Inhibitor Sildenafil Research Articles

Identification of potent and orally efficacious phosphodiesterase inhibitors in Cryptosporidium parvum-infected immunocompromised male mice

Cryptosporidium parvum and C. hominis are parasites that cause life-threatening diarrhea in children and immunocompromised people. There is only one approved treatment that is modestly effective for children and ineffective for AIDS patients. Here, screening 278 compounds from the Merck KGaA, Darmstadt, Germany collection and accelerated follow-up enabled by prior investigation of the compounds identifies a series of pyrazolopyrimidine human phosphodiesterase (PDE)-V (hPDE-V) inhibitors with potent anticryptosporidial activity and efficacy following oral administration in C. parvum-infected male mice. The lead compounds affect parasite host cell egress, inhibit both C. parvum and C. hominis, work rapidly, and have minimal off-target effects in a safety screening panel. Interestingly, the hPDE-V inhibitors sildenafil and the 4-aminoquinoline compound 7a do not affect Cryptosporidium. C. parvum expresses one PDE (CpPDE1) continuously during asexual growth, the inhibited life stage. According to homology modeling and docking, the lead compounds interact with CpPDE1. Bulkier amino acids (Val900 and His884) in the CpPDE1 active site replace alanines in hPDE-V and block sildenafil binding. Supporting this, sildenafil kills a CRISPR-engineered Cryptosporidium CpPDE1 V900A mutant. The CpPDE1 mutation also alters parasite susceptibility to pyrazolopyrimidines. CpPDE1 is therefore a validated pyrazolopyrimidine molecular target to exploit for target-based optimization for improved anticryptosporidial development.

New and Emerging Therapeutic Drugs for the Treatment of Pulmonary Arterial Hypertension: A Systematic Review.

Pulmonary arterial hypertension (PAH) is a serious, progressive, and potentially fatal lung disease characterized by a gradual increase in mean pulmonary arterial pressure to over 20 mmHg at rest. The pathogenesis of PAH is multifactorial. It involves dynamic obstruction of the pulmonary vasculature through vasoconstriction, structural obstruction due to adverse vascular remodeling, and pathological obstruction caused by vascular fibrosis and stiffening, which reduces compliance. PAH often presents with vague initial symptoms and is frequently diagnosed at an advanced stage. The increased pulmonary arterial pressure leads to vascular remodeling, eventually resulting in right ventricular hypertrophy and failure. PAH is a rare condition with a median life expectancy of three years, underscoring the need for effective treatment alternatives. Several FDA-approved therapeutic options are available, including prostacyclin analogs (epoprostenol, iloprost, and treprostinil), the non-prostanoid IP receptor agonist selexipag, selective endothelin receptor antagonists (ERA) (ambrisentan, bosentan, and macitentan), phosphodiesterase 5 inhibitors (sildenafil and tadalafil), and the soluble guanylate cyclase (sGC) stimulator riociguat. Despite these advancements, current medications do not provide a permanent cure. This study presents an overview of current and emerging PAH therapies through a systematic literature review. It involved an analysis of nine studies and a review of 800 papers from reputable journals published between 2013 and June 2023. The research focused on drug effects on the six-minute walk distance (6-MWD) and associated side effects in randomized controlled trials. The review found that while udenafil, imatinib, racecadotril, sotatercept, anastrozole, riociguat, tacrolimus, and ralinepag were evaluated, imatinib was notably associated with adverse side effects. Conversely, udenafil, racecadotril, sotatercept, anastrozole, riociguat, tacrolimus, and ralinepag were found to be safe, well-tolerated, and effective in improving hemodynamic measures and 6-MWDs. This study aims to summarize the developing treatment options currently under clinical trials, highlighting the need for further trials before their application in clinical practice.

