Ameliorative effects of sildenafil against carbon tetrachloride induced hepatic fibrosis in rat model through downregulation of osteopontin gene expression.

The liver carries out many essential tasks, such as synthesising cholesterol, controlling the body's storage of glycogen, and detoxifying metabolites, in addition to performing, and regulating homeostasis. Hepatic fibrosis is a pathological state characterized by over accumulation of extracellular matrix (ECM) including collagen fibers. Sildenafil (a selective inhibitor of type 5 phosphodiesterase) has anti-inflammatory, antioxidant and anti-apoptotic properties. It is commonly used to treat erectile dysfunction in male. The purpose of the current investigation was to evaluate sildenafil's hepatoprotective potential against liver fibrosis in rats that was caused by carbon tetrachloride (CCl4). Liver enzymes and oxidative markers as well as profibrotic genes were determined. The findings showed that sildenafil alleviates the hepatic dysfunctions caused by CCl4 by restoring normal levels of ALT, AST, and GGT as well as by restoring the antioxidant status demonstrated by increased glutathione (GSH), and catalase. In addition, a significantly down-regulated the mRNA expressions of profibrotic genes [collagen-1α, IL-1ß, osteopontin (OPN), and transforming growth factor-ß (TGF-ß)]. Additionally, sildenafil lessens the periportal fibrosis between hepatic lobules, congestion and dilatation in the central vein, and the inflammatory cell infiltrations. As a result, it is hypothesized that sildenafil may be helpful in the management of hepatotoxicity brought on by CCl4 through suppressing OPN.

Preliminary Efficacy of Topical Sildenafil Cream for the Treatment of Female Sexual Arousal Disorder: A Randomized Controlled Trial.

OBJECTIVE: To assess the efficacy of topical sildenafil cream, 3.6% among healthy premenopausal women with female sexual arousal disorder. METHODS: We conducted a phase 2b, exploratory, randomized, placebo-controlled, double-blind study of sildenafil cream. Coprimary efficacy endpoints were the change from baseline to week 12 in the Arousal Sensation domain of the SFQ28 (Sexual Function Questionnaire) and question 14 of the FSDS-DAO (Female Sexual Distress Scale-Desire, Arousal, Orgasm). RESULTS: Two hundred women with female sexual arousal disorder were randomized to sildenafil cream (n=101) or placebo cream (n=99). A total of 174 participants completed the study (sildenafil 90, placebo 84). Among the intention-to-treat (ITT) population, which included women with only female sexual arousal disorder and those with female sexual arousal disorder with concomitant sexual dysfunction diagnoses or genital pain, although the sildenafil cream group demonstrated greater improvement in the SFQ28 Arousal Sensation domain scores, there were no statistically significant differences between sildenafil and placebo cream users in the coprimary and secondary efficacy endpoints. An exploratory post hoc subset of the ITT population with an enrollment diagnosis of female sexual arousal disorder with or without concomitant decreased desire randomized to sildenafil cream reported significant increases in their SFQ28 Arousal Sensation domain score (least squares mean 2.03 [SE 0.62]) compared with placebo cream (least squares mean 0.08 [SE 0.71], P =.04). This subset achieved a larger mean improvement in the SFQ28 Desire and Orgasm domain scores. This subset population also had significantly reduced sexual distress and interpersonal difficulties with sildenafil cream use as measured by FSDS-DAO questions 3, 5, and 10 (all P ≤.04). CONCLUSION: Topical sildenafil cream improved outcomes among women with female sexual arousal disorder, most significantly in those who did not have concomitant orgasmic dysfunction. In particular, in an exploratory analysis of a subset of women with female sexual arousal disorder with or without concomitant decreased desire, topical sildenafil cream increased sexual arousal sensation, desire, and orgasm and reduced sexual distress. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov , NCT04948151.

A novel standard-free detection of adulteration method for sildenafil derivatives in dietary supplements.

