Dr. Lee was born in Shanghai, China, and received his college and medical training in the United States. He is fluent in English and three Chinese dialects. He graduated with chemistry departmental honors from Harvey Mudd College. He was appointed president of AOA society at UCLA School of Medicine. He underwent internal medicine residency and gastroenterology fellowship training at Cedars Sinai Medical Center.
Dr. Nabili received his undergraduate degree from the University of California, San Diego (UCSD), majoring in chemistry and biochemistry. He then completed his graduate degree at the University of California, Los Angeles (UCLA). His graduate training included a specialized fellowship in public health where his research focused on environmental health and health-care delivery and management.
Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
The common PDE5 drugs approved in the United States are sildenafil (Viagra), vardenafil (Levitra), or tadalafil (Cialis). Actual head-to-head trials between these drugs have not been done to date to see which is the superior drug. Details on each of these medications for erectile dysfunction are outlined below.
Sildenafil (Viagra)
What is sildenafil (Viagra)?
Sildenafil (Viagra) was the first oral phosphodiesterase type 5 (PDE5)
inhibitor approved by the FDA in the United States for the treatment of
erectile dysfunction (it is not approved for women). Sildenafil inhibits
PDE5, which is an enzyme that destroys cGMP. By inhibiting the destruction of cGMP by PDE5,
sildenafil allows cGMP to accumulate. The cGMP in turn prolongs relaxation of the smooth
muscle of the corpora cavernosa. Relaxation of the corpora cavernosa smooth muscle allows
blood to flow into the penis resulting in increased engorgement of the penis. In short,
sildenafil increases blood flow into the penis and decreases blood flow out of the penis.
How effective is sildenafil (Viagra)?
Sildenafil is used for the treatment of erectile dysfunction of either
physical or psychological cause. It has been found to be effective in treating
erectile dysfunction in men with coronary artery disease, diabetes mellitus,
hypertension, depression, coronary artery bypass surgery, and men who are taking
antidepressants and several classes of anti-hypertensives.
In randomized controlled trials, an estimated 60% of men with diabetes, and
80% of men without diabetes experienced improved erections with sildenafil.
How should sildenafil (Viagra) be administered?
Sildenafil is available as oral tablets at doses of 25, 50, and 100 mg. It
should be taken approximately one hour before sexual activity. In some men, the
onset of action of the drug may be as early as 11-20 minutes. Sildenafil should
be taken on an empty stomach for best results since absorption and effectiveness
of sildenafil can be diminished if it is taken shortly after a meal,
particularly a meal that is high in fat.
What is the dose of sildenafil (Viagra)?
In prescribing sildenafil, a doctor considers the age, general health status,
and other medication(s) the patient is taking. The usual starting dose for
most men is 50 mg, however, the doctor may increase or decrease the dose depending on
side effects and effectiveness. The maximum recommended dose is 100 mg every 24
hours, however, many men will need 100 mg of sildenafil for optimal effectiveness, and
some doctors are recommending 100 mg as the starting dose.
Metabolism (breakdown) of sildenafil is slowed by aging, liver and kidney
dysfunction, and concurrent use of certain medications (such as erythromycin -- an
antibiotic, and protease inhibitors, for HIV). Slowed breakdown allows sildenafil
to accumulate in the body and potentially may increase the risk of side effects.
Therefore in men over 65, in men with substantial kidney and liver disease, and
in men who also are taking protease inhibitors, the doctor will initiate
sildenafil at a lower dose (25 mg) to avoid accumulation of sildenafil in the
body. A protease inhibitor ritonavir (Norvir) is especially potent in increasing
the accumulation of sildenafil, thus men who are taking Norvir should not take
sildenafil doses higher than 25 mg and at a frequency of no greater than once in
48 hours.
What are the side effects of sildenafil (Viagra)?
Sildenafil has been found to be well tolerated without important side
effects. The reported side effects are usually mild and include headache,
flushing, nasal congestion, nausea, dyspepsia, (stomach discomfort), diarrhea, and abnormal vision
(seeing a bluish hue or brightness).
Sildenafil can cause hypotension (abnormally low blood pressure that can lead
to fainting and even shock) when given to patients who are taking nitrates
(for heart disease).