Modifying the gastric tumor microenvironment with tadalafil: A transcriptomic analysis of immune signatures from underserved patients of southern Arizona.

e16104 Background: Gastric adenocarcinoma (GAC) is the fifth most common cancer worldwide with significant morbidity and mortality. Recently, southern Arizona has seen a concerning surge in incidence of GAC due to ineffective H. pylori screening and treatment. Moreover, peri-operative chemotherapy treatment in stage IB-III GAC represents an area of unmet need for new targets. Our center serves a catchment area that is 40% Hispanic and sees a high volume of GAC patients, making this our research focus. Our preclinical work in Helicobacter infected mice showed a subset of myeloid derived suppressor cells (MDSCs) expressing Schlafen4 (SLFN4) concurrently with gastric metaplasia, a GAC precursor. SLFN4+ MDSCs exhibit robust transcriptional signatures associated with type I interferon(IFN-I) inducible genes, coupled with T cell suppressor function. Pharmacological inhibition via phosphodiesterase (PDE) 5,6 inhibitor sildenafil resulted in the suppression of SLFN4, reversal of T cell suppression, and mitigation of metaplasia. This is the first clinical study aimed to characterize SLFN12L, the human ortholog of mouse SLFN4, and to analyze the neoplastic and immune signatures in GAC before and after PDE5 inhibition with tadalafil. Methods: Using single-cell RNA sequencing, we examined tissues from GAC patients enrolled in a "Window of Opportunity" study (NCT05709574). The patients receive tadalafil (20mg) for 14 days, followed by combined tadalafil and FLOT (5-fluorouracil, leucovorin, oxaliplatin, and docetaxel) for 8 weeks. Gastric tissue and blood samples were collected i) before treatment, ii) after 14 days of tadalafil, and iii) after 8 weeks of combined treatment. We have enrolled 3 Hispanic patients to date with ongoing enrollment. Results: Tumors exhibited responses as per radiologic and pathologic criteria. In contrast to SLFN4, primarily expressed in myeloid cells, SLFN12L was found in most CD14+T lymphocytes and natural killer cells. A prominently activated and expanded myeloid population expressing SLFN12L was identified in the gastric mucosa of GAC patients. These cells exhibited transcriptional signatures associated with IFN-I signaling and immunosuppressive activities, diminishing after tadalafil treatment. Within GAC tissue, a notable increase in exhausted T cells and regulatory T cells was observed, decreasing after tadalafil. Post-tadalafil testing showed tissue PDE5/6 inhibition and higher plasma cGMP. Effector T cells exhibited an upward trend following tadalafil, suggesting a reduction in tumor immunosuppression. Conclusions: Preliminary data of this ongoing study show that tadalafil treatment combined with FLOT, has the potential to decrease SLFN12L+ MDSC, to attenuate their immunosuppression, and potentially inhibit tumor progression. The trial is active and further analysis will be presented in due course.

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

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. 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. 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. These findings provide evidence that migraine induction via the cGMP pathway can occur even under CGRP receptor blockade. ClinicalTrials.gov: Identifier NCT05889455.

Management of Pregnant Women with Atrial Septal Defect and Pulmonary Hypertension: A Case Report

Background: Pulmonary Hypertension (PH) is a condition where there is an increase in Pulmonary Vascular Resistance (PVR) and an increase in the mean Pulmonary Arterial Pressure (mPAP) to more than 20 mmHg. PH can occur in someone with Congenital Heart Disease (CHD). PH conditions can aggravate pregnancy in women with CHD. Women with PH are recommended not to undergo pregnancy. However, it is possible for women with CHD with PH conditions to undergo pregnancy. In these conditions, optimizing PH therapy is essential so that pregnant women with PH do not experience a worsening of the condition and can carry out their pregnancy well until delivery. Case presentation: A 38-year-old female patient with a history of Atrial Septal Defect-Pulmonary Hypertension came for common control to the cardiac clinic with the pregnancy condition of her 4th child, who was just discovered when she was six months pregnant. Since giving birth to her third child, the patient began complaining of being quickly tired when doing activities accompanied by swollen legs that disappeared with rest. The patient went to a cardiologist for an echocardiography examination and was diagnosed with Atrial Septal Defect (ASD)-Pulmonary Hypertension (PH). Since then, the patient has been routinely treated by a cardiologist with Pulmonary Hypertension drugs, including Phospodiesterase5 (PDE5) inhibitors (Sildenafil) and Prostacyclin Analogue (Dorner). The patient had done Transesophageal Echocardiography (TEE) with the results of ASD secundum suitable for closure by the device. Patients with Right Heart Catheterization (RHC) results, ASD secundum with PH High Flow High Resistance reactive to Vasoreactivity Test. Since the patient was found to be pregnant, the patient continued to use Sildenafil and discontinued the use of Dorner. The patient then continued treatment in a multidisciplinary team. Conclusion: Management of pregnant women with CHD and PH is essential because the condition of PH itself further aggravates the condition of pregnancy. Medical management for PH in pregnant women follows the guidelines for the safety of drugs in pregnancy so that the choice of therapy is crucially related to the goal of treatment to control the PH condition in the patient but still pay attention to safety in pregnancy conditions. Keyword: Congenital Heart Disease, Phosphodiesterase-5 (PDE-5)- Inhibitor, Prostacyclin Analogue, Pulmonary Hypertension.