The rapid and accurate detection of illegal adulteration of chemical drugs into dietary supplements is a big challenge in the food chemistry field. Detection of compounds without a standard reference is even more difficult; however, this is a common situation. Here in this study, a novel "standard-free detection of adulteration" (SFDA) method was proposed and phosphodiesterase-5 inhibitor derivatives were used as an example to figure out the possibility and reliability of this SFDA method. After analysis by quadrupole coupled time of flight-tandem mass spectrometry detection and multivariable statistics, six common fragment ions were chosen to indicate whether adulteration was present or not, while 20 characteristic fragment ions indicated whether adulteration was by nitrogen-containing heterocycles or by anilines. Furthermore, the quantitative methods were conducted by high-performance liquid chromatography-tandem mass spectrometry. In a word, this strategy allows for a quick determination of dietary supplement adulteration without any need for standard materials, improving the efficacy of food safety testing.

Cerebrovascular Effects of Sildenafil in Small Vessel Disease: The OxHARP Trial.

BACKGROUND: Vascular cognitive impairment due to cerebral small vessel disease is associated with cerebral pulsatility, white matter hypoperfusion, and reduced cerebrovascular reactivity (CVR), and is potentially improved by endothelium-targeted drugs such as cilostazol. Whether sildenafil, a phosphodiesterase-5 inhibitor, improves cerebrovascular dysfunction is unknown. METHODS: OxHARP trial (Oxford Haemodynamic Adaptation to Reduce Pulsatility) was a double-blind, randomized, placebo-controlled, 3-way crossover trial after nonembolic cerebrovascular events with mild-moderate white matter hyperintensities (WMH), the most prevalent manifestation of cerebral small vessel disease. The primary outcome assessed the superiority of 3 weeks of sildenafil 50 mg thrice daily versus placebo (mixed-effect linear models) on middle cerebral artery pulsatility, derived from peak systolic and end-diastolic velocities (transcranial ultrasound), with noninferiority to cilostazol 100 mg twice daily. Secondary end points included the following: cerebrovascular reactivity during inhalation of air, 4% and 6% CO2 on transcranial ultrasound (transcranial ultrasound-CVR); blood oxygen-level dependent-magnetic resonance imaging within WMH (CVR-WMH) and normal-appearing white matter (CVR-normal-appearing white matter); cerebral perfusion by arterial spin labeling (magnetic resonance imaging pseudocontinuous arterial spin labeling); and resistance by cerebrovascular conductance. Adverse effects were compared by Cochran Q. RESULTS: In 65/75 (87%) patients (median, 70 years;79% male) with valid primary outcome data, cerebral pulsatility was unchanged on sildenafil versus placebo (0.02, -0.01 to 0.05; P=0.18), or versus cilostazol (-0.01, -0.04 to 0.02; P=0.36), despite increased blood flow (∆ peak systolic velocity, 6.3 cm/s, 3.5-9.07; P<0.001; ∆ end-diastolic velocity, 1.98, 0.66-3.29; P=0.004). Secondary outcomes improved on sildenafil versus placebo for CVR-transcranial ultrasound (0.83 cm/s per mm Hg, 0.23-1.42; P=0.007), CVR-WMH (0.07, 0-0.14; P=0.043), CVR-normal-appearing white matter (0.06, 0.00-0.12; P=0.048), perfusion (WMH: 1.82 mL/100 g per minute, 0.5-3.15; P=0.008; and normal-appearing white matter, 2.12, 0.66-3.6; P=0.006) and cerebrovascular resistance (sildenafil-placebo: 0.08, 0.05-0.10; P=4.9×10-8; cilostazol-placebo, 0.06, 0.03-0.09; P=5.1×10-5). Both drugs increased headaches (P=1.1×10-4), while cilostazol increased moderate-severe diarrhea (P=0.013). CONCLUSIONS: Sildenafil did not reduce pulsatility but increased cerebrovascular reactivity and perfusion. Sildenafil merits further study to determine whether it prevents the clinical sequelae of small vessel disease. REGISTRATION: URL: https://www.clinicaltrials.gov/study/NCT03855332; Unique identifier: NCT03855332.

Induction of cGMP-mediated migraine attacks is independent of CGRP receptor activation.

