Other Uses of Viagra

Viagra is now being used to treat not only erectile dysfunction (ED) but also pulmonary hypertension. And the drug may have potential for treating several other conditions, according to a recent report. The three ED medications currently on the market—Viagra, Levitra, and Cialis—all work by the same means, and they have similar side effects.

The most common are headaches and facial flushing, which occur in 15% of men. Other reactions include nasal congestion, indigestion, and back pain. These side effects are mild and temporary. The most important worry about ED pills is their ability to widen arteries enough to lower blood pressure. And men who are taking nitrates should never use any of the ED pills.

Although some of the drugs’ side effects may be troublesome, others may be helpful, and scientists are studying whether ED pills might help treat a variety of nonsexual problems. Viagra (sildenafil) has been on the market longest and is most studied. It’s yet not clear if the other ED pills offer similar benefits, but Viagra, at least, may prove useful for some other conditions, including these:

Pulmonary hypertension

Viagra is now marketed under the name Revatio for this uncommon but serious disorder of high pressure in the blood vessels leading to the lungs.

Mountain sickness

Viagra can reduce pulmonary artery pressure at high altitude and improve the ability to exercise in low oxygen conditions.

Raynaud’s phenomenon

In affected individuals, exposure to the cold triggers spasm of the small arteries that supply blood to the fingers, toes, or both, which become pale, cold, and painful. Both Viagra and Levitra have been helpful in clinical trials.

Heart disease

Studies suggest Viagra might help patients with congestive heart failure or diastolic dysfunction.

Further details are published in the August 2007 issue of Harvard Men’s Health Watch.

FDA approves daily Cialis doses

NEW YORK (Reuters) - Eli Lilly and Co on Tuesday said U.S. regulators approved once-daily use of two low-dose forms of its Cialis anti-impotence drug, offering greater convenience for men expecting frequent sexual activity.

The Indianapolis drugmaker said the once-daily formulations, in dosages of 2.5 milligrams and 5 milligrams, will allow men to attempt sexual activity any time between doses.

"In clinical trials, when taken without restrictions on the timing of sexual activity, Cialis for once daily use improved erectile function over the course of therapy," Lilly said in a release.

The low-dose daily formulations, already approved in parts of Europe, "may be most appropriate for men with erectile dysfunction who anticipate more frequent sexual activity (e.g. twice weekly)," Lilly said.

The company said the low-dose formulations provide "a new option for men who may be looking for a dosing option that can be taken without regard to timing of sexual activity."

The treatment, which has global annual sales of $1.2 billion, has been available in the United States since 2003 in dosages of 5 milligrams, 10 milligrams and 20 milligrams, and taken as needed. Those dosages provide effectiveness for up to 36 hours.

Company spokeswoman Keri McGrath said no dosage forms of the medicine, including the newly approved lower ones, are appropriate for heart patients who take nitrates, including nitroglycerin.

Members of the class of drugs to which Cialis belongs -- including Pfizer Inc's rival Viagra and GlaxoSmithKline Plc's Levitra -- can dangerously lower blood pressure when used alongside nitrates.

The drugs, used by millions of men worldwide, also carry new warnings about potential risk of sudden hearing loss.

Shares of Lilly were up $1.05, or 1.9 percent, to $55.60 in morning trading on the New York Stock Exchange, in line with a 2 percent advance for the drug sector.

Study finds Viagra increases release of key reproductive hormone. Part 2.

The new report was published online Aug. 9 and appears in an upcoming issue of the Journal of Physiology. In the study, the scientists measured oxytocin released from rat pituitaries in response to neural stimulation. When the pituitaries were treated with sildenafil, they responded to the stimulation by releasing three times as much oxytocin as they did without the drug. Importantly, the drug had little if any effect on hormone release in the absence of stimulation, Jackson says. "Erectile dysfunction drugs do not induce erections spontaneously, they enhance the response to sexual stimulation," he says. "The same thing is happening in the posterior pituitary - Viagra will not induce the release of oxytocin on its own, but it will enhance the amount of release you get in response to electrical stimulation."

Though he doesn't think his findings raise any significant safety issues related to Viagra use, he does think it provides strong rationale for studies of additional effects and new potential uses. "A big question raised by our study is, will sildenafil do the same thing to the nerve terminals that release oxytocin [in the brain]"" he says. The cells that supply oxytocin to the pituitary come from a brain structure called the hypothalamus, which also sends hormones throughout the brain.

Though sildenafil's effects on these pathways are still unknown, work by other researchers has shown that oxytocin-sensitive cells in the brain play a role in the neural control of erectile responses, suggesting that Viagra and its kin may work through multiple channels.

The famous blue pills could have other uses as well. Oxytocin has been linked to the ability to make strong social bonds, while sildenafil was recently shown to improve hamsters' abilities to adjust the timing of their internal clocks to overcome simulated jet lag. "This is one piece in a puzzle in which many pieces are still not available," Jackson says. "But it raises the possibility that erectile dysfunction drugs could be doing more than just affecting erectile dysfunction."

Study finds Viagra increases release of key reproductive hormone. Part 1.

Researchers at the University of Wisconsin-Madison report this month that sildenafil increases the amount of oxytocin released by stimulation of the posterior pituitary gland, a small structure directly underneath the brain that regulates hormone levels in response to neural signals.
The finding is the first indication of a chemical mechanism through which erectile dysfunction drugs like Viagra may have physical effects besides increasing blood flow to sexual organs, says study author Meyer Jackson, a physiology professor at the UW-Madison School of Medicine and Public Health.
Sometimes called the "love hormone" or "cuddle chemical," oxytocin plays several important roles in social interactions and reproduction, including triggering uterine contractions and lactation. It is also released during orgasm and has been linked to sexual arousal.
Oxytocin release is regulated by an enzyme that acts like a braking system, limiting hormone release by dampening neural excitation of the cells. This same enzyme, phosphodiesterase type 5, also limits blood flow by contracting the muscles around blood vessels.
In both places, sildenafil works by blocking this enzyme, essentially releasing the brakes, explains Jackson. In blood vessels, relaxing smooth muscle increases blood flow, which corrects erectile dysfunction, and in the posterior pituitary, the cells become more responsive. "The same stimulation will produce more [oxytocin] release." He says, "I think this is a missing link in terms of trying to sort out the issues around whether there are additional effects of phosphodiesterase type 5 inhibitors," which include Viagra, Levitra and Cialis.