of the prognostic value and consider prescribing other vasodilators.

Molsidomine alleviates acetic acid-induced colitis in rats by reducing oxidative stress, inflammation and apoptosis

Ulcerative colitis (UC) is a subcategory of intestinal inflammatory bowel disease characterized by up-regulation of proinflammatory cytokines and oxidative stress. The current study was designed to assess the probable protective effect of the nitric oxide (NO) donor, molsidomine, in experimental colitis model in rats. Rats were haphazardly classified into four groups: control, acetic acid, acetic acid + molsidomine (1 mg/kg) and acetic acid + molsidomine (2 mg/kg). Molsidomine (1 and 2 mg/kg/day) was administered by intra-peritoneal injection for 7 days prior to induction of UC. On the 8th day, colitis was induced by intra-rectal instillation of 2 ml of (4% v/v) acetic acid in normal saline using a pediatric plastic catheter. The rats were sacrificed 1 day following colitis induction, blood samples were obtained; colons and livers were isolated then underwent macroscopic, biochemical, histopathological and immunohistochemical examination. Pretreatment with molsidomine significantly reduced disease activity index, colon mass index, colonic macroscopic and histological damage. Besides, molsidomine significantly reduced the serum levels of alanine transaminase (ALT) (58.7 ± 8.9 & 59.7 ± 8 vs 288.75 ± 31.4 in AA group) and aspartate transaminase (AST) (196.2 ± 37.4 & 204 ± 30 vs 392.7 ± 35.6 in AA group). Moreover, molsidomine effectively decreased malondialdehyde (MDA) and total nitrate/nitrite (NOx) contents, and up regulated the enzymatic activity of superoxide dismutase (SOD) and glutathione level (GSH) in colonic and hepatic tissues. With regard to anti-inflammatory mechanisms, molsidomine suppressed tumor necrosis factor-alpha (TNF-α) (792.5 ± 16.7 & 448 ± 12.1 vs 1352.5 ± 45.8 in AA group) in colonic tissues and (701 ± 19 & 442.5 ± 22.5 vs 1501 ± 26 in AA group) in hepatic tissues as well as nuclear transcription factor kappa B (NF-kB/p65) levels (416.2 ± 4.1 & 185.5 ± 14.2 vs 659.2 ± 11.5 in AA group) in colonic tissues and (358 ± 6.2 & 163.5 ± 9.6 vs 732.5 ± 5.5 in AA group) in hepatic tissues. In addition, molsidomine significantly decreased inducible nitric oxide synthase (iNOS) levels (8.1 ± 0.1 & 4.9 ± 0.1 vs 16 ± 0.1 in AA group) in colonic tissues and (8.6 ± 0.3 & 6.1 ± 0.1 vs 17.8 ± 0.1 in AA group) in hepatic tissues, and myeloperoxidase (MPO) contents (10.5 ± 0.4 & 6.6 ± 0.3 vs 20.9 ± 0.6 in AA group) in colonic tissues and (13.1 ± 0.2 & 6.3 ± 0.06 vs 23.9 ± 1.4 in AA group) in hepatic tissues at p > 0.05. Furthermore, it suppressed apoptosis by reducing expression of Caspase 3 and Bax in colonic and hepatic tissues. Therefore, molsidomine might be a promising candidate for the treatment of UC.

Sydnone Methides-A Forgotten Class of Mesoionic Compounds for the Generation of Anionic N-Heterocyclic Carbenes

Sydnone methides are described from which only one single example has been mentioned in the literature so far. Their deprotonation gave anions which can be formulated as π-electron rich anionic N-heterocyclic carbenes. Sulfur and selenium adducts were stabilized as their methyl ethers, and mercury, gold as well as rhodium complexes of the sydnone methide carbenes were prepared. Sydnone methide anions also undergo C-C coupling reactions with 1-fluoro-4-iodobenzene under Pd(PPh3 )4 and CuBr catalysis. 77 Se NMR resonance frequencies and 1 JC4-Se as well as 1 JC4-H coupling constants have been determined to gain knowledge about the electronic properties of the anionic N-heterocyclic carbenes. The carbene carbon atom of the sydnone methide anion 3 j resonates at δ=155.2 ppm in 13 C NMR spectroscopy at -40 °C which is extremely shifted upfield in comparison to classical N-heterocyclic carbenes.

Nitric Oxide-Based Treatment of Poor-Grade Patients After Severe Aneurysmal Subarachnoid Hemorrhage

Background

Patients with aneurysmal subarachnoid hemorrhage (aSAH) require close treatment in neuro intensive care units (NICUs). The treatments available to counteract secondary deterioration and delayed ischemic events remain restricted; moreover, available neuro-monitoring of comatose patients is undependable. In comatose patients, clinical signs are hidden, and timing interventions to prevent the evolution of a perfusion disorder in response to fixed ischemic brain damage remain a challenge for NICU teams. Consequently, comatose patients often suffer secondary brain infarctions. The outcomes for long-term intubated patients w/wo pupil dilatation are the worst, with only 10% surviving. We previously added two nitroxide (NO) donors to the standard treatment: continuous intravenous administration of Molsidomine in patients with mild-to-moderate aSAH and, if required as a supplement, intraventricular boluses of sodium nitroprusside (SNP) in high-risk patients to overcome the so-called NO-sink effect, which leads to vasospasm and perfusion disorders. NO boluses were guided by clinical status and promptly reversed recurrent episodes of delayed ischemic neurological deficit. In this study, we tried to translate this concept, the initiation of intraventricular NO application on top of continuous Molsidomine infusion, from awake to comatose patients who lack neurological–clinical monitoring but are primarily monitored using frequently applied transcranial Doppler (TCD).

Methods

In this observational, retrospective, nonrandomized feasibility study, 18 consecutive aSAH comatose/intubated patients (Hunt and Hess IV/V with/without pupil dilatation) whose poor clinical status precluded clinical monitoring received standard neuro-intensive care, frequent TCD monitoring, continuous intravenous Molsidomine plus intraventricular SNP boluses after TCD-confirmed macrospasm during the daytime and on a fixed nighttime schedule.

