Newer phosphodiesterase inhibitors: comparison with established agents

Rapid Screening and Quantitative Determination of Illegal Phosphodiesterase Type 5 Inhibitors (PDE-5i) in Herbal Dietary Supplements

Phosphodiesterase type 5 inhibitors (PDE-5i) are the first-line medication for oral erectile dysfunction, which are used according to the prescription of doctors. However, these substances have been found illegally in supplementary foods. The quality and safety of dietary supplements for enhancing male sexual performance have been questioned, raising the need for continual development of analytical methods. Liquid chromatography coupled with high-resolution mass spectrometry has become one of the most effective methods to identify and measure PDE-5i concentration. In this research, we focused on (i) developing and validating an effective screening and quantitation method for more than 53 PDE-5i in ingredients and supplementary products using LC-Q-Exactive after a simple sample extraction and (ii) assessing PDE-5i content in natural-based supplementary products available in Vietnam market. The extraction method used a small amount of organic solvent, which makes it more environmentally friendly (greener). The developed method has a limit of detection of 0.4 mg/kg, a limit of quantitation of 1.2 mg/kg, recoveries from 80 to 110%, and repeatability lower than 15%. Ninety-two herbal supplementary foods and ingredients used for enhancement of male sexual performance available in Vietnamese markets were collected. Fourteen PDE-5i including conventional and novel analogous were detected and measured in eighteen food supplements and two formulation ingredient samples.

Pharmacodynamics, pharmacokinetics and clinical efficacy of phosphodiesterase-5 inhibitors

INTRODUCTION

Phosphodiesterase type 5 inhibitors (PDE5Is) are the first-line drugs in the management of erectile dysfunction (ED). However, over the past two decades tremendous efforts have been made to identify new clinical uses of PDE5Is beyond their roles in ED. Areas covered: Basic science articles, clinical trials, reviews, and meta-analysis published between 1996 and 2015 were searched using MEDLINE (PubMed interface) to collect the most relevant and impactful studies from our perspectives as practicing urologists. This review mainly focuses on the level one evidence-based clinical efficacy and drug-related toxicity of oral PDE5Is. In addition, drug discovery, pharmacokinetics and pharmacodynamics, potential use in other diseases, and future directions are discussed. Expert opinion: On-demand PED5Is for the treatment of ED has shifted toward chronic administration in a broad spectrum of conditions that are thought to be associated with endovascular health. Several studies have shown that PDE5Is may play a cardioprotective or neuroprotective role. Further studies are under way to verify beneficial effects of PDE5I in non-urological conditions.

MORE THAN ONE DECADE OF VIAGRA: WHAT LESSONS CAN BE LEARNED FROM INTELLECTUAL PROPERTY RIGHTS IN THE ERECTILE DYSFUNCTION MARKET?

The general objective of this study is to investigate the erectile dysfunction pharmaceutical market over the past two decades (1990–2010) through patent data analysis. The study of the erectile dysfunction market allows the analysis of the technological trajectory of Viagra® in its several phases, since the launching of a radical innovation, going through the accommodation of incremental innovations and eventually the release of generic versions of that product. This is a descriptive, documentary, longitudinal research that analyses five research hypotheses. The results show how the erectile dysfunction market has developed over the years and the lessons that can be extracted regarding Intellectual Property Rights for countries, companies and governments, including political and social considerations about how much should a patent protect innovation.

A review of analytical methods for the determination of four new phosphodiesterase type 5 inhibitors in biological samples and pharmaceutical preparations

The introduction of oral phosphodiesterase type 5 inhibitor therapy in 1998 revolutionized the treatment of erectile dysfunction. Erectile dysfunction is the most common sexual problem in men. It often has a profound effect on intimate relationships and quality of life. The analysis of pharmaceuticals is an important part of the drug development process as well as for routine analysis and quality control of commercial formulations. Whereas the determination of sildenafil citrate, vardenafil and tadalafil are well documented by a variety of methods, there are few publications about the determination of udenafil, lodenafil carbonate, mirodenafil and avanafil. The paper presents a brief review of the action mechanism, adverse effects, pharmacokinetics and the most recent analytical methods that can determine drug concentration in biological matrices and pharmaceutical formulations of these four drugs.