Impotence (ED) (cont.)
Vardenafil (Levitra)
What is vardenafil (Levitra)?
Vardenafil (Levitra) was the second oral medicine approved by the United FDA
in the US for the treatment of erectile dysfunction. Like sildenafil (Viagra),
vardenafil (Levitra) inhibits PDE5 which
destroys cGMP (as discussed earlier).
How effective is vardenafil (Levitra)?
Vardenafil was evaluated in four multicenter, randomized, placebo-controlled
trials involving more than 2400 men (78% white, 7% black, 2% Asian, 3% Hispanic)
with erectile dysfunction. Two of these trials were conducted in special
erectile dysfunction populations; one in men with diabetes mellitus, another in
men who developed erectile dysfunction after prostate surgery. The doses of
vardenafil in the four studies were 5 mg, 10 mg, and 20 mg.
In all four studies, vardenafil was significantly better than placebo in
improving men's ability to achieve and maintain erections in all age
categories (less than 45, 45-65,and greater than 65 years of age) and in all
races.
How should vardenafil (Levitra) be administered?
The recommended starting dose of vardenafil is 10 mg taken orally
approximately 1 hour before sexual activity. The dose may be adjusted higher or
lower depending on efficacy and side effects. The maximum recommended dose is 20
mg, and the maximum recommended dosing frequency is no more than once per day.
Vardenafil can be taken with or without food.
What are the side effects of vardenafil (Levitra)?
Vardenafil is generally well tolerated with only mild side effects. These
side effects include headache, flushing, nasal congestion, dyspepsia, body
aches, dizziness, nausea, and increased blood levels of the muscle enzyme
creatine kinase.
There have been rare reports of priapism (prolonged and painful erections
lasting more than 6 hours) with the use of oral PDE5 inhibitors such as
vardenafil, sildenafil and tadalafil.
Patients with blood cell diseases such as
sickle cell anemia, leukemia, and multiple myeloma have higher than normal risks
of developing priapism.
Priapism untreated can cause injury to the penis tissue and lead to
permanent loss of potency. If there is prolonged erection (longer than 4 hours),
immediate medical assistance should be sought.
Who should not use vardenafil (Levitra)?
Vardenafil (Levitra) can cause hypotension (abnormally low blood pressure,
which can lead to fainting and even shock) when given to patients who are taking
nitrates. Patients taking nitrates daily, even patients taking nitrates only once a day,
should not take vardenafil. Most commonly used nitrates are medications
to relieve angina (chest pain due to insufficient blood supply to heart muscle
because of narrowing of the coronary arteries). These include nitroglycerine
tablets, patches, ointments, sprays, pastes, and isosorbide dinitrate and
isosorbide mononitrate. Other nitrates such as amyl nitrate and butyl nitrate
are found in some recreational drugs called "poppers".
Vardenafil should not be used with alpha-blockers, medicines used to treat
high blood pressure and benign prostate hypertrophy (BPH), because the
combination of vardenafil and an alpha-blocker may lower the blood pressure
greatly and lead to dizziness and fainting. Examples of alpha-blockers include
tamsulosin (Flomax), terazosin (Hytrin), doxazosin (Cardura), alfuzosin
(Uroxatrol), and prazosin (Minipress).
Men with a rare heart condition known as long QT syndrome should not take
vardenafil since this may lead to abnormal heart rhythms. The QT interval is the
time it takes for the heart's muscle to recover after it has contracted. The
QT interval is measured with an electrocardiogram (EKG). Some patients have longer than normal QT
intervals, and they may develop potentially life-threatening abnormal heart
rhythms, especially when given certain medications. Since long QT syndrome can
be inherited, men with a family history of long QT syndrome should not take
vardenafil. Furthermore, vardenafil is not recommended for men who are taking
medications that can affect the QT interval such as quinidine (Quinaglute,
Quinidex), procainamide (Pronestyl; Procan-SR; Procanbid), amiodarone
(Cordarone), and sotalol (Betapace).
There is insufficient information on the safety of vardenafil in men with the
following conditions:
- Unstable angina (chest pain due to coronary artery
disease that occurs at rest or with minimal physical exertion)
- Low blood pressure (a resting systolic blood pressure
less than 90mm Hg)
- Uncontrolled high blood pressure (greater than
170/110 mm Hg)
- Recent stroke or heart attack
(within 6 months)
- Uncontrolled, potentially life-threatening abnormal
heart rhythms
- Severe liver disease
- Severe kidney failure requiring dialysis
- Severe heart failure or disease of the heart's valves, for example,
aortic stenosis
- Retinitis pigmentosa
Therefore, men with these conditions should not use vardenafil without having
these conditions evaluated and stabilized first. For example, men with
uncontrolled high blood pressure should have their blood pressure controlled; and
men with potentially life-threatening abnormal heart rhythms should have these
rhythms controlled.
When there is angina or heart failure, the doctor may need to determine
whether the heart has enough reserve to safely carry out the work necessary for
sexual activity by performing cardiac treadmill stress testing.
What precautions should be taken when using vardenafil (Levitra)?
Metabolism (breakdown) of vardenafil can be slowed by aging, liver disease,
and concurrent use of certain medications (such as erythromycin, ketoconazole (Nizoral),
and protease inhibitors). Slowed breakdown allows vardenafil to accumulate in
the body and potentially increase the risk for side effects. Therefore, in men
over age 65, with liver dysfunction, or who are also taking medication(s) that can
slow the breakdown of vardenafil, the doctor will initiate vardenafil at low
doses to avoid its accumulation. For example:
- Men taking erythromycin or ketoconazole should not
take more than 5 mg of vardenafil in a 24-hour period.
- Men taking high doses of ketoconazole (Nizoral)
should not take more than 2.5 mg of vardenafil in a 24-hour period.
- Men with moderately severe liver disease also should
not take more than a 5 mg dose of vardenafil in a 24-hour period.
- Men
taking the protease inhibitor (for the treatment of HIV/AIDS) indinavir (Crixivan
) should not take more than 2.5 mg of vardenafil in a 24-hour period.
- Men taking another
protease inhibitor ritonavir (Norvir) should not take more than 2.5 mg of
vardenafil every 72 hours.
Next: tadalafil (Cialis) »
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