Results

Very likely associated with the application of SNP, which is a matter of further investigation, vasospasm-related TCD findings promptly and reliably reversed or substantially weakened (p < 0.0001) afterward. Delayed cerebral ischemia (DCI) occurred only during loose, low-dose or interrupted treatment (17% vs. an estimated 65% with secondary infarctions) in 17 responders. However, despite their worse initial condition, 29.4% of the responders survived (expected 10%) and four achieved Glasgow Outcome Scale Extended (GOSE) 8–6, modified Rankin Scale (mRS) 0–1 or National Institutes of Health Stroke Scale (NIHSS) 0–2.

Conclusions

Even in comatose/intubated patients, TCD-guided dual-compartment administration of NO donors probably could reverse macrospasm and seems to be feasible. The number of DCI was much lower than expected in this specific subgroup, indicating that this treatment possibly provides a positive impact on outcomes. A randomized trial should verify or falsify our results.

Drug-Nutraceutical Co-Crystal and Salts for Making New and Improved Bi-Functional Analgesics

The discovery and development of effective analgesics is greatly lagging behind the steadily rising prevalence of chronic pain. Currently prescribed analgesics for chronic pain are lacking in efficacy mainly due to their narrowly-targeted mechanism of action. Driving neuronal hyperexcitability that underlies symptoms of chronic pain are multiple non-neuronal processes, among which are tissue hypoxia and oxidative stress. Here we demonstrate the design, synthesis, and activity of new multi-component bi-functional analgesic crystalline solids, co-crystals, and salts, based on pairing of vasodilatory anti-hypoxic drugs pentoxifylline, clonidine and linsidomine with antioxidant nutraceuticals protocatechuic acid, α-lipoic acid, and caffeic acid. After validation, chemical and structural characterization of these novel salts and co-crystals, topical formulations of the products were tested in a rat model of complex regional pain syndrome. Analgesic effects achieved with the salts and co-crystal exceeded the efficacy and/or potency of constituent compounds indicating that more effective, advanced analgesics can readily be developed by careful pairing of compounds that simultaneously target multiple neural and non-neural processes driving chronic pain.

Nitric Oxide Mediated Degradation of CYP2A6 via the Ubiquitin-Proteasome Pathway in Human Hepatoma Cells

Several cytochrome P450 enzymes are known to be down-regulated by nitric oxide (NO). CYP2A6 is responsible for the metabolism of nicotine and several other xenobiotics, but its susceptibility to down-regulation by NO has not been reported. To address this question, we used Huh7 human hepatoma cell lines to express CYP2A6 with a C-terminal V5 tag (CYP2A6V5). NO donor treatment [dipropylenetriamine NONOate (DPTA)] down-regulated CYP2A6 protein to approximately 40% of control levels in 4 hours. An NO scavenging agent protected CYP2A6 from down-regulation by DPTA in a concentration-dependent manner, demonstrating that the down-regulation is NO-dependent. Experiments with the protein synthesis inhibitor cycloheximide showed that CYP2A6 protein down-regulation occurs posttranslationally. In the presence of proteasome inhibitors MG132 or bortezomib, NO-treated cells showed an accumulation of a high molecular mass signal, whereas autophagy inhibitors chloroquine and 3-methyladenine and the lysosomal and calpain inhibitor E64d had no effect. Immunoprecipitation of CYP2A6 followed by Western blotting with an antiubiquitin antibody showed that the high molecular mass species contain polyubiquitinated CYP2A6 protein. This suggests that NO led to the degradation of protein via the ubiquitin-proteasome pathway. The down-regulation by NO was blocked by the reversible CYP2A6 inhibitor pilocarpine but not by the suicide inhibitor methoxsalen, demonstrating that down-regulation requires NO access to the active site but does not require catalytic activity of the enzyme. These findings provide novel insights toward the regulation of CYP2A6 in a human cell line and can influence our understanding of CYP2A6-related drug metabolism. SIGNIFICANCE STATEMENT: This study demonstrates that the nicotine metabolizing enzyme CYP2A6 is down-regulated by nitric oxide, a molecule produced in large amounts in the context of inflammation and that is also inhaled from cigarette smoke. This occurs via ubiquitination and proteasomal degradation, and does not require catalytic activity of the enzyme. This work adds to the growing knowledge of the selective effect and mechanism of action of nitric oxide (NO) on cytochrome P450 enzymes and suggests a possible novel mode of interaction between nicotine and NO in cigarette smokers.

Cytoprotective Effects of Dinitrosyl Iron Complexes on Viability of Human Fibroblasts and Cardiomyocytes

Nitric oxide (NO) is an important signaling molecule that plays a key role in maintaining vascular homeostasis. Dinitrosyl iron complexes (DNICs) generating NO are widely used to treat cardiovascular diseases. However, the involvement of DNICs in the metabolic processes of the cell, their protective properties in doxorubicin-induced toxicity remain to be clarified. Here, we found that novel class of mononuclear DNICs with functional sulfur-containing ligands enhanced the cell viability of human lung fibroblasts and rat cardiomyocytes. Moreover, DNICs demonstrated remarkable protection against doxorubicin-induced toxicity in fibroblasts and in rat cardiomyocytes (H9c2 cells). Data revealed that the DNICs compounds modulate the mitochondria function by decreasing the mitochondrial membrane potential (ΔΨ_m). Results of flow cytometry showed that DNICs were not affected the proliferation, growth of fibroblasts. In addition, this study showed that DNICs did not affect glutathione levels and the formation of reactive oxygen species in cells. Moreover, results indicated that DNICs maintained the ATP equilibrium in cells. Taken together, these findings show that DNICs have protective properties in vitro. It was further suggested that DNICs may be uncouplers of oxidative phosphorylation in mitochondria and protective mechanism is mainly provided by the leakage of excess charge through the mitochondrial membrane. It is assumed that the DNICs have the therapeutic potential for treating cardiovascular diseases and for decreasing of chemotherapy-induced cardiotoxicity in cancer survivors.

