In the mid 1990s a new class of medicines arrived that revolutionized the treatment of erectile dysfunction. These medicines are known as the "phosphodiesterase inhibitors. " They led to further understanding of the mechanism of erection or how the body makes the penis erect. Studies were done on a molecule called Nitric oxide and the ability of this molecule to cause relaxation of the penile smooth muscle. To understand how the medicines work, it is important to understand the way the human body makes an erection.
To initiate an erection, there must be stimulation of the central nervous system (the mind) by visual stimuli or by physically touching the genital area. This triggers a biochemical reaction in the penis that causes the blood vessels and muscle cells to relax. Think of the penis as two long balloons that run side by side. These structures are called corporeal bodies. They have continuous blood flow to them, but when the man is not aroused, they are flaccid or “less full.” This is similar to the balloon without air. With stimulation, there is the release of a molecule called nitrous oxide. This triggers a chain of molecular events or pathways that eventually cause the relaxation of the penile “balloons,” or corporeal bodies. The corporeal bodies are composed of muscle cells, and the relaxation of these muscle cells causes the “balloons” to get bigger and allow more blood to flow into them. This is similar to air filling out the balloons and becoming longer and more rigid.
The phosphodiesterase inhibitors are the most commonly prescribed medication for erectile dysfunction. The common preparations available on the market are sildenafil (Viagra), vardenafil (Levitra) and tadalafil (Cialis). These pills are taken by mouth and work on the nitrous oxide pathway and enhance the body’s ability to maintain erection.
In general, each pill is taken before sexual activity. These medications are not for everyone, however, and should only be administered under the direction of your physician. Do not take these medications if your doctor has you on a medication called nitroglycerine for your heart. Certain other medications, such as alpha blockers (these are medications used for the prostate) should be used with caution. Combined use of these medications can result in dangerously low blood pressure and damage to the circulatory system (heart, brain, etc.)
It must be emphasized that all of a patient’s medications must be known by every doctor (or specialist) to avoid cross reaction or adverse side effects. As stated in earlier blog entries, a patient must have the general medical health to undergo sexual activity before trying these medications. Sexual activity can raise the heart rate similar to running a few laps around a track.
Ideally, for the best results, the medications should be taken approximately thirty minutes prior to the time of desired sexual activity, and the less food you have in your stomach at the time the pill is taken, the better. A large fatty meal like a double bacon cheeseburger can delay the absorption of the medication and delay the onset of erection. Cialis can take a little longer to start working but it lasts much longer in the blood stream. It is often labeled as the “weekender” because it can last in the patient’s system for up to thirty-six hours.