Inhaled pan-phosphodiesterase inhibitors ameliorate ovalbumin-induced airway inflammation and remodeling in murine model of allergic asthma.

Asthma is a heterogeneous, chronic respiratory disease characterized by airway inflammation and remodeling. Phosphodiesterase (PDE) inhibitors represent one of the intensively studied groups of potential anti-asthmatic agents due to their affecting both airway inflammation and remodeling. However, the effect of inhaled pan-PDE inhibitors on allergen induced asthma has not been reported to date. In this study we investigated the impact of two, representative strong pan-PDE inhibitors from the group of 7,8-disubstituted derivatives of 1,3-dimethyl-3,7-dihydro-1H-purine-2,6-dione: compound 38 and 145, on airway inflammation and remodeling in murine model of ovalbumin (OVA)-challenged allergic asthma. Female Balb/c mice were sensitized and challenged with OVA, 38 and 145 were administrated by inhalation, before each OVA challenge. The inhaled pan-PDE inhibitors markedly reduced the OVA-induced airway inflammatory cell infiltration, eosinophil recruitment, Th2 cytokine level in bronchoalveolar lavage fluid, as well as both, total and OVA-specific IgE levels in plasma. In addition, inhaled 38 and 145 decreased many typical features of airway remodeling, including goblet cell metaplasia, mucus hypersecretion, collagen overproduction and deposition, as well as Tgfb1, VEGF, and α-SMA expression in airways of allergen challenged mice. We also demonstrated that both 38 and 145 alleviate airway inflammation and remodelling by inhibition of the TGF-ß/Smad signaling pathway activated in OVA-challenged mice. Taken together, these results suggest that the investigated pan-PDE inhibitors administered by inhalation are dual acting agents targeting both airway inflammation and remodeling in OVA-challenged allergic asthma and may represent promising, anti-asthmatic drug candidates.

E2027 Cardiac Safety Evaluation With Concentration-Response Modeling of ECG Data to Inform Dose Selection in Studies in Patients With Dementia With Lewy Bodies.

BACKGROUND: E2027 is a novel, highly selective and potent inhibitor of phosphodiesterase 9 in development for dementia with Lewy bodies. Cardiac safety assessments for emerging agents are essential to avoid drug-induced QT interval prolongation, which may predispose individuals to potentially fatal ventricular arrhythmias. To evaluate the cardiac safety of E2027 and to inform dose selection for the phase 2 study of E2027 in dementia with Lewy bodies, we evaluated concentration-response modeling of pooled electrocardiogram data. PATIENTS AND METHODS: A post hoc concentration-QTc analysis evaluated potential QT effects using data from 2 randomized, double-blind studies in healthy subjects: a single ascending dose (SAD) study and a multiple ascending dose (MAD) study. Daily E2027 doses ranged from 5 to 1200 mg. RESULTS: A linear mixed-effects model was used to establish the relationship between plasma concentrations of E2027 and change from the baseline of QTcF (ΔQTcF). A significant but shallow relationship was observed in the estimated slope of the concentration-ΔQTcF: 0.002 ms/ng/mL (90% confidence interval: 0.0007-0.0031) with a small, nonsignificant treatment effect-specific intercept of -0.6 ms. Based on this pooled concentration-QTc analysis, an effect on the QTcF interval >10 ms can be excluded up to E2027 plasma concentrations of ∼3579 ng/mL, corresponding to a dose at least 4-fold larger than the 50 mg phase 2 dose. CONCLUSION: This pooled post hoc analysis evaluating cardiac safety of E2027 demonstrated that clinically concerning QTcF prolongation and related cardiac complications are highly unlikely with proposed E2027 doses planned for phase 2.

Vinpocetine ameliorates developmental hyperserotonemia induced behavioral and biochemical changes: role of neuronal function, inflammation, and oxidative stress.