Nitric oxide-regulated proteolysis of human CYP2B6 via the ubiquitin-proteasome system

We showed previously that rat cytochrome P450 CYP2B1 undergoes NO-dependent proteasomal degradation in response to inflammatory stimuli, and that the related human enzyme CYP2B6 is also down-regulated by NO in primary human hepatocytes. To investigate the mechanism of CYP2B6 down-regulation, we made several cell lines (HeLa and HuH7 cells) in which native CYP2B6 or CYP2B6 with a C-terminal V5 tag (CYP2B6V5) are expressed from a lentiviral vector with a cytomegalovirus promoter. Native CYP2B6 protein was rapidly down-regulated in HeLa cells within 3h of treatment with the NO donor (Z)-1-[2-(2-Aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate, while its mRNA level was not down-regulated. Treatment of the cells with the NO donor (Z)-1-[N-(3-aminopropyl)-N-(3-ammoniopropyl)amino]diazen-1-ium-1,2-diolate also resulted in rapid down-regulation of CYP2B6 activity, measured as the formation of 7-hydroxy-4-trifluoromethylcoumarin, as well as 2B6 protein in the CYP2B6 HeLa cell line. CYP2B6V5 was also down-regulated by NO donors in HuH7 cells. Down-regulation was observed in the presence of cycloheximide, demonstrating that this occurs via a post-translational mechanism. We generated a HeLa cell line expressing both CYP2B6V5 and human nitric oxide synthase 2 (NOS2), the latter under positive control by tetracycline. The cellular NO produced by doxycycline treatment also effectively down-regulated CYP2B6 protein, which was blocked by the co-treatment with the NOS2 competitive inhibitor L-N^G-nitroarginine methyl ester (L-NAME). We next investigated the proteolytic enzymes responsible for NO-dependent CYP2B6 degradation. Neither calpain inhibitors (N-Acetyl-L-leucyl-L-leucyl-L-norleucinal, carbobenzoxy-valinyl-phenylalaninal), nor lysosomal protease inhibitors (3-methyladenine and chloroquine) inhibited the NO dependent CYP2B6V5 down-regulation. The proteasome inhibitors MG132 and bortezomib attenuated, but did not completely block the NO-induced down-regulation in the HuH7 cell line. However, when cells were co-treated with NO donor and proteasome inhibitors, high molecular mass species could be detected on native CYP2B6 as well as CYP2B6V5 Western blots. Further investigation demonstrated that CYP2B6 protein was polyubiquitinated and this was dramatically enhanced by co-treatment with NO donor and bortezomib. Taken together, our data demonstrate that CYP2B6 is down-regulated in an NO-dependent manner via ubiquitination and proteasomal degradation.

Effects of Aging and Oxidative Stress on Spermatozoa of Superoxide-Dismutase 1- and Catalase-Null Mice

Advanced paternal age is linked to complications in pregnancy and genetic diseases in offspring. Aging results in excess reactive oxygen species (ROS) and DNA damage in spermatozoa; this damage can be transmitted to progeny with detrimental consequences. Although there is a loss of antioxidants with aging, the impact on aging male germ cells of the complete absence of either catalase (CAT) or superoxide dismutase 1 (SOD1) has not been investigated. We used CAT-null (Cat(-/-)) and SOD1-null (Sod(-/-)) mice to determine whether loss of these antioxidants increases germ cell susceptibility to redox dysfunction with aging. Aging reduced fertility and the numbers of Sertoli and germ cells in all mice. Aged Sod(-/-) mice displayed an increased loss of fertility compared to aged wild-type mice. Treatment with the pro-oxidant SIN-10 increased ROS in spermatocytes of aged wild-type and Sod(-/-) mice, while aged Cat(-/-) mice were able to neutralize this ROS. The antioxidant peroxiredoxin 1 (PRDX1) increased with age in wild-type and Cat(-/-) mice but was consistently low in young and aged Sod(-/-) mice. DNA damage and repair markers (γ-H2AX and 53BP1) were reduced with aging and lower in young Sod(-/-) and Cat(-/-) mice. Colocalization of γ-H2AX and 53BP1 suggested active repair in young wild-type mice but reduced in young Cat(-/-) and in Sod(-/-) mice and with age. Oxidative DNA damage (8-oxodG) increased in young Sod(-/-) mice and with age in all mice. These studies show that aged Sod(-/-) mice display severe redox dysfunction, while wild-type and Cat(-/-) mice have compensatory mechanisms to partially alleviate oxidative stress and reduce age-related DNA damage in spermatozoa. Thus, SOD1 but not CAT is critical to the maintenance of germ cell quality with aging.

A Case of Hyperacute Onset of Vasospasm After Aneurysmal Subarachnoid Hemorrhage and Refractory Vasospasm Treated with Intravenous and Intraventricular Nitric Oxide: A Mini Review

BACKGROUND

A case of hyperacute vasospasm, indicating a poor prognosis after aneurysmal subarachnoid hemorrhage (SAH), is reported, and a review is presented of the literature addressing use of nitric oxide (NO) donors in cases of refractory vasospasm and recurrent delayed cortical ischemias (DCI).

CASE DESCRIPTION

A 65-year-old woman was admitted within 1 hour after aneurysmal SAH (Hunt and Hess grade III, Fisher modified by Frontera grade IV). A hyperacute vasospasm had been confirmed arteriographically, the right middle cerebral artery (MCA) aneurysm was immediately coiled and a standard antivasospastic therapy was started. Within 48 hours, the patient developed cerebral vasospasm with DCI. Because the standard therapy failed to control clinical symptoms and to address severe vasospasm, an individualized rescue treatment with NO donors was initiated. A continuous intravenous molsidomine infusion was started and clinical stabilization was achieved for a week (Hunt and Hess grade I; World Federation of Neurological Surgeons grade I; Glasgow Coma Scale score, 15) after which vasospasm and DCI recurred. During a subsequent DCI, we escalated NO donor therapy by adding intraventricular boluses of sodium nitroprusside (SNP). Over the course of the following 22 days, 7 transient DCIs (Glasgow Coma Scale score, 8) were treated with boluses of SNP during continued molsidomine therapy and each time vasospasm and DCI were completely reversed. Despite initial poor prognosis, the clinical outcome was excellent; at 3, 6, and 12 months follow-up the patient's modified National Institutes of Health-Stroke Scale and modified Rankin Scale scores were 0, with no cognitive deficits.