Therefore, patients taking nitrates daily should not take sildenafil.
Nitrates are used most commonly to relieve angina (chest pain due to
insufficient blood supply to the heart muscle because of narrowing of the
coronary arteries); these include nitroglycerine tablets, patches, ointments,
sprays, and pastes, as well as isosorbide dinitrate, and isosorbide mononitrate.
Other nitrates such as amyl nitrate and butyl nitrate also are found in some
recreational drugs called "poppers."
Sildenafil should be used cautiously in men on alpha blockers such as
doxazosin (Cardura), terazosin (Hytrin), and tamsulosin (Flomax). There have been occasional reports of low
blood pressure in men who have taken the two classes of drugs simultaneously and
therefore it is recommended that there be at least a span of four to six hours between
the ingestion of sildenafil and alpha blockers.
There have been rare reports of priapism (prolonged and painful erections
lasting more than six hours) with the use of PDE5 inhibitors such as sildenafil, vardenafil, and tadalafil,
especially when sildenafil is used in combination with injection of medications
into the corpora cavernosa or intraurethral suppositories.
Patients with blood cell diseases such as
sickle cell anemia, leukemia, and multiple myeloma have higher than normal risks
of developing priapism.
Untreated priapism
can cause injury to the penis and lead to permanent impotence. Therefore,
sildenafil should not be used in combination with intraurethral suppositories
and corpora cavernosa injections. If there is prolonged erection (longer than
four
hours), immediate medical assistance should be obtained.
Is it safe for men with heart disease to use sildenafil (Viagra)?
Sildenafil has been found to be effective and safe in the treatment of
erectile dysfunction in men with stable heart disease due to atherosclerosis of
the coronary arteries, provided that they are not on any type of nitrates. The real concern
is not as much the safety of sildenafil but the risk of sexual activity in
triggering heart attacks or abnormal heart rhythms in patients with heart
disease.
The risk of developing heart attacks or abnormal heart rhythms during sex is
low in men with well-controlled hypertension, mild disease of the heart
valves, well-controlled heart failure, mild and stable angina (with a favorable
treadmill stress test), successful coronary stenting or bypass surgery, and a
remote history of heart attack (more than eight weeks previously). Sildenafil can be
used safely in men in these low-risk groups.
The risk of heart attack or abnormal heart rhythms during sex is higher in men with unstable angina (angina that occurs at rest or with minimal exertion), poorly controlled hypertension, moderate to severe heart failure, moderate to severe disease of the heart valves, recent heart attack (less than
two weeks previously), potentially life-threatening disorders of heart rhythm such as recurrent ventricular tachycardia, and moderate to severe disease of the heart muscles. In these men, doctors usually stabilize or treat the heart conditions before prescribing sildenafil.
Before starting sildenafil for erectile dysfunction, a doctor may need to
determine whether the heart can safely achieve the workload necessary for sexual
activity. For example, in men with coronary artery heart disease, a doctor may
perform a treadmill stress test to determine whether there is adequate blood
supply to the heart muscle while exercising at levels comparable to sexual
activity.
Diabetes mellitus is a chronic condition characterized by high levels of sugar (glucose) in the blood. The two types of diabetes are referred to as type 1 (insulin dependent) and type 2 (non-insulin dependent). Symptoms of diabetes include increased urine output, thirst, hunger, and fatigue. Treatment of diabetes depends on the type.
Liver disease can be cause by a variety of things including infection (hepatitis), diseases such as gallstones, high cholesterol or triglycerides, blood flow obstruction to the liver, and toxins (medications and chemicals). Symptoms of liver disease depends upon the cause; however, common symptoms may include nausea, vomiting, upper right abdominal pain, and jaundice. Treatment depends upon the cause of the liver disease.
Low testosterone can affect both men and women. Causes of low testosterone in males include undescended testicles and injury to the scrotum. Low testosterone in females includes ovary conditions. Treatment for low testosterone in men includes testosterone replacement therapy. Currently there is no FDA approved testosterone treatment for women.
Cholesterol is naturally produced by the body, and is a building block for cell membranes and hormones. Low-density lipoprotein (LDL) cholesterol is the "bad" cholesterol, conversely, high-density lipoprotein (HDL) cholesterol is the "good" cholesterol. High cholesterol treatment includes lifestyle changes (diet and exercise), and medications such as statins, bile acid resins, and fibric acid derivatives.
