The incidence of erectile difficulties (ED) is rising. About three million Canadian men are faced with the physical and emotional lows associated with ED. Based on large-scale studies, it is clear that both the incidence and severity of ED increases with age. This is of major significance given Canada’s exploding baby boomer population.
The Erectile ProcessThe brain and central nervous system (CNS) play an important role in the normal erectile process. “During sexual stimulation, dopamine is released and a signal is transmitted to the sacral spinal cord. This leads to stimulation of nerves supplying the penis, resulting in vasodilation of blood vessels and a rigid erection,” says Dr. Francois Benard, a neurourologist at the Centre Hopital Universitaire de Montreal in Montreal, QC. “It is important, therefore, for physicians to recognize the significance of the brain’s role in an erection,” he added.
Drug Intervention in the Erectile ProcessFortunately, there are options today for men who suffer from ED. One class helps men achieve an erection by increasing levels of nitric oxide, a chemical in the body that has shown to help dilate blood vessels, increasing blood flow to the penis. However, results show that onset of erection can take up to 60 minutes.
A newer class of ED medication, targets the dopamine receptors in the brain, said to be the first step of the erectile process.
Apomorphine: A Novel Mode of ActionApomorphine is a dopamine receptor agonist that works in the brain to improve diminished erectile function by enhancing the natural signal to the penis following sexual stimulation, similar to the way men normally have erections. Apomorphine works through the central nervous system, producing a series of events that enhances the ability to achieve and maintain penile erection.
“Apomorphine is distinct from other oral therapies, which act by blocking the action of certain enzymes involved in the erectile response,” says Dr. Peter Pommerville, a urologist at Royal Jubilee Hospital in Victoria, BC. “Furthermore, apomorphine is administered sublingually (under the tongue), entering the bloodstream quickly and bypassing the gastro-intestinal tract. The rapid absorption into the bloodstream allows for its fast onset of action, typically under 20 minutes,” he adds.
Apomorphine’s safety profile can also be attributed to its novel mode of action. In clinical studies and from prescription data in Europe, it is evident that side effects and adverse events are at a very low level.
ED and Heart DiseaseSeveral major clinical studies suggest that ED is a marker of underlying coronary artery disease (CAD) and is even a predictor of CAD risk. Among men with ED who had no symptoms of CAD, 40% had at least one coronary artery narrowing.
In addition, recent estimates put the 10 year risk of developing CAD at 65% for all ED patients. As a result, physicians need to be vigilant in the early diagnosis of ED, ensuring that patients receive treatment with a therapy that is effective, safe and well-tolerated.
There should be special consideration of patients with ED in respect to their cardiac status. Because nitrates are commonly prescribed for CAD and often the standard care of the emergency treatment of heart attacks, treatment with other ED medications can potentially become dangerous.
“Men with ED are more likely to have cardiovascular conditions,” said Dr. Jeremy Heaton, a urologist at Kingston General Hospital and Professor of Urology and Pharmacology at Queens University in Kingston, ON. “Unlike other oral treatments that work directly on the circulatory system, apomorphine’s mode of action provides a well-tolerated option for men who may take medications for cardiovascular disorders or who may unexpectedly require nitrates for a heart attack.”Clinical Data
Apomorphine has been extensively studied in clinical trials involving more than 5,000 patients, with more than 120,000 doses administered. It has been studied in men with varying severity of erectile difficulties. The effectiveness of apomorphine was measured by the ability to produce an erection firm enough for intercourse.
“Apomorphine offers several benefits for patients in that it works fast, and it works similarly to the way men normally have erections,” says Dr. Heaton. “Long-term data in men who continued in studies demonstrate that once apomorphine begins working, it keeps working. In fact, it is reliable 90% of the time in these men.”
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