CONCLUSIONS

The review of the literature suggested that combined intravenous molsidomine with intraventricular SNP treatment reversed refractory, recurrent vasospasm and DCIs probably by addressing the hemoglobin NO sink effect, NO depletion, and decreased NO availability after aneurysmal SAH.

The preferential nNOS inhibitor 7-nitroindazole and the non-selective one N(G)-nitro-L-arginine methyl ester administered alone or jointly with L-DOPA differentially affect motor behavior and monoamine metabolism in sham-operated and 6-OHDA-lesioned rats

Reciprocal interactions between nitrergic and dopaminergic systems play a key role in the control of motor behavior. In the present study, we performed a comparative analysis of motor behavior (locomotor activity, catalepsy, rotational behavior) and monoamine metabolism in the striatum and substantia nigra of unilaterally sham-operated and 6-OHDA-lesioned rats treated with the preferential neuronal nitric oxide synthase (nNOS) inhibitor 7-nitroindazole (7-NI) or the non-selective one N(G)-nitro-L-arginine methyl ester (L-NAME), alone or in combination with L-DOPA. Each NOS inhibitor given alone (50mg/kg) induced a distinct catalepsy 30 min after injection but only 7-NI impaired spontaneous locomotion after 10 min. In 6-OHDA-lesioned rats, chronic L-DOPA (25mg/kg) induced 2.5-h long contralateral rotations. 7-NI (30 and 50mg/kg) markedly reduced the intensity of L-DOPA-induced contralateral rotations while extending their duration until 4.5h whereas L-NAME (50 and 100mg/kg) only tended to attenuate their intensity without affecting the duration. 7-NI but not L-NAME significantly increased endogenous tissue DA levels in the nigrostriatal system of both sham-operated and 6-OHDA-lesioned rats. In L-DOPA-treated group, 7-NI significantly enhanced the L-DOPA-derived tissue DA content in this system and decreased the level of the intracellular DA metabolite DOPAC produced by monoamine oxidase (MAO). In contrast to 7-NI, L-NAME decreased markedly DA content and did not affect DOPAC level in the ipsilateral striatum. It means that the differences in 7-NI and L-NAME-mediated modulation of L-DOPA-induced behavioral and biochemical effects resulted not only from the inhibition of NOS activity but also from differences in their ability to inhibit MAO.

Molsidomine for the prevention of vasospasm-related delayed ischemic neurological deficits and delayed brain infarction and the improvement of clinical outcome after subarachnoid hemorrhage: a single-center clinical observational study

OBJECT Delayed ischemic neurological deficits (DINDs) and cerebral vasospasm (CVS) are responsible fora poor outcome in patients with aneurysmal subarachnoid hemorrhage (SAH), most likely because of a decreased availability of nitric oxide (NO) in the cerebral microcirculation. In this study, the authors examined the effects of treatment with the NO donor molsidomine with regard to decreasing the incidence of spasm-related delayed brain infarctions and improving clinical outcome in patients with SAH. METHODS Seventy-four patients with spontaneous aneurysmal SAH were included in this post hoc analysis. Twenty-nine patients with SAH and proven CVS received molsidomine in addition to oral or intravenous nimodipine. Control groups consisted of 25 SAH patients with proven vasospasm and 20 SAH patients without. These patients received nimodipine therapy alone. Cranial computed tomography (CCT) before and after treatment was analyzed for CVS-related infarcts. A modified National Institutes of Health Stroke Scale (mNIHSS) and the modified Rankin Scale (mRS) were used to assess outcomes at a 3-month clinical follow-up. RESULTS Four of the 29 (13.8%) patients receiving molsidomine plus nimodipine and 22 of the 45 (48%) patients receiving nimodipine therapy alone developed vasospasm-associated brain infarcts (p < 0.01). Follow-up revealed a median mNIHSS score of 3.0 and a median mRS score of 2.5 in the molsidomine group compared with scores of 11.5 and 5.0, respectively, in the nimodipine group with CVS (p < 0.001). One patient in the molsidomine treatment group died, and 12 patients in the standard care group died (p < 0.01). CONCLUSIONS In this post hoc analysis, patients with CVS who were treated with intravenous molsidomine had a significant improvement in clinical outcome and less cerebral infarction. Molsidomine offers a promising therapeutic option in patients with severe SAH and CVS and should be assessed in a prospective study.

Aged neuronal nitric oxide knockout mice show preserved olfactory learning in both social recognition and odor-conditioning tasks

There is evidence for both neurotoxic and neuroprotective roles of nitric oxide (NO) in the brain and changes in the expression of the neuronal isoform of NO synthase (nNOS) gene occur during aging. The current studies have investigated potential support for either a neurotoxic or neuroprotective role of NO derived from nNOS in the context of aging by comparing olfactory learning and locomotor function in young compared to old nNOS knockout (nNOS^−/−) and wildtype control mice. Tasks involving social recognition and olfactory conditioning paradigms showed that old nNOS^−/− animals had improved retention of learning compared to similar aged wildtype controls. Young nNOS^−/− animals showed superior reversal learning to wildtypes in a conditioned learning task, although their performance was weakened with age. Interestingly, whereas young nNOS^−/− animals were impaired in long term memory for social odors compared to wildtype controls, in old animals this pattern was reversed, possibly indicating beneficial compensatory changes influencing olfactory memory may occur during aging in nNOS^−/− animals. Possibly such compensatory changes may have involved increased NO from other NOS isoforms since the memory deficit in young nNOS^−/− animals could be rescued by the NO-donor, molsidomine. Both nNOS^−/− and wildtype animals showed an age-associated decline in locomotor activity although young nNOS^−/− animals were significantly more active than wildtypes, possibly due to an increased interest in novelty. Overall our findings suggest that lack of NO release via nNOS may protect animals to some extent against age-associated cognitive decline in memory tasks typically involving olfactory and hippocampal regions, but not against declines in reversal learning or locomotor activity.

