Single-dose Tadalafil Reduces Opening Urethral Pressure: A Randomized, Double-blind, Placebo-controlled, Crossover Trial in Healthy Women.

INTRODUCTION AND HYPOTHESIS: Phosphodiesterase enzymes are widely distributed in female urogenital tissues. Yet, the understanding of their physiological roles and the impact of phosphodiesterase inhibitors on lower urinary tract symptoms in women remains limited. Current hypotheses are conflicting: one suggests that vasodilation might expand the periurethral vascular plexus, leading to increased urethral pressure, whereas the other proposes a relaxation of urethral musculature, resulting in decreased pressure. To further clarify this, we investigated the effect of tadalafil on the opening urethral pressure and voiding function in healthy women. METHODS: We conducted a randomized, double-blind, placebo-controlled crossover trial involving 24 healthy women. Participants were randomly assigned to receive a single dose of tadalafil (40 mg) or placebo during their initial visit and then switched to the alternative treatment during their second visit. Opening urethral pressure was measured with urethral pressure reflectometry during both resting and squeezing conditions of the pelvic floor. Subsequently, voiding parameters were recorded. RESULTS: Compared with placebo, a single dose of tadalafil significantly reduced opening urethral pressure during both resting (-6.8 cmH20; 95% confidence interval [CI], -11.8 to -1.9; p = 0.009) and squeezing conditions (-8.8 cmH20; 95% CI, -14.6 to -3.1; p = 0.005). Voiding parameters did not show significant differences (average flow rate: -0.8 ml/s [95% CI, -2.0 to 0.4; p = 0.2]; maximum flow rate: -1.7 ml/s [95% CI, -4.8 to 1.5; p = 0.3]). CONCLUSIONS: A single dose of 40 mg tadalafil moderately reduced urethral pressure in healthy women, without affecting voiding parameters. The clinical implications of this are yet to be determined.

Enhancement of the Clastogenic Effects of Topotecan In Vivo by Tyrosyl-DNA Phosphodiesterase 1 Inhibitors.

Topotecan administered intraperitoneally at single doses of 0.25, 0.5, and 1 mg/kg induced chromosomal aberrations in bone marrow cells of F1(CBA×C57BL/6) hybrid mice in a dose-dependent manner. A tyrosyl-DNA phosphodiesterase 1 (TDP1) inhibitor, an usnic acid derivative OL9-116 was inactive in a dose range of 20-240 mg/kg, but enhanced the cytogenetic effect of topotecan (0.25 mg/kg) at a dose of 40 mg/kg (per os). The TDP1 inhibitor, a coumarin derivative TX-2552 (at doses of 20, 40, 80, and 160 mg/kg per os), increased the level of aberrant metaphases induced by topotecan (0.25 mg/kg) by 2.1-2.6 times, but was inactive at a dose of 10 mg/kg. The results indicate that TDP1 inhibitors enhance the clastogenic activity of topotecan in mouse bone marrow cells in vivo and are characterized by different dose profiles of the co-mutagenic effects.

Vinpocetine, a phosphodiesterase 1 inhibitor, mitigates atopic dermatitis-like skin inflammation.

Atopic dermatitis (AD) is the most common inflammatory pruritic skin disease worldwide, characterized by the infiltration of multiple pathogenic T lymphocytes and histological symptoms such as epidermal and dermal thickening. This study aims to investigate the effect of vinpocetine (Vinp; a phosphodiesterase 1 inhibitor) on a 1-chloro-2,4-dinitrobenzene (DNCB)-induced AD-like model. DNCB (1%) was administered on day 1 in the AD model. Subsequently, from day 14 onward, mice in each group (Vinp-treated groups: 1 mg/kg and 2 mg/kg and dexamethasone- treated group: 2 mg/kg) were administered 100 µl of a specific drug daily, whereas 0.2% DNCB was administered every other day for 30 min over 14 days. The Vinp-treated groups showed improved Eczema Area and Severity Index scores and trans-epidermal water loss, indicating the efficacy of Vinp in improving AD and enhancing skin barrier function. Histological analysis further confirmed the reduction in hyperplasia of the epidermis and the infiltration of inflammatory cells, including macrophages, eosinophils, and mast cells, with Vinp treatment. Moreover, Vinp reduced serum concentrations of IgE, interleukin (IL)-6, IL-13, and monocyte chemotactic protein-1. The mRNA levels of IL-1ß, IL-6, Thymic stromal lymphopoietin, and transforming growth factor-beta (TGF-ß) were reduced by Vinp treatment. Reduction of TGF-ß protein by Vinp in skin tissue was also observed. Collectively, our results underscore the effectiveness of Vinp in mitigating DNCB-induced AD by modulating the expression of various biomarkers. Consequently, Vinp is a promising therapeutic candidate for treating AD.