Hyperserotonemia, during the early developmental phase, generates behavioral and biochemical phenotypes associated with autism spectrum disorder (ASD) in rats. Phosphodiesterase­1 (PDE1) inhibitors are known to provide benefits in various brain conditions. We investigated the role of a selective PDE1 inhibitor, vinpocetine on ASD­related behavioral phenotypes (social behavioral deficits, repetitive behavior, anxiety, and hyperlocomotion) in a developmental hyperserotonemia (DHS) rat model. Also, effects on biochemical markers related with neuronal function brain derived neurotrophic factor (BDNF) and phosphorylated cAMP response element binding protein (pCREB), inflammation interleukins (IL­6 and IL­10) and tumor necrosis factor-alpha (TNF­α), and oxidative stress (TBARS and GSH) were studied in important brain areas (frontal cortex, cerebellum, hippocampus, and striatum). Administration of 5­methoxytryptamine (5­MT) to rats prenatally (gestational day 12) and in early developmental stages postnatal day (PND 0 - PND 20), resulted in impaired behavior and brain biochemistry. Administration of vinpocetine daily (10 and 20 mg/kg) to 5­MT rats from PND 21 to PND 48 resulted in an improvement of behavioral deficits. Also, vinpocetine administration significantly increased the levels of BDNF, ratio of pCREB/ CREB, IL­10, and GSH, and significantly decreased TNF­α, IL­6, and TBARS levels in different brain areas. Finally, our correlation analysis indicated that behavioral outcomes were significantly associated with the biochemical outcome. Vinpocetine, a selective PDE1 inhibitor, rectified important behavioral phenotypes related with ASD, possibly by improving markers of neuronal function, brain inflammation, and brain oxidative stress. Thus, PDE1 could be a potential target for pharmacological interventions and furthering our understanding of ASD pathogenesis.

Psychosis beas a rare side effect of sildenafil: a case report.

BACKGROUND: Sildenafil citrate is a commonly used medication for the management of erectile dysfunction. Previous studies have described some neuropsychiatric side effects of this medication. So far, however, there has been little discussion about sildenafil-induced psychosis. CASE PRESENTATION: We here present the case of a 32-year-old Iranian male, without a known psychiatric history, who developed psychotic symptoms following initiation of sildenafil. We also postulate a mechanism by which this may occur. CONCLUSIONS: This report highlights the importance of watchful observation for the occurrence of this rare but serious side effect. Further studies are needed to clarify the precise mechanism that causes sildenafil-induced psychosis.

Do commonly used prostate medications alter prostate MRI and fusion biopsy performance?

AIMS: To determine whether phosphodiesterase inhibitors (PDEi) or α-antagonists (AA) were associated with differences in region of interest (ROI) characteristics or prostate cancer detection on fusion biopsy (FB). MATERIALS AND METHODS: Records from 847 consecutive patients undergoing FB at three separate institutions over a period of 2 years were retrospectively reviewed. Associations between medication use, Prostate Imaging Reporting & Data System (PIRADS) scores, and ROI locations were assessed with ordinal logistic regression. Associations with lesion size and International Society of Urologic Pathology (ISUP) grade group (GG) on biopsy were tested using multivariate regression. RESULTS: Medication use included PDEi in 14.2% and AA in 23.0%. PDEi use was associated with 19.3% smaller lesion diameter (-2.8 mm; CI from -4.8 to -0.7; p < 0.01) and lower PIRADS scores on MRI (OR 0.60; CI 0.40 - 1.00; p = 0.05). AA use was associated with higher PIRADS scores (OR 1.43; CI 0.97 - 2.11; p = 0.06), fewer positive fusion-directed biopsy cores (-28.6%, CI from -57.9 to 0.01%, p = 0.05), and downgrading on final pathology (-19%; CI from -40 to 2%; p = 0.06). CONCLUSION: For PIRADS scores ≥ 3, PDEi use is associated with smaller ROI and lower PIRADS scores, while AA use is associated with higher PIRADS scores. Neither medication was associated with differences in biopsy GG. Prospective studies are needed to investigate the discordance between multi-parametric magnetic resonance imaging (mpMRI) results and oncologic outcomes associated with PDEi and AA use.

A randomized controlled trial comparing the effects of Vitamin E, Ursodeoxycholic acid and Pentoxifylline on Egyptian non-alcoholic steatohepatitis patients.

