Erectile
dysfunction is a common adverse effect of a number of drugs, and it
often has a great effect on patient compliance. This subject as a risk
factor is lightly discussed here and further discussed in more detail
later in the textbook. It is important to recognize that many of the
drugs associated with ED are used to treat conditions that are
themselves risk factors for ED, thus the interpretation of ED in the
setting of pharmacological therapy is often difficult in the clinical
setting.
Selective Serotonin Reuptake Inhibitors
Selective
serotonin reuptake inhibitors (SSRIs) have gained notoriety as a common
cause of several manifestations of sexual dysfunction. SSRI-induced ED
rather than sexual dysfunction, though, is rarely reported in the
literature and is limited mostly to case reports.
Antihypertensive Agents
Several
antihypertensive agents have been implicated in ED, yet the evidence is
limited. Older thiazide diuretic treatments have been associated with
mild effects on erectile function.
Many
of these studies have limited clinical implications as they were
conducted with chlorthalidone, a thiazide-like diuretic. A recent study
suggested that beta-blocker-induced ED is likely psychogenic rather than
organic. Clonidine is reported to cause ED in both human and animal
studies through agonism of central alpha-2 adrenoreceptors.
Statins and Viagra online Canadian pharmacy
Statins
are HMG-CoA reductase inhibitors that are a commonly used medication
for the treatment of hyperlipidemia. Do et al. conducted a study to
investigate the association between exposure to statins and the
occurrence of ED. The study was limited to males age 18–30. They found a
statistically significant association for statins with induction and
worsening of ED. Further studies are needed to distinguish the severity
of the effect on ED between the many different statin drugs that are
currently in use.
Antipsychotics
Antipsychotic
medications are also implicated in ED. These drugs exert their effects
primarily by antagonism of dopamine receptors but have effects on
several other receptors. In addition, dopamine antagonism causes
hyperprolactinemia which contributes to the sexual dysfunction
associated with these drugs.
Antiandrogens
Antiandrogens
are a well-known cause of sexual dysfunction and ED. In recent studies,
finasteride has been shown to cause minimal ED at higher doses (5 mg)
for prostate cancer prevention, and almost no effect on erectile
function at low doses (1 mg) for the treatment of alopecia.
Illicit Substances and Nicotine
Several
illicit substances cause ED. In addition, men on methadone maintenance
therapy for heroin dependence have been reported to have significant
impairment of erectile function. The use of tobacco products, and
specifically nicotine, is associated with ED in both chronic and acute
exposure. Nicotine produces vasoconstriction through its actions on
endothelial cells through a likely underproduction and degradation of
nitric oxide. A recent study of healthy men between the ages of 18 and
27 reported that the use of nicotine gum immediately decreased erectile
response to visual stimuli despite unchanged subjective measurements of
sexual arousal. This study may imply an immediate neurogenic and
hemodynamic response of the penile tissue to nicotine. Furthermore,
chronic cigarette smoking is also associated with an independently
increased risk of ED and clinically significant damage to penile
vasculature.
Ethanol
The
role of ethanol, while classically thought to impede erectile function,
has been less clear in the literature. Sublingual viagra pharmacy Despite the association of
alcohol consumption and sexual activity, very little objective evidence
exists on the effect of acute ethanol intoxication on erectile function.
The data on chronic ethanol exposure is also mixed. Ethanol exposure in
an animal model showed histologic evidence of both endothelial damage
and metabolic dysfunction. Impairment of smooth muscle relaxation due to
endothelial dysfunction was pronounced while neurogenic smooth muscle
relaxation remained intact.