Vardenafil

Pharmacokinetics and Bioequivalence of Vardenafil Hydrochloride in Healthy Chinese Volunteers

Vardenafil hydrochloride tablet is an inhibitor of phosphodiesterase type 5, primarily for the treatment of erectile dysfunction. This postprandial study evaluated the pharmacokinetics and bioequivalence of the test and reference formulations of vardenafil hydrochloride tablets in healthy Chinese volunteers. An open, randomized, single-center, single-dose, 2-period, 2-sequence bioequivalence test was conducted on 66 healthy subjects under fed conditions. Subjects were randomly assigned to a 20-mg test or reference formulation with a 7-day washout period. Venous blood samples (4 mL) were collected from each subject 25 times spanning predose (0 hour) to 24 hours after dosing. The plasma concentration of vardenafil was determined by high-performance liquid chromatography-tandem mass spectrometry. Sixty-two volunteers completed the study. Under fed conditions, the maximum plasma concentration was 29.1 ng/mL, the area under the concentration-time curve (AUC) from time 0 to the time of the last measurable concentration was 85.3 ng•h/mL, and AUC from time 0 to infinity was 87.1 ng•h/mL. The 90% confidence intervals of the geometric mean ratio of AUC time 0 to the time of the last measurable concentration and AUC from time 0 to infinity were within the bioequivalence acceptance range of 0.80-1.25. The test formulation was a bioequivalent alternative to the reference formulation when taken under fed conditions in healthy Chinese subjects.

A synchronous spectrofluorometric technique for simultaneous detection of alfuzosin and tadalafil: applied to tablets and spiked biological samples

A facile, accurate, eco-friendly and sensitive spectrofluorometric method was evolved to assay alfuzosin hydrochloride (AFH) and tadalafil (TDF) in different matrices. Such a co-administered combination is clinically used for the treatment of lower urinary tract symptoms. Both compounds are characterized by their native fluorescence spectra upon excitation at specific wavelengths. Their characteristic fluorescence spectra were used for sensitive assay of the studied analytes in tablets and human biological samples. The assay principle is based on first-order synchronous spectrofluorometric scan using Δλ = 60 nm in which AFH peaks were recorded at 366 nm. Meanwhile, TDF measurements were recorded at 293 nm in the same scans without overlap with AFH spectra. Recent analytical chemistry trends were implemented to lessen occupational and environmental perils, using ethanol as a diluting solvent for method optimization and application. Linearity ranges were 5.0-90.0 and 10.0-100.0 ng ml^-1 for AFH and TDF, respectively in their raw materials with average % recoveries of 100.44% and 99.73% in raw materials, 100.15% and 100.20% in spiked plasma, and 97.14% and 99.99% in spiked urine. The proposed method was successfully applied to Prostetrol and Starkoprex commercial tablets with no interference with common tablet additives.

A synchronous spectrofluorometric technique for simultaneous detection of alfuzosin and tadalafil: applied to tablets and spiked biological samples

A facile, accurate, eco-friendly and sensitive spectrofluorometric method was evolved to assay alfuzosin hydrochloride (AFH) and tadalafil (TDF) in different matrices. Such a co-administered combination is clinically used for the treatment of lower urinary tract symptoms. Both compounds are characterized by their native fluorescence spectra upon excitation at specific wavelengths. Their characteristic fluorescence spectra were used for sensitive assay of the studied analytes in tablets and human biological samples. The assay principle is based on first-order synchronous spectrofluorometric scan using Δλ = 60 nm in which AFH peaks were recorded at 366 nm. Meanwhile, TDF measurements were recorded at 293 nm in the same scans without overlap with AFH spectra. Recent analytical chemistry trends were implemented to lessen occupational and environmental perils, using ethanol as a diluting solvent for method optimization and application. Linearity ranges were 5.0-90.0 and 10.0-100.0 ng ml^-1 for AFH and TDF, respectively in their raw materials with average % recoveries of 100.44% and 99.73% in raw materials, 100.15% and 100.20% in spiked plasma, and 97.14% and 99.99% in spiked urine. The proposed method was successfully applied to Prostetrol and Starkoprex commercial tablets with no interference with common tablet additives.