OBJECTIVE: Currently, no NASH-specific therapies are approved by the US Food and Drug Administration. This study aimed to compare the clinical effect of vitamin E (Vit. E), Ursodeoxycholic Acid (UDCA) and pentoxifylline (PTX) on Egyptian patients with NASH with exploration of their possible roles on inflammatory cytokines and chemokines mainly Interleukin 6 (IL6) and Monocyte Chemoattractant Protein-1 (CCL2/MCP-1). PATIENTS AND METHODS: We conducted a 3-month, randomized, single-blind study in 102 Egyptian NASH patients who were divided into three groups; group 1 received Vit. E 400 mg twice a day, group 2 received UDCA 250 mg twice a day and group 3 received PTX 400 mg twice daily. Liver aminotransferases (AST, ALT), IL6, CCL2/MCP-1, albumin, bilirubin, and lipid panel were measured both before and after intervention intake. RESULTS: A significant decrease was found in liver aminotransferases, serum cytokine and chemokine in participants after Vit. E, UDCA or PTX intake. Compared to the UDCA and PTX groups, liver aminotransferases, serum cytokine and chemokine showed a more statistically significant reduction after Vit. E administration (50%, 43%, 57% and 55% for ALT, AST, IL6 and CCL2/MCP-1, respectively). In contrast, other biochemical tests showed non-significant change after any drug intake. None of the tested drugs showed significant safety issues in this population. CONCLUSIONS: Treatment with Vit. E, UDCA and PTX was both safe and effective in improving hepatic aminotransferases and inflammatory markers in Egyptian NASH patients. The superior effect of Vit. E compared to UDCA and PTX may suggest that oxidative stress plays a key role in disease progression of NASH patients. Moreover, IL6 and CCL2/MCP-1 may be used with or without ALT for treatment evaluation of NASH people.

Safety, tolerability, and pharmacokinetics of the novel pan-phosphodiesterase inhibitor ZSP1601 in healthy subjects: a double-blinded, placebo-controlled first-in-human single-dose and multiple-dose escalation and food effect study.

Background: The pharmacokinetics (PK), safety, and tolerability profiles of ZSP1601, a first-in-class pan-phosphodiesterase (PDE) inhibitor, were evaluated in healthy Chinese volunteers.Research design and methods: This Phase 1a study consisted of a double-blinded, randomized, placebo-controlled single ascending dose (SAD) (25 to 350 mg), multiple ascending doses (MAD) (50 or 100 mg QD), and a two-period crossover food effect study (100 mg).Results: ZSP1601 was quickly absorbed, with maximum plasma concentrations (Cmax) reached at 1.25 to 2.50 h (median Tmax). The exposures exhibited dose-proportional increases, while the mean half-life (t1/2) ranged from 6.34-8.64 h. Steady-state was reached within seven days in the MAD study. The mean steady trough concentrations were 423 and 588 ng/mL, respectively. ZSP1601 accumulation was low, with ratios ≤ 1.5. The bioavailability of ZSP1601 was equivalent under fasted and fed states. All adverse events (AEs) were assessed as mild or moderate, with headaches as the most common. The highest single doses (275 and 350 mg) yielded more AEs, yet the rates were similar with the placebo cohorts in the MAD study.Conclusions: The safety and PK profiles of ZSP1601 support further efficacy evaluation in nonalcoholic steatohepatitis patients.Trial registration: The trial is registered at ClinicalTrials.gov (CT.gov identifier: NCT03392779).

An update of cyclic nucleotide phosphodiesterase as a target for cardiac diseases.

INTRODUCTION: Cyclic nucleotides, cAMP, and cGMP, are important second messengers of intracellular signaling and play crucial roles in cardiovascular biology and diseases. Cyclic nucleotide phosphodiesterases (PDEs) control the duration, magnitude, and compartmentalization of cyclic nucleotide signaling by catalyzing the hydrolysis of cyclic nucleotides. Individual PDEs modulate distinct signaling pathways and biological functions in the cell, making it a potential therapeutic target for the treatment of different cardiovascular disorders. The clinical success of several PDE inhibitors has ignited continued interest in PDE inhibitors and in PDE-target therapeutic strategies. AREAS COVERED: This review concentrates on recent research advances of different PDE isoforms with regard to their expression patterns and biological functions in the heart. The limitations of current research and future directions are then discussed. The current and future development of PDE inhibitors is also covered. EXPERT OPINION: Despite the therapeutic success of several marketed PDE inhibitors, the use of PDE inhibitors can be limited by their side effects, lack of efficacy, and lack of isoform selectivity. Advances in our understanding of the mechanisms by which cellular functions are changed through PDEs may enable the development of new approaches to achieve effective and specific PDE inhibition for various cardiac therapies.