Treating diabetes with combination of phosphodiesterase 5 inhibitors and hydroxychloroquine-a possible prevention strategy for COVID-19?

Type 2 diabetes (T2D) is one of the major risk factors for developing cardiovascular disease and the resultant devastating morbidity and mortality. The key features of T2D are hyperglycemia, hyperlipidemia, insulin resistance, and impaired insulin secretion. Patients with diabetes and myocardial infarction have worse prognosis than those without T2D. Moreover, obesity and T2D are recognized risk factors in developing severe form of COVID-19 with higher mortality rate. The current lines of drug therapy are insufficient to control T2D and its serious cardiovascular complications. Phosphodiesterase 5 (PDE5) is a cGMP specific enzyme, which is the target of erectile dysfunction drugs including sildenafil, vardenafil, and tadalafil. Cardioprotective effects of PDE5 inhibitors against ischemia/reperfusion (I/R) injury were reported in normal and diabetic animals. Hydroxychloroquine (HCQ) is a widely used antimalarial and anti-inflammatory drug and its hyperglycemia-controlling effect in diabetic patients is also under investigation. This review provides our perspective of a potential use of combination therapy of PDE5 inhibitor with HCQ to reduce cardiovascular risk factors and myocardial I/R injury in T2D. We previously observed that diabetic mice treated with tadalafil and HCQ had significantly reduced fasting blood glucose and lipid levels, increased plasma insulin and insulin-like growth factor-1 levels, and improved insulin sensitivity, along with smaller myocardial infarct size following I/R. The combination treatment activated Akt/mTOR cellular survival pathway, which was likely responsible for the salutary effects. Therefore, pretreatment with PDE5 inhibitor and HCQ may be a potentially useful therapy not only for controlling T2D but also reducing the rate and severity of COVID-19 infection in the vulnerable population of diabetics.

Effect of phosphodiesterase type 5 inhibitors on major adverse cardiovascular events and overall mortality in a large nationwide cohort of men with erectile dysfunction and cardiovascular risk factors: A retrospective, observational study based on healthcare claims and national death index data.

BACKGROUND: Treatment with phosphodiesterase type 5 inhibitors (PDE-5is) is effective in treating erectile dysfunction (ED). AIM: The objective of this study was to determine the effect of PDE-5is on the incidence of major adverse cardiovascular (CV) events (MACE; composite outcome of CV death, hospitalization for myocardial infarction, coronary revascularization, stroke, heart failure, and unstable angina pectoris) and overall mortality. METHODS: A retrospective observational cohort study was conducted in a large US claims database in men with ≥1 diagnosis of ED without prior MACE within 1 year, from January 1, 2006, to October 31, 2020. The exposed group had ≥1 claim for PDE-5i and the unexposed group had no claims for PDE-5i, and the groups were matched up to 1:4 on baseline risk variables. OUTCOME: The primary outcome was MACE and the secondary outcomes were overall mortality and individual components of MACE, determined by multivariable Cox proportional hazard modeling. RESULTS: Matched plus multivariable analyses showed that MACE was lower by 13% in men exposed (n = 23 816) to PDE-5is (hazard ratio [HR] 0.87; 95% CI 0.79-0.95; P = .001) vs nonexposure (n = 48 682) over mean follow-up periods of 37 and 29 months, respectively, with lower incidence of coronary revascularization (HR 0.85; 95% CI 0.73-0.98; P = .029), heart failure (HR 0.83; 95% CI 0.72-0.97; P = .016), unstable angina (HR 0.78; 95% CI 0.64-0.96; P = .021), and CV death (HR 0.61; 95% CI 0.41-0.90; P = .014) with PDE-5i exposure. Phosphodiesterase type 5 inhibitor-exposed men had a 25% lower incidence of overall mortality (HR 0.75; 95% CI 0.65-0.87; P < .001). Men without coronary artery disease (CAD) but with CV risk factors at baseline showed a similar pattern. In the main study cohort, men in the highest quartile of PDE-5i exposure had the lowest incidence of MACE (HR 0.45; 95% CI 0.37-0.54; P < .001) and overall mortality (HR 0.51; 95% CI 0.37-0.71; P < .001) vs the lowest exposure quartile. In a subgroup with baseline type 2 diabetes (n = 6503), PDE-5i exposure was associated with a lower MACE risk (HR 0.79; 95% CI 0.64-0.97; P = .022). CLINICAL IMPLICATIONS: PDE-5is may have cardioprotective effects. STRENGTHS AND LIMITATIONS: Strengths are the large numbers of participants and consistency of the data; limitations include the retrospective nature of the study and unknown confounders. CONCLUSIONS: In a large population of US men with ED, PDE-5i exposure was associated with lower incidence of MACE, CV death, and overall mortality risk compared to non-exposure. Risk reduction correlated with PDE-5i exposure level.

