Health@Heart Philip S. Chua, M.D. Viagra Revisited How extensively has Viagra been prescribed todate? Since we first reported on Viagra (Sildenafil Citrate) in the June 18, 1998 issue of the Cebu Daily News, two months after it was introduced in the United States, more than 25 million prescriptions for Viagra have been written so far by more than 290,000 physicians in US alone. The overall success rate has been outstanding, with very few minor and transient side effects and few complications reported. It has been found to be a safe medication so long as it is taken on the advice of a physician and taken properly according to the guidelines set by Pfizer, the manufacturer. Is this drug only for men who are impotent? No. Inability to have a sustained erection in man is not caused only by an organic disease. Psychological factors play a big role in male potency. Those under the usual stresses in life could develop a certain degree of impotence. Even men younger than fifty, who were otherwise healthy except for having ED (Erectile Dysfunction) have been benefited by Viagra in their ability to regain and maintain a normal potency. About 33% of men over 40 and as many as 15 million men in the US have erectile dysfunction. How does Viagra help ? The physiologic mechanism of male erection involves release of nitric oxide (NO) in the corpus cavernosum (core of the penile shaft) during sexual stimulation. NO activates the enzyme guanylate cyclase, which results in the increase level of cyclic guanosine monophosphate (cGMP), producing smooth muscle relaxation in the corpus cavernosum and allowing more inflow of blood to engorge the male organ, causing erection. Viagra enhances the effect of nitric oxide by inhibiting an enzyme (PDE5) that degrades cGMP, thus helping maintain a higher level of cGMP in the corpus cavernosum. Is Viagra sold over the counter? No. This is a prescription drug. One needs to see a physician to be properlyscreened and advised about this medication, since there are possible side effects and complications. What is the most serious reported complication of Viagra? Deaths have been reported, but rather few compared to the volumes of Viagra taken in the world today. Medically, the incidence of this complication is considered low, and the drug is deemed safe by the medical community. Some of these deaths were from natural causes (like heart attack) which could have happened even without Viagra, since sexual activity in itself has some risk among those with untreated heart disease. Many of these deaths were found not to be directly related to Viagra, but rather due to the combination of Viagra and nitrates (heart medications that open up arteries) or due to misuse or abuse. The Pfizer warning is very clear and precise: Patients taking any form of nitrates must not take Viagra. Patients’ failure to heed the guidelines and this warning has caused most of the deaths. What are the side effects? Some persons experience side effects and others do not. The most common side effects, which are temporary, include any of the following: headache, flushing, mild gastric distress, nasal congestion, urinary tract infection, mild blurring of vision, mild dizziness, and skin rash. Can Viagra cause cancer? Pfizer reports that Viagra is not carcinogenic in extensive laboratory studies done on this drug. There is no evidence either that the drug is toxic to embryo, or to fetus, or that it is teratogenic. Does Viagra affect fertility or sperm motility? No, Viagra does not affect fertility or the morphology or motility of sperm. Does Viagra increase libido? No, not directly anyway. There must be passion and stimulation between the partners involved before Viagra works. If there is no mutual attraction and desire, this drug will not work. Will Viagra work for females? The efficacy of Viagra in women is still under scientific investigation in the United States. There are some good preliminary indications that this same drug may, in fact, be helpful also to women. The mechanism of action in females is the same as in males. The “engorgement or erection” is in the clitoris of women. The final official scientific verdict on this matter will be forthcoming soon. How long does the effect of Viagra last? The recommended initial dosage of 50 mg tablet taken orally lasts more than 2 hours in most, and even longer in some men. Erection is sustained until the sex act is completed, and gradually and normally subsides a few minutes thereafter. Any annoying distraction or any undesirable incident, before, during or after the sexual activity, will physiologically discourage erection. If a man is not taking medications containing Nitrates, is Viagra safe? Yes, according to scientific literature and medical experience. Taken properly under a physician’s supervision, Viagra is safe. The person contemplating to take Viagra must therefore see his physician for a good medical checkup and advice. Besides, one needs a physician’s prescription to purchase this medication, which is considered a wonder drug by the medical community. Any other drugs in the pipeline? Yes. Vasomax, a form of phentolamine made by Texas-based Zonagen, Inc, could be taken orally and takes effect within 15 minutes, now being reviewed by the FDA. Apomorphine is another drug being investigated for its value as a potency drug.
Philip S. Chua, M.D. is the Chairman of Cardiovascular Surgery of the Cebu Cardiovascular Center of the Cebu Doctors’ Hospital, Cebu City, Philippines, where he and his team perform open heart surgery. He trained under the world-renowned heart transplant surgeon, Denton A. Cooley, M.D., at the Texas Heart Institute in Houston, Texas. He is the President and Chairman of the Board of the Philippine Heart, Inc. in Munster, Indiana, U.S.A., where he also practices and does cardiac surgery.
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