Hormone medicines

Sildenafil

A PDE5 inhibitor for erectile dysfunction; its short-term clinical response does not establish performance enhancement or freedom from interaction risk.

Randomized erectile-dysfunction evidence

Sildenafil molecular structure — Structure reference · C22H30N6O4S

Practical use

Applying the explained evidence

Where it fits: A PDE5 inhibitor for erectile dysfunction; its short-term clinical response does not establish performance enhancement or freedom from interaction risk.
Put the information into practice: The strongest data below involve men with erectile dysfunction. Improvement during treatment does not prove correction of an endocrine cause, and no muscle-gain or cycle-safety outcome was measured.
Diagnosis before a number: Write down the symptoms, the reason a test was ordered, and the medicines already used. An isolated hormone result is a question to interpret, not a stand-alone reason to add another medicine.
Keep this limit in view: This counts attempts in a specified period, not the percentage of men responding or an individual forecast.

Viagra prescribing information

Pivotal randomized trials

Overview

Sildenafil enhances the nitric-oxide/cGMP response by inhibiting PDE5. Viagra is a US-approved erectile-dysfunction medicine. It facilitates the response to sexual stimulation rather than directly increasing testosterone or establishing the cause of erectile symptoms.

Risks and limitations

Nitrates, organic nitrites and riociguat are contraindicated. Other blood-pressure-lowering medicines and CYP3A4 inhibitors can alter risk. Headache, flushing, dyspepsia and visual disturbance occur; chest pain, sudden vision/hearing loss or an erection over four hours warrants urgent assessment.

How to read this

The strongest data below involve men with erectile dysfunction. Improvement during treatment does not prove correction of an endocrine cause, and no muscle-gain or cycle-safety outcome was measured.

Research explained

Two distinct pivotal trials

Who was studied

532 men in a 24-week fixed-arm trial; 329 different men in a 12-week flexible-treatment trial.

Successful attempts: sildenafil: 69 %
Successful attempts: placebo: 22 %

What was found

During the last four weeks of the flexible trial, 69% of intercourse attempts succeeded with sildenafil versus 22% with placebo. In the separate fixed-arm trial, the highest studied arm’s erection-achievement score rose from 2.0 to 4.0 on a 5-point scale.

What it cannot establish

Separate populations and endpoints; neither trial measures muscle growth or cycle safety.

Read the original study

Two