Postmicturition dribble in men with no previous urogenital surgery: Systematic review and meta-analysis of treatment modalities.

INTRODUCTION: Postmicturition dribble (PMD) is common in males. Little is known about PMD etiology, but it is either secondary to urethral/prostatic surgery or primary (no previous surgery). Despite PMD's high prevalence, the effectiveness of its treatment modalities remains lacking. OBJECTIVE: To undertake a systematic review of the available treatments for primary PMD in adult males and meta-analysis of their effectiveness. MATERIALS AND METHODS: We searched four electronic databases from inception to 2023 for original articles that evaluated PMD treatments in male adults without previous urethral/prostatic surgery (PROSPERO protocol CRD42023444591). Study quality and risk of bias were evaluated using established tools. We extracted a range of variables including treatment modality used and its effectiveness on PMD volume and patient complaint. Meta-analysis was undertaken where feasible, and where this was not feasible, narrative synthesis was conducted. RESULTS: Out of 335 studies, four were included (four clinical trials, n = 344 patients). Two trials used physical/behavioral therapy (pelvic floor muscle exercises [PFMEs], urethral milking); the other two employed phosphodiesterase (PDE5) inhibitors (tadalafil, Udenafil). All studies were of good quality, but physical/behavioral therapy studies had some risk of bias. As the two physical/behavioral therapy studies used heterogenous outcome measures, narrative synthesis showed PMD volume improvement with PFMEs more than with urethral milking, both modalities were more effective than counseling, and in one study, PFMEs were effective in reducing PMD self-reported complaint than counseling. Meta-analyses of the two PDE5 inhibitors studies showed a large effect size with high heterogeneity for decreased PMD volume favoring PDE5 inhibitors over placebo (g = -0.86, 95% confidence interval [CI] -1.75; 0.02, p = 0.05; I2 = 88%); and a significant improvement equivalent to -1.06 points on the Hallym PMD Questionnaire score with no discernable heterogeneity (95% CI -1.65; -0.47, p = 0.0004; I2 = 0%), favoring PDE5 inhibitors compared to controls. CONCLUSIONS: Physical/behavioral therapy and PDE5 inhibitors are effective primary PMD treatments. PMD management studies in males with no previous urethral/prostatic surgery are very scarce and lack the use of consistent/comparable outcome measures. Further studies addressing these deficiencies would benefit this very thin evidence base.

Rolipram and pentoxifylline combination ameliorates the morphological abnormalities of dorsal root ganglion neurons in experimental diabetic neuropathy by reducing mitochondrial dysfunction and apoptosis.