A novel reuptake inhibitor, IP2015, induces erection by increasing central dopamine and peripheral nitric oxide release.

An estimated 40% of patients with erectile dysfunction have a poor prognosis for improvement with currently available treatments. The present study investigated whether a newly developed monoamine transport inhibitor, IP2015, improves erectile function. We investigated the effects of IP2015 on monoamine uptake and binding, erectile function in rats and diabetic mice and the effect on corpus cavernosum contractility. IP2015 inhibited the uptake of 5-HT, noradrenaline and dopamine by human monoamine transporters expressed in cells and in rat brain synaptosomes. Intracavernosal pressure measurement in anaesthetized rats revealed that IP2015 dose-dependently increased the number and the duration of spontaneous erections. Whereas pretreatment with the dopamine D2-like receptor antagonists, clozapine and (-)-sulpiride, or cutting the cavernosal nerve inhibited IP2015-induced erectile responses, the phosphodiesterase type 5 inhibitor sildenafil further enhanced the IP2015-mediated increase in intracavernosal pressure. IP2015 also increased the number of erections in type 2 diabetic db/db mice. Direct intracavernosal injection of IP2015 increased penile pressure, and in corpus cavernosum strips, IP2015 induced concentration-dependent relaxations. These relaxations were enhanced by sildenafil and blunted by endothelial cell removal, a nitric oxide synthase inhibitor, NG-nitro-l-arginine and a D1-like receptor antagonist, SCH23390. Quantitative polymerase chain reaction (qPCR) showed the expression of the dopamine transporter in the rat corpus cavernosum. Our findings suggest that IP2015 stimulates erectile function by a central mechanism involving dopamine reuptake inhibition and direct NO-mediated relaxation of the erectile tissue. This novel multi-modal mechanism of action could offer a new treatment approach to erectile dysfunction.

Cone photoreceptor phosphodiesterase PDE6H inhibition regulates cancer cell growth and metabolism, replicating the dark retina response

BackgroundPDE6H encodes PDE6γ′, the inhibitory subunit of the cGMP-specific phosphodiesterase 6 in cone photoreceptors. Inhibition of PDE6, which has been widely studied for its role in light transduction, increases cGMP levels. The purpose of this study is to characterise the role of PDE6H in cancer cell growth.MethodsFrom an siRNA screen for 487 genes involved in metabolism, PDE6H was identified as a controller of cell cycle progression in HCT116 cells. Role of PDE6H in cancer cell growth and metabolism was studied through the effects of its depletion on levels of cell cycle controllers, mTOR effectors, metabolite levels, and metabolic energy assays. Effect of PDE6H deletion on tumour growth was also studied in a xenograft model.ResultsPDE6H knockout resulted in an increase of intracellular cGMP levels, as well as changes to the levels of nucleotides and key energy metabolism intermediates. PDE6H knockdown induced G1 cell cycle arrest and cell death and reduced mTORC1 signalling in cancer cell lines. Both knockdown and knockout of PDE6H resulted in the suppression of mitochondrial function. HCT116 xenografts revealed that PDE6H deletion, as well as treatment with the PDE5/6 inhibitor sildenafil, slowed down tumour growth and improved survival, while sildenafil treatment did not have an additive effect on slowing the growth of PDE6γ′-deficient tumours.ConclusionsOur results indicate that the changes in cGMP and purine pools, as well as mitochondrial function which is observed upon PDE6γ′ depletion, are independent of the PKG pathway. We show that in HCT116, PDE6H deletion replicates many effects of the dark retina response and identify PDE6H as a new target in preventing cancer cell proliferation and tumour growth.