Utilization of a micellar matrix for simultaneous spectrofluorimetric estimation of alfuzosin hydrochloride and vardenafil hydrochloride

A sensitive and direct spectrofluorimetric method was developed for simultaneous quantitation of two co-administered drugs, namely, alfuzosin hydrochloride (AFH) and vardenafil hydrochloride (VRH). Both drugs exhibited native fluorescence properties that could be exploited to assay them in biological fluids with high sensitivity. Spectrofluorimetric analysis of AFH and VRH is based on excitation of both drugs at 265 nm where emission spectra were recorded separately for AFH and VRH at 380 and 485 nm, respectively. Micellar trends in analytical chemistry were adopted to minimize both environmental and occupational hazards, using distilled water and sodium dodecyl sulphate (serves as a micellar medium that enhanced the sensitivity of AFH and VRH) for analysis of both drugs in their raw materials, tablets, and human biological fluids (plasma and urine). Linearity ranges were 1.0-16.0 and 10.0-700.0 ng mL^-1 for AFH and VRH, respectively. The proposed method was successfully assessed for analysis of AFH and VRH in spiked human plasma and urine samples over the following concentrations: 1.0-12.0 ng mL^-1 and 4.0-400.0 ng mL^-1 for both drugs, simultaneously with mean recoveries of 101.08 % and 102.06 % in plasma and 96.75 % and 92.8 % in urine. Statistical analysis of the practical results has proved quite good agreement and revealed there were no significant differences in the accuracy and precision with those obtained by the comparison methods. The proposed method was applied successfully to Prostetrol® and Powerecta® commercial tablets without interference with tablet additives.

Phosphodiesterase 5 inhibitors as novel agents for the treatment of Alzheimer's disease

Alzheimer's disease (AD), characterized by a progressive impairment of memory and cognition, is a major health problem in both developing and developed countries. Currently, no drugs can reverse the progression of AD. Phosphodiesterase 5 (PDE5) is a critical component of the cyclic guanosine monophosphate/protein kinase G (cGMP/PKG) signaling pathway in neurons, the inhibition of which has produced neuroprotective effects, and PDE5 inhibitors have recently been thought to be potential therapeutic agents for AD. In this paper, we summarized the outstanding progress that has been made in PDE5 inhibitors as anti-AD agents with encouraging results in animal studies, clinical trials and the investigations on the underlying mechanisms. The novel PDE5 inhibitors reported recently in the treatment of AD were also reviewed and discussed.

Trends in erectile dysfunction research from 2008 to 2018: a bibliometric analysis

Insufficient penile erection to facilitate vaginal penetration is a medical condition referred to as erectile dysfunction (ED). By the year 2025, the number of ED cases across the world is expected to reach 322 million. There are numerous publications and studies in the field of ED over the past decades. Our aim is to comprehensively analyze the global scientific outputs of ED research and show the trends and hotspots in ED research. Data of publications were downloaded from the Web of Science Core Collection. We used CiteSpace IV and Excel 2016 to analyze literature information, including journals, countries/regions, institutes, authors, citation reports, and research frontiers. Until October 26, 2018, a total of 8880 papers in ED research were identified as published between 2008 and 2018. Journal of Sexual Medicine published the most articles. The United States contributed the most publications and occupied leading positions in H-index value and the number of ESI top papers. Maggi M owned the highest co-citations. The keyword "Oxidative stress" ranked first in the research front-line. The amount of articles published in ED research has been stable from 2008 to 2018. The United States showed enormous progress in ED research, and is still the dominant country. Oxidative stress, vardenafil, and late-onset hypogonadism were the latest research frontiers and should be paid more attention.

Genetic Understanding of Stroke Treatment: Potential Role for Phosphodiesterase Inhibitors

Phosphodiesterase (PDE) gene family is a large family having at least 21 genes and multiple versions (isoforms) of the phosphodiesterase enzymes. These enzymes catalyze the inactivation of intracellular mediators of signal transduction such as cAMP and cGMP and therefore, play a pivotal role in various cellular functions. PDE inhibitors (PDEI) are drugs that block one or more of the five subtypes of the PDE family and thereby prevent inactivation of the intracellular cAMP and cGMP by the respective PDE-subtypes. The first clinical use of PDEI was reported almost three decades ago. Studies later found the ability of these compounds to increase the levels of ubiquitous secondary messenger molecules that can cause changes in vascular tone, cardiac function and other cellular events and thus these findings paved the way for their use in various medical emergencies. PDEs are found to be distributed in many tissues including brain. Therefore, new therapeutic agents in the form of PDEI are being explored in neurodegenerative diseases including stroke. Although studies have revealed their use in cerebral infarction prevention, their full-fledged application in times of neurological emergency or stroke in specific has been very limited so far. Nevertheless, recent investigations suggest PDE4 and PDE5 inhibitors to play a vital role in mitigating stroke symptoms by modulating signaling mechanisms in PDE pathway. Further, extensive research in terms of their pharmacological properties like dosing, drug specific activities, use of simultaneous medications, ancillary properties of these compounds and studies on adverse drug reactions needs to be carried out to set them as standard drugs of use in stroke.