Diabetic neuropathy (DN) is the most prevalent complication of diabetes. Pharmacological treatments for DN are often limited in efficacy, so the development of new agents to alleviate DN is essential. The aim of this study was to evaluate the effects of rolipram, a selective phosphodiesterase-4 inhibitor (PDE-4I), and pentoxifylline, a general PDE inhibitor, using a rat model of DN. In this study, a diabetic rat model was established by i.p. injection of STZ (55 mg/kg). Rats were treated with rolipram (1 mg/kg), pentoxifylline (100 mg/kg), and combination of rolipram (0.5 mg/kg) and pentoxifylline (50 mg/kg), orally for 5 weeks. After treatments, sensory function was assessed by hot plate test. Then rats were anesthetized and dorsal root ganglion (DRG) neurons isolated. Cyclic adenosine monophosphate (cAMP), adenosine triphosphate (ATP, adenosine diphosphate and mitochondrial membrane potential (MMP) levels, Cytochrome c release, Bax, Bcl-2, caspase-3 proteins expression in DRG neurons were assessed by biochemical and ELISA methods, and western blot analysis. DRG neurons were histologically examined using hematoxylin and eosin (H&E) staining method. Rolipram and/or pentoxifylline significantly attenuated sensory dysfunction by modulating nociceptive threshold. Rolipram and/or pentoxifylline treatment dramatically increased the cAMP level, prevented mitochondrial dysfunction, apoptosis and degeneration of DRG neurons, which appears to be mediated by inducing ATP and MMP, improving cytochrome c release, as well as regulating the expression of Bax, Bcl-2, and caspase-3 proteins, and improving morphological abnormalities of DRG neurons. We found maximum effectiveness with rolipram and pentoxifylline combination on mentioned factors. These findings encourage the use of rolipram and pentoxifylline combination as a novel experimental evidence for further clinical investigations in the treatment of DN.

The protective role of phosphodiesterase inhibitors in preventing colorectal cancer and advanced colorectal polyps: a systematic review and meta-analysis.

AIM: Inflammatory cells within the tumour microenvironment are the driving forces behind colorectal cancer (CRC) tumourigenesis. Understanding the different pathways involved in CRC carcinogenesis paves the way for effective repurposing of drugs for cancer prevention. Emerging data from preclinical and clinical studies suggest that, due to their antiproliferative and anti-inflammatory properties, phosphodiesterase-5 inhibitors (PDE5i) might have an anticancer effect. The aim of this study was to clarify through systematic review and meta-analysis of published peer-reviewed studies whether an association exists between PDE5i use and CRC risk. METHOD: This study was guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Prospective registration was performed on PROSPERO (CRD42022372925). A systematic review was performed for studies reporting CRC and advanced colorectal polyp incidence in PDE5i 'ever-users' and PDE5i 'never-users'. Meta-analysis was performed using RevMan version 5. RESULTS: Four observational cohort studies and two case-control studies, comprising 995 242 patients were included in the final analysis, of whom 347 126 were PDE5i ever-users. Patients who were PDE5i ever-users had a significantly lower incidence of CRC or advanced colorectal polyps than never-users (OR 0.88, CI 0.79-0.98, p = 0.02). To examine the primary preventative role of PDE5i, subgroup analysis of four studies including patients without a previous history of CRC found that use of PDE5i was associated with a lower incidence of CRC (OR 0.85, CI 0.75-0.95, p = 0.005, I2 = 64%). There was no significant temporal relationship found between PDE5i use and CRC risk as both current users and previous users had a significantly lower incidence of CRC than never-users. CONCLUSION: Our study found a significant anticancer effect of PDE5i, as shown by a reduced risk of CRC in the context of both primary and secondary CRC prevention.

Treatment of Ureteral Stent-Related Symptoms.

BACKGROUND: The aim of the study was to assess the effectiveness of the main classes of drugs used at reducing morbidity related to ureteric stents. SUMMARY: After establishing a priori protocol, a systematic electronic literature search was conducted in July 2019. The randomized clinical trials (RCTs) selection proceeded in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines and was registered (PROSPERO ID 178130). The risk of bias and the quality assessment of the included RCTs were performed. Ureteral Stent Symptom Questionnaire (USSQ), International Prostate Symptom Score (IPSS), and quality of life (QoL) were pooled for meta-analysis. Mean difference and risk difference were calculated as appropriate for each outcome to determine the cumulative effect size. Fourteen RCTs were included in the analysis accounting for 2,842 patients. Alpha antagonist, antimuscarinic, and phosphodiesterase (PDE) inhibitors significatively reduced all indexes of the USSQ, the IPSS and QoL scores relative to placebo. Conversely, combination therapy (alpha antagonist plus antimuscarinic) showed in all indexes of the USSQ, IPSS, and QoL over alpha antagonist or antimuscarinic alone. On comparison with alpha blockers, PDE inhibitors were found to be equally effective for urinary symptoms, general health, and body pain parameters, but sexual health parameters improved significantly with PDE inhibitors. Finally, antimuscarinic resulted in higher decrease in all indexes of the USSQ, the IPSS, and QoL relative to alpha antagonist. KEY MESSAGE: Relative to placebo, alpha antagonist alone, antimuscarinics alone, and PDE inhibitors alone have beneficial effect in reducing stent-related symptoms. Furthermore, there are significant advantages of combination therapy compared with monotherapy. Finally, PDE inhibitors are comparable to alpha antagonist, and antimuscarinic seems to be more effective than alpha antagonist alone.