BACKGROUND: The cAMP and cGMP pathways are implicated in the initiation of migraine attacks, but their interactions remain unclear. Calcitonin gene-related peptide (CGRP) triggers migraine attacks via cAMP, whereas the phosphodiesterase-5 inhibitor sildenafil induces migraine attacks via cGMP. Our objective was to investigate whether sildenafil could induce migraine attacks in individuals with migraine pre-treated with the CGRP-receptor antibody erenumab. METHODS: In this randomized, double-blind, placebo-controlled, cross-over study, adults with migraine without aura received a single subcutaneous injection of 140 mg erenumab on day 1. They were then randomized to receive sildenafil 100 mg or placebo on two experimental days, each separated by at least one week, between days 8 and 21. The primary endpoint was the difference in the incidence of migraine attacks between sildenafil and placebo during the 12-h observation period after administration. RESULTS: In total, 16 participants completed the study. Ten participants (63%) experienced a migraine attack within 12 h after sildenafil administration compared to three (19%) after placebo (p = 0.016). The median headache intensity was higher after sildenafil than after placebo (area under the curve (AUC) for the 12-h observation period, p = 0.026). Furthermore, sildenafil induced a significant decrease in mean arterial blood pressure (AUC, p = 0.026) and a simultaneous increase in heart rate (AUC, p < 0.001) during the first hour after administration compared to placebo. CONCLUSION: These findings provide evidence that migraine induction via the cGMP pathway can occur even under CGRP receptor blockade. TRIAL REGISTRATION: ClinicalTrials.gov: Identifier NCT05889455.

Sildenafil amplifies calcium influx and insulin secretion in pancreatic ß cells.

Sildenafil, a phosphodiesterase-5 (PDE5) inhibitor, has been shown to improve insulin sensitivity in animal models and prediabetic patients. However, its other metabolic effects remain poorly investigated. This study examines the impact of sildenafil on insulin secretion in MIN6-K8 mouse clonal ß cells. Sildenafil amplified insulin secretion by enhancing Ca2+ influx. These effects required other depolarizing stimuli in MIN6-K8 cells but not in KATP channel-deficient ß cells, which were already depolarized, indicating that sildenafil-amplified insulin secretion is depolarization-dependent and KATP channel-independent. Interestingly, sildenafil-amplified insulin secretion was inhibited by pharmacological inhibition of R-type channels, but not of other types of voltage-dependent Ca2+ channels (VDCCs). Furthermore, sildenafil-amplified insulin secretion was barely affected when its effect on cyclic GMP was inhibited by PDE5 knockdown. Thus, sildenafil stimulates insulin secretion and Ca2+ influx through R-type VDCCs independently of the PDE5/cGMP pathway, a mechanism that differs from the known pharmacology of sildenafil and conventional insulin secretory pathways. Our results reposition sildenafil as an insulinotropic agent that can be used as a potential antidiabetic medicine and a tool to elucidate the novel mechanism of insulin secretion.

Prophylactic sildenafil to prevent bronchopulmonary dysplasia: A systematic review and meta-analysis.

BACKGROUND: Bronchopulmonary dysplasia (BPD) persists as one of the foremost factors contributing to mortality and morbidity in extremely preterm infants. The effectiveness of administering sildenafil early on to prevent BPD remains uncertain. The aim of this study was to investigate the efficacy and safety of prophylactically administered sildenafil during the early life stages of preterm infants to prevent mortality and BPD. METHODS: MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Cumulative Index to Nursing and Allied Health Literature, and Ichushi were searched. Published randomized controlled trials (RCTs), non-RCTs, interrupted time series, cohort studies, case-control studies, and controlled before-and-after studies were included. Two reviewers independently screened the title, abstract, and full text, extracted data, assessed the risk of bias, and evaluated the certainty of evidence (CoE) following the Grading of Recommendations Assessment and Development and Evaluation approach. The random-effects model was used for a meta-analysis of RCTs. RESULTS: This review included three RCTs (162 infants). There were no significant differences between the prophylactic sildenafil and placebo groups in mortality (risk ratio [RR]: 1.32; 95% confidence interval [CI]: 0.16-10.75; very low CoE), BPD (RR: 1.20; 95% CI: 0.79-1.83; very low CoE), and all other outcome assessed (all with very low CoE). The sample sizes were less than the optimal sizes for all outcomes assessed, indicating the need for further trials. CONCLUSIONS: The prophylactic use of sildenafil in individuals at risk of BPD did not indicate any advantageous effects in terms of mortality, BPD, and other outcomes, or increased side effects.

Benchtop NMR Coupled with Chemometrics: A Workflow for Unveiling Hidden Drug Ingredients in Honey-Based Supplements.

Recently, benchtop nuclear magnetic resonance (NMR) spectrometers utilizing permanent magnets have emerged as versatile tools with applications across various fields, including food and pharmaceuticals. Their efficacy is further enhanced when coupled with chemometric methods. This study presents an innovative approach to leveraging a compact benchtop NMR spectrometer coupled with chemometrics for screening honey-based food supplements adulterated with active pharmaceutical ingredients. Initially, fifty samples seized by French customs were analyzed using a 60 MHz benchtop spectrometer. The investigation unveiled the presence of tadalafil in 37 samples, sildenafil in 5 samples, and a combination of flibanserin with tadalafil in 1 sample. After conducting comprehensive qualitative and quantitative characterization of the samples, we propose a chemometric workflow to provide an efficient screening of honey samples using the NMR dataset. This pipeline, utilizing partial least squares discriminant analysis (PLS-DA) models, enables the classification of samples as either adulterated or non-adulterated, as well as the identification of the presence of tadalafil or sildenafil. Additionally, PLS regression models are employed to predict the quantitative content of these adulterants. Through blind analysis, this workflow allows for the detection and quantification of adulterants in these honey supplements.

Sildenafil Reverses the Neuropathological Alzheimer's Disease Phenotype in Cholinergic-Like Neurons Carrying the Presenilin 1 E280A Mutation.

Background: Familial Alzheimer's disease (FAD) presenilin 1 E280A (PSEN 1 E280A) is characterized by functional impairment and the death of cholinergic neurons as a consequence of amyloid-ß (Aß) accumulation and abnormal phosphorylation of the tau protein. Currently, there are no available therapies that can cure FAD. Therefore, new therapies are urgently needed for treating this disease. Objective: To assess the effect of sildenafil (SIL) on cholinergic-like neurons (ChLNs) harboring the PSEN 1 E280A mutation. Methods: Wild-type (WT) and PSEN 1 E280A ChLNs were cultured in the presence of SIL (25µM) for 24 h. Afterward, proteinopathy, cell signaling, and apoptosis markers were evaluated via flow cytometry and fluorescence microscopy. Results: We found that SIL was innocuous toward WT PSEN 1 ChLNs but reduced the accumulation of intracellular Aß fragments by 87%, decreased the non-physiological phosphorylation of the protein tau at residue Ser202/Thr205 by 35%, reduced the phosphorylation of the proapoptotic transcription factor c-JUN at residue Ser63/Ser73 by 63%, decreased oxidized DJ-1 at Cys106-SO3 by 32%, and downregulated transcription factor TP53 (tumor protein p53), BH-3-only protein PUMA (p53 upregulated modulator of apoptosis), and cleaved caspase 3 (CC3) expression by 20%, 32%, and 22%, respectively, compared with untreated mutant ChLNs. Interestingly, SIL also ameliorated the dysregulation of acetylcholine-induced calcium ion (Ca2+) influx in PSEN 1 E280A ChLNs. Conclusions: Although SIL showed no antioxidant capacity in the oxygen radical absorbance capacity and ferric ion reducing antioxidant power assays, it might function as an anti-amyloid and antiapoptotic agent and functional neuronal enhancer in PSEN 1 E280A ChLNs. Therefore, the SIL has therapeutic potential for treating FAD.

Predicting gastric emptying of drug substances taken under postprandial conditions by combination of biorelevant dissolution and mechanistic in silico modeling.

Physiologically based pharmacokinetic (PBPK) models can help to understand the effects of gastric emptying on pharmacokinetics and in particular also provide a platform for understanding mechanisms of food effects, as well as extrapolation between different postprandial conditions, whether standardized clinical or patient-oriented, non-clinical conditions. By integrating biorelevant dissolution data from the GastroDuo dissolution model into a previously described mechanistic model of fed-state gastric emptying, we simulated the effects of a high-calorie high-fat meal on the pharmacokinetics of sildenafil, febuxostat, acetylsalicylic acid, theobromine and caffeine. The model was able to simulate the variability in Cmax and tmax caused by the presence of the stomach road. The main influences investigated to affect the gastric emptying process were drug solubility (theobromine and caffeine), tablet dissolution rate (acetylsalicylic acid) and sensitivity to gastric motility (sildenafil and febuxostat). Finally, we showed how PBPK models can be used to extrapolate pharmacokinetics between different prandial states using theobromine as an example with results from a clinical study being presented.

An in vitro and in vivo study of electrospun polyvinyl alcohol/chitosan/sildenafil citrate mat on 3D-printed polycaprolactone membrane as a double layer wound dressing.

Double-layer dermal substitutes (DS) generally provide more effective therapeutic outcomes than single-layer substitutes. The architectural design of DS incorporates an outer layer to protect against bacterial invasions and maintain wound hydration, thereby reducing the risk of infection and the frequency of dressing changes. Moreover, the outer layer is a mechanical support for the wound, preventing undue tension in the affected area. A 3D-printed polycaprolactone (PCL) membrane was utilized as the outer layer to fabricate DS wound dressing. Simultaneously, a polyvinyl alcohol/chitosan/sildenafil citrate (PVA/CS/SC) scaffold was electrospun onto the PCL membrane to facilitate cellular adhesion and proliferation. Scanning electron microscopy (SEM) analysis of the PCL filaments revealed a consistent cross-sectional surface and structure, with an average diameter of 562.72 ±â€¯29.15 µm. SEM results also demonstrated uniform morphology and beadless structure for the PVA/CS/SC scaffold, with an average fiber diameter of 366.77 ±â€¯1.81 nm for PVA/CS. The addition of SC led to an increase in fiber diameter while resulting in a reduction in tensile strength. However, drug release analysis indicated that the SC release from the sample can last up to 72 h. Animal experimentation confirmed that DS wound dressing positively accelerated wound closure and collagen deposition in the Wistar rat skin wound model.

PDE5 inhibition mitigates heart failure in hyperlipidemia.

PDE5 inhibitors was reported to play a protective role in both regulating lipid metabolism and reducing heart failure (HF). This study aimed to clarify the effectiveness of PDE5 inhibitors against hyperlipidemia-related HF by combining evidence from population-based study and animal models. The nationwide cohort study found that post-diagnostic use of PDE5 inhibitors was associated with a significantly lower risk of HF compared with patients who used alprostadil, especially among individuals with hyperlipidemia (adjusted HR = 0.56, 95% CI = 0.40-0.78). In animal models, sildenafil significantly recovered the cardiac structure and function induced by AAB surgery, as well as reversed liver dysfunction and ameliorated hyperlipidemia induced by HFD via reducing the level of ALT, AST and serum lipids. Lipidomic analysis identified four lipid metabolites involved in sildenafil administration, including FA 16:3, LPC O-18:1, DG24:0_18:0 and SE28:1/20:4. This study revealed the protective effect of PDE5 inhibitors against HF in hyperlipidemia, indicating the potential of being repurposed as an adjuvant for HF prevention in patients with hyperlipidemia if these findings can be further confirmed in clinical trials.

Social Perceptions of Masculinity and Sexual Esteem Are Impacted by Viagra Use, Testosterone, and Sexual Performance.

Sexual behaviors play a role in the social construction of masculinity. Moreover, this stereotype has been capitalized upon by pharmaceutical companies, as well as those that sell products not approved by the U.S. Food and Drug Administration, for purposes of marketing sexual medicines. Stereotypical notions of masculinity, however, also emphasize the importance of self-reliance, which may cause some to look unfavorably upon the use of sexual medicine. Consistent with this notion, a male target was viewed as more masculine when his female partner consistently reached orgasm, unless he had no history of erectile dysfunction (ED), but was taking Viagra anyway (Experiment 1; N = 522). In addition, when his partner consistently reached orgasm, ratings of his sexual esteem were also lower if he used Viagra than if he did not, but only if he had no history of ED. In Experiment 2 (N = 711), although there was no effect of a male target's use of testosterone, social perception of his masculinity and sexual esteem increased as his "natural" levels of testosterone increased. In addition, exploratory analysis revealed that if the male target had low (but not normal or high) "natural" levels of testosterone, ratings of his masculinity were higher if his female partner consistently had an orgasm, which suggests that female orgasm served to "rescue" masculinity. Because expectations about drugs drive their use, it is important to address preconceived notions about the use of sexual medicines for purposes of enhancing masculinity and sexual esteem, as the social perception of their use is much more complex.

Sildenafil-induced spinal cord infarction: a case report.

Spinal cord infarction is a rare condition, accounting for only a small percentage of strokes. It can be classified into cervical and thoracolumbar infarctions, with various factors contributing to its occurrence. Sildenafil, a phosphodiesterase type 5 inhibitor commonly used for erectile dysfunction, has been associated with cardiovascular side effects, including transient hypotension. In this case report, we present the unusual occurrence of spinal cord infarction in a 65-year-old man who had self-administered high doses of sildenafil without a doctor's prescription. The patient experienced severe radicular pain in the lumbar region and subsequent weakness in the lower limbs. Evaluation revealed an anterior spinal cord infarction in the thoracic region, confirmed by MRI imaging. After excluding other potential causes, it was concluded that the intake of sildenafil likely led to systemic hypotension, resulting in spinal cord infarction. This case highlights the importance of considering sildenafil as a possible contributor to spinal cord infarction, particularly when used at high doses. Further studies are needed to better understand the relationship between sildenafil and vascular complications, including spinal cord infarction.

Randomized, Multicenter Study to Assess the Effects of Different Doses of Sildenafil on Mortality in Adults With Pulmonary Arterial Hypertension.

BACKGROUND: Sildenafil, approved for pulmonary arterial hypertension (PAH), has a recommended adult dose of 20 mg TID, with a previously approved 5-mg TID dose by the US Food and Drug Administration. Safety concerns arose because of common off-label use of higher doses, particularly after pediatric data linked higher doses to increased mortality. To assess this, the Food and Drug Administration mandated a study evaluating the effects of various sildenafil doses on mortality in adults with PAH. METHODS: This randomized, double-blind study compared sildenafil at doses of 5, 20, or 80 mg TID in adults with PAH. The primary objective was noninferiority of 80 mg of sildenafil versus 5 mg for all-cause mortality. Secondary end points included time to clinical worsening and change in 6-minute walk distance at 6 months. Interim analyses were planned at 50% and 75% of the anticipated mortality events. Safety and tolerability were assessed in the intention-to-treat population. RESULTS: The study was halted after the first interim analysis, demonstrating noninferiority for 80 mg of sildenafil versus 5 mg. Of 385 patients enrolled across all dose groups, 78 died. The primary analysis showed a hazard ratio of 0.51 (99.7% CI, 0.22-1.21; P<0.001 for noninferiority) for overall survival comparing 80 mg of sildenafil with 5 mg. Time to clinical worsening favored 80 mg of sildenafil compared with 5 mg (hazard ratio, 0.44 [99.7% CI, 0.22-0.89]; P<0.001). Sildenafil at 80 mg improved 6-minute walk distance from baseline at 6 months compared with 5 mg (least square mean change, 18.9 m [95% CI, 2.99-34.86]; P=0.0201). No significant differences were found between 80 mg of sildenafil and 20 mg in mortality, clinical worsening, and 6-minute walk distance. Adverse event-related drug discontinuations were numerically higher with 80 mg of sildenafil. CONCLUSIONS: Sildenafil at 80 mg was noninferior to sildenafil at 5 mg when examining all-cause mortality in adults with PAH. Secondary efficacy end points favored 80 mg of sildenafil over 5 mg. On the basis of these findings, the Food and Drug Administration recently revoked the approval of 5 mg of sildenafil for adults with PAH, reinforced 20 mg TID as the recommended dose, and now allows dose titration up to 80 mg TID, if needed. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02060487.

An Improved PDE6D Inhibitor Combines with Sildenafil To Inhibit KRAS Mutant Cancer Cell Growth.

The trafficking chaperone PDE6D (or PDEδ) was proposed as a surrogate target for K-Ras, leading to the development of a series of inhibitors that block its prenyl binding pocket. These inhibitors suffered from low solubility and suspected off-target effects, preventing their clinical development. Here, we developed a highly soluble, low nanomolar PDE6D inhibitor (PDE6Di), Deltaflexin3, which has the lowest off-target activity as compared to three prominent reference compounds. Deltaflexin3 reduces Ras signaling and selectively decreases the growth of KRAS mutant and PDE6D-dependent cancer cells. We further show that PKG2-mediated phosphorylation of Ser181 lowers K-Ras binding to PDE6D. Thus, Deltaflexin3 combines with the approved PKG2 activator Sildenafil to more potently inhibit PDE6D/K-Ras binding, cancer cell proliferation, and microtumor growth. As observed previously, inhibition of Ras trafficking, signaling, and cancer cell proliferation remained overall modest. Our results suggest reevaluating PDE6D as a K-Ras surrogate target in cancer.

Phosphodiesterase 5A regulates the vomeronasal pump in mice.

The vomeronasal organ (VNO) is a specialized chemoreceptive structure in many vertebrates that detects chemical stimuli, mostly pheromones, which often elicit innate behaviors such as mating and aggression. Previous studies in rodents have demonstrated that chemical stimuli are actively transported to the VNO via a blood vessel-based pumping mechanism, and this pumping mechanism is necessary for vomeronasal stimulation in behaving animals. However, the molecular mechanisms that regulate the vomeronasal pump remain mostly unknown. In this study, we observed a high level of expression of phosphodiesterase 5A (PDE5A) in the vomeronasal blood vessel of mice. We provided evidence to support the potential role of PDE5A in vomeronasal pump regulation. Local application of PDE5A inhibitors-sildenafil or tadalafil-to the vomeronasal organ (VNO) reduced stimulus delivery into the VNO, decreased the pheromone-induced activity of vomeronasal sensory neurons, and attenuated male-male aggressive behaviors. PDE5A is well known to play a role in regulating blood vessel tone in several organs. Our study advances our understanding of the molecular regulation of the vomeronasal pump.

Differences in ocular adverse events associated with phosphodiesterase-5 inhibitors: a real-world pharmacovigilance study.

OBJECTIVE: Our study aims to characterize the ocular safety profiles of phosphodiesterase type 5 (PDE5) inhibitors and explore the differences among different PDE5 inhibitors. METHODS: We analyzed reports on ocular adverse events associated with sildenafil, vardenafil and tadalafil submitted to the FDA Adverse Event Reporting System (FAERS) database from the first quarter of 2004 to the first quarter of 2023. Disproportionality analysis was conducted to evaluate reporting risk profiles. RESULTS: Among 61,211 reports qualifying for analysis, 5,127 involved sildenafil, 832 vardenafil, and 3,733 tadalafil. All PDE5 inhibitors showed increased reporting odds ratios (ROR) for ocular adverse events, with vardenafil highest (ROR 4.47) followed by sildenafil and tadalafil. Key ocular adverse events included cyanopsia, optic ischemic neuropathy, visual field defects, unilateral blindness and blindness. Sildenafil showed the highest disproportionality for cyanopsia (ROR 1148.11) while vardenafil and tadalafil showed the highest disproportionality for optic ischemic neuropathy. Time-to-onset analysis also revealed significant differences, with sildenafil having a later median time-to-onset compared to vardenafil and tadalafil. CONCLUSIONS: This comprehensive pharmacovigilance study reveals distinct patterns of ocular adverse events associated with PDE5 inhibitors. These findings contribute to a better understanding of the safety profiles of PDE5 inhibitors and may guide healthcare professionals in clinical decision-making.