Depression is an illness that involves the body, mood, and thoughts and affects the way a person eats and sleeps, the way one feels about oneself, and the way one thinks about things. The principal types of depression are major depression, dysthymia, and bipolar disease (also called manic-depressive disease).
Parkinson's disease is a slowly progressive neurologic disease characterized by a fixed inexpressive face, a tremor at rest, slowing of voluntary movements, a gait with short accelerating steps, peculiar posture and muscle weakness, caused by degeneration of an area of the brain called the basal ganglia, and by low production of the neurotransmitter dopamine. Most patients are over 50, but at least 10 percent are under 40.
Testicular pain, or pain in the testicle or testicles are caused by a variety of diseases or conditions such as testicular trauma, testicular torsion, testicular cancer, epididymitis, and orchitis. Common symptoms of pain in the testicle or testicles are abdominal pain, urinary pain or incontinence, fever, nausea, vomiting, and pain in the scrotum or testicle. Treatment depends on the cause of the testicular pain or pain in the testicles.
Drug addiction is a chronic disease that causes drug-seeking behavior and drug use despite negative consequences to the user and those around him. Though the initial decision to use drugs is voluntary, changes in the brain caused by repeated drug abuse can affect a person's self-control and ability to make the right decisions and increase the urge to take drugs. Drug abuse and addiction are preventable.
Male sexual dysfunction can be caused by physical or psychological problems. Common sexual problems in men include erectile dysfunction (impotence or ED), premature ejaculation and loss of libido. Treatment for sexual dysfunction in men may involve medication, hormone therapy, psychological therapy, and the use of mechanical aids.
Diabetic Neuropathy is a complication of diabetes that causes damage to the nerves; this is related to the blood glucose of the body being too high for a long period of time. The four types of neuropathy include peripheral, autonomic, proximal and focal.
Smoking is an addiction. More than 430,000 deaths occur each year in the U.S. from smoking related illnesses. Secondhand smoke or "passive smoke" also harm family members, coworkers, and others around smokers. There are a number of techniques available to assist people who want to quit smoking.
Penis disorders (male reproductive problems) include priapism, Peyronie's disease, balanitis, phimosis, paraphimosis, and penile cancer. Read on for causes, symptoms, diagnosis, and treatment. These disorders can affect a man's fertility and sexual functioning. A variety of treatments are available for these disorders.
Prolactinoma is an adenoma (benign tumor) of the pituitary gland. Causes of many prolactinomas are unknown. Symptoms in women include changes in menstruation and infertility, decreased libido, or painful intercourse due to vaginal dryness. The most common symptom in men is impotence (erectile dysfunction). Treatment of prolactinomas are medication or surgery.
Enjoying a satisfying sex life as we age is important to both physical and mental health. As we age, diseases and conditions may pose challenges in our sexual health, and sexual experiences. Learn how to manage your conditions and still have a gratifying sex life as you age.
Anabolic steroids are synthetic substances that are related to testosterone and promote skeletal muscle growth and the development of male sexual characteristics in both men and women. In the 1930s, it was discovered that anabolic steroids could promote skeletal muscle growth in lab animals, which lead to anabolic steroid abuse by bodybuilders and weight lifters.
Sexual health information including birth control, impotence, herpes, sexually transmitted diseases, staying healthy, women's sexual health concerns, and men's sexual health concerns. Learn about the most common sexual conditions affecting men and women.
Peyronie's disease is a condition characterized by a hard lump, or plaque, that forms within the penis. Symptoms of Peyronie's disease range from mild to severe. Treatment for Peyronie's disease includes medication, and often surgery.
Men's health is an important component to a happy lifestyle and healthy relationships. Eating healthy, exercise, managing stress, and knowing when to have medical tests for a particular age is key to disease prevention in men.
Having diabetes can mean early onset and increased severity of bladder symptoms (urinary incontinence and urinary tract infections) and changes in sexual function. Men may have erectile dysfunction; and women may have problems with sexual response and vaginal lubrication. Keep your diabetes under control, and you can lower your risk of sexual and urologic problems.
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