Effect of Cilostazol in Animal Models of Cerebral Ischemia and Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis.

BACKGROUND: Cilostazol, a phosphodiesterase III inhibitor, appears to be a promising agent for preventing cerebral ischemia in patients with aneurysmal subarachnoid hemorrhage. Here, the authors perform a systematic review and meta-analysis to quantitatively assess the effects of cilostazol on brain structural and functional outcomes in animal models of cerebral ischemia and subarachnoid hemorrhage-induced cerebral vasospasm. METHODS: By using the PRISMA guidelines, a search of the PubMed, Scopus, and Web of Science was conducted to identify relevant studies. Study quality of each included study for both systematic reviews were scored by using an adapted 15-item checklist from the Collaborative Approach to Meta-Analysis of Animal Data from Experimental Studies. We calculated a standardized mean difference as effect size for each comparison. For each outcome, comparisons were combined by using random-effects modeling to account for heterogeneity, with a restricted maximum likelihood estimate of between-study variance. RESULTS: A total of 22 (median [Q1, Q3] quality score of 7 [5, 8]) and 6 (median [Q1, Q3] quality score of 6 [6, 6]) studies were identified for cerebral ischemia and subarachnoid hemorrhage-induced cerebral vasospasm, respectively. Cilostazol significantly reduced the infarct volume in cerebral ischemia models with a pooled standardized mean difference estimate of - 0.88 (95% confidence interval [CI] [- 1.07 to - 0.70], p < 0.0001). Cilostazol significantly reduced neurofunctional deficits in cerebral ischemia models with a pooled standardized mean difference estimate of - 0.66 (95% CI [- 1.06 to - 0.28], p < 0.0001). Cilostazol significantly improved the basilar artery diameter in subarachnoid hemorrhage-induced cerebral vasospasm with a pooled standardized mean difference estimate of 2.30 (95% CI [0.94 to 3.67], p = 0.001). Cilostazol also significantly improved the basilar artery cross-section area with a pooled standardized mean estimate of 1.88 (95% CI [0.33 to 3.43], p < 0.05). Overall, there was between-study heterogeneity and asymmetry in the funnel plot observed in all comparisons. CONCLUSIONS: Published animal data support the overall efficacy of cilostazol in reducing infarct volume and neurofunctional deficits in cerebral ischemia models and cerebral vasospasm in subarachnoid hemorrhage models.

Why Not Dipyridamole: a Review of Current Guidelines and Re-evaluation of Utility in the Modern Era.

Dipyridamole is an old anti-platelet and coronary vasodilator agent that inhibits platelet phosphodiesterase and increases interstitial adenosine levels. Its use in coronary artery disease (CAD) has fallen out of practice in the modern era with the advent of new anti-platelet agents, and most modern guidelines on the management of CAD either neglect to comment on its utility or outright recommend against it. The majority of the studies used in these guidelines are outdated and took place in an era when high doses of aspirin were used and statins were not widely utilized. There is growing evidence in rat models of dipyridamole's synergy with statins through adenosine modulation resulting in significant myocardial protection against ischemia-reperfusion injury and limitation of infract size. The data in human studies are limited but show a similar potential synergy between dipyridamole and statins. It would thus be prudent to reconsider the recommendations against the use of dipyridamole in CAD and to re-evaluate its possible role and potential benefits through well-designed randomized trials combining it with statins, low-dose aspirin, and/or other anti-platelet agents.

