New treatments for erectile dysfunction are constantly under investigation by scientists. Pharmaceutical companies are hot on the trail of several drugs, some of which may be improvements on those already available; others may attack the challenge of erectile dysfunction from new directions. Researchers are also pursuing more innovative approaches, including gene therapy and stem cell therapy. Together with current treatment methods, experts are putting together new treatments for erectile dysfunction and other sexual health issues.
Several new treatments for erectile dysfunction are in the pipeline. One of them is Udenafil (Zydena®), which works similarly to the other available drugs, although it reportedly is effective for up to 12 hours. The drug has been approved in Korea and Russia but not the United States. Studies by udenafil’s manufacturer, Dong-A Pharm Tech Co., Ltd., report that compared with placebo, 88% of men who took 75 mg of udenafil daily for 12 weeks achieved an erection sufficient for intercourse. In a secondary test, udenafil also improved urinary tract symptoms associated with benign prostatic hyperplasia in 65% of men who took the drug.(Health Reserve)
In a randomized, double-blind, placebo-controlled study published in the Journal of Sexual Medicine, 103 men with erectile dysfunction were given either udenafil (50 men) or placebo (53 men) for four weeks. The researchers reported that udenafil significantly improved the maintenance of erection in 54.7% of men compared with 28.3% who took placebo, and that the drug was effective for 12 hours after dosing. (Park 2010)
In November 2009, Warner Chilcott partnered with Dong-A Pharm Tech Co. to conduct phase III trials of udenafil in the United States. More than 1,100 men will reportedly participate in the trials, and if the results are positive, it will likely be 2013 before the drug becomes available in the United States.
Another type of drug being investigated to recover erectile function is called an immunophilin ligand. Immunophilins are proteins present in immune and nerve tissues, and they are receptors for medications that have immunosuppressant properties. Some of those drugs include tacrolimus, cyclosporine, and rapamycin. Although these drugs suppress the immune system and thus increase the risk of infection, they also protect nerves, which makes them a possible candidate for preventing nerve damage associated with prostatectomy. Thus far a study in rats at Johns Hopkins has suggested that use of tacrolimus resulted in greater recovery of erectile function after trauma than rats that did not receive the drug. (Sezen)
Gene therapy is an experimental technique that uses genes to prevent or cure disease or a medical condition. Basically, it involves inserting a gene into a person’s cells rather than using a drug or surgery. The genetic material is used to compensate for abnormal genes.
Genes are delivered to the cells via a carrier called a vector. Certain viruses, such as retroviruses, are usually used as vector because they can infect the cell and be modified before they are injected so they do not cause disease. Gene therapy must overcome many technical challenges before it will be ready to treat erectile dysfunction.
Thus far, gene therapy has been tested in animal models to restore normal function to the penis, and only one human trial has been published in the peer-reviewed literature. (Harraz 2010)
Although the work in this area is still in its infancy, preliminary studies indicate that stem cells may help improve erectile function. In animal studies, fat-derived stem cells placed near blood vessels became smooth muscle, which is important because this is a muscle type that often fails to function properly. In a study of type 2 diabetic rats, the researchers found that injection of these stem cells improved blood pressure in the intracavernosal tissue (the spongy tissue in the penis).
At the annual meeting of the American Urological Association in May 2008, Tom F. Lue, MD, presented results of a pilot experiment in which he injected umbilical cord blood stem cells into men who had not responded to standard erectile dysfunction medications. Once the stem cells are injected into the affected area, they help produce new blood vessels in the de-oxygenated tissues, which can lead to improved erectile function. (AUA meeting) Synthetic cord blood stem cells also are under investigation as a candidate for new treatments for erectile dysfunction. In clinics outside the United States, some clinics use autologous adult stem cells (cells collected from a patient’s own bone marrow) to treat erectile dysfunction.
Erectile dysfunction is a challenge to treat, and one reason is that there are three main structures that must operate optimally for an erection to occur: the erection nerves, smooth muscles, and endothelium. Right now, erectile dysfunction is, for the most part, treated with one therapy at a time. Penile rehabilitation ventures into using two treatments, pills and penile injections.
As more and more potential new treatments for erectile dysfunction are uncovered, including new drugs in the pipeline, gene therapy, and stem cell therapy, physicians may soon be treating erectile dysfunction with combination therapy. Another area of possible merit is the use of erectile dysfunction pills (PDE5s) and statins, which are drugs used to lower cholesterol. Scientists have begun exploring the close relationship between erectile dysfunction and high cholesterol and the impact of the use of both statins and PDE5 inhibitors in men who have both of these conditions. (Miner)
References for New Treatments for Erectile Dysfunction
Health Reserve for udenafil:
Park HJ et al. Efficacy of udenafil for the treatment of erectile dysfunction up to 12 hours after dosing: randomized placebo-controlled trial. J Sex Med 2010 Jun; 7(6): 2209-16
Sezen SF et al. Role of immunophilins in recovery of erectile function after cavernous nerve injury. J Sex Med 2009 Mar; 6 Suppl 3:340-46
Harraz A et al. Emerging gene and stem cell therapies for the treatment of erectile dysfunction. Nature Reviews Urology 2010 Mar; 7:143-52
Presentation at the Annual Meeting of the American Urological Association, May 17-22, 2008, Orange County Convention Center, Orlando, FL, by Tom F. Lue, MD
Miner M, Billups KL. Erectile dysfunction and dyslipidemia