UNASSIGNED: This study aimed to develop a microemulsion (ME)-based skin delivery platform containing sildenafil citrate (SC)-ME and evaluate its in vitro skin permeability.
UNASSIGNED: Accurate MEs were prepared using pseudo-ternary phase diagrams and a full factorial design with three variables at two levels. After the design phase, suitable ratios of oil, water, and a mixture of surfactant (S) and cosurfactant (CS) were selected to prepare various SC-ME formulations. These SC-MEs were analyzed for stability, droplet size, in vitro SC release, skin permeability, and viscosity properties.
UNASSIGNED: The droplet size of the ME samples ranged from 6.24 to 32.65 nm, with viscosities between 114 to 239 cps. Release profiles indicated that 26 to 60% of SC was released from the different SC-MEs within 24 hours. All ME formulations significantly enhanced the permeability coefficient (P) through rat skin. Specifically, the flux (Jss) in SC-ME7 increased by approximately 117 times (Jss = 0.0235 mg/cm2.h) compared to the control sample (0.0002 mg/cm2.h).
UNASSIGNED: The study concluded that the proportions of the water or oil phase and the S/CS mixture in the MEs significantly influenced the physicochemical characteristics and permeation parameters. The selected MEs improved both the permeability coefficient and the rate of permeation through rat skin. The enhanced drug delivery through and into deep skin layers is a key attribute of an ideal dermal ME. These findings suggest that MEs could serve as effective transdermal delivery systems for SC and similar drugs. However, in vivo assays and clinical research are needed to confirm the therapeutic efficacy of MEs.

BACKGROUND: Priapism is defined as erection that lasts for more than 4 h without sexual stimulation. There are various causes of priapism, but there are no reports of sildenafil-induced priapism in dogs. In human medicine, there were no pre-marketing reports of priapism caused by sildenafil, but post-marketing surveillance has shown that it is rare. In cases of pulmonary hypertension in dogs, sildenafil is the first-line drug of choice for symptomatic relief.
METHODS: An 11-year-old neutered male Maltese dog that presented with tachypnea and cough was diagnosed with myxomatous mitral valve disease, American College of Veterinary Internal Medicine (ACVIM) stage C, and was treated medically. Eighteen months after the diagnosis, severe pulmonary hypertension occurred due to left heart disease. At 20 months postdiagnosis, pleural effusion occurred, and sildenafil (2 mg/kg twice daily) was added to the existing treatment. Two weeks later, the dyspnea recurred, confirming pleural fluid recurrence, and sildenafil was increased to 2 mg/kg thrice daily. One day later, the patient developed persistent erections and penile pain. Penile amputation and urethrostomy were recommended but were refused; therefore, analgesia and palliative care were provided. The patient died of acute dyspnea 22 months after the first presentation, with no specific priapism recurrence at the time of death.
CONCLUSIONS: To the best of our knowledge, this is the first report of sildenafil-induced priapism in a dog with pulmonary hypertension.

Drug reactions with eosinophilia and systemic symptoms (DRESS) syndrome and Stevens-Johnson syndrome-toxic epidermal necrolysis (SJS-TEN) are reactive entities of aberrant cytotoxic immunologic reactions to exogenous medications. While they are conventionally seen as distinct, separate conditions, we present a case of a rare evolution of DRESS syndrome into SJS-TEN in the setting of simultaneous amoxicillin-clavulanate initiation and long-term sildenafil use in a 66-year-old South Asian female with a known history of prior DRESS syndrome and pulmonary arterial hypertension. We discuss the conditions leading to her unique clinical presentation and provide considerations for future clinical encounters.

OBJECTIVE: In the present study, the effect of sildenafil on the pharmacokinetics of metformin was studied in experimental rats, and we also postulated the molecular mechanism by performing molecular docking studies.
METHODS: Analysis of metformin and sildenafil (SIL) from rat plasma was done by high performance liquid chromatography. Optimum chromatographic separation and quantification of MET, SIL and Cetirizine was achieved on Phenomenex EVO C18 column with triethyl amine (0.3%): Methanol: Acetonitrile (70:05:25 v/v) as mobile phase maintaining flow rate of 1 ml/min, the detector was tuned at 224 nm. The extraction of MET and sildenafil from rat plasma was achieved by solid-phase extraction using Strata-X cartridges. The method was validated as per the ICH guidelines. For docking studies, the crystal structure of organic cation transporter 1 (OCT1) protein and multidrug and toxin extrusion (MATE) protein (5XJJ) were downloaded from the PubChem database. The docking study was performed by PyRx virtual screening software, and the results were analyzed by BIOVIA Discovery Studio.
RESULTS: The validation of HPLC method was done, intraday and interday precision study of HPLC method demonstrated %RSD values less than 5%, the extraction recovery for MET and SIL were near to 80 % for low, medium and high QC samples. The plasma stability of MET and SIL showed % RSD values <10% for low, medium, and high QC samples. A sensitivity study for MET and SIL in rat plasma suggested a lower limit of quantification values of 8 and 10 ng/mL, respectively. The pharmacokinetic parameters were recorded, Cmax of experimental and control rats was 611.2 and 913.2 ng/mL; t1/2 1.66 and 1.98, AUC (0-t) 1637.5 and 2727.24, AUC (0-∞) 1832.38 and 2995.24 for MET. The results suggested that the Cmax of MET in experimental rats (MET + SIL) was 33.07% lower than the control (MET only) and also the t1/2 was 0.32 h shorter. Docking analysis suggested a higher binding affinity of sildenafil with MATE protein (5XJJ) compared to OCT1, suggesting possible involvement of MATE family proteins for pharmacokinetic alterations of MET.
CONCLUSIONS: The HPLC and solid-phase extraction method were developed and applied successfully for the pharmacokinetics of MET and SIL. Intake of SIL altered the pharmacokinetics of MET in rats. Molecular docking studies suggested the involvement of MATE family proteins for alterations of MET pharmacokinetics.