The Interplay between cGMP and Calcium Signaling in Alzheimer's Disease.

Cyclic guanosine monophosphate (cGMP) is a ubiquitous second messenger and a key molecule in many important signaling cascades in the body and brain, including phototransduction, olfaction, vasodilation, and functional hyperemia. Additionally, cGMP is involved in long-term potentiation (LTP), a cellular correlate of learning and memory, and recent studies have identified the cGMP-increasing drug Sildenafil as a potential risk modifier in Alzheimer's disease (AD). AD development is accompanied by a net increase in the expression of nitric oxide (NO) synthases but a decreased activity of soluble guanylate cyclases, so the exact sign and extent of AD-mediated imbalance remain unclear. Moreover, human patients and mouse models of the disease present with entangled deregulation of both cGMP and Ca2+ signaling, e.g., causing changes in cGMP-mediated Ca2+ release from the intracellular stores as well as Ca2+-mediated cGMP production. Still, the mechanisms governing such interplay are poorly understood. Here, we review the recent data on mechanisms underlying the brain cGMP signaling and its interconnection with Ca2+ signaling. We also discuss the recent evidence stressing the importance of such interplay for normal brain function as well as in Alzheimer's disease.

Clinical Implication of Phosphodiesterase-4-Inhibition.

The pleiotropic function of 3',5'-cyclic adenosine monophosphate (cAMP)-dependent pathways in health and disease led to the development of pharmacological phosphodiesterase inhibitors (PDE-I) to attenuate cAMP degradation. While there are many isotypes of PDE, a predominant role of PDE4 is to regulate fundamental functions, including endothelial and epithelial barrier stability, modulation of inflammatory responses and cognitive and/or mood functions. This makes the use of PDE4-I an interesting tool for various therapeutic approaches. However, due to the presence of PDE4 in many tissues, there is a significant danger for serious side effects. Based on this, the aim of this review is to provide a comprehensive overview of the approaches and effects of PDE4-I for different therapeutic applications. In summary, despite many obstacles to use of PDE4-I for different therapeutic approaches, the current data warrant future research to utilize the therapeutic potential of phosphodiesterase 4 inhibition.

Synthesis and in vitro evaluation of anti-inflammatory, antioxidant, and anti-fibrotic effects of new 8-aminopurine-2,6-dione-based phosphodiesterase inhibitors as promising anti-asthmatic agents.

Phosphodiesterase (PDE) inhibitors are currently an extensively studied group of compounds that can bring many benefits in the treatment of various inflammatory and fibrotic diseases, including asthma. Herein, we describe a series of novel N'-phenyl- or N'-benzylbutanamide and N'-arylidenebutanehydrazide derivatives of 8-aminopurine-2,6-dione (27-43) and characterized them as prominent pan-PDE inhibitors. Most of the compounds exhibited antioxidant and anti-inflammatory activity in lipopolysaccharide (LPS)-induced murine macrophages RAW264.7. The most active compounds (32-35 and 38) were evaluated in human bronchial epithelial cells (HBECs) derived from asthmatics. To better map the bronchial microenvironment in asthma, HBECs after exposure to selected 8-aminopurine-2,6-dione derivatives were incubated in the presence of two proinflammatory and/or profibrotic factors: transforming growth factor type ß (TGF-ß) and interleukin 13 (IL-13). Compounds 32-35 and 38 significantly reduced both IL-13- and TGF-ß-induced expression of proinflammatory and profibrotic mediators, respectively. Detailed analysis of their inhibition preferences for selected PDEs showed high affinity for isoenzymes important in the pathogenesis of asthma, including PDE1, PDE3, PDE4, PDE7, and PDE8. The presented data confirm that structural modifications within the 7 and 8 positions of the purine-2,6-dione core result in obtaining preferable pan-PDE inhibitors which in turn exert an excellent anti-inflammatory and anti-fibrotic effect in the bronchial epithelial cells derived from asthmatic patients. This dual-acting pan-PDE inhibitors constitute interesting and promising lead structures for further anti-asthmatic agent discovery.

Phosphodiesterase inhibitors and prostaglandin analogues in dermatology: A comprehensive review.

