The US Food and Drug Administration (FDA) and the pharmaceutical company Pfizer advised doctors last week about new warnings and information added to the labeling of the impotence drug sildenafil (Viagra). The changes have been made in response to reports of cardiovascular adverse events in patients using the drug and nitrate heart drugs. According to the FDA's last surveillance update, there were 123 deaths worldwide reported from March through July 1998 for patients taking sildenafil. Of the 69 men who died in the US, 74% had one or more risk factor for cardiovascular or cerebrovascular disease, the agency said.
Dr. Mercola's Comment:
On March 27, 1998 the FDA approved Viagra. I have warned readers of this newsletter on three previous occasions of the dangers of this drug and I would like to offer some practical alternatives. Much of this information is taken from the excellent newsletter that Dr. Ward Dean (Vitamin Research News Vol 12. #9, November 1998) publishes.
Viagra was initially investigated as a potential anti-angina medication, based on its ability to release nitric oxide and increase blood flow to the heart. Viagra failed as a heart medication, but London researchers became excited when many of the men in the clinical trials reported the frequent occurrence of unaccustomed erections and improved sexual performance.
Five years after this serendipitous finding, Viagra was granted approval as a treatment for men suffering from difficulty in achieving erection. In the two months following its release, over one million prescriptions were issued, making it one of the most successful drugs ever introduced. Viagra may even provide similar benefits, enhancing sexual sensation and orgasmic enjoyment, for women and the drug is now in clinical trials for that purpose.
Viagra Alternatives.
Vascular smooth muscle cells surround arteries and arterioles, contracting and relaxing the arteries to regulate blood pressure. The given state of smooth muscle cells, and their effect on blood pressure, understandably have a profound effect on the male sexual organ.
Normally, in the presence of sexual stimulation, blood flow is directed into pockets known as the corpus cavernosum, contained within the shaft of the penis. The resulting inflow of blood leads to the enlargement and stiffening of the penis. This engorgement is triggered by a short-lived neurotransmitter. Nitric oxide, synthesized from the oxidation of the amino acid arginine, activates an enzyme that manufactures cyclic guanosine monophosphate (cGMP) which is a biochemical signaling enzyme. Under normal circumstances, cGMP directs the smooth muscle cells to relax, leading to the dilation of the penile arteries.
However, immediately following release of nitric oxide and production of cGMP another enzyme, another enzyme, cGMP phosphodiesterase type 5 (PDE-5), is activated. PDE-5's main activity is to destroy cGMP almost as fast as it is formed. The result of this breakdown of cGMP by PDE-5 is a rapid decrease in smooth muscle relaxation and a loss of blood flow to the penis. Subsequently, the penis returns to a flaccid state.
Unfortunately, as we age, cellular concentrations of cGMP decrease. Viagra works to achieve and maintain erections by enhancing the effect of nitric oxide and maintaining higher levels of cGMP. The way Viagra does this is to selectively inhibit the cGMP destroying actions of PDE-5. By blocking the actions of this enzyme system, cGMP is no longer broken down. This leads to elevated cGMP levels in the corpus cavernosum. This, in turn, prevents relaxation of the smooth muscle in the corpus cavernosum, increases blood flow to the genitals, and leads to stronger erections and intensified sensations.
Aside from the risk of dying and increasing the risk of retinal dysfunction, the biggest drawback to Viagra is the high cost, which can range upwards of $10 per pill. Fortunately, there is a safer, less expensive and more natural way to achieve many of the actions to Viagra. The key is L-arginine, the direct precursor to nitric oxide.
In the 1990s, scientists discovered that L-arginine, a non-essential amino acid, commonly found in the diet, is an oxidative precursor of nitric oxide. Under conditions in which nitric oxide is produced for a specified physiologic purpose, the concentration of L-arginine from which nitric oxide is formed, can be a limiting factor. Researchers at New York University School of Medicine gave L-arginine to a group of 15 men and found that six received benefit. Doses are around 1000 to 3000 mg per day.
Sexual arousal occurs not just in the genitals, but in the whole body and especially in the brain. For men, it actually begins when the brain sends impulses down the spinal cord and out to the nerves that serve the penis. These impulses trigger the production of nitric oxide. The neurotransmitter that causes the sexual message is acetlycholine (ACH). ACH also seems to control sexual behavior through its activity in the brain. For women, ACH is also a very important part of sexual function. With too little ACH, sexual activity goes down. ACH is involved in the buildup toward orgasm and the urethral and vaginal contractions that occur during orgasm.
One way to safely and effectively enhance ACH levels in the body is to take supplements of choline ( 1000 to 3000 mg) and vitamin B5 (500 to 1500 mg) so that the body will produce more ACH. Vitamin B5, also known as pantothenic acid, actually seems to enhance endurance by two routes. The first is by increasing ACH and the second is its role in the energy producing Krebs cycle. The choline and vitamin B5 are ideally taken about 20 to 30 minutes before sex in order to get the full effect.
Yohimbe and yohimbine is from a native tree in West Africa. For centuries a tea distilled from the inner bark of this tree has been used to amplify male virility and sexual prowess. Yohimbine’s primary path of action duplicates a key biochemical role in male erection. Yohimibine acts upon a specific network of nerve cells called the alpha-2-adrengeric system. Yohimbine shuts down this system which increases the flow of blood through arteries into the penis while at the same time decreasing the blood flow from the penis through veins. It also results in higher levels of ACH. Several controlled trials have been done with yohimbine and the response rate is about 40 percent.
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