Involvement of the insular nitric oxide signaling pathway in the expression of morphine-induced conditioned place preference in rats

Nitric oxide (NO) has been recently reported to play an important role in the rewarding effects of addictive drugs. The regional NO signaling in the brain, however, is not completely clear. Here, we studied the effects of insular NO signaling on the expression of morphine-induced conditioned place preference (CPP). Insular microinjection of the NO inhibitors N-nitro L-arginine methyl ester (L-NAME) and 7-nitroindazole reduced the expression of morphine-induced CPP. The NO donor molsidomine, in contrast, reversed L-NAME-induced reduction of CPP expression. These results suggest that insular NO signaling is involved in the expression of morphine-CPP.

ROS-responsive microspheres for on demand antioxidant therapy in a model of diabetic peripheral arterial disease

A new microparticle-based delivery system was synthesized from reactive oxygen species (ROS)-responsive poly(propylene sulfide) (PPS) and tested for "on demand" antioxidant therapy. PPS is hydrophobic but undergoes a phase change to become hydrophilic upon oxidation and thus provides a useful platform for ROS-demanded drug release. This platform was tested for delivery of the promising anti-inflammatory and antioxidant therapeutic molecule curcumin, which is currently limited in use in its free form due to poor pharmacokinetic properties. PPS microspheres efficiently encapsulated curcumin through oil-in-water emulsion and provided sustained, on demand release that was modulated in vitro by hydrogen peroxide concentration. The cytocompatible, curcumin-loaded microspheres preferentially targeted and scavenged intracellular ROS in activated macrophages, reduced in vitro cell death in the presence of cytotoxic levels of ROS, and decreased tissue-level ROS in vivo in the diabetic mouse hind limb ischemia model of peripheral arterial disease. Interestingly, due to the ROS scavenging behavior of PPS, the blank microparticles also showed inherent therapeutic properties that were synergistic with the effects of curcumin in these assays. Functionally, local delivery of curcumin-PPS microspheres accelerated recovery from hind limb ischemia in diabetic mice, as demonstrated using non-invasive imaging techniques. This work demonstrates the potential for PPS microspheres as a generalizable vehicle for ROS-demanded drug release and establishes the utility of this platform for improving local curcumin bioavailability for treatment of chronic inflammatory diseases.

Nitrosyl iron complexes with enhanced NO donating ability: synthesis, structure and properties of a new type of salt with the DNIC cations [Fe(SC(NH2)2)2(NO)2]+

A new structural type of water-soluble iron nitrosyl complexes with thiocarbamide has been obtained.

Systematic analysis of the ability of Nitric Oxide donors to dislodge biofilms formed by Salmonella enterica and Escherichia coli O157:H7

Biofilms in the industrial environment could be problematic. Encased in extracellular polymeric substances, pathogens within biofilms are significantly more resistant to chlorine and other disinfectants. Recent studies suggest that compounds capable of manipulating nitric oxide-mediated signaling in bacteria could induce dispersal of sessile bacteria and provide a foundation for novel approaches to controlling biofilms formed by some microorganisms. In this work, we compared the ability of five nitric oxide donors (molsidomine, MAHMA NONOate, diethylamine NONOate, diethylamine NONOate diethylammonium salt, spermine NONOate) to dislodge biofilms formed by non-typhoidal Salmonella enterica and pathogenic E. coli on plastic and stainless steel surfaces at different temperatures. All five nitric oxide donors induced significant (35-80%) dispersal of biofilms, however, the degree of dispersal and the optimal dispersal conditions varied. MAHMA NONOate and molsidomine were strong dispersants of the Salmonella biofilms formed on polystyrene. Importantly, molsidomine induced dispersal of up to 50% of the pre-formed Salmonella biofilm at 4°C, suggesting that it could be effective even under refrigerated conditions. Biofilms formed by E. coli O157:H7 were also significantly dispersed. Nitric oxide donor molecules were highly active within 6 hours of application. To better understand mode of action of these compounds, we identified Salmonella genomic region recA-hydN, deletion of which led to an insensitivity to the nitric oxide donors.

Comparative short-term effect of once-daily molsidomine on chronic angina in general practitioners' versus cardiologists' coronary patient populations

INTRODUCTION

The direct nitric oxide donor molsidomine is commonly used to relieve symptoms in chronic angina thanks to its vasodilatory properties that induce both a reduction in myocardial oxygen demand and an increase in coronary blood flow. The objective of this study was to compare the short-term effect of molsidomine 16 mg once daily (Coruno(®), Therabel Pharmaceuticals Ltd, Dublin, Ireland) in patients with stable angina previously on molsidomine 8 mg twice daily, in care of general practitioners (GPs) versus cardiologists.

METHODS

A total of 53 and 80 patients treated by GPs and cardiologists, respectively, took part in this multicenter, open-label clinical trial. Frequency of anginal attacks, short-acting nitroderivative tablets consumption, and subjective clinical status were evaluated, as was tolerability to molsidomine through the reporting of adverse events (AEs), the recording of vital parameters-resting blood pressure, heart rate, and electrocardiogram-and routine blood analyses.

RESULTS

Although demographic and clinical characteristics were significantly different in GPs' compared with cardiologists' patients, the effect of either the 8 mg or the 16 mg molsidomine formulation on anginal crises and nitroderivatives consumption was similar in both patient cohorts, with a trend for the 16 mg formulation to be more efficient on symptoms in elderly patients. Subjective assessment of the beneficial effect of molsidomine 16 versus 8 mg was comparable in GPs' and cardiologists' patients independently of age, "no change" being the most often reported item. Self-evaluation of functional capacity in elderly showed on the whole no difference between the two patient cohorts, only magnitude of pace and total score on molsidomine 16 mg being higher in cardiologists' compared with GPs' patients, and total score in cardiologists' patients higher on molsidomine 16 mg compared with 8 mg. Incidences of AEs and drug-related AEs, as well as proportions of patients reporting such AEs, were similar between GPs' and cardiologists' patient cohorts as between molsidomine 8 and 16 mg formulations. Molsidomine 16 mg once daily had no clinically significant effect on blood pressure, heart rate, electrocardiogram or blood parameters, and compliance with treatment was excellent in whatever patient cohort.

CONCLUSION

Despite significant demographic and clinical differences between patients in care of GPs and cardiologists, molsidomine was equally efficient in these two patient cohorts, with a trend towards less anginal attacks in the elderly when treated with the 16 mg compared with the 8 mg formulation. Compliance and tolerability to the drug were excellent in both patient cohorts.

