30.11.11

Spider Venom, The New Viagra?


Spider Venom, The New Viagra?
Michael Bell
University of Pittsburgh

Brazilian Banana Spider


A spider, known as Phoneutria nigriventer, or the Banana Spider common to South and Central America produces a venom with some very interesting side effects, one of which is priapism. Kenia Nunes, a researcher at the Medical College of Georgia, has produced a study that has shown that the banana spider’s venom might prove useful in the treatment of erectile dysfunction in men and possibly sexual dysfunction in women who are resistant to current treatment options like Cialis and Viagra. Both of these currently available drugs can cause sometimes dangerous side effects like heart attacks and strokes. Diabetic patients would benefit the most because erectile dysfunction mechanisms in these patients are multifactorial and often lead to resistance to current therapy options. The banana spider boasts the world’s most lethal venom and delivers a gruesome death by oxygen deprivation, loss of motor control, and severe pain (Emma, W., Discover Magazine). The venom of the spider is composed of a variety of polypeptides which have been shown to elicit various biological activities. Most of the polypeptides are neurotoxins which have direct effects on ion channels and produce symptoms like paralysis, respiratory arrest, and other neurological anomalies (Nunes, KP et al, 2011). One particular peptide, Tx2-6, is of interest and has proven to be the culprit for producing priapism, or an extended period of erectile response, in spider bite victims. In Nunes’s study, Tx2-6 was isolated and injected both subcutaneously and directly into the penis of diabetic, impotent, lab mice. After both types of injections, an erectile response was seen. The major pelvic ganglion, which is responsible for erectile response, was stimulated in the test subjects and a measurement of intercavernosal pressure was taken, all of which demonstrated that Tx2-6 was responsible for potentiating an erectile response. In a prior study, also done by Nunes, Tx2-6 was incubated in cavernosal strips taken from the penises of laboratory mice and relaxation of the cavernosal tissue was seen further proving the effectiveness of Tx2-6 in producing an erection (Nunes, K.P. et al, 2011). Nunes theorizes that Tx2-6 operates by increasing local nitric oxide levels. Nitric Oxide is a chemical that is responsible for triggering the chemical chain reaction that leads to an erection. A deficit of this chemical could lead to erectile dysfunction. Nunes also theorizes that the venom could be useful in treating female sexual dysfunction because the female clitoris consists of cavernosal tissue and works via a similar mechanism during sexual arousal. Nunes goes on to say that this naturally occurring chemical could emerge as a new pharmacological tool in conditions where vascular and endothelial dysfunction persists and that increasing nitric oxide, in this case, would be able to reverse the erectile dysfunction. According to the study done by Nunes, the drug could be available as early as 2013, although the issue of naturally occurring availability was not addressed. It is assumed that the drug would be able to be replicated in a laboratory rather than using naturally occurring venom from spiders. Nunes’s research claims to have produced a side effect free solution to erectile dysfunction. No reported side effects were seen in the laboratory animals, however human trials have not been conducted and inferring that Tx2-6 is safe for human use is a bit of a leap at this point. According to Nunes, the population most benefited by the new drug would be diabetics and she makes no reference to how it would generalize to people who have erectile dysfunction who are not diabetic, in fact non diabetic animals were not tested in the study. If this new found drug is truly side effect free and safe for human consumption it would make a viable alternative for E.D. treatment but why would anyone want to use it? To answer this, let’s take a look at the current options for treatment. Currently the most common treatment for erectile dysfunction is the use of either Viagra or Cialis, both of which are contraindicated in patients who are at an increased risk for heart problems or strokes. These drugs work by altering your blood pressure and for a cardiac patient this could lead to some serious problems like cardiac arrest or death. Some of the other more serious side effects include loss of vision or hearing. A second option for treating E.D. is an injection directly into the penis. Drugs such as papaverine, when used in impotence injections, dilate and relax the blood vessels and enable the penis to engorge with blood, thereby creating an erection. They too are not without risks and side effects. Repeated injections can create scaring and lead to more problems with maintaining an erection. Bruising and infection can occur. This type of treatment is also contraindicated in patients who have had cancer. Penile implants are another option. Implants require a surgical procedure and involve placing an inflatable device into the shaft of the penis or sometimes a device that has a flexible core. When a patient wants an erection he can push a button located under the skin and the device will inflate or in the case of the flexible insert, the patient just bends the penis upward. Side effects include surgical complications like infections and damage to the penis and risk of general anesthesia. Flexible inserts make the penis appear erect at all times so they can often be embarrassing and cumbersome to deal with. Lastly, vacuum devices are an option for erectile dysfunction treatment. A clear cylinder, which fits over the penis and forms a seal, is used in conjunction with a vacuum pump. The vacuum device is activated and pulls the blood into the penis which causes the penis to fill with blood and an erection results. This treatment also has some disadvantages. Bruising, damage to the penis from over inflation, and blood clots are a few. Overuse can actually cause more dysfunction. The resultant erection is only temporary and often subsides quickly after the device is removed and before intercourse can occur. The device is cumbersome to use and takes time and preplanning. As you can see, most of the available treatments are not without risk of serious side effects and pain to the person being treated. If a medication like Tx2-6 could be developed for use in humans and was side effect free it would be the obvious choice for erectile dysfunction treatment. In a pill form it would be convenient and wouldn’t require cumbersome devices or pre-planning. The user wouldn’t have to worry about undergoing surgery or have to make the choice to risk dangerous side effects. According to the study done by Nunes, the drug could be available as early as 2013.

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