Due to immune-mediated nature, medicines with immunomodulatory and anti-inflammatory effects can used to treat many dermatologic diseases. Phosphodiesterase and prostaglandins are involved in many inflammatory pathways that cause cutaneous disorders. Phosphodiesterase inhibitors (PDEIs) and prostaglandin analogues are currently employed to treat several dermatologic disorders. Given the few comprehensive reviews in this context, focusing on the dermatologic applications and efficacy of these medicines appears valuable. The present comprehensive review was, therefore, performed on the applications of PDEIs and prostaglandin analogues in different cutaneous disorders. All the relevant articles were selected to perform this review by searching databases such as Medline, Google Scholar, Scopus, and Web of Science. Oral PDEIs, especially apremilast, is an effective medicine in psoriasis and a number of other cutaneous disorders such as vitiligo. Topical PDEIs, including crisaborole ointment 2%, is a safe and effective treatment in atopic dermatitis. Prostaglandin analogues, especially their topical forms such as latanoprost and bimatoprost, have different applications in cutaneous disorders, including pigmentary disorders, especially vitiligo and hair repigmentation; for instance, bimatoprost is used for eyelash repigmentation. Prostaglandin analogues are also used in alopecia, including androgenetic alopecia and alopecia areata. Oral (apremilast) and topical (crisaborole) PDEIs and topical prostaglandin analogues, including latanoprost and bimatoprost, were found safe and effective in different skin diseases. In terms of efficiency and safety, these medicines compete with other medications of similar use even with higher efficacy and fewer side effects that necessitate further studies.

Reno-protective effects of Phosphodiesterase 5 inhibitors.

The kidneys are vital organs that play an important role in removing waste materials from the blood, electrolyte balance, blood pressure regulation, and red blood cell genesis. Kidney disease can be caused by various factors, including diabetes, ischemia/reperfusion injury, and nephrotoxic agents. Inflammation and oxidative stress play a key role in the progression and pathogenesis of kidney diseases. Acute kidney injury (AKI) and chronic kidney disease (CKD) are important health problems worldwide, as they are associated with a long-term hospital stay, and increased morbidity and mortality in high-risk patients. Current standard therapeutic options are not sufficient to delay or stop the loss of kidney function. Therefore, it is necessary to develop new therapeutic options. Phosphodiesterase 5 inhibitors (PDE5Is) are a currently available class of drugs that are used to treat erectile dysfunction and pulmonary hypertension in humans. However, recent evidence suggests that PDE5Is have beneficial renoprotective effects via a variety of mechanisms. In this review, the benefits of PDE5 inhibitors in clinical conditions associated with kidney disease, such as diabetic nephropathy, ischemia-reperfusion injury, and acute and chronic kidney injury, are summarized.

Phosphodiesterase Inhibitors in Acute Lung Injury: What Are the Perspectives?

Despite progress in understanding the pathophysiology of acute lung damage, currently approved treatment possibilities are limited to lung-protective ventilation, prone positioning, and supportive interventions. Various pharmacological approaches have also been tested, with neuromuscular blockers and corticosteroids considered as the most promising. However, inhibitors of phosphodiesterases (PDEs) also exert a broad spectrum of favorable effects potentially beneficial in acute lung damage. This article reviews pharmacological action and therapeutical potential of nonselective and selective PDE inhibitors and summarizes the results from available studies focused on the use of PDE inhibitors in animal models and clinical studies, including their adverse effects. The data suggest that xanthines as representatives of nonselective PDE inhibitors may reduce acute lung damage, and decrease mortality and length of hospital stay. Various (selective) PDE3, PDE4, and PDE5 inhibitors have also demonstrated stabilization of the pulmonary epithelial-endothelial barrier and reduction the sepsis- and inflammation-increased microvascular permeability, and suppression of the production of inflammatory mediators, which finally resulted in improved oxygenation and ventilatory parameters. However, the current lack of sufficient clinical evidence limits their recommendation for a broader use. A separate chapter focuses on involvement of cyclic adenosine monophosphate (cAMP) and PDE-related changes in its metabolism in association with coronavirus disease 2019 (COVID-19). The chapter illuminates perspectives of the use of PDE inhibitors as an add-on treatment based on actual experimental and clinical trials with preliminary data suggesting their potential benefit.