Vasoactive and Antiarrhythmic Drugs During Percutaneous Coronary Intervention

The objective in percutaneous coronary intervention (PCI) is to treat flow-limiting atherothrombotic coronary plaques mechanically. Many types of antithrombotic drugs are used to prevent ischemic complications during manipulation of catheters, guidewires, balloons, and stents in coronary arteries while minimizing the risk of bleeding. However, many other types of pharmacologic agents are also used to facilitate PCI. This review focuses on the most commonly used adjunct drugs during PCI. In addition, a recommendation of which drugs should be stopped or interrupted in patients undergoing PCI is provided.

Molsidomine, a nitric oxide donor, modulates rotational behavior and monoamine metabolism in 6-OHDA lesioned rats treated chronically with L-DOPA

Some biochemical and histological studies of Parkinson's disease patients' brains and 6-OHDA-lesioned rats suggest that dopaminergic dennervation of the striatum leads to the nitrergic system hypofunction in this structure. Hence, recently the modulation of nitric oxide (NO)- soluble guanylyl cyclase-cyclic GMP signaling is considered to be a new target for the treatment of Parkinson's disease. The aim of our study was to examine the impact of chronic combined treatment with low doses of the NO donor molsidomine (2 and 4mg/kg) and L-DOPA (12.5 and 25mg/kg) on rotational behavior and monoamine metabolism in the striatum (STR) and substantia nigra (SN) of unilaterally 6-OHDA-lesioned rats. Chronic administration of molsidomine at a dose of 2mg/kg jointly with 25mg/kg of L-DOPA significantly decreased the number of contralateral rotations when compared to L-DOPA alone. Other combinations of the examined drug doses were less effective. The tissue DA levels in the ipsilateral STR and SN after the last chronic doses of molsidomine (2mg/kg) and L-DOPA (12.5 or 25mg/kg), were significantly higher than after L-DOPA alone. Chronic L-DOPA treatment alone or jointly with a lower dose of molsidomine decreased 5-HT levels and accelerated its catabolism in the examined structures. However, combination of a higher dose of molsidomine with L-DOPA (25mg/kg) did not reduce 5-HT content while its catabolism was less intensive. The obtained results show that low doses of molsidomine can modulate rotational behavior and tissue DA and 5-HT concentrations in the STR and SN of 6-OHDA-lesioned rats treated chronically with L-DOPA.

Electrophysiological and neurochemical characterization of 7-nitroindazole and molsidomine acute and sub-chronic administration effects in the dopaminergic nigrostrial system in rats

Nitric oxide (NO) plays an important role in the integration of information processed by the basal ganglia nuclei. Accordingly, considerable evidence has emerged indicating a role for NO in pathophysiological conditions such as Parkinson's disease (PD) and other neurodegenerative disorders. Despite these recent advances, the nitrergic modulation of the dopamine (DA) nigrostriatal system is still unclear. In order to fill this gap, in this study we used in vivo electrophysiology and ex vivo neurochemical analysis to further investigate the effect of NO signaling in rat substantia nigra pars compacta (SNc) and the striatum. Acute and subchronic (4 days) pharmacological manipulation of the NO system using 7-nitroindazole (7-NI, 50 mg kg(-1) i.p.) and molsidomine (MOL, 40 mg kg(-1) i.p.) treatment caused significant changes in both DA SNc neurons electrophysiological properties and striatal DA and 3,4-dihydroxyphenylacetic acid (DOPAC) levels. It is worth noting that acute inhibition of NO production decreased DA nigrostriatal neurotransmission while its subchronic inhibition was instead excitatory. Thus, a crucial role for NO in the modulation of nigrostriatal DA function is suggested together with a potential role for inhibitors of NO sythase in the treatment of PD.

Chemical model systems for cellular nitros(yl)ation reactions

S-nitros(yl)ation belongs to the redox-based posttranslational modifications of proteins but the underlying chemistry is controversial. In contrast to current concepts involving the autoxidation of nitric oxide ((.)NO, nitrogen monoxide), we and others have proposed the formation of peroxynitrite (oxoperoxonitrate (1(-))as an essential intermediate. This requires low cellular fluxes of (.)NO and superoxide (UO2(-)), for which model systems have been introduced. We here propose two new systems for nitros(yl)ation that avoid the shortcomings of previous models. Based on the thermal decomposition of 3-morpholinosydnonimine,equal fluxes of (.)NO and UO2(-) were generated and modulated by the addition of (.)NO donors or Cu,Zn superoxide dismutase. As reactants for S-nitros(yl)ation, NADP+-dependent isocitrate dehydrogenase and glutathione were employed, for which optimal S-nitros(yl)ation was observed at nanomolar fluxes of (.)NO and UO2(-) at a ratio of about 3:1. The previously used reactants phenol and diaminonaphthalene (C- and Nnitrosation)demonstrated potential participation of multiple pathways for nitros(yl)ation. According to our data, neither peroxynitrite nor autoxidation of UNO was as efficient as the 3 (.)NO/1 UO2(-) system in mediating S-nitros(yl)ation. In theory this could lead to an elusive nitrosonium (nitrosyl cation)-like species in the first step and to N2O3 in the subsequent reaction. Which of these two species or whether both together will participate in biological S-nitros(yl)ation remains to be elucidated. Finally, we developed several hypothetical scenarios to which the described (.)NO/UO2-flux model could apply, providing conditions that allow either direct electrophilic substitution at a thiolate or S-nitros(yl)ation via transnitrosation from S-nitrosoglutathione.

Comparative effects of once-daily molsidomine in coronary patients from two distinct European ethnicities

INTRODUCTION

Molsidomine, a direct nitric oxide donor, is frequently used in several European countries for the treatment of stable angina. The aim of this study was to compare the effects of a new once-daily 16-mg dose formulation, Coruno (Therabel Pharmaceuticals, Loughrea, Ireland), in patients with stable angina belonging to two distinct European ethnicities.

METHODS

A total of 261 Hungarian and 267 Polish patients took part in this multicenter, randomized, double-blind, placebo-controlled clinical trial. Exercise testing was performed after the first administration of molsidomine and repeated after a 2-week treatment. Frequency of anginal attacks, short-acting nitroderivative tablet consumption, and incidence of adverse events were also evaluated.