The immunomodulatory role of PDEs inhibitors in immune cells: therapeutic implication in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by inflammatory synovitis and progressive joint. Although the etiology is extremely complex, overwhelming evidence suggests that dysregulation or imbalance of the immune system plays a central role in disease pathogenesis. The bone loss and joint destruction are immunological insults mediated by infiltration and abnormal activation of various immune cells. Since pharmacological inhibition of cyclic nucleotide phosphodiesterases (PDEs), which degrade cyclic AMP and cyclic GMP, can regulate the activity of multiple immune cells, which are considered as a potential strategy for treating RA. Therefore, this review attempted to summarize the modulating effects of PDEs on immune cells and described the molecular underpinnings and potential clinical application of PDEs inhibitors for RA.

Translational Development Strategies for TAK-063, a Phosphodiesterase 10A Inhibitor.

BACKGROUND: TAK-063 is an inhibitor of phosphodiesterase 10A (PDE10A), an enzyme highly expressed in medium spiny neurons of the striatum. PDE10A hydrolyzes both cyclic adenosine monophosphate and cyclic guanosine monophosphate and modulates dopamine signaling downstream of receptor activation in both direct and indirect pathways of the striatum. TAK-063 exhibited antipsychotic-like effects in animal models; however, the translatability of these models to the clinical manifestations of schizophrenia and the meaningfulness for new targets such as PDE10A has not been established. METHODS: The TAK-063 phase 1 program included a comprehensive translational development strategy with the main objective of determining whether the antipsychotic-like pharmacodynamic effects seen in nonclinical models would translate to human subjects. To evaluate this objective, we conducted a single-rising dose study (84 healthy subjects), a positron emission tomography (PET) study (12 healthy subjects), a functional magnetic resonance imaging blood oxygen level-dependent (BOLD) study (27 healthy subjects), and a multiple-rising dose study that included people with schizophrenia (30 healthy Japanese subjects and 47 subjects with stable schizophrenia). In addition, assessments of cognition and electroencephalography (27 healthy subjects and 47 subjects with stable schizophrenia) were included. RESULTS: PDE10A engagement by TAK-063 was verified with a novel PET radiotracer for use in primates and humans. TAK-063 showed favorable pharmacokinetic and safety profiles in humans, and TAK-063 reduced ketamine-induced changes in electroencephalography and BOLD signaling in animal models and healthy human subjects. In addition, analogous effects on cognition were observed in animal models and human subjects. CONCLUSIONS: Overall, the phase 1 results showed some consistent evidence of antipsychotic activity. This translational strategy may be valuable for the future development of novel therapeutic approaches, even when relevant nonclinical models are not available.

Combination of the phosphodiesterase 10A inhibitor, MR1916 with risperidone shows additive antipsychotic-like effects without affecting cognitive enhancement and cataleptic effects in rats.

AIM: Phosphodiesterase 10A (PDE10A) inhibitors not only have antipsychotic-like effects but also cause cognitive enhancement without affecting extrapyramidal side effects in rodents, suggesting that PDE10A may be a novel approach for the treatment of schizophrenia. However, how a combination of PDE10A inhibitor with a currently available antipsychotic drug, risperidone contributes to the effect of each compound in rats remains unclear. The purpose of the present study was to examine the combination effects of MR1916 with a currently available antipsychotic drug, risperidone, in rats. METHODS: We examined the combination effects of the PDE10A inhibitor, MR1916 with risperidone on conditioned avoidance response (CAR) to assess antipsychotic-like effects in rats. We also examined them on catalepsy as extrapyramidal side effects and novel object recognition test in cognitive functions in rats. RESULTS: MR1916 (0.025-0.2 mg/kg, p.o.) and risperidone (0.75-6 mg/kg, p.o.) alone attenuated the CAR in a dose-dependent manner. The combination of MR1916 (0.025 mg/kg, p.o.) with risperidone (0.75 mg/kg, p.o.) significantly enhanced the attenuation of CAR without increasing the escape failure response. At the same dosage, the cataleptic effects were not enhanced by combined treatment of MR1916 with risperidone. Furthermore, the enhancement of object recognition memory induced by MR1916 (0.3 mg/kg, p.o.) was not affected by the combination with risperidone (0.75 mg/kg, p.o.). CONCLUSION: The combination of MR1916 with risperidone may have additive antipsychotic-like effects without affecting extrapyramidal side effects, and the cognitive-enhancing effect of MR1916 may not be interfered with the addition of risperidone.