Vascular reactivity is altered in the placentas of fetuses with congenital diaphragmatic hernia

IntroductionInfants with congenital diaphragmatic hernia (CDH) often develop pulmonary hypertension but frequently fail to respond to vasodilator therapy, for instance because of an altered pulmonary vasoreactivity. Investigating such alterations in vivo is impossible. We hypothesised that these alterations are also present in fetoplacental vessels, since both vasculatures are exposed to the same circulating factors (e.g. endothelin-1) and respond similarly to certain stimuli (e.g. hypoxia). As proof-of-concept, we compared fetoplacental vasoreactivity between healthy and CDH-affected placentas. MethodsFetoplacental vascular function of healthy and antenatally diagnosed left-sided CDH fetuses was assessed by wire myography. Placental expression of enzymes and receptors involved in the altered vasoreactive pathways was measured using quantitative PCR. ResultsCDH arteries (n = 6) constricted more strongly to thromboxane A2 agonist U46619 (p < 0.001) and dilated less to bradykinin (p = 0.01) and nitric oxide (NO)-donor sodium nitroprusside (p = 0.04) than healthy arteries (n = 8). Vasodilation to prostacyclin analogue iloprost and adenylate cyclase stimulator forskolin, and vasoconstriction to endothelin-1 were not different between both groups. Angiotensin II did not induce vasoconstriction. Phosphodiesterase inhibitors sildenafil and milrinone did not affect responses to sodium nitroprusside, forskolin, or U46619. The mRNA expression of guanylate cyclase 1 soluble subunit alpha 1 (p = 0.003) and protein kinase cyclic guanine monophosphate (cGMP)-dependent 1 (p = 0.02) were reduced in CDH versus healthy placentas. DiscussionThe identified changes in the thromboxane and NO-cGMP pathways in the fetoplacental vasculature correspond with currently described alterations in the pulmonary vasculature in CDH. Therefore, fetoplacental arteries may provide an opportunity to predict pulmonary therapeutic responses in infants with CDH.

Abstract 18503: Endogenously Released Factors From Doxorubicin-Treated Breast Cancer Spheroids Contribute to Toxicity in Human Cardiomyocytes: Protective Effect of Combination Therapy With PDE5-mTOR Inhibitors

Background: We previously demonstrated that a novel combination therapy with the phosphodiesterase 5 (PDE5) inhibitor (sildenafil, Sild) and mTOR inhibitor (rapamycin, Rapa) potentiates doxorubicin (DOX)-induced breast cancer cell killing, but attenuates cardiotoxicities. However, it remains unclear whether there are any factors released from cancer cells treated with DOX that contribute to the injury in cardiomyocytes, which can be modified by Sild and Rapa in combination. Therefore, we designed experiments using spheroid cultures of breast cancer and human AC-16 cardiomyocytes to determine the role of endogenously released factors following treatment with DOX. Methods &amp; Results: Spheroid cultures of breast cancer MDA-MB-231 cells were treated with DOX (1 μμ), and/or Sild (10 μμ) and Rapa (100 nμ) for 48 hours. The medium was replaced and spheroids were further incubated for 48 hours in the fresh medium. Thereafter, the AC-16 cardiomyocytes were treated with the medium from drugs-treated spheroids for 48 hours. Our results showed that treatment with DOX and/or Sild and Rapa was highly effective in reducing the size of spheroids as compared to the control ( Fig. A ). Moreover, Western blots showed that p-mTOR/mTOR and p-S6/S6 were induced and p-AKT/AKT was suppressed after DOX treatment in cancer cells, which were normalized following treatment with Sild and Rapa ( Fig. B ). The medium from DOX-treated spheroids caused increase of cardiomyocytes death as assessed by trypan blue exclusion assay, which was attenuated by co-treatment with the medium from Sild and Rapa treated spheroids ( Fig. C ). Conclusion: These results suggest that cardiotoxicity of chemotherapeutic agents could be partly contributed by the endogenously released unknown factors from tumors, which can be modulated by a novel combination treatment with Sild and Rapa via regulating mTOR-signaling pathways.

Phosphodiesterase-5 inhibitors tadalafil and sildenafil potentiate nitrergic-nerve mediated relaxations in the bladder vasculature