RESULTS

Demographic and clinical characteristics were significantly different in Hungarian compared with Polish patients. Hungarian patients had a lower proportion of males, were shorter in stature, had less previous smoking experience, consumed more alcohol, had less severe coronary disease (electrocardiographic evidence, rate of anginal crises, and nitroderivative consumption), and higher exercise capacity. However, molsidomine-related improvement in exercise capacity at start of the study was similar in both cohorts. After a 2-week treatment, improvement was fully maintained in Polish and only minimally reduced in Hungarian patients. Furthermore, molsidomine reduced significantly more anginal episodes and nitroderivative consumption in the more severely affected Polish cohort. Proportions of patients reporting drug-related adverse events were similar on placebo and molsidomine in both cohorts. Most of the adverse events were not severe and resolved spontaneously. Less myocardial ischemia and gender (including height, a confounding covariate) acted positively and negatively, respectively, on the higher exercise capacity of Hungarian versus Polish patients.

CONCLUSION

The once-daily 16-mg molsidomine formulation is effective and has good tolerability in both patient cohorts. Molsidomine does not induce any meaningful tolerance issues in Hungarian or Polish patients with stable angina, despite significant demographic and clinical disparities.

ORIGINAL RESEARCH—ED PHARMACOTHERAPY: Do Food and Dose Timing Affect the Efficacy of Sildenafil? A Randomized Placebo‐Controlled Study

INTRODUCTION

Sildenafil citrate has been used worldwide by men with erectile dysfunction. The prescribing information for sildenafil suggests ingestion 1 hour before sexual activity and also notes reduced maximum plasma concentration and delayed time to maximum concentration following ingestion with a high-fat meal. The clinical impact of coingestion of food and these factors has never been evaluated.

AIM

To determine, using a naturalistic study design, whether sildenafil taken 1 hour before or during a meal compared with usual ingestion 30-60 minutes before sexual activity affects efficacy or patient satisfaction.

METHODS

After a 1-2-week washout, 48 men (29-79 years old), currently satisfied with sildenafil, followed each of four regimens: (A) sildenafil 1 hour before a meal and placebo 30-60 minutes before planned coitus vs. (B) placebo 1 hour before a meal and sildenafil 30-60 minutes before coitus; and (C) sildenafil during a meal and placebo 30-60 minutes before coitus vs. (D) placebo during a meal and sildenafil 30-60 minutes before coitus. Subjects were not instructed to change their regular dietary habits during the course of the study.

MAIN OUTCOME MEASURES

Change from baseline in the International Index of Erectile Function (IIEF) Erectile Function (EF) domain score, responses to Sexual Encounter Profile (SEP) questions 2 (erection sufficient for penetration) and 3 (erection sufficient to complete intercourse), and measures of patient preference and satisfaction.

RESULTS

Mean changes in IIEF-EF domain scores were 11.4 for regimens A and B and 11.2 for C and D. Positive SEP2 responses were recorded for 93.9% and 91.8% of intercourse attempts in A and B and 91.4% and 92.6% in C and D. Corresponding results for SEP3 were 84.7% and 85.9%, and 83.4% and 87.5%, respectively. There were no significant differences between pairs of treatments on satisfaction. The time between sildenafil ingestion and intercourse attempt (0-0.5 to >10 hours) had no significant effect on responses to SEP2, but decreased responses to SEP3 from a maximum of 92.8% at 1.5-2 hours to 81.6% at more than 10 hours (P = 0.003).

CONCLUSIONS

No significant loss of efficacy occurs when sildenafil is taken shortly before or with a meal. The duration of action for sildenafil may exceed 10 hours.

Tolerability to 1-year treatment with once-daily molsidomine in patients with stable angina

Prolonged-release molsidomine 16 mg once daily) QD (has proved effective in the short-term treatment of patients with stable angina. The purpose of this multicenter study was to assess its long-term tolerability and clinical effectiveness. A total of 320 patients with stable angina were treated for 1 year with molsidomine 16 mg QD administered open label as monotherapy or add-on therapy, when beta blockers and/or calcium antagonists were prescribed concomitantly) in 128 patients, ie, 40% of cases), depending on the severity of disease and/or local therapeutic policies. In all, 293 patients (91.6%) completed the study. The proportion of patients who reported drug-related adverse events (AEs) was 9.1%, which is not significantly different (P=.13) from the 5.9% observed during previous short-term (2-4 wk) treatment. Headache accounted for 80.6% of all drug-related AEs and required discontinuation of the drug in one quarter of patients who reported the symptom (ie, 1.9% of the 320 patients involved in the study). No serious drug-related AEs occurred during the study. Tolerability to molsidomine, evaluated with use of a visual analog scale (VAS), improved by 20% from beginning to end of 1-year follow-up. Two-by-two Bonferroni's comparisons were significant at the .05 level between the 2-month assessment and assessments performed at 8, 10, and 12 months. No age-time interaction was noted (P=.82). Heart rate, blood pressure, electrocardiogram, and blood parameters showed no statistically significant or clinically relevant changes during the study. Compliance with treatment was satisfactory throughout the follow-up period. There was no significant change in the weekly frequency of anginal attacks and consumption of short-acting nitroderivatives during the 1-year study (P=.07 and P=.12,respectively), but their frequency was significantly (ie, approximately 50%) lower than during a preceding short-term treatment period (P<.0001 and P=.014, respectively). Subjective clinical status, evaluated through an appropriate VAS, improved by 38% from start to end of 1-year follow-up. Bonferroni's comparisons between baseline and subsequent 2-month evaluations were all significant at the .05 level. No age-time interaction could be seen for frequency of anginal attacks and consumption of short-acting nitroderivatives, nor for clinical status )P=.10, P=.11, and P=.51, respectively). Neither tolerability to molsidomine nor effectiveness of the drug was biased by concomitant antianginal therapies, insofar as none of these parameters showed a significant treatment type (ie, molsidomine administered as monotherapy or add-on therapy)-time interaction (VAS for tolerability: P=.44; angina: P=.39; nitroderivatives: P=.72; VAS for clinical status: P=.62). Molsidomine 16 mg QD administered for 1 y to patients with stable angina was well tolerated and remained effective during the entire treatment period, independent of age and concomitant antianginal therapy.