Prior Antiplatelet Therapy, Excluding Phosphodiesterase Inhibitor Is Associated with Poor Outcome in Patients with Spontaneous Intracerebral Haemorrhage.

There is conflicting results on whether prior antiplatelet therapy (APT) is associated with poor outcome in spontaneous intracerebral haemorrhage (ICH) patients. To determine whether prior APT is associated with spontaneous ICH, and whether there is a difference between the different types of APT, including cyclooxygenase inhibitor (COX-I), adenosine diphosphate receptor inhibitor (ADP-I) and phosphodiesterase inhibitor (PDE-I). A retrospective study of patients with ICH diagnosed between 2001 and 2013 in the National Health Insurance Research Database. Baseline unbalance between APT and non-APT groups was solved by multivariable adjustment (primary analysis) and propensity score matching (sensitivity analysis). Patients with prior APT had a higher rate of in-hospital death (odds ratio [OR], 1.16; 95% confidence interval [CI], 1.09-1.23) compared to non-APT group. Compared to non-APT group, there was a greater rate of in-hospital death with spontaneous ICH with ADP-I (OR, 1.49; 95% CI, 1.24-1.79) and COX-I (OR, 1.17; 95% CI, 1.09-1.25). PDE-I exhibited no difference in in-hospital death with spontaneous ICH (OR, 1.03; 95% CI, 0.91-1.16) compared to non-APT group. Remarkably, the in-hospital mortality rate was significantly higher in the ADP-I group than in the PDE-I group (hazard ratio, 1.45; 95% CI, 1.17-1.80). In this study, ADP-I and COX-1, but not PDE-I, are the most likely contributors to the association of APT with poor outcome with spontaneous ICH patients. These findings suggest that the complexity of the different mechanism of actions of prior APT can alter the outcome in spontaneous ICH.

Phosphodiesterase 10A Inhibitor Monotherapy Is Not an Effective Treatment of Acute Schizophrenia.

BACKGROUND: Current treatments for psychotic symptoms associated with schizophrenia often provide inadequate efficacy with unacceptable adverse effects. Improved therapeutics have long been a goal of research. Preclinical testing suggests that phosphodiesterase 10A (PDE10A) inhibitors may provide a novel approach to treating psychosis associated with schizophrenia. METHODS: The efficacy and safety of a highly selective PDE10A inhibitor, PF-02545920, was evaluated in a phase 2 multicenter, randomized, double-blind, placebo-controlled, parallel-group study. Eligible patients (18-65 years) with an acute exacerbation of schizophrenia were randomized 2:2:1:2 to PF-02545920 (5 or 15 mg every 12 hours [Q12H] titrated), risperidone (3 mg Q12H), or placebo for 28 days (n = 74:74:37:74). The primary objectives were to evaluate the efficacy of PF-02545920 using the Positive and Negative Syndrome Scale (PANNS) and safety/tolerability. RESULTS: At day 28, PF-02545920 (either dose) was not significantly different from placebo for mean change from baseline in the PANNS total score (primary end point) or most other end points. Pharmacokinetics exposures seemed adequate for binding/inhibiting PDE10A enzyme. Risperidone was statistically different from placebo for the PANNS total score, demonstrating study sensitivity. Incidence rates for adverse events were similar among the groups. Both doses of PF-02545920 were generally well tolerated. Dystonia occurred in 1, 6, 0, and 3 patients in the PF-02545920 5 mg Q12H, PF-02545920 15 mg Q12H, risperidone, and placebo groups, respectively. CONCLUSIONS: Neither dose of PF-02545920 was superior to placebo for the primary and most secondary end points. This indicates that PDE10A inhibition does not produce an antipsychotic effect in patients with acute exacerbation of schizophrenia.