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-1β, osteopontin (OPN), and transforming growth factor-β (TGF-β)]. 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.

UNASSIGNED: A national additional risk minimization measures (aRMMs) program was implemented to train pharmacists for safe supply of non-prescription Viagra Connect® (VC) to erectile dysfunction (ED) patients in United Kingdom (UK). A survey aimed to evaluate the effectiveness of aRMMs.
UNASSIGNED: A cross-sectional, web-based survey enrolled ED patients who purchased at least 1 supply of VC in UK, using a structured self-administered questionnaire. Patients were assessed for the suitability of VC and received appropriate advice from pharmacists. Descriptive statistics were used.
UNASSIGNED: The final sample had 297 patients, who reported that pharmacists inquired about blood pressure and heart comorbidities (91.9%), relevant illnesses (87.9%), medications (86.5%), ED diagnosis (82.2%), and were advised to consult their doctor regarding ED (51.2%). Furthermore, 85.5% of patients were advised on how to take VC correctly, 82.2% on possible side effects for which they might have to discontinue taking VC and consult their doctor, 80.1% on being informed that ED could be caused by underlying conditions. About 65.0% reported that they had visited (19.2%) or planned to visit (45.8%) their doctor. A majority (68.7%) also indicated that they had received advice on lifestyle modifications to manage their ED-related health risks.
UNASSIGNED: This survey provided a reasonable confirmation of the effectiveness of the VC aRMMs program and assurance that ED patients, when requesting and purchasing VC in UK pharmacies, are assessed appropriately for suitability of VC and receive the appropriate advice from pharmacists.
A national additional risk minimization measures (aRMMs) program was implemented to train pharmacists for safe supply of non-prescription VC to erectile dysfunction (ED) patients in United Kingdom (UK). A cross-sectional, web-based survey enrolled ED patients who purchased at least 1 supply of VC in UK, using a structured self-administered questionnaire. Patients were assessed for the suitability of VC and received appropriate advice from pharmacists. The final sample had 297 patients, who reported that pharmacists inquired about blood pressure and heart comorbidities, relevant illnesses, medications, ED diagnosis, and were advised to consult their doctor regarding ED. Additionally, most of the patients had consulted or planned to consult their doctors, on how to take VC correctly, on possible side effects for which they might have to discontinue taking VC and consult their doctor, on being informed that ED could be caused by underlying conditions, and on lifestyle modifications. A majority also indicated that they had received advice on lifestyle modifications to manage their ED-related health risks. This survey provided a reasonable confirmation of the effectiveness of the VC aRMMs program and assurance that ED patients, when requesting and purchasing VC in UK pharmacies, are assessed appropriately for suitability of VC and receive the appropriate advice from pharmacists.

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).
CONCLUSIONS: 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.
BACKGROUND: ClinicalTrials.gov , NCT04948151.

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 β 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 β 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.

UNASSIGNED: 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.
UNASSIGNED: 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.
UNASSIGNED: 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).
UNASSIGNED: 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.
UNASSIGNED: URL: https://www.clinicaltrials.gov/study/NCT03855332; Unique identifier: NCT03855332.

UNASSIGNED: Sildenafil, a common over-the-counter pill often self-administered at high doses for erectile dysfunction, has been reported to rarely cause prothrombotic events and sudden cardiac death in a few case reports. Therefore, we investigated the in vitro and in vivo effect of sildenafil treatment and dosage on platelet activation and mitogen-activated protein kinase (MAPK) phosphorylation. BALB/C mice were segregated into four groups, each having four mice each (control, low [3.25 mg/kg], medium [6.5 mg/kg], and high [13 mg/kg] sildenafil), and after the treatment, blood was drawn from each mouse and washed platelets prepared. Washed platelets were incubated with CD41 PE-Cy7 and Phospho-p38 MAPK PE antibodies and analyzed using a flow cytometer for platelet activation and adenosine 5\'- diphosphate (ADP)/collagen-induced MAPK phosphorylation. Washed platelets obtained from the venous blood of 18 human volunteers, were incubated with PAC-1 FITC and Phospho-p38 MAPK PE antibodies, and platelet activation (ADP and collagen), followed by flow cytometry analysis. There was a significant increase in both platelet activation as well as MAPK phosphorylation in the presence of collagen in the high-dose (13 mg/kg) sildenafil group (P = 0.000774). Further, increased platelet activation was observed in samples that were treated with high-dose sildenafil as compared to the untreated samples (P < 0.00001). These studies show the risk of prothrombotic episodes in patients on high-dose sildenafil (100 mg), in those with even mild endothelial dysfunction due to ADP, and collagen-induced platelet activation through MAPK phosphorylation, which was not seen in the low-and intermediate-dose cohorts.