Prescription du viagra

The usual dosage range for the intracaver-nosal form of alprostadil is 1.25 to 2.5 mcg. The maximum dose is 60 mcg up to 3 times a week, allowing at least 24 hours between each dose.

Some adverse effects include penile pain, bruising at the injection site, priapism, hematoma/ecchymosis, hypotension, headache, and dizziness.

The usual dosage range for the intraurethral form of alprostadil is 125 to 250 mcg up to a dose of 1000 mcg.

It is recommended that this system be administered after urination to facilitate absorption.

Adverse effects include penile pain, urethral burning, dizziness, hypotension, minor urethral bleeding/spotting, and female partner burning/itching. Using alprostadil is contraindicated in men with a predisposition to pri-apism, men in whom sexual activity is inadvisable or contraindicated, and men with abnormal penile anatomy/penile implants.

Men using the intraurethral form of alprostadil to treat their ED should avoid sexual intercourse with pregnant women because the alprostadil may cause harm to the unborn fetus. Other Therapies Trazodone, which is an atypical antidepressant with serotonergic and alpha-adrenolytic activity, is thought to help erection by indirectly stimulating corporeal smooth muscle relaxation.(10,11)Reports of prolonged erection and improved sexual function have prompted use of trazodone to treat ED. Although preliminary data showed efficacy, double-blind, placebo-controlled trials have shown marginal efficacy of trazodone in treating organic ED.(12)Trazodone also may be considered for patients with psy-chogenic ED. Yohimbine, an indole alkaloid obtained from the bark of the yohimbine tree, is a centrally acting alpha(2) adrenergic-receptor antagonist.

It acts at the adrenergic receptors in brain centers associated with libido and erection, and it may facilitate stimulated erections.(10)A meta-analysis of 7 randomized, placebo-controlled studies of men with erectile dysfunction showed that yohimbine was better than placebo in treating ED. This benefit was most significant, however, in patients with psychogenic ED, and efficacy was only marginal in patients with organic ED.(13)Yohimbine is generally recommended for those with psy-chogenic ED.(14) Papaverine is an opium alkaloid that inhibits phosphodiesterase at the postreceptor level and induces smooth muscle relaxation in the sinusoids and dilation of helicine arteries.(10)It increases cAMP and cGMP concentrations in penile erectile tissue, thus facilitating erection. It is effective and low in cost but can cause significant priapism and fibrosis when used alone at higher dosages. This adverse-effect profile limits routine use of papaverine; however, lower dosages can be utilized if used in combination with other vasoactive injection therapy.

(Phentolamine, a competitive alpha(1) and alpha(2)adrenergic-receptor blocking agent, dilates arteries and abolishes sympathetic prescription du viagra inhibition of erections.

Although it does not cause erections alone, it can be used in combination with other vasoactive injection therapy.(10)Significant adverse effects with phentolamine include orthostatic hypotension and tachycardia.

Oral phentolamine has been reported to be effective in treating ED and is available in several South American countries but not in the United States.

Intracavernous therapy with the lower dosages of combination papaverine and phentolamine is effective in treating ED, is better tolerated, and can be considered for patients who fail with traditional agents. Other combinations include intracavernous therapy with papaverine and alprostadil or with phentolamine and alprostadil. The most effective combination is intracavernous therapy with papaver-ine, phentolamine, and alprostadil (also known as trimix). The response rate with trimix may be as high as 90%.(11) Conclusion ED affects a vast number of men in the United States, and it is one of the most common untreated medical disorders.

Sildenafil is a major discovery in the treatment prescription du viagra of ED.

Although not completely effective in all patients, efficacy rates are high for sildenafil. Alprostadil is another effective treatment option, but it requires patient acceptance of the route of administration. A suitable medication therapy can be selected at the discretion of both the physician and the patient. Newer agents, such as vardenafil, will soon be available for use, and other therapies are in clinical development.

Erectile dysfunction and premature ejaculation: underlying causes and available treatments. This review examines the underlying causes associated with ED and PE and evaluates currently available treatment options and those under investigation.

Erectile and ejaculatory disorders comprise the most prevalent sexual disorders in men, with erectile dysfunction (ED) primarily affecting aging men who have coexisting morbidities such as cardiovascular disease and diabetes mellitus.

Premature ejaculation (PE) can affect men of all ages and is not typically associated with underlying organic disorders

but

Although many efficacious treatment options are currently available and recommended for the management of PE, several challenges remain in bringing the first desirable, safe, and effective FDA-approved drug to the US market.

This review examines the underlying causes associated with ED and PE and evaluates currently available treatment options and those under investigation.

2010;45:17-27.) Erectile dysfunction (ED) and ejaculatory disorders prescription du viagra such as premature ejaculation (PE) are considered the most common types of sexual dysfunction in men. "The inability to achieve or maintain an erection sufficient for satisfactory sexual performance," is a commonly accepted definition of impotence by the National Institutes of Health; however it is now recognized by the American Urological Association (AUA) as ED.

