Erectile dysfunction (ED) in men is amenable to correction with
Viagra in a majority of patients. The accumulated experience
of prescribing Viagra across the broad continuum of men suffering
from ED is sufficient for a meaningful assessment of the safety
of Viagra in clinical practice. The use of Viagra necessitates
caution in cardiac failure and when used within six months of
acute myocardial infarction and stroke. It is inadvisable in
patients with unstable angina pectoris. The co-administration
of Viagra with organic nitrates, for example, glyceryl trinitrate
or isosorbide dinitrate, is unsafe. The relative contraindications
to Viagra in cardiovascular disease are uncontrolled hypertension
and impaired cardiac reserve. With respect to interactions with
other drugs, the potential influence on the metabolism of Viagra
by medications that affect the cytochrome-P-450 system does
not translate into clinical effects. The vasodilatory properties
of sildenafil citrate are largely responsible for unwanted effects.
The most common side effects are headache, flushing (due to
vasodilation), and dyspepsia (due to relaxation of the smooth
muscle of the gastroesophageal sphincter with reflux). In the
recommended single-dose range (25-100 mg), the use of Viagra
for erectile dysfunction, in the absence of contraindications,
is extremely safe provided the drug is taken under proper conditions.
