First introduced to the U.S. market in 1998, Viagra was a breakthrough drug, offering impotent men a chance to resume relatively normal love lives. With the help of the little blue pill, men who had previously been unable to achieve and maintain an erection strong enough for sexual activity were suddenly back in the game.
Sixteen years after its introduction, Viagra is still the biggest-selling impotence drug in the United States despite increasing competition from rival medications that work in much the same way as Viagra does.
Viagra Leads Cialis
U.S. retail sales of Viagra tallied $1.165 billion in 2013, compared with $1.056 billion for Cialis, Viagra’s closest competitor, according to data from Drugs.com. U.S. 2013 sales figures from Medscape Medical News differ somewhat from those of Drugs.com but still show Viagra sales of $1.197 billion outpacing Cialis sales of $1.086 billion.
Based on its data, Medscape Medical News reports that Viagra came in 37th in Medscape’s list of the top 100 best-selling U.S. drugs in 2013. Cialis came in 42nd on the list.
Although both Viagra and Cialis are approved by the FDA to treat impotence, Viagra is available in tablets of varying strength that are to be taken an hour or so before sexual activity. Cialis markets a longer-lasting formulation for use as needed, as well as lower-strength pills that are intended for daily use and must be taken once every day to ensure effectiveness.
European Patent Expires
While Viagra continues to sell well outside the United States, it is losing ground to rival drugs as well as generic formulations of Viagra that are now available in Europe where Pfizer’s patent for Viagra expired in mid-2013.
In terms of global sales, Cialis in 2013 overtook Viagra as the world’s best-selling medication for the treatment of erection dysfunction. According to FirstWord Pharma, international sales of Cialis totaled $2.16 billion in 2013, up from about $1.93 billion the previous year. By contrast, global sales of Viagra slipped in 2013 to $1.88 billion from 2012 sales of $2.05 billion. The slippage in international sales was primarily reflective of Pfizer’s loss of the Viagra patent in Europe.
Sharp Price Drop in U.K.
As Pfizer’s Viagra patent was about to expire in the U.K., “The Guardian” reported that as many as 20 generic drugmakers had lined up to market their versions of the little diamond-shaped pills that have been such a big money-maker for Pfizer. The U.K. newspaper reported that with the generic versions of Viagra on the market, the price per pill in the United Kingdom would drop from roughly $15.50 to $1.50.
Helping to prolong Viagra’s market leadership in the United States was an August 2011 ruling by a U.S. federal judge that protects Pfizer’s market exclusivity through 2019. The judge’s decision blocked an attempt by Teva Pharmaceuticals to market a generic version of Viagra.
Agreement with Teva
In a subsequent settlement with Teva, announced in December 2013, Pfizer agreed to allow the drug manufacturer to release a generic version of Viagra on Dec. 11, 2017, or earlier under certain circumstances. Under this agreement, Teva will pay Pfizer a royalty in return for Teva’s license to produce a generic formulation of Viagra.
In its report on Viagra’s 15th anniversary in March 2013, CNN said that based on sales in 2012, Viagra held 45 percent of the U.S. market for impotence drugs. It also reported that Cialis was close behind.
Viagra Big in Corsica
In a January 2014 report, “The Connexion,” an English-language newspaper in France, said that sales of Viagra were higher in Corsica than in any other part of France. Other French areas with high levels of Viagra consumption include Alsace and Ile-de-France, the latter of which is the Paris metropolitan area.
Latin America has also seen strong sales of Viagra, accounting for roughly 13 percent of the drug’s worldwide sales in 2010, according to Fox News. Demand is particularly high in Mexico, the report said.
PDE5 Inhibitors
Sildenafil citrate, the active ingredient in Viagra, belongs to the same family of drugs as the active ingredients in rival drugs. Collectively, these drugs are known as PDE5 inhibitors, so-called because they block the effects of an enzyme known as phosphodiesterase-5, which can make it difficult for the penis to attain erection.
To become erect, the penis must fill with blood. This process occurs when blood vessels that supply blood to the penis expand at the same time that blood vessels carrying blood away from the penis contract.
Sexual Desire Essential
While Viagra and other drugs of its type make it possible to achieve and maintain an erection, they do not spontaneously cause an erection to happen. That still happens the old-fashioned way and is triggered by feelings of sexual desire.
In men, those feelings cause a release of nitric oxide to the penis. Nitric oxide causes another enzyme known as guanylate cyclase to produce a byproduct known as cGMP (cyclic guanosine monophosphate), which plays a key role in the contraction and expansion of blood vessels to and from the penis.
PDE5 Attacks cGMP
Left to do its own thing, the PDE5 enzyme attacks cGMP and in the process prevents erection or ends it prematurely. Sildenafil citrate and the other PDE5 inhibitors temporarily block the effects of PDE5, thus allowing erection to occur.
Viagra comes in tablets of 25, 50, and 100 milligrams. It is designed to be taken roughly one hour before sexual activity and is usually effective for four hours or slightly more. Most doctors start patients with a 50-milligram dose, which can be increased or reduced depending on how the patient reacts to the initial dose.
Most Side Effects Mild
Viagra’s side effects are generally mild, and most disappear with continued use. According to MayoClinic.com, the most common side effects are flushing, headache, indigestion, muscle pain (particularly back pain), runny or stuffy nose, and temporary vision changes. Patients who experience partial or complete loss of vision or hearing and erections that last more than four hours should contact a medical professional immediately.
Because Viagra causes a temporary lowering of overall blood pressure, it should never be taken concurrently with nitrate-based drugs, because in combination they can cause a precipitous drop in blood pressure that leads to unconsciousness or even death.
A prescription is necessary to buy Viagra, which can be ordered online from eDrugstore.com. If you have a prescription from your own doctor you can scan or fax that to eDrugstore along with your order. If you have no prescription, eDrugstore can arrange an online consultation with a licensed U.S. physician who can prescribe the drug if he or she deems it necessary. Best of all, eDrugstore supplies FDA-approved drugs from U.S.-licensed pharmacies that can be shipped discreetly to your home.
Don Amerman is a freelance author who writes extensively about a wide array of nutrition and health-related topics.
Photo credit: hagerstenguy
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