Pentoxifylline and vitamin E reduce the severity of radiotherapy-induced oral mucositis and dysphagia in head and neck cancer patients: a randomized, controlled study.

The purpose of this study was to assess the impact of pentoxifylline and vitamin E on the incidence and severity of radiotherapy-induced oral mucositis and dysphagia in head and neck cancer patients. This is a prospective, randomized, controlled study. Head and neck cancer patients receiving 30-35 radiotherapy fractions with or without concurrent chemotherapy excluding those intolerant to xanthines, with any bleeding tendency were included. Sixty patients were enrolled; 30 patients received radiotherapy (control group) and 30 patients received radiotherapy with pentoxifylline and vitamin E (intervention group). The incidence, severity, onset and duration of oral mucositis and/or dysphagia were assessed. Locoregional control, quality of life, need for hospitalization, radiotherapy breaks, and adverse events were recorded and compared between groups. Pentoxifylline and vitamin E combination did not affect the incidence or the onset of oral mucositis or dysphagia. After adjusting for age, the combination reduced the incidence of severe oral mucositis (p = 0.01) and dysphagia (p = 0.012). The combination decreased the duration of oral mucositis and dysphagia by 5 weeks (p = 0.002) and 4 weeks (p = 0.003), respectively. The study drugs reduced the need for hospitalization (p = 0.002) and for radiotherapy breaks (p = 0.002) with improvement of FOIS (p = 0.014), EQ-5D index (p = 0.009) and VAS score (p = 0.012). Pentoxifylline and vitamin E decreased the occurrence of dysgeusia (p = 0.026) and fatigue (p = 0.026) without compromising locoregional control. Pentoxifylline/vitamin E combination reduced the severity and duration of acute radiotherapy-induced oral mucositis and dysphagia in head and neck cancer patients.Trial registry ClinicalTrials.gov registration number: NCT02397486.

Pentoxifylline, progression of chronic kidney disease (CKD) and cardiovascular mortality: long-term follow-up of a randomized clinical trial.

BACKGROUND: Pentoxifylline could reduce proteinuria and slow renal disease progression. We previously conducted a single-blind, randomized, controlled trial that showed that pentoxifylline decreases inflammatory markers and stabilizes renal function. SETTING AND PARTICIPANTS: 91 participants (46 in the pentoxifylline group and 45 in the control group) followed up for 7 additional years. STUDY DESIGN: Post hoc analysis of a long-term follow-up after completion of the 12-months trial. INTERVENTION: Pentoxifylline treatment (400 mg/twice a day) or standard treatment. OUTCOME: Renal event (defined as starting dialysis therapy and/or doubling serum creatinine and/or ≥ 50% decrease in estimated glomerular filtration rate) and cardiovascular mortality. RESULTS: During follow-up, a renal event was recorded in 24 patients from control group (13 initiated dialysis therapy and serum creatinine doubled in 11) and 11 patients from PTF group (7 initiated dialysis and serum creatinine doubled in 4) (log Rank: 5.822, p = 0.016). The possible protector effect of PTF was more significant in albuminuric patients and was independently of diabetes mellitus presence. Treatment with PTF reduced the renal events by 35% compared to the control group in a Cox model adjusted for diabetes mellitus, albuminuria and basal renal function (HR 0.65 (0.45-0.94), p = 0.022). Cardiovascular mortality was significantly reduced in PTF treatment (2 patients vs. 10 in control group) (log Rank 5.0977, p = 0.024). PTF treatment reduced cardiovascular mortality in 55% adjusted for diabetes mellitus and age (HR 0.45 (0.21-0.98), p = 0.044) (Table 3). LIMITATIONS: Small sample size, single center, not double blind and post hoc follow-up analysis. CONCLUSIONS: Long-term treatment with pentoxifylline may slow the rate of progression of kidney disease and reduce cardiovascular risk.

The Potential Role of Arginine Supplements on Erectile Dysfunction: A Systemic Review and Meta-Analysis.