Recent studies suggest that lower urinary tract dysfunction may arise due to changes in local perfusion. Phosphodiesterase-5 inhibitors can improve urinary bladder blood flow, although the local mechanisms have not been fully elucidated. The aim was to pharmacologically characterise the vascular supply to the bladder and determine the mechanisms underlying the effects of the phosphodiesterase-5 inhibitors tadalafil and sildenafil. Responses of isolated rings of porcine superior vesical arteries to electrical field stimulation (EFS) were measured in the absence and presence of inhibitors of key neurotransmitter systems. Vasodilation responses to nitric oxide (NO) donors were also recorded, and the effects of phosphodiesterase-5 inhibitors on all responses determined. EFS caused biphasic responses with an initial vasoconstriction and a slower developing vasodilation. Vasoconstriction was mediated by ATP (55%) and noradrenaline (45%) release, whilst vasodilation was reduced by L-NNA (100 μM) (80%) and propranolol (1 μM) (20%). The nitrergic component was inhibited (81%) by L-NPA, a selective inhibitor of neuronal nitric oxide synthase (nNOS). Endothelial removal did not affect vasodilation. Tadalafil and sildenafil depressed noradrenaline-evoked vasoconstriction (by 26.8% and 35.5% respectively, P < 0.01), enhanced vasodilation to EFS (by 27.8% and 51.8% respectively, p < 0.01) and enhanced responses to NO donors nitroprusside, SIN-1, and SNAP, increasing pIC50 values (P < 0.01), without affecting maximal responses. In conclusion, neuronal NOS has a predominant role in regulating vascular tone of the porcine superior vesical artery and potentiation of nNO-mediated vasodilation is the primary mechanism underlying effects of phosphodiesterase-5 inhibitors in the bladder vasculature.

Determination of Five Phosphodiesterase-5 Inhibitors in Multiple Honey-Based Consumer Products by Chromatographic Technique in Rat Plasma

This study aimed to develop and verify a simple HPLC-based quantitative approach to simultaneously determine the phosphodiesterase-5 inhibitors (PDE5Is) sildenafil, vardenafil, udenafil, avanafil, and tadalafil in a tablet dosage form mixed with honey obtained form Jordanian market in rat plasma. PDE5Is block phosphodiesterase-5 (PDE-5). This blockage, in turn, triggers vasodilation by phosphorylating downstream effector molecules. Chromatographic separation was performed on a HypersilTM C18 column (150 mm × 4.6 mm, 5 µm, Thermo Fisher Inc., Waltham, MA, USA). An acetonitrile:10% Triethylamine solution (57:43) at pH 5.5 (adjusted with orthophosphoric acid), 20 µL injection volume, 1 mL/min flow rate, 25 °C temperature, and eluent monitoring at 250 nm was used to execute the current approach. Linearity was observed in the 9.6–14.4 µg/mL concentration ranges for sildenafil, udenafil, avanafil, and tadalafil, and 2.4–3.6 µg/mL for vardenafil. Each dosage form was recovered within acceptable limits at three distinct concentrations, and the assay selectivity indicated no interference from the inactive substances in the formulation. Sildenafil, vardenafil, udenafil, avanafil, and tadalafil had retention times of 3.5, 4.3, 6.2, 9.7, and 12.8 min, respectively, and tadalafil was 12.8 min. The present analytical method is comprehensive and universal for measuring the five drugs. Such an analytical method can be routinely used to detect the combination of these drugs.

Myocardial stretch-induced compliance is abrogated under ischemic conditions and restored by cGMP/PKG-related pathways.

Introduction: Management of acute myocardial infarction (MI) mandates careful optimization of volemia, which can be challenging due to the inherent risk of congestion. Increased myocardial compliance in response to stretching, known as stretch-induced compliance (SIC), has been recently characterized and partly ascribed to cGMP/cGMP-dependent protein kinase (PKG)-related pathways. We hypothesized that SIC would be impaired in MI but restored by activation of PKG, thereby enabling a better response to volume loading in MI. Methods: We conducted experiments in ex vivo rabbit right ventricular papillary muscles under ischemic and non-ischemic conditions as well as pressure-volume hemodynamic evaluations in experimental in vivo MI induced by left anterior descending artery ligation in rats. Results: Acutely stretching muscles ex vivo yielded increased compliance over the next 15min, but not under ischemic conditions. PKG agonists, but not PKC agonists, were able to partially restore SIC in ischemic muscles. A similar effect was observed with phosphodiesterase-5 inhibitor (PDE5i) sildenafil, which was amplified by joint B-type natriuretic peptide or nitric oxide donor administration. In vivo translation revealed that volume loading after MI only increased cardiac output in rats infused with PDE5i. Contrarily to vehicle, sildenafil-treated rats showed a clear increase in myocardial compliance upon volume loading. Discussion: Our results suggest that ischemia impairs the adaptive myocardial response to acute stretching and that this may be partly prevented by pharmacological manipulation of the cGMP/PKG pathway, namely, with PDE5i. Further studies are warranted to further elucidate the potential of this intervention in the clinical setting of acute myocardial ischemia.