Efficacy of Novel Pyrazolone Phosphodiesterase Inhibitors in Experimental Mouse Models of Trypanosoma cruzi.

Pyrazolones are heterocyclic compounds with interesting biological properties. Some derivatives inhibit phosphodiesterases (PDEs) and thereby increase the cellular concentration of cyclic AMP (cAMP), which plays a vital role in the control of metabolism in eukaryotic cells, including the protozoan Trypanosoma cruzi, the etiological agent of Chagas disease (CD), a major neglected tropical disease. In vitro phenotypic screening identified a 4-bromophenyl-dihydropyrazole dimer as an anti-T. cruzi hit and 17 novel pyrazolone analogues with variations on the phenyl ring were investigated in a panel of phenotypic laboratory models. Potent activity against the intracellular forms (Tulahuen and Y strains) was obtained with 50% effective concentration (EC50) values within the 0.17 to 3.3 µM range. Although most were not active against bloodstream trypomastigotes, an altered morphology and loss of infectivity were observed. Pretreatment of the mammalian host cells with pyrazolones did not interfere with infection and proliferation, showing that the drug activity was not the result of changes to host cell metabolism. The pyrazolone NPD-227 increased the intracellular cAMP levels and was able to sterilize T. cruzi-infected cell cultures. Thus, due to its high potency and selectivity in vitro, and its additive interaction with benznidazole (Bz), NPD-227 was next assessed in the acute mouse model. Oral dosing for 5 days of NPD-227 at 10 mg/kg + Bz at 10 mg/kg not only reduced parasitemia (>87%) but also protected against mortality (>83% survival), hence demonstrating superiority to the monotherapy schemes. These data support these pyrazolone molecules as potential novel therapeutic alternatives for Chagas disease.

A dose-ranging study of the inhaled dual phosphodiesterase 3 and 4 inhibitor ensifentrine in COPD.

BACKGROUND: Many patients with chronic obstructive pulmonary disease (COPD) still experience daily symptoms, exacerbations, and accelerated lung function decline, even when receiving maximal combined treatment with inhaled long-acting bronchodilators and corticosteroids. Novel treatment options are needed for these patients. Phosphodiesterases (PDEs) are enzymes that impact a range of cellular functions by modulating levels of cyclic nucleotides, and there is evidence to suggest that combined inhibition of PDE3 and PDE4 can have additive (or perhaps synergistic) effects. This study investigated the efficacy and safety of ensifentrine, a first-in-class dual inhibitor of PDE 3 and 4, in patients with COPD. METHODS: This randomised, double-blind, placebo-controlled, parallel-group, dose-ranging study recruited patients with COPD, post-bronchodilator forced expiratory volume in 1 s (FEV1) 40-80% predicted and FEV1/forced vital capacity ratio ≤ 0.7. Patients were randomised equally to inhale nebulised ensifentrine 0.75, 1.5, 3 or 6 mg or placebo, all twice daily. PRIMARY OUTCOME: placebo-adjusted difference in peak FEV1 (assessed over 3 h) at Week 4. RESULTS: The study took place between July 2017 and February 2018. Of 405 patients randomly assigned to medication, 375 (92.6%) completed the study. For peak FEV1 at Week 4, all four ensifentrine doses were superior to placebo (p ≤ 0.0001) with least squares mean differences of 146 (95% CI 75-216), 153 (83-222), 200 (131-270) and 139 (69-210) mL for ensifentrine 0.75, 1.5, 3 and 6 mg, respectively. Respiratory symptoms (assessed using the Evaluating Respiratory Symptoms questionnaire) were also significantly improved with all ensifentrine doses at Week 4. Adverse events were reported by 33.3, 44.4, 35.4 and 36.3% patients with ensifentrine 0.75, 1.5, 3 and 6 mg, respectively, and 39.2% with placebo. CONCLUSIONS: In this four-week Phase IIb study, all four ensifentrine doses significantly improved bronchodilation and symptoms, with a dose-ranging effect from 0.75 to 3 mg twice daily, and all doses well tolerated. The study supports the continuing development of ensifentrine in COPD. TRIAL REGISTRATION: EudraCT 2016-005205-40, registered 30 May 2017.