The most famous drug in the world is sildenafil citrate. What’s that? You never heard of it? Perhaps you’re more familiar with its trade name, Viagra. Viagra was once known only as UK-92, 480. The UK portion of the name referred to the United Kingdom, where Viagra was developed in the labs of the giant drug company Pfizer. Chemists were attempting to produce a drug that could effectively treat high blood pressure and angina pectoris, which is pain in the chest related to coronary artery disease. Although the new compound proved weak in treating angina, it produced a readily apparent side effect: pronounced penile erection. The suits at Pfizer immediately recognized the broad implications of the discovery and patented the drug in 1996. The trade name Viagra was chosen, and the FDA approved the drug in 1998. The era of the little blue pill had begun.
These days Viagra is used by more than 20 million men to treat impotence, and at the height of its popularity it generated worldwide sales of $2 billion. Although sales have declined because of the introduction of similar drugs that work faster and last longer, you still frequently see televised ads that push Viagra as a key to marital bliss. Indeed, Viagra’s popularity has inspired a number of natural copycats, often referred to as “herbal Viagra.” One such supplement contained an analog called acetildenafil. While it did work like Viagra, we don’t have any safety or effectiveness data on it. That makes it similar to many of the substances routinely used in bodybuilding supplements.
Viagra works by preventing the premature breakdown of cyclic GMP, a substance that operates at the cellular level to relax smooth muscle. When that happens in the tissues of the penis, blood flow is increased, resulting in penile erection. Viagra increases the presence of cyclic GMP by inhibiting phosphodiesterase type-5, an enzyme that helps break it down.
In the body, nitric oxide—a staple in many bodybuilding supplements—increases cyclic GMP naturally. The nutritional precursor of NO production in the body is the amino acid arginine, which helps explain why arginine is the primary ingredient in NO-boosting supplements as well as in most herbal Viagra products.
When you take a drug by mouth, your liver plays the primary role in breaking it down and excreting it from the kidneys. So it is with Viagra. Consequently, having either liver or kidney dysfunction is considered a contraindication for using Viagra, which places stress on both organs. When you take Viagra with a meal rich in fats, its absorption is reduced, with the time taken to reach maximum blood concentration increased by about an hour. The maximum concentration itself is reduced by a third under those conditions.
While the primary medical use for Viagra is to treat male impotence—it’s ineffective for women’s sexual problems—it’s also often prescribed to block sexual side effects induced by such drugs as antidepressants. In that situation, Viagra can help women who experience side effects related to sexual function. Five years ago the FDA approved Viagra for the treatment of a less frequent but serious medical condition called primary pulmonary hypertension. Increased incidence of PPH in users of the popular diet drug combo known as fen-phen led to fen-phen’s removal from the market. PPH refers to a localized increase in the blood pressure of the lungs, which increases the workload on the right ventricle of the heart and can eventually result in heart failure. Viagra, however, helps counter PPH. It’s also useful for treating altitude sickness, an affliction common in mountain climbers that can result in pulmonary edema, or excess fluid in the lungs.
As you might expect, considering the sexual effects of Viagra, it’s also been used as a recreational drug. Those who use it that way believe that it boosts sex drive and improves sexual performance. Some even think that Viagra can increase penis size. While there’s no evidence of that—unless you consider converting a soft-off into a hard-on to be an increase—it benefits sexual performance only for those experiencing difficulties in that area. One study, however, did find that Viagra decreased postejaculatory refraction time—you know, the time it takes to get another erection after ejaculation. Some men might consider that useful, which explains its popularity with male porn actors.
Those who use recreational drugs that produce impotence often combine them with Viagra to prevent that side effect. Mixing it with one party drug, amyl nitrate, however, could prove fatal due to an acute lowering of blood pressure. A study published three years ago found that Viagra could prevent jet lag—in hamsters. So you might want to give your hamster some Viagra the next time your little friend plans an extended trip.
One of the more interesting uses of Viagra has been in sports. Famed baseball pitcher Roger Clemens denied using performance-enhancing drugs during his baseball career but openly admitted using Viagra—not for sexual purposes but rather because he was told that it could enhance endurance and increase oxygen delivery to muscles. Clemens said that it produced facial flushing and a rapidly beating heart. An Italian professional cyclist was suspended after being caught with 82 unprescribed Viagra pills. Victor Conte, architect of the infamous BALCO drug scandal, said that he routinely provided Viagra to such famous athletes as Barry Bonds and Marion Jones.
What about bodybuilding? Viagra has turned up in the drug stacks used by many bodybuilders, along with the usual anabolics, such as testosterone, growth hormone and anabolic steroids. At first it may appear that the bodybuilders would take Viagra primarily to counter sexual side effects induced by other drugs they’re using. Others may use it because they think it supercharges NO, leading to a greater muscle pump and more efficient oxygen delivery to muscles. Recent research has uncovered a more direct effect of Viagra: It boosts testosterone.1,2
It turns out that cyclic AMP and cyclic GMP both boost testosterone production, and Viagra potently boosts cyclic GMP. At the right concentration, NO helps testosterone synthesis in the Leydig cells of the testes, though too much of it acts as a pro-oxidant and suppresses T production. Increasing cyclic GMP also increases a protein called STAR, which regulates the transport of cholesterol—the raw material for sex hormones—into cellular mitochondria in the testes. Scientists suspect that a lack of STAR activity is one of the major reasons men experience a decline in T output as they age.
Another study suggests that women who use a topical form of Viagra can reduce the appearance of cellulite in their fat.3 Increased concentration of connective tissue in female fat deposits that gives cellulite its particular appearance also chokes off small blood vessels. That, in turn, suppresses oxygen in the tissue and leads to inflammation and increased collagen synthesis. Collagen is the main connective-tissue protein, and the more the body produces, the greater the appearance of cellulite. By helping unchoke the small blood vessels associated with cellulite deposits, topical Viagra may be able to lessen the cellulite look.
While many of Viagra’s properties seem impressive and despite its apparent widespread availability over the Internet, it’s nonetheless important to remember that it’s a potent drug. The most common adverse effects associated with Viagra include headaches, flushing, indigestion, nasal congestion—a nose-on?—and impaired vision. Some users find themselves seeing everything with a blue tint. Getting too enthusiastic or using too large a dose can cause an erection that doesn’t subside, a condition known as priapism. That can cause serious injury to the penis. Even worse, Viagra can induce severe low blood pressure, even a heart attack in rare instances. A more recent side effect linked to the drug is sudden hearing loss.
1 Saraiva, K., et al. (2009). Chronic treatment with sildenefil stimulates Leydig cell and testosterone secretion.Int J Exp Pathol. 90:454-62.
2 Andric, S.A., et al. (2010). Sildenafil treatment in vivo stimulates Leydig cell steroidogenesis via cAMP and cGMP signaling pathway. Am J Physiol Endocrinol Metab. 299(4):E544-50
3 Altabas, K., et al. (2009). From cellulite to smooth skin: Is Viagra the new dream cream? Med Hypoth. 73(1): 118-119.