Should patients be given an initial low test dose of sildenafil?

Assessment of correlations between sildenafil use and comorbidities and lifestyle factors using wastewater-based epidemiology

Sildenafil (SIL) is widely used to treat erectile dysfunction. Information on its consumption and the factors influencing its use is limited in China. In this study, we sampled composite influent wastewater samples from 33 Chinese cities and analyzed SIL using liquid chromatography-tandem mass spectrometry. SIL consumption was estimated using wastewater-based epidemiology (WBE) and ranged from 10.6 mg/d/1000 people to 132 mg/d/1000 people, with a mean of 53 mg/d/1000 people. Prescription sales (3570 kg) accounted for 13.3% of the estimated SIL use (26842 kg) in 2018, thereby implying that SIL illicit use was greater than prescription use in China. Some regional differences were observed in SIL use, which was significantly higher in North China than South China (p < 0.05), thereby reflecting that the prevalence of SIL was affected by differences in lifestyle and socioeconomic factors. We found significant positive correlations between SIL use and consumption of allopurinol, hydrochlorothiazide, nicotine, and alcohol, thereby suggesting that the prevalence of SIL was associated with the prevalence of gout, hypertension, smoking, and drinking. Moreover, age structures, internet use, and marriage rates were positively correlated with SIL use, whereas the unemployment rate was negatively correlated with SIL use. Our study demonstrates that WBE is valuable for medical research to investigate licit and illicit drug use and to assess the underlying associations of different chemical uses.

Relationship between nocturnal penile tumescence parameters, International Index of Erectile Function symptom scores and sildenafil responses

OBJECTIVE

To evaluate the correlation between International Index of Erectile Function (IIEF) questionnaire scores, nocturnal penile tumescence parameters and sildenafil response in patients with erectile dysfunction using a minimal investigations approach.

MATERIAL AND METHODS

A total of 97 patients without any risk factors for erectile dysfunction were included. After completing the IIEF questionnaire, nocturnal penile tumescence monitoring was performed in all patients for 1 or 2 nights. Subsequently, sildenafil was given at a dosage of 50 or 100 mg according to the response. The relationship between nocturnal penile tumescence results, the severity of erectile dysfunction according to the IIEF questionnaire and sildenafil response was evaluated using Pearson's chi2 test.

RESULTS

Based on the questionnaire scores, 25 patients (25.8%) had mild, 44 (45.4%) had moderate and 28 (28.8%) had severe erectile dysfunction. Forty-four patients (45.4%) had normal and 53 (54.6%) had abnormal parameters after nocturnal penile tumescence recording. The sildenafil response was positive in 63 patients (64.9%) who were given 50 mg and in 26 (26.8%) who were given 100 mg. However, eight patients (8.2%) did not respond to sildenafil. While the severity of erectile dysfunction according to IIEF scores and the sildenafil response did not show any correlations with nocturnal penile tumescence results, there was a statistically significant relationship between sildenafil response and the severity of erectile dysfunction.

CONCLUSION

Changing concepts in the evaluation of ED have resulted in the use of effective therapeutic applications consistent with the degree of symptoms of patients without the waste of time caused by performing expensive, invasive, ineffective and time-consuming diagnostic tests.

Infarto agudo de miocardio asociado al consumo de sildenafil. Aportación de caso y revisión de la literatura

Erectile dysfunction affects more than 30 million men in The United States. Since the FDA approved the use of Sildenafil, prescription of this medication has been raising. Adverse events of Sildenafil includes: fatigue, dyspnea, and hypotension. Reported adverse cardiac events associated with the medication use include myocardial infarction, ventricular tachycardia, angina and death, raising concerns about the safety of this agent in patients with coronary artery disease. Published guidelines regarding the management of cardiac patients with erectile dysfunction suggest that Sildenafil may be hazardous in patients with ischemic heart disease. In patients using Sildenafil, myocardial infarctions have been reported to the Food and Drug Administration. Now, we report a patient with myocardial infarction after taking 100 mg of Sildenafil without sexual activity.

Neurologic, psychological, and aggressive disturbances with sildenafil

BACKGROUND

Anecdotal reports and case studies have described psychological disturbances and aggressive behavior in some men taking sildenafil. In the course of assisting the defense in a trial in which a man was alleged to have committed rape and in which sildenafil was implicated, a mechanistic hypothesis was formulated by the first author for central nervous system (CNS) adverse effects associated with the use of sildenafil.