The challenge of real-time measurements of nitric oxide release in the brain

Nitric oxide (NO) acts as a signalling molecule in the brain. NO has been implicated in a variety of central functions such as learning, plasticity and neurodegeneration. It is also involved in regulation of autonomic homeostasis at different levels of neuraxis including the nucleus tractus solitarii. In spite of the ample evidence for NO-mediated signalling many aspects of its mechanism of action the brain remain unknown largely due to the difficulties of NO detection in real time coupled with its unique ability to freely cross cellular membranes. Here we give a brief overview of the currently available options for NO detection in the brain (such as electrochemistry, fluorescent indicators, electron-paramagnetic resonance) and consider some of their limitations. We conclude that it would be extremely useful to develop a highly sensitive probe for NO detection with some kind of build-in amplification which would magnify the changes triggered by NO to allow its detection within microdomains of the brain tissue in real time.

Peroxynitrite induces an alternative NF-kappaB activation pathway in L8 rat myoblasts

The role of peroxynitrite in NF-kappaB activation remains controversial. This study investigated NF-kappaB activation by peroxynitrite in skeletal myocytes. Myocytes were treated with NO and peroxynitrite donors. Both NO and peroxynitrite caused NF-kappaB activation (measured by p65 nuclear translocation and luciferase expression). NO donor-induced NF-kappaB activation was transient, dependent on I-kappaB alpha degradation, and was decreased in the presence of I-kappaB alpha super-repressor. Conversely, peroxynitrite donors induced NF-kappaB activation that was dependent on tyrosine nitration of I-kappaB alpha, but independent of its serine phosphorylation and degradation. This activation did not decrease in the presence of I-kappaB alpha super-repressor. Prolonged exposure to peroxynitrite resulted in nontransient NF-kappaB activation and high iNOS expression. Proteasome inhibitor MG-132 did not diminish SIN-1-induced NF-kappaB activation. Tyrosine nitration inhibitor EGCG re-established transient NF-kappaB activation with I-kappaB alpha degradation after SIN-1 treatment. EGCG, but not MG-132 decreased SIN-1- dependent iNOS expression. Peroxynitrite activates NF-kappaB in skeletal myocytes through an alternative mechanism, in which I-kappaB alpha is nitrated on tyrosine and dissociated from NF-kappaB, thus enabling its nontransient activation. This resulted in prolonged iNOS expression. Hence, peroxynitrite may exacerbate inflammatory responses mediated by NF-kappaB.

Efficacy and safety of once- and twice-daily formulations of molsidomine in patients with stable angina pectoris: double-blind and open-label studies

Molsidomine, a sydnonimine acting as a heterocyclic direct nitric oxide donor, has been used for many years in several European countries for the treatment of patients with stable angina pectoris. The efficacy and tolerability of a novel once-daily 16-mg formulation of molsidomine (M16) were compared with those of the currently used twice-daily 8-mg molsidomine tablet (M8) in 666 patients. Study 1, a multicenter, randomized, double-blind, placebo-controlled, twin crossover study, involved 533 patients given acute and 2-week treatment with each drug formulation. Study 2, a multicenter, open-label, sequential, add-on trial, compared M16 and M8 in 133 patients. Drug effects on exercise capacity (study 1 only), frequency of anginal attacks and consumption of short-acting itroderivatives, and incidence of adverse events (AEs) were evaluated. Compared with placebo, M16 increased exercise capacity by 15% (P<.001) at the start of study 1 and by 13% (P<.001) after 2 weeks' treatment, and was not inferior to M8. In terms of anginal attack frequency and nitroderivative consumption, M16 was not inferior to M8 in either study. Moreover, compared with M8, M16 produced a statistically and clinically significant reduction in the incidence of anginal attacks in elderly (>/=75 y) but not in younger patients (<75 y) (study 2), nor in patients from study 1. No significant difference from M8 was found in either study in short-acting nitroderivative consumption. No tolerance to M8 or M16 was observed after 2-week treatment. No statistically significant differences in incidences of all AEs and drug-related AEs were observed between M16 and M8 in either study. The same held true for proportions of patients experiencing AEs and drug-related AEs on M16 vs M8: in study 1-14.3% and 11.8% for all AEs (P=.218), 6.9% and 5.4% for drug-related AEs (P=.280); in study 2-1.3% and 1.3% for all AEs, 0% and 1.3% for drug-related AEs (P>.10) in young patients; and in the elderly, 3.6% and 0% for drug-related AEs (P>.10). Only the proportion of elderly patients with all AEs was significantly higher with M16 than with M8: 14.5% vs 1.8% (P=.039). M16 once daily was effective and well tolerated in investigated patients with stable angina pectoris, particularly the elderly, affording 24 hours of therapeutic activity. M16 was not inferior to M8 given twice daily in terms of efficacy, safety profile, and tolerability.

Nitric oxide stimulates the erythrocyte for ascorbate recycling

S-Nitrosothiols act as carrier and reservoir of nitric oxide (NO), and release NO under stimulation of ascorbate (Asc). Erythrocyte can regenerate Asc from its oxidised products, thus saving this powerful antioxidant. In this paper the effect of donors of NO, superoxide, and peroxynitrite (SpNONOate, KO(2), and SIN-1, respectively) on the erythrocyte production of Asc was investigated. We report here that NO stimulated, while superoxide and peroxynitrite decreased, the Asc recycling. The NO-stimulating effect on the erythrocyte production of Asc was confirmed by using GSNO, a natural occurring S-nitrosothiol, as NO donor. These data highlight a new property of NO, that is the stimulation of erythrocytes for their Asc recycling. Such a property might contribute to regenerate Asc from its oxidised forms, thus preventing its depletion in the circulation. Temperature and pH significantly affected, both in absence and presence of NO, the recycling of Asc by erythrocytes. We propose that a positive feedback, involving the reciprocal stimulation between Asc and S-nitrosothiols, might enhance productions of Asc by erythrocytes and NO release by circulating S-nitrosothiols.