Clinical use of alprostadil topical cream in patients with erectile dysfunction: a review

Erectile dysfunction (ED) is a common and debilitating disorder seen in over 50% of men older than 70 years. Oral phosphodiesterase type 5 (PDE5) inhibitors are the mainstay of treatment for ED, but cannot be used by a significant subset of patients due to systemic side effects and drug-drug interactions. Second-line therapy may include intracavernosal therapies, but are associated with poor compliance due to their invasive nature. Alprostadil has a mechanism of action different from that of PDE5 inhibitors. Clinical trials have shown topical alprostadil cream to be effective, increasing the erectile function (EF) score of the International Index of EF by up to 13 points from baseline. It has also proven to be safe and well tolerated, with mild-to-moderate and transient treatment-related adverse events that are generally localized to the application site. Topical alprostadil cream is a safe and effective second-line therapy for ED, indicated for those who cannot tolerate, or are not satisfied with, oral PDE5 inhibitor therapy.

Vardenafil dihydrochloride

Vardenafil (VAR) is synthetic, highly selective, and potent inhibitor of phosphodiesterase-5 which competitively inhibits cyclic guanosine monophosphate (cGMP) hydrolysis and thus increases cGMP levels. It is clinically approved for treatment of erectile dysfunction in men, including diabetic and postprostatectomy patients. Several methods of VAR synthesis are included in this review. UV spectroscopy of VAR showed a λmax of approximately 270nm, and IR spectroscopy principal peaks were observed at 3420 (NH), 1724 (CO), 1600 (CC, and CN), 1491 (CHCH) cm(-1). Characteristic carbonyl (CO) carbon was observed in nuclear magnetic resonance spectroscopy at 162.44ppm. The molecular mass was observed at m/z=488.9 (molecular weight=488.2) and the fragmentation pattern was studied using ion trap mass spectrometry. In addition, different analytical methods for determination of vardenafil are also described in this profile. Pharmacokinetic properties of VAR have great impact on efficacy. VAR is rapidly absorbed and slowly metabolized, with an absolute bioavailability of 15%. It is extensively metabolized by CYP3A4 into several metabolites, the most pharmacologically active of which is N-desethyl VAR (M1). The elimination half-life of VAR and M1 is about 4-5h. VAR is primarily excreted as metabolites in the feces and to a small extent in urine. VAR is generally well tolerated, with a favorable safety profile and few transient side effects, including headache, flushing, dyspepsia, and rhinitis.

Anti-platelet therapy: phosphodiesterase inhibitors

Inhibition of platelet aggregation can be achieved either by the blockade of membrane receptors or by interaction with intracellular signalling pathways. Cyclic adenosine 3',5'-monophosphate (cAMP) and cyclic guanosine 3',5'-monophosphate (cGMP) are two critical intracellular second messengers provided with strong inhibitory activity on fundamental platelet functions. Phosphodiesterases (PDEs), by catalysing the hydrolysis of cAMP and cGMP, limit the intracellular levels of cyclic nucleotides, thus regulating platelet function. The inhibition of PDEs may therefore exert a strong platelet inhibitory effect. Platelets possess three PDE isoforms (PDE2, PDE3 and PDE5), with different selectivity for cAMP and cGMP. Several nonselective or isoenzyme-selective PDE inhibitors have been developed, and some of them have entered clinical use as antiplatelet agents. This review focuses on the effect of PDE2, PDE3 and PDE5 inhibitors on platelet function and on the evidence for an antithrombotic action of some of them, and in particular of dipyridamole and cilostazol.

The Efficacy and Safety of Vardenafil in East Asian Men with Erectile Dysfunction

INTRODUCTION

Previous clinical studies assessing the efficacy and safety of vardenafil, an oral phosphodiesterase type 5 inhibitor, in men with erectile dysfunction (ED) have consisted mostly of Caucasian patients.

AIM

The aim of this article is to describe the efficacy and safety of vardenafil in men of East Asian ethnicity with ED.

METHODS

Data were pooled from two 12-week, double-blind studies that included 306 East Asian men randomized to placebo or 10 mg of vardenafil.

