| Treatment
Treatment depends on the cause. Testosterone supplements may be
used for cases due to hormonal deficiency. However, the cause is
more usually lack of adequate penile blood supply as a result of
damage to inner walls of blood vessels. This damage is more frequent
in older men, and often associated with disease, in particular diabetes.
Treatments (with the exception of testosterone supplementation,
where effective) work on a temporary basis: they enable an erection
to be attained and maintained long enough for intercourse, but do
not permanently improve the underlying condition.
ED can in many cases be treated by drugs taken orally, injected,
or as penile suppositories. These drugs increase the efficacy of
NO, which dilates the blood vessels of corpora cavernosa. When oral
drugs or suppositories fail, injections (e.g. of apomorphine) into
the erectile tissue of the penile shaft may work.
When pharmacological methods fail, a purpose-designed external
vacuum pump can be used to attain erection, with a separate compression
ring fitted to the penis to maintain it. These pumps should be distinguished
from other "penis pumps" (supplied without compression
rings) which, rather than being used for temporary treatment of
impotence, are claimed to increase penis length if used frequently,
or vibrate as an aid to masturbation.
More drastically, inflatable or rigid penile implants may be fitted
surgically. Implants are irreversible and costly.
All these mechanical methods are based on simple principles of
hydraulics and mechanics and are quite reliable, but have their
disadvantages.
In a few cases there is a vascular problem which can be treated
surgically.
Uncontroversial treatments
PDE5 Inhibitors
The cyclic nucleotide phosphodiesterases constitute a group of enzymes
that catalyze the hydrolysis of the cyclic nucleotides cyclic AMP
and cyclic GMP. They exist in different molecular forms and are
unevenly distributed throughout the body. These multiple forms or
subtypes of phosphodiesterase were initially isolated from rat brain
by Uzunov and Weiss in 1972 and were soon afterward shown to be
selectively inhibited by a variety of drugs in brain and other tissues
(Weiss,1975; Fertel and Weiss, 1976). The potential for selective
phosphodisterase inhibitors to be used as therapeutic agents was
predicted as early as 1977 by Weiss and Hait. This prediction has
now come to pass in a variety of fields, one of which is in the
pharmacologic treatment of erectile dysfunction
One of the forms of phophodiesterase is termed PDE5. The prescription
PDE5 inhibitors sildenafil (Viagra®),
vardenafil (Levitra®)
and tadalafil (Cialis®)
are prescription drugs which are taken orally. They work by blocking
the action of PDE5, which causes cGMP to degrade. CGMP specific
phosphodiesterase type 5|cGMP]] causes the smooth muscle of the
arteries in the penis to relax, allowing the corpus cavernosum to
fill with blood.
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