INTRODUCTION: The efficacy and safety of arginine supplements in erectile dysfunction (ED) remain debatable. AIM: To assess the potential role of arginine supplements on ED as alternatives to phosphodiesterase inhibitors. METHODS: Studies published up to April 2018 that evaluated the efficacy of arginine supplements were identified from multiple databases (Google Scholar, PubMed, Medline, Embase, Kiss, DBpia, and Cochrane databases). Studies comparing arginine supplements with placebo or no treatment; focusing only on patients with mild to moderate severity of ED; and presenting outcomes such as improvement rate, International Index of Erectile Function (IIEF) score, and adverse effects were included. Subgroup analysis for arginine alone and arginine in combination with other substances was further conducted to increase interpretability. MAIN OUTCOME MEASURE: The strength of the association between arginine supplements and ED was assessed using relative odds ratios and weighted mean differences with 95% CI. RESULTS: In total, 10 randomized controlled trials met the inclusion criteria, reporting the outcomes of 540 patients with ED. The analysis demonstrated that arginine supplements with dosage ranging from 1,500 to 5,000 mg significantly improved ED compared with placebo or no treatment (odds ratios, 3.37 [1.29, 8.77], P = .01, I2 = 44). Arginine supplements also caused significant improvements in the IIEF subdomain scores of overall satisfaction, intercourse satisfaction, orgasmic function, and erectile function, whereas the IIEF sexual desire score remain unchanged. The adverse effect rate in the arginine-treated group was 8.3%, and that in the placebo group was 2.3%, none of which were severe. CLINICAL IMPLICATIONS: Arginine supplements can be recommended to patients with mild to moderate ED. STRENGTH & LIMITATIONS: The strength of this study is that it is the first meta-analysis to assess the potential role of arginine supplements in ED compared with placebo or no treatment. A limitation is that the treatment dosage and duration varied among studies, which may have contributed to study heterogeneity. CONCLUSION: The results of our systematic review and meta-analysis provide evidence on the effectiveness of arginine supplements for mild to moderate ED. Rhim HC, Kim MS, Park Y-J, et al. The Potential Role of Arginine Supplements on Erectile Dysfunction: A Systemic Review and Meta-Analysis. J Sex Med 2019;16:223-234.

Experimental and investigational phosphodiesterase inhibitors in development for asthma.

INTRODUCTION: Severe, inadequately-controlled asthma remains a clinical challenge. For this reason, clinical trials and preclinical experimental studies on novel agents as an add-on therapies continue emerge. Phosphodiesterases (PDEs) are enzymes that regulate the function of immune cells by hydrolyzing cyclic guanosine monophosphate/cGMP and cyclic adenosine monophosphate/cAMP. PDEs are divided into subfamilies [PDE3, PDE4, PDE5 and PDE7] which are mainly found in the respiratory tract. Inhibitors of PDEs have already been approved for COPD and pulmonary hypertension. AREAS COVERED: The role of PDE inhibitors in asthma treatment and the possible mechanism of action via their anti-inflammatory and/or bronchodilating effect are discussed. EXPERT OPINION: Novel PDE inhibitors exhibiting fewer adverse events may have a role as add-on therapies in asthma treatment in the future. More clinical trials are necessary to prove their efficacy and evaluate their safety profile before approval by regulatory bodies is granted.

PF-04447943, a Phosphodiesterase 9A Inhibitor, in Stable Sickle Cell Disease Patients: A Phase Ib Randomized, Placebo-Controlled Study.

This phase Ib study randomized patients with stable sickle cell disease (SCD) aged 18-65 years to twice-daily PF-04447943 (a phosphodiesterase 9A inhibitor; 5 or 25 mg) or placebo, with/without hydroxyurea coadministration, for up to 29 days. Blood samples were collected at baseline and various posttreatment time points for assessments of PF-04447943 pharmacokinetics (PKs)/pharmacodynamics (PDs). Change from baseline in potential SCD-related biomarkers was evaluated. Of 30 patients, 15 received hydroxyurea and 28 completed the study. PF-04447943, with/without hydroxyurea, was generally well tolerated, with no treatment-related serious adverse events. Plasma PF-04447943 exposure was dose proportional. Twice-daily PF-04447943 25 mg significantly reduced the number and size of circulating monocyte-platelet and neutrophil-platelet aggregates and levels of circulating soluble E-selectin at day 29 vs. baseline (adjusted P < 0.15). PF-04447943 demonstrated PK/PD effects suggestive of inhibiting pathways that may contribute to vaso-occlusion. This study also provides guidance regarding biomarkers for future SCD studies.