OBJECTIVE

To examine whether there was any scientific information available to suggest a possible mechanism for or an association between exposure to sildenafil and aggressive behavior.

METHODS

The scientific literature on sildenafil, nitric oxide (NO), and the NO-cyclic-guanosine monophosphate (cyclic-GMP) signaling pathway was reviewed. Adverse event reports that referenced sildenafil and were filed with the Food and Drug Administration Adverse Event Reporting System between January 4, 1998, and February 21, 2001, also were examined.

RESULTS

Published studies reported that sildenafil crosses the blood-brain barrier, that it exerts various biochemical and physiologic effects in the brain, and that it affects information processing. Other published reports indicated that phosphodiesterase type 5 (PDE-5), NO synthase, and guanylyl cyclase are present at highest activities in areas of the brain responsible for behavior, sexual drive, and emotion, and that NO modulates aggression and sexual behavior in male mice. In addition, 274 adverse event reports designated sildenafil as the primary suspect of various neurologic disturbances, amnesia, and aggressive behavior.

DISCUSSION

Evidence has been presented for an association between sildenafil and various CNS adverse effects, including aggressive behavior. Whether sildenafil causes these effects by inhibiting PDE-5 in the brain, accumulating cyclic-GMP, decreasing NO, and affecting cell-cell signaling and modulation of aggressive behavior requires further investigation.

CONCLUSIONS

It is recommended that, before prescribing sildenafil for erectile dysfunction, clinicians should caution their patients and their partners on the possibility of neurologic, emotional, or psychological disturbances; amnesia or loss of consciousness; or aggressive behavior.

A risk-benefit assessment of sildenafil in the treatment of erectile dysfunction

Sildenafil is an oral treatment for erectile dysfunction (ED). It acts as an inhibitor of 3',5'-cyclic guanosine monophosphate-phosphodiesterase type 5. An effective treatment for ED is required to produce an erectile response sufficient for satisfactory sexual performance. This has been documented for sildenafil in men with ED of differing aetiologies and baseline severity in various types of clinical trials. Sildenafil treatment is characterised by a good tolerability profile and low treatment digcontinuation rate caused by treatment-related adverse effects. Most of the adverse effects associated with sildenafil are extensions of the pharmacological action of the drug. There is no significant difference in the adverse effect profile (headache, flushing, dyspepsia, nasal congestion and abnormal vision) of this agent as assessed by clinical data obtained either in the pre- and postlaunch periods. Because of its acceptable risk-benefit ratio, sildenafil can be prescribed to a very large group of patients with ED. The reports of serious cardiovascular events associated with the use of sildenafil (including anecdotal reports of deaths) have been very thoroughly analysed. A number of studies have not shown any difference in the risk of serious cardiovascular events in sildenafil- and placebo-treated patients. However, when making a risk-benefit evaluation, certain subgroups of patients need to be considered separately. In particular, sildenafil is contraindicated in patients receiving nitrate therapy. In some other subgroups of patients, the risks and benefits of treatment need to be assessed on an individual basis and it is hoped that additional data will clarify any possible risks associated with sildenafil administration such patients. It is helpful to compare the risk-benefit profile of sildenafil with the characteristics of other oral drugs for ED. According to the preliminary data, apomorphine and phentolamine are possible future options for the treatment of ED; however, there needs to be further clinical evaluation of these agents. Initial data have shown that sildenafil can be successfully combined with intracavernosal injection in patients nonresponders to either therapy. In conclusion, favourable characteristics make sildenafil suitable for the first-line therapy for a substantial proportion of patients with ED.

Is the sildenafil product information adequate to facilitate informed therapeutic decisions?

BACKGROUND

Optimal therapeutics and the prevention of adverse drug effects begin with complete information. When new drugs are released, the manufacturer's product information is the main and often only readily available source of drug information and, therefore, greatly influences treatment strategies. Thus, it is vital that the information in the package insert is not only complete, but also as relevant as possible for the great diversity of patients that physicians encounter.

OBJECTIVE

To review the product information for sildenafil for comprehensiveness and accuracy, with respect to whether the information is sufficient to facilitate optimal therapeutics and to prevent avoidable adverse events in the wide diversity of patients with erectile dysfunction seen in clinical practice.

DATA SOURCES

Sildenafil package inserts, unpublished information provided by the manufacturer, Food and Drug Administration reports, and articles retrieved through MEDLINE through March 2000.