1 ED reportedly affects up to 40% of men between the ages of 40 and 70 and is more likely to develop with aging.

2-4 Despite broad consensus on a single definition, PE is commonly characterized by the inability to delay ejaculation, which occurs before or soon after the initiation of intercourse and is subsequently associated with feelings of distress or frustration. 5,6 Unlike ED which is more prevalent in older men, PE is considered one of the most common male sexual disorders and occurs with similar frequency in men, independent of age.

The penis is comprised of several key structures: the corpus cavernosum encased within the tunica albuginea, the corpus spongiosum containing the urethra, and the extensive vascular system of arteries and veins.

8 In the flaccid state, penile smooth muscle tissue is contracted and arterial blood flow which supplies the sinusoidal cavities within the pair of corpora cavernosa is equal to venous drainage from them.

With the exception of nocturnal penile tumescence, a sensory stimulus initiates the

erectile

cGMP

The second pathway involves prostaglandin E 1 -mediated activation of G proteins within smooth muscle cells, followed by stimulation of adenylate cyclase and increased production of cyclic adenosine monophosphate (cAMP) from adenosine triphosphate (ATP). 9 By decreasing intracellular calcium concentrations, both cGMP and cAMP cause smooth muscle relaxation, which leads to increased cavernosal arterial blood flow and decreased venous drainage resulting in an erection.

Neurogenic disorders involving the central nervous system (CNS) or peripheral nervous system such as stroke, spinal cord injury, Parkinson's disease, and multiple sclerosis have also been associated with ED. Furthermore, patients with a history of benign prostatic hyperplasia (BPH), Peyronie's disease, hypogonadism, or those who have had a radical prostatectomy secondary to prostate cancer are at greater risk of developing ED.

Drug induced causes of erectile dysfunction are common and can complicate the medical management of underlying conditions associated with ED such as hypertension, depression, and BPH (Table 1). Beta blockers, selective serotonin reuptake inhibitors (SSRIs), and the uroselective alpha adrenergic receptor antagonists have been associated with the loss of libido or ejaculatory disorders, which can result in drug discontinuation by patients and suboptimal treatment of these conditions. Researchers examining the role of drug exposures in the prevalence of erectile dysfunction found that hypertensive patients taking selected antihypertensive therapy increased the odds of ED prevalence, compared with patients not taking selected antihypertensive therapy (odds ratio [OR] 3.0, 95% confidence interval [CI] 1.6-5.9).

Despite the high prevalence of erectile disorders, identifying the presence of this condition remains challenging for the physician as patients are often reluctant to discuss this sensitive problem.

Although patients may be more inclined to share these issues when the discussion is initiated by their healthcare provider, physicians' themselves may also have some uneasiness with this conversation. A recent review of several studies found that the prompt recognition and treatment of ED symptoms associated with underlying endothelial cell dysfunction may improve ED related outcomes by decreasing the development or progression of vascular comorbidities. Approximately 80% of men diagnosed with ED will have organic disease; thus the AUA diagnosis and treatment guidelines recommend a thorough medical history and physical examination for all patients with suspected ED to identify underlying vascular, neurologic, or hormonal abnormalities.

14 The medical history should include a complete assessment of risk factors associated with organic ED and identification of comorbidities (ie, Peyronie's disease, history of penile surgery) that may present unique challenges to developing an effective treatment response. Patients should also be assessed for co-occurring anxiety or depressive disorders to rule out a psychogenic etiology.

Several tools have been developed to assess treatment outcomes such as the International Index of Erectile Function (IIEF), the Erectile Dysfunction of Inventory of Treatment Satisfaction (EDITS), and the Premature Ejaculation Tool.

The IIEF is a self-administered questionnaire that contains 15 questions which assess several domains, such as: erectile function, orgasm, sexual desire, and satisfaction.

1 The IIEF-5 is an abbreviated version of the IIEF which serves as a useful measure of treatment response and is generally more applicable to a clinical practice setting.

Patient diaries, such as the Sexual Encounter Profile (SEP), are also commonly utilized to document improvement in clinical outcomes.

Questions 2 and 3 from the SEP address a patient's ability to attain an erection sufficient for intercourse (SEP2) and the maintenance of the erection through completion of intercourse (SEP3).

Currently available agents for the management of ED include: the oral phosphodiesterase type 5 (PDE 5) inhibitors, intraurethral and intracavernous prostaglandin E 1 formulations, injectable phentolamine and papaverine, and testosterone preparations. Trazodone, yohimbine, and herbal products have been utilized in the treatment of ED but are not recommended for use by the AUA.

The arrival of sildenafil (Viagra) to the US market in 1998 was the first FDA approved oral PDE 5 inhibitor. It was followed shortly by vardenafil (Levitra) and tadalafil (Cialis) in 2003, marking a shift in the management of ED as more patients began to seek treatment with the availability of these more convenient pharmacologic options.