MAIN OUTCOME MEASURES

Efficacy variables included the International Index of Erectile Function-erectile function (IIEF-EF) domain score, questionnaires of Sexual Encounter Profile (SEP2 and SEP3), and a Global Assessment Question (GAQ). Safety assessments included laboratory tests, vital signs, 12-lead electrocardiogram recordings, and patients' reporting of adverse events.

RESULTS

A total of 306 East Asian men with ED were treated with placebo (N = 151) or vardenafil (N = 155). Mean baseline IIEF-EF domain scores (placebo, 13.4; vardenafil, 14.2) were consistent with moderate ED. At end point, the patients treated with vardenafil had a significantly greater increase in IIEF-EF domain score compared with placebo (24.2 vs. 15.9; P < 0.0001). The average per patient penetration (SEP2) success rate was significantly higher in the vardenafil group compared with placebo (88% vs. 58%; P < 0.0001). Moreover, the average per patient intercourse completion (SEP3) success rate was significantly higher in the vardenafil group compared with placebo (69% vs. 23%; P < 0.0001). Positive GAQ responses were reported by 85% of patients receiving vardenafil, compared with 33% of those receiving placebo. The most frequent adverse events were vasodilatation (primarily facial flushing), rhinitis, and headache, all of which were of mild intensity.

CONCLUSIONS

Vardenafil is an effective, well-tolerated oral drug for the treatment of East Asian men with moderate ED of broad-spectrum etiology.

An integrated analysis of alprostadil topical cream for the treatment of erectile dysfunction in 1732 patients

OBJECTIVE

To assess the safety and efficacy of topical alprostadil cream for erectile dysfunction (ED).

METHODS

Patients with an ED score of 25 or less on the erectile function domain of the International Index of Erectile Function (IIEF) were randomly assigned to placebo or topical alprostadil cream (100, 200, or 300 microg) for at-home use for 12 weeks in two multicenter, double-blind, parallel-group studies. Patients receiving organic nitrates and patients with diabetes were included. Primary end points included the change in score for the erectile function domain of the IIEF and the change from baseline for the Sexual Encounter Profile (SEP) questions 2 (vaginal penetration success) and 3 (maintenance of erection to ejaculation). Safety was based on observed and reported adverse events and clinical laboratory results. Data from each study were pooled into a single integrated analysis.

RESULTS

A total of 1732 patients received placebo (n = 434) or topical alprostadil cream at 100 microg (n = 434), 200 microg (n = 430), or 300 microg (n = 434). The mean changes from baseline to end point in IIEF erectile function (EF) domain scores were -0.7, 1.6, 2.5, and 2.4 points for each group, respectively (P <0.001). Scores on SEP questions 2 and 3 improved slightly but significantly for all drug treatment groups compared with placebo (P <0.001). Most adverse events were localized to the application site and resolved within 2 hours.

CONCLUSIONS

Topical alprostadil cream significantly improves ED in a broad range of patients. Most adverse events were limited to the application site and were generally well tolerated.

Vardenafil for the Treatment of Erectile Dysfunction: A Critical Review of the Literature Based on Personal Clinical Experience

OBJECTIVE

To critically review the literature on vardenafil in the treatment of erectile dysfunction while integrating the clinical findings with the personal experience of the authors.

METHODS

Analysis of published full-length papers that were identified through Medline search from January 2000 through May 2004. Abstracts published in peer-reviewed journals from the same period were also considered.

RESULTS

Efficacy, tolerability and safety, as reported in the peer-reviewed literature compares well with the authors' personal experience. Authors' personal observations include discussions on potency, selectivity, selection of initial dose, counselling for patients characteristically considered difficult-to-treat (diabetes, prostatectomy, depression), including the determination of the maximal efficacious dose and the possible role of daily dosing, optimisation of the use of vardenafil according to its pharmacokinetic and pharmacodynamic profiles (onset and reliability), and management of ED patients with or at risk for cardiovascular disease.

CONCLUSIONS

Extensive experience with vardenafil as reported in peer reviewed literature confirms the important role of vardenafil in the management of patients with ED. The development of each physician's own experience with vardenafil is key to optimise overall satisfaction of this therapy by the patient and his partner.

Differences in hemodynamic and oxygenation responses to three different phosphodiesterase-5 inhibitors in patients with pulmonary arterial hypertension: a randomized prospective study

OBJECTIVES

We sought to compare the short-term impact of three different phosphodiesterase-5 (PDE5) inhibitors on pulmonary and systemic hemodynamics and gas exchange parameters in patients with pulmonary arterial hypertension (PAH).