DATA SYNTHESIS

Deficiencies or inaccuracies persist in the sildenafil product information regarding sildenafil's effects on blood pressure; potential drug interactions with cimetidine, protease inhibitors, some antihypertensive drugs, alcohol, and drugs that may competitively inhibit cytochrome P450 pathways; and recommended sildenafil doses for older patients.

CONCLUSIONS

For physicians to practice optimal therapeutics, adequate, clinically relevant drug information is required. Several brief changes and additions in the sildenafil product information would assist physicians in making therapeutic decisions regarding the use of sildenafil in a very diverse patient population and in avoiding preventable adverse events.

Comparison of FDA reports of patient deaths associated with sildenafil and with injectable alprostadil

BACKGROUND

Sildenafil (Viagra) has been linked to 240 deaths (128 verified, 112 unverified) reported to the Food and Drug Administration (FDA) during 7.5 months of availability, and to 522 reported deaths after 13 months of availability. To date, no updated information about FDA-reported deaths has emerged, and no comparative analyses have been published.

OBJECTIVE

To compare the mortality rates between sildenafil and injectable alprostadil, both of which are used exclusively for treating erectile dysfunction.

METHODS

A comparison of the number of deaths per filled prescriptions reported to the FDA involving sildenafil and injectable alprostadil was undertaken to perhaps provide further insight into this issue. Materials included FDA statements on sildenafil adverse event reports to the FDA involving sildenafil and injectable alprostadil, and data on prescriptions filled for sildenafil and injectable alprostadil.

RESULTS

The number of deaths per prescriptions filled reported in association with sildenafil was significantly greater (5.15-6.28 times) than in association with injectable alprostadil.

DISCUSSION

Previous explanations for sildenafil-associated deaths have been based on the expected attrition within the population of men with erectile dysfunction and its commonly associated disorders, the physiologic stress of renewed sexual activity, and a pharmacologic effect of sildenafil. The results of this analysis may indicate that a pharmacologic effect of sidenafil is responsible for these deaths. However, other factors may also explain these findings: a greater frequency of reporting of sildenafil-associated events by physicians, a difference in the populations using these two drugs, or the number of prescriptions filled may not accurately reflect actual exposure.

CONCLUSIONS

Further study should be undertaken to clarify the issues associated with sildenafil-related deaths. In the meantime, reasonable precautions might be considered in prescribing sildenafil, such as initiating treatment with a low test dose of sildenafil.

Sildenafil citrate: a therapeutic update

BACKGROUND

Since its approval by the US Food and Drug Administration in March 1998, sildenafil citrate has been used by millions of men for the treatment of erectile dysfunction. Recent studies and consensus reports have expanded our understanding of its efficacy, safety, contraindications, and drug interactions.

OBJECTIVE

This paper reviews recent studies of the efficacy of sildenafil, its adverse effects and drug interactions, and socioeconomic factors involved in its use, with a focus on specific patient populations (prostate cancer, diabetes mellitus, ischemic heart disease, spinal cord injuries, neurologic disorders).

METHODS

Clinical studies, case reports, and commentaries and editorials concerning sildenafil published in the international literature between January 1999 and August 2000 were identified through searches of MEDLINE, PREMEDLINE, and International Pharmaceutical Abstracts, using the terms sildenafil, Viagra, and erectile dysfunction.

RESULTS

Sildenafil has demonstrated effectiveness in men with erectile dysfunction associated with prostatectomy, radiation therapy, diabetes mellitus, certain neurologic disorders, and drug therapy (eg, selective serotonin reuptake inhibitors [SSRIs]). It has not been as effective in women with sexual dysfunction, with the exception of SSRI-associated sexual dysfunction. Some disorders unrelated to sexual dysfunction (eg, esophageal motility dysfunction) may also respond to sildenafil. In the general population, sildenafil is considered to have an acceptable tolerability profile; however, patients with moderate to severe cardiovascular disease or those taking nitrate therapy are at increased risk for potentially serious cardiovascular adverse effects with sildenafil therapy. In addition, patients taking drugs that inhibit the cytochrome P450 3A4 isozyme, which metabolizes sildenafil, may experience increased drug concentrations and possible toxicity from normal doses of sildenafil.

CONCLUSIONS

Sildenafil is an effective first-line therapy for erectile dysfunction in men. The decision to prescribe this agent should include such considerations as the cost-risk-benefit balance, patient access, drug distribution pathways, and prescription drug coverage.