Viagra

sildenafil citrate

Viagra (sildenafil citrate) has been effective for many men since receiving Food and Drug Administration (FDA) approval in March 1998. Studies have shown Viagra to be effective in about 70 percent of male patients, particularly when impotence has a psychological cause.

Yohimbine, a controversial tablet derived from the bark of the yohimbe tree in Africa, has been available for decades, pre-dating the FDA. Some studies have shown yohimbine to be effective in up to 40 percent of cases studied, mostly in men with impotence due to psychological cause. Other oral substances have been purported to offer greater sexual ability, although little data supports any of these claims.

Other medications similar to Viagra currently are being developed by drug companies and are being reviewed by the FDA.

How Viagra works

During stimulation, the body releases chemicals causing blood vessels to open up and supply more blood to the penis. Enzymes break down these chemicals and allow an erection to go down. Viagra blocks the action of those enzymes. By blocking the enzyme, blood flow to the penis increases, resulting in an erection. The drug will not produce an erection at recommended doses without sexual stimulation.

According to information provided by the manufacturer, the drug generally is absorbed within 30 minutes to two hours; is effective for about 4 hours; and then is excreted from the body. The drug is retained in the body longer in men with severe kidney impairment or liver disease and in healthy men age 65 or older.

In one study of 4,500 men, many of whom had diabetes, about 60 percent reportedly were able to have sexual intercourse after taking the drug. In another study of men with erectile dysfunction attributed to complications of diabetes, 57 percent of those taking the drug reported improved erections compared to 10 percent of the men taking a placebo (an inactive substance).

Viagra provides no protection against sexually transmitted diseases (STDs) or the Human Immunodeficiency Virus (HIV), which causes AIDS. Men using the drug should take necessary precautions to protect against these diseases.

Side effects and cautions

Viagra is not without side effects and risks, ranging from mild to quite serious. The most common include:

* Headaches - usually mild

* Temporary vision changes, such as light sensitivity or seeing a blue halo around lights

* Indigestion

Less common side effects include:

* Drops in blood pressure after use

* Prolonged or painful erections lasting more than six hours

* Heart attacks, sudden cardiac death, ventricular arrhythmia, brain hemorrhage, transient ischemic attack (TIA) and high blood pressure have been reported; most of these patients had preexisting heart disease risk factors

Reports of death

More than 6 million prescriptions were written for Viagra (about 50 million pills) from its introduction in March 1998 through mid-November 1998. During that period the FDA received reports of 130 deaths of American men who died after having been prescribed the drug. The FDA reported:

The average age of the men who died was 64

Ninety men had one or more risk factors for heart disease, such as high blood pressure, high cholesterol, smoking or diabetes; 77 had cardiovascular events, ranging from heart attacks to sudden cardiac arrest.

About one-third of the deaths occurred within four or five hours of taking the drug; 27 happened during or right after sexual intercourse, according to the FDA.

Sixteen of the men who died took or were given nitroglycerin. Viagra carries a warning on its label advising men taking nitrates in any form not to take Viagra because of the deadly blood pressure drop that can occur when the two drugs are combined. Nitroglycerin, a nitrate, is used to treat heart problems.

Viagra is NOT recommended for men who:

* Are on any form of nitrate medication

* Should not engage in sexual activity because of underlying heart or cardiovascular problems

* Have suffered a heart attack, stroke, or life-threatening arrhythmia (irregular heart beat) within the last 6 months

* Have liver or kidney disease

* Have low or high blood pressure (lower than 90/50) or hypertension (higher than 170/110)

* Have heart failure or blood vessel disease, unstable angina or congestive heart failure

* Take a complicated, multiple drug treatment for blood pressure

* Take certain prescription drugs like erythromycin or cimetidine; Viagra may last longer in these men and lead to life-threatening drops in blood pressure

* Have a known hypersensitivity to any component of the drug

* Use other treatments for impotence because studies have not been done on the combination effects

* Have a serious eye condition, retinitis pigmentosa

Men with the following conditions should use the drug with caution and only after checking with their doctors:

* Known heart disease or risk factors for heart conditions

* Bleeding disorders or active peptic ulcers

* Anatomical deformity of the penis

* Predisposition to sickle cell anemia, multiple myeloma or leukemia

* Serious eye conditions like retinopathy, which is a common complication of diabetes (An eye exam may be needed before taking the drug.)

Medications containing nitrates

The following medications are among those that contain nitrates:

Nitroglycerin

Deponit
Minitran
Nitrok
Nitro-Bid
Nitrocine
Nitroderm
Nitro Disc
Nitro-Dur
Nitrogard
Nitroglycerin
Nitroglycerin T/R
Nitroglyn
Nitrol ointment
Nitrolingual spray
Nitrong
Nitro-Par
Nitropress
Nitro SA
Nitrospan
Nitrostat
Nitro-trans system
Nitro transdermal
Nitro-Time
Transiderm-Nitro
Tridil

Isosorbide Mononitrate

Imdur
ISMO
Isosorbide mononitrate
Monoket

Isosorbide Nitrate

Dilatrate-SR
Iso-Bid
Isordil
Isordil tembids
Isosorbide dinitrate
Isosorbide dinitrate LA
Sorbitrate
Sorbitrate SA

Pentaerythritol Tetranitrate

Peritrate
Peritrate SA

Erythrityl Tetranitrate

Cardilate

Isosorbide Dinitrate/Phenobarbital

Isordil w/PB

Illicit Substances Containing Organic Nitrates

Amyl Nitrate or nitrite -- It is known that amyl nitrate or nitrite is sometimes abused. In abuse situations, amyl nitrate or nitrite may be known by various names, including "poppers." Viagra should not be used with these illegal substances as death could occur.

Source: American College of Cardiology/American Heart Association) Expert Consensus Statement. J Am Coll Cardiol 1999; 33:273-82.

Be sure to check with your doctor about any other medications you are taking that may interact with Viagra.

Seek immediate medical attention if you take Viagra and experience:

* Heart attack symptoms, such as chest pain or pressure - Tell the doctor or emergency room staff that you have taken the drug.

* An erection lasting more than four hours - This is painful and could damage tissues in the penis, causing permanent loss of potency.

Use in women

Viagra has not received approval from the Food and Drug Administration for use in women, infants or children. While some women report that taking the drug has improved their sex life, additional research is needed. There are no adequate and well-controlled studies of the drug in women, and particularly in women who are or subsequently become pregnant.

Generally, sexual difficulties in women are believed to be related to reduced blood flow in the genital area, diminished vaginal lubrication, increased time to vaginal arousal and diminished sensation and difficulty reaching orgasm. Like sexual dysfunction in men, sexual difficulties in women are believed to occur mainly in postmenopausal women who have diabetes, high cholesterol, circulation problems and who smoke.

Women with diabetes are prone to urinary tract infections. According to Harvard Women's Health Watch, a study reported an increase in urinary tract infections (UTIs) in women ages 55 to 75. Thinning and reduced mucus secretion of the lining of the vagina makes postmenopausal women more susceptible to urinary tract infections.

Treatments for reducing the frequency of UTIs include:

* Drinking fluids and emptying the bladder both before and after sex.

* Drinking cranberry juice, which contains compounds helpful in preventing urinary tract infections.