BACKGROUND

The PDE5 inhibitor sildenafil has been reported to cause pulmonary vasodilation in patients with PAH. Vardenafil and tadalafil are new PDE5 inhibitors, recently being approved for the treatment of erectile dysfunction.

METHODS

Sixty consecutive PAH patients (New York Heart Association functional class II to IV) who underwent right heart catheterization received short-term nitric oxide (NO) inhalation and were subsequently assigned to oral intake of 50 mg sildenafil (n = 19), 10 mg (n = 7) or 20 mg (n = 9) vardenafil, or 20 mg (n = 9), 40 mg (n = 8), or 60 mg (n = 8) tadalafil. Hemodynamics and changes in oxygenation were assessed over a subsequent 120-min observation period.

RESULTS

All three PDE5 inhibitors caused significant pulmonary vasorelaxation, with maximum effects being obtained after 40 to 45 min (vardenafil), 60 min (sildenafil), and 75 to 90 min (tadalafil). Sildenafil and tadalafil, but not vardenafil, caused a significant reduction in the pulmonary to systemic vascular resistance ratio. Significant improvement in arterial oxygenation (equally to NO inhalation) was only noted with sildenafil.

CONCLUSIONS

In PAH patients, the three PDE5 inhibitors differ markedly in their kinetics of pulmonary vasorelaxation (most rapid effect by vardenafil), their selectivity for the pulmonary circulation (sildenafil and tadalafil, but not vardenafil), and their impact on arterial oxygenation (improvement with sildenafil only). Careful evaluation of each new PDE5 inhibitor, when being considered for PAH treatment, has to be undertaken, despite common classification as PDE5 inhibitors.

Neuroprotective Effects of Recombinant Thrombomodulin in Controlled Contusion Spinal Cord Injury Implicates Thrombin Signaling

Although the central nervous system (CNS) of mammals has had poor prospects for regeneration, recent studies suggest this might improve from blocking "secondary cell loss" or apoptosis. In this regard, intravenous activated protein C (aPC) improved neurologic outcomes in a rat compression spinal cord injury (SCI) model. Protein C activation occurs when the serine protease thrombin binds to the cell surface proteoglycan thrombomodulin (TM) forming a complex that halts coagulation. In culture, rTM blocks thrombin's activation of protease-activated receptors (PARs), that mediate thrombin killing of neurons and glial reactivity. Both PAR1 and prothrombin are rapidly upregulated after contusion SCI in rats, prior to peak apoptosis. We now report neuroprotective effects of intraperitoneal soluble recombinant human rTM on open-field locomotor rating scale (BBB) and spinal cord lesion volume when given 1 h after SCI. BBB scores from four separate experiments showed a 7.6 +/- 1.4 absolute score increase (p < 0.05) at 3 days, that lasted throughout the time course. Histological sections at 14 days were even more dramatic where a twofold reduction in lesion volume was quantified in rTM-treated rats. Thionin staining revealed significant preservation of motor neuronal profiles both at, and two segments below, the lesion epicenter. Activated caspase-3 immunocytochemistry indicated apoptosis was quite prominent in motor neurons in vehicle (saline) controls, but was dramatically reduced by rTM. Microglia, increased and activated after injury, were reduced with rTM treatment. Taken together, these and previous results support a prominent role for coagulation-inflammation signaling cascades in the subacute changes following SCI. They identify a neuroprotective role for rTM by its inhibition of thrombin generation and blockade of PAR activation.

Erectile dysfunction and cardiovascular disease

Cardiovascular disease and erectile dysfunction (ED) are closely interrelated disease processes. Erectile dysfunction reportedly affects 10 million to 20 million men in the United States and more than 100 million men worldwide. Each year, about 500,000 persons in the United States survive a myocardial infarction, and an estimated 11 million have existing cardiovascular disease, making the issue of sexual function and cardiac disease relevant to many patients. We explore the relationship between ED and the presence of cardiovascular disease in the general population. We also review the prevalence and pathophysiological associations of ED and cardiovascular disease. The risks of sexual activity for patients with cardiovascular disease are discussed, as are prevention and treatment strategies for ED in this patient population.

Vardenafil: a review of its use in erectile dysfunction

Vardenafil (Levitra) is a potent and highly selective oral phosphodiesterase type 5 (PDE5) inhibitor. Vardenafil improved erectile function in men with mild to severe erectile dysfunction (ED) of varying aetiology in two randomised, double-blind, multicentre, fixed-dose studies of 12 or 26 weeks' duration. Men receiving vardenafil 10 or 20 mg had significantly greater improvements in International Index of Erectile Function (IIEF) questionnaire erectile function domain scores than placebo recipients. Moreover, improvements in penetration and maintenance of erection (assessed using IIEF or Sexual Encounter Profile [SEP] questions) were significantly greater with vardenafil 5-20 mg than with placebo. Improvements in IIEF intercourse satisfaction and orgasmic function domain scores were significantly greater with vardenafil 10 or 20 mg than with placebo and the proportion of patients with a positive response to a Global Assessment Question (GAQ) concerning improvement in erections after 12 or 26 weeks' therapy was significantly higher with vardenafil 5-20 mg than with placebo. Vardenafil improved erectile function in men with ED associated with diabetes mellitus or ED following unilateral or bilateral nerve-sparing radical retropubic prostatectomy in two randomised, double-blind, multicentre, fixed-dose, 3-month studies. In both studies, improvements from baseline in the erectile function domain score of the IIEF and in positive responses to SEP questions were significantly greater with vardenafil 10 or 20 mg than with placebo. In addition, a significantly higher proportion of vardenafil 10 or 20 mg recipients than placebo recipients had positive GAQ responses. Vardenafil was generally well tolerated in men with ED; treatment-emergent adverse events were of mild to moderate intensity and transient in nature. The most commonly reported adverse events (typical of those seen with PDE5 inhibitors) in vardenafil 5-20 mg recipients included headache, flushing, rhinitis, dyspepsia and sinusitis. There were no reports of abnormal colour vision in men with ED taking vardenafil at clinically recommended doses (5-20 mg).

CONCLUSION

Vardenafil is a potent and highly selective oral PDE5 inhibitor. It is effective and generally well tolerated in men with mild to severe ED of varying aetiology, as well as in men with ED associated with diabetes mellitus or ED after radical prostatectomy. Vardenafil should be considered a first-line treatment option in men with ED who are suitable candidates for oral PDE5 inhibitor therapy.

Structure of the catalytic domain of human phosphodiesterase 5 with bound drug molecules

Phosphodiesterases (PDEs) are a superfamily of enzymes that degrade the intracellular second messengers cyclic AMP and cyclic GMP. As essential regulators of cyclic nucleotide signalling with diverse physiological functions, PDEs are drug targets for the treatment of various diseases, including heart failure, depression, asthma, inflammation and erectile dysfunction. Of the 12 PDE gene families, cGMP-specific PDE5 carries out the principal cGMP-hydrolysing activity in human corpus cavernosum tissue. It is well known as the target of sildenafil citrate (Viagra) and other similar drugs for the treatment of erectile dysfunction. Despite the pressing need to develop selective PDE inhibitors as therapeutic drugs, only the cAMP-specific PDE4 structures are currently available. Here we present the three-dimensional structures of the catalytic domain (residues 537-860) of human PDE5 complexed with the three drug molecules sildenafil, tadalafil (Cialis) and vardenafil (Levitra). These structures will provide opportunities to design potent and selective PDE inhibitors with improved pharmacological profiles.

Phosphodiesterase 5 inhibitors in male sexual dysfunction

PURPOSE OF REVIEW

Phosphodiesterase 5 inhibitors are preferred by most men for the oral treatment of erectile dysfunction. In many guidelines, this therapy is recommended as first-line therapy because of convenience, high efficacy, and low rates of side-effects. Sildenafil was the first drug for the treatment of erectile dysfunction, introduced in 1998. There are now two new phosphodiesterase 5 inhibitors, vardenafil and tadalafil, for which approval was recently given in the European Union and is expected this year in the United States.

RECENT FINDINGS

Sildenafil has proved to be a very effective medicinal product. According to initial studies, vardenafil and tadalafil have demonstrated efficacy comparable to that of sildenafil. However, fewer data are available evaluating the adverse effects of vardenafil and tadalafil, particularly on their long-term use and their use in high-risk groups. Interestingly, vardenafil and tadalafil have a higher potency than sildenafil. Moreover, the long life of tadalafil has been associated with an erectogenic potential of the drug lasting for more than 24 h. The advantage of this is the possibility of a patient engaging in sexual activity more than once after a single administration of the drug.

SUMMARY

In the future, in addition to sildenafil, the new phosphodiesterase 5 inhibitors vardenafil and tadalafil will play an important role in the management of erectile dysfunction, depending on the patient's health profile.