Sildenafil, a phosphodiesterase-5 inhibitor, stimulates angiogenesis and bone regeneration in an atrophic non-union model in mice

Non-union formation represents a major complication in trauma and orthopedic surgery. The phosphodiesterase-5 (PDE-5) inhibitor sildenafil has been shown to exert pro-angiogenic and pro-osteogenic effects in vitro and in vivo. Therefore, the aim of the present study was to analyze the impact of sildenafil in an atrophic non-union model in mice. After creation of a 1.8 mm segmental defect, mice femora were stabilized by pin-clip fixation. Bone regeneration was analyzed by means of X-ray, biomechanics, photoacoustic and micro-computed tomography (µCT) imaging as well as histological, immunohistochemical and Western blot analyses at 2, 5 and 10 weeks after surgery. The animals were treated daily with either 5 mg/kg body weight sildenafil (n = 35) or saline (control; n = 35) per os. Bone formation was markedly improved in defects of sildenafil-treated mice when compared to controls. This was associated with a higher bending stiffness as well as an increased number of CD31-positive microvessels and a higher oxygen saturation within the callus tissue. Moreover, the bone defects of sildenafil-treated animals contained more tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts and CD68-positive macrophages and exhibited a higher expression of the pro-angiogenic and pro-osteogenic markers cysteine rich protein (CYR)61 and vascular endothelial growth factor (VEGF) when compared to controls. These findings demonstrate that sildenafil acts as a potent stimulator of angiogenesis and bone regeneration in atrophic non-unions.

Dispersive magnetic solid-phase extraction for synthetic PDE-5 inhibitors determination by high-performance liquid chromatography with tandem mass spectrometry

A dispersive magnetic solid-phase extraction (DMPSE) procedure has been developed to preconcentrate four synthetic phosphodiesterase type 5 (PDE-5) inhibitors (sildenafil, desmethylsildenafil, vardenafil and tadalafil) from different samples (human hair, energy drinks, lubricating gels and dietary supplements). The target compounds were isolated from the solid samples by solid-liquid extraction in basic aqueous medium and the extract was submitted to DMSPE using multiwalled carbon nanotubes/Fe3O4@polypyrrole (MWCNTs/Fe3O4@PPy). For this, 20 mg of the magnetic nanocomposite was added to 30 mL of sample solution/extract and vortexed for 10 min before proceeding to the desorption step using 1 mL of methanol. Analysis was carried out by liquid chromatography with tandem mass spectrometry using electrospray ionization and a triple quadrupole mass analyzer (LC-ESI-QqQ-MS/MS). Matrix-matched calibration was applied for quantification. Limits of detection ranged between 0.01 and 0.22 ng mL−1 for energy drinks and between 0.25 and 7.5 ng g−1 for hair, lubricating gels, and dietary supplements. Relative standard deviations in the 4.3–12.2% (n = 10) were obtained for repeatability studies. The trueness of the proposed method was studied by fortifying the samples at two concentration levels and recoveries in the 85–112% range were obtained. None of the PDE-5 inhibitors studied were detected in real samples.

Proniosomal Gel-Loaded Phosphodiesterase Inhibitors (Sildenafil, Vardenafil, and Tadalafil): Prospects for Topical Penile Therapy of Tadalafil for Treatment of Erectile Dysfunction.

Oral phosphodiesterase inhibitors have emerged as a game changer for the treatment of erectile dysfunction (ED) since attaining FDA approval for its first member, sildenafil, in 1998. Topical penile therapy could be a viable replacement for oral medication that would transform the treatment of ED for many decades to come. This innovative idea could offer a safer topical alternative with less vision and cardiovascular side effects than the oral route. This work aims at developing proniosomal gels for three selected members (sildenafil, vardenafil, and tadalafil) and investigating the proniosomal gels on a rodent model. Niosomes derived from the parent proniosomal gels were characterized for entrapment efficiency (EE%), size, polydispersity index (PDI), zeta potential, and morphology. Proniosomal gels were evaluated for skin permeation, in vivo mating behaviors, and biochemical assays of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) post penile topical administrations. The optimized proniosomes loaded with tadalafil (F1-T) were compared with oral tablets (Cialis®). Proniosomal gels demonstrated significant enhancement of skin penetration by up to 5.5-fold, compared to control topical suspension. Tadalafil-loaded proniosomes showed superior skin permeability over sildenafil- and vardenafil-loaded proniosomes. In addition, significant improvement was noticed regarding intromission number, intromission ratio, NO, and cGMP for the proniosomal gel F1-T, compared to the untreated control. No statistically significant (p > 0.05) differences in sexual performance or biochemical parameters (NO and cGMP levels) were recorded among orally and topically (tadalafil proniosomal gel) administered groups. These findings support tadalafil topical penile therapy as a promising alternative to the oral route.