All 3 agents exert their effect by selectively blocking PDE 5 in cavernosal smooth muscle cells, which leads to a greater concentration of cGMP, thereby enhancing the effects of smooth muscle relaxation and cavernosal blood flow resulting in prolonged erectile function. The efficacy of the PDE 5 inhibitors has been demonstrated in several patient populations with ED due to organic and psychogenic causes. In a pooled analysis of several sildenafil studies, 63%, 74%, and 82% of sildenafil-treated patients who received 25 mg, 50 mg, and 100 mg, respectively, reported improvement in their erections, compared to only 24% of placebo-treated patients. 15 Similar results were observed in vardenafil-treated patients in whom escalating doses were also associated with better outcomes, between 58% and 66% of patients on vardenafil reported success with intercourse regardless of the drug dose.

18 Two studies in tadalafil-treated patients showed that 62% and 77% of patients were successful with SEP2, compared to 39% and 43% of placebo-treated patients, respectively ( P 17 Despite a lack of trials that compare these agents, all are considered equally effective for the treatment of ED by the AUA. As a result of their mild vasodilatory effects, caution should be exercised when the PDE 5 inhibitors are coadministered with other antihypertensive agents. The administration of nitrate-containing preparations are contraindicated with sildenafil, vardenafil, and tadalafil due to the profound hypotensive effects of this drug combination.

Furthermore, because of the underlying association of ED with cardiovascular disease, clinicians should carefully assess whether these agents are indicated in a particular patient.

The Princeton Consensus

Conference

20 The Second Princeton Consensus Conference reaffirmed these criteria in 2004.

Transient visual changes and disturbances in color vision have been reported rarely with the administration of the PDE 5 inhibitors, because these agents are known to exhibit partial selectivity for the PDE 6 enzyme that prescription du viagra is present in rod and cone photoreceptors. 22 More recent postmarketing reports of decreased vision or complete loss of vision as a result of nonarteritic anterior ischemic optic neuropathy (NAION) have led to further investigation of a temporal relationship between the PDE 5 inhibitors and this condition. NAION is an uncommon visual disorder that can lead to decreased visual acuity as a result of a swollen or "crowded optic disc" and is typically more prevalent in patients with a small cup-to-disc ratio and comorbidities such as hypertension, hyperlipidemia, stroke, and coagulation disorders.

22 Given that the risk factors for NAION share a close association with underlying disorders observed in ED patients receiving treatment with PDE 5 inhibitors, it remains unclear whether these agents increase the likelihood of developing NAION.

Prior to the market arrival of the oral PDE 5 inhibitors, alprostadil, a prostaglandin E 1 analog that facilitates the erectile response through cavernosal smooth muscle relaxation, was considered the treatment of choice for the management of ED. 12 Alprostadil remains the preferred second-line treatment option for patients who are unable to tolerate, or have an inadequate treatment response to the PDE 5 inhibitors. 14 Alprostadil is commercially available as Caverject Impulse and Edex intracavernous injections, as well as Muse urethral suppositories. At the time of this review, Caverject Impulse is temporarily unavailable through the drug manufacturer.

Alprostadil, when administered via intracavernous injection, has a quick onset of action and typically results in an erection within 5 to 20 minutes.

23 Patients who are ideal candidates for intracavernous therapy should receive thorough education and training on proper self-injection technique. Initial dosing and titration is performed within the physician's office utilizing the lowest dose necessary to produce a 30 to 60 minute erection sufficient for intercourse.

24 The initial recommended dose of intracavernous alprostadil is 2.5 µg and should be titrated in 5 to 10 µg increments until a response is observed. The average doses used in clinical studies ranged from 10 to 20 µg and the recommended injection frequency is no more than 3 times weekly.

Alprostadil urethral suppositories are absorbed through the urethral lining within 10 minutes and have a duration of action of about 30 to 60 minutes.

25 Self administration of suppositories within the urethra can be challenging; patients should be closely supervised in the office setting during the initial treatment period. A low starting dose of 125 to 250 µg is recommended and may be titrated to 500 µg or 1,000 µg as tolerated. Clinical studies evaluating the efficacy of alprostadil have generally found that the intracavernous injections are more effective than the urethral suppository formulations. In a randomized, open-label, multicenter study involving 111 patients, 82.2% of intracavernous administrations resulted in successful intercourse, compared to 47.4% of urethral alprostadil suppository administrations ( P 28 Similar results were found in a study that compared intracavernous injection to urethral suppository use in 66 patients with ED. Of alprostadil injections, 85% led to intercourse, compared to only 55% of suppository administrations ( P 27.

Both dosage formulations of alprostadil are administered locally and rapidly metabolized, making systemic side effects relatively uncommon with these agents. Local side effects such as penile pain associated with injection and urethral burning are the most common treatment-associated complications, occurring with variable incidence but reported in 17% to 37% of patients in clinical studies.