A Comparison of Nifedipine Versus a Combination of Nifedipine and Sildenafil Citrate in the Management of Preterm Labour.

Background Preterm delivery is a significant contributor to neonatal and infant morbidity and mortality. Preventive methods are preferable to treatment protocols for reducing perinatal mortality and morbidity. The calcium channel blocker nifedipine has the potential to be employed as a tocolytic, whereas the phosphodiesterase inhibitor sildenafil citrate promotes smooth muscle relaxation. Objective This study aims to examine the tocolytic effect of nifedipine in combination with sildenafil citrate in managing preterm labour (PTL). Methods After approval from the ethical board, 160 patients fulfilling the selection criteria were enrolled in the study from the outpatient and emergency department of obstetrics and gynaecology, University of Lahore, Pakistan. After taking written informed consent, their demographic profile, i.e., name, age, gestational age at presentation, parity, and expected date of delivery was noted. Patients were randomly assigned in a 1:1 ratio to two study groups (Group A: sildenafil citrate + nifedipine) and (Group B: nifedipine) using a computer-generated random number table to obtain a trial sequence. In group A, each patient was given nifedipine 20 mg orally, followed by 10 mg orally every eight hours for 48 hours and vaginal administration of sildenafil citrate, 25 mg at eight-hour intervals, for 48 hours. In group B, females were given nifedipine 20 mg orally, followed by 10 mg orally every 8 hours for 48 hours. They were kept admitted for 72 hours.SPSS Statistics version 21.0 (IBM Corp. Released 2012. IBM SPSS Statistics for Windows, Version 21.0. Armonk, NY: IBM Corp.) was used to enter and analyse the collected data. Mean and standard deviation was calculated for quantitative variables like age, gestational age at presentation, gestational age at delivery, and BMI. Frequency and percentage were calculated for parity and preterm delivery. Results The study involved 160 patients, with the average age in Group A being 29.60±4.9 years and in Group B being 30.96±4.98 years. In terms of gestational age at delivery, Group A had an average of 34.16±1.7 weeks, while Group B had an average of 33.5±1.8 weeks (p-value<0.05). Preterm delivery was observed in 68.5% of Group A and 41.3% of Group B, with a significant p-value of 0.001. The study also discovered that the duration of prolonged pregnancy was significantly higher in Group A compared to Group B, with averages of 14.96±10.37 days and 10.24±8.97 days, respectively (p-value=0.002). Conclusion The results of this study suggest that the combination of sildenafil citrate and nifedipine may offer a promising new approach to improving pregnancy outcomes in cases of PTL. In the present study, sildenafil citrate plus nifedipine showed a significant effect in the management of PTL and prolongation in mean gestational age at delivery.

PDE5 inhibitor drugs for use in dementia.

Potent phosphodiesterase-5 (PDE5) inhibitors are in clinical use as vasodilators.In animals PDE5 inhibitors enhance synaptic function and cognitive ability.In humans the PDE5 inhibitor sildenafil is associated with reduced risk of Alzheimer's disease.Licensed PDE5 inhibitors have potential for repurposing in dementia.Prospective clinical trials of PDE5 inhibitors are warranted.

An atypical erectile dysfunction patient with infertility treated with penile prosthesis implantation and testicular epididymal sperm aspiration (TESA)-intracytoplasmic sperm injection (ICSI): A case report.

Erectile dysfunction (ED) is common in middle-aged and elderly men, affecting more than 100 million males worldwide. Most ED cases can be attributed to organic and/or psychological factors. Here we report an atypical ED case with no clear manifestation fitting the diagnosis for recognized types of ED. The 35-year-old male is unable to have normal erection since puberty, and unable to complete intercourse with his wife. He had no history of trauma, surgery or psychiatric/psychological disease. The patient has a normal male karyotype. There is no significant finding in physical examination, nocturnal penile tumescence test, and ultrasound measurement of penis vascular functions. The serum levels of major hormones are all in normal ranges. Atypical ED, psychogenic ED not excluded; infertility. Oral phosphodiesterase inhibitors Tadalafil (20 mg, BIW) or Sildenafil (50 mg, BIW) had no effect in this patient. Penile prosthesis implantation helped the patient to acquire normal sexual life, but did solve the ejaculation failure and infertility. Motile sperms were obtained by testicular epididymal sperm aspiration under the guidance of ultrasound, and intracytoplasmic sperm injection was performed with occytes retrieved from his wife. The patient sexual life was significantly improved after penile prosthesis implantation; the patient wife is currently in the first trimester of pregnancy as the result of in vitro fertilization. The no response to phosphodiesterase type 5 inhibitors (PDE5) treatment may suggest an impediment of PDE5-related pharmacological pathways or the presence of defect/injury in the neural system. This special case raises a question if some patients with persistent ED may have similar manifestations and can be treated with the same procedures.

The nitric oxide-cyclic GMP-KATP channels pathway contributes to the effects of montelukast against gastric damage induced by ethanol

The leukotrienes, lipid mediators, have a role in gastric damage induced by ethanol. Here, the gastroprotective effect of montelukast, an antagonist of the leukotriene receptor, and the involvement of the NO-cGMP-KATP channel pathway, were evaluated in gastric damage induced by ethanol in rats. For this, l-arginine, l-NAME, methylene blue (guanylate cyclase inhibitor), sildenafil, diazoxide, or glibenclamide (ATP-sensitive potassium channel blocker) were administered 30 min before montelukast (0.1, 1, 10, and 20 mg/kg, by mouth [p.o.]). After 1 h, to induce gastric damage, the rats received absolute ethanol (4 mL/kg, p.o.), and then microscopic, macroscopic, and pro-inflammatory parameters (TNF-α and IL-1β) were assessed. Results obtained here revealed that montelukast significantly attenuated the macroscopic and microscopic lesions induced by ethanol. Montelukast also reduced IL-1β and TNF-α levels. It was also observed that NOS inhibitor (l-NAME), methylene blue, and glibenclamide inhibited the effects of montelukast in the stomach. Moreover, the NO precursor (l-arginine), the PDE-5 inhibitor (sildenafil), and a potassium channel opener (diazoxide) before montelukast produced gastroprotective effects. In conclusion, the effect of montelukast against gastric lesions induced by ethanol is mediated, at least in part, through the pathway of the NO-cGMP-KATP channel.

Phosphodiesterase 5 (PDE-5) inhibitors (sildenafil, tadalafil, and vardenafil) effects on esophageal motility: a systematic review

BackgroundEsophageal motility disorders are a group of disorders associated with dysfunctional swallowing resulting from impaired neuromuscular coordination. Phosphodiesterase 5 (PDE-5) inhibitors induce smooth relaxation and are proposed as a treatment option for esophageal motility disorders such as achalasia.MethodsThis study is conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We systematically searched MEDLINE/ PubMed, Scopus, EMBASE, and Web of Science databases for esophageal outcomes of individuals treated with PDE5 inhibitors. A random effect meta-analysis was conducted.ResultsA total of 14 studies were included. They were conducted in different countries, with Korea and Italy having the highest number of articles. The main drug assessed was sildenafil. PDE-5 inhibitors resulted in a significant reduction in lower esophageal sphincter pressure (SMD − 1.69, 95% CI: -2.39 to -0.99) and the amplitude of contractions (SMD − 2.04, 95% CI: -2.97 to -1.11). Residual pressure was not significantly different between the placebo and sildenafil groups (SMD − 0.24, 95% CI: -1.20 to 0.72). Furthermore, a recent study reported contractile integral, stating that ingestion of sildenafil leads to a significant reduction in distal contractile integral and a significant increase in proximal contractile integral.ConclusionPDE-5 inhibitors significantly reduce LES resting pressure and esophageal peristaltic vigor, decreasing esophageal body contractility and contraction reserve. Therefore, using these drugs in patients affected by esophageal motility disorders may potentially improve their condition regarding symptom relief and prevention of further associated complications. Future reports investigating larger sample size is necessary in order to establish definite evidence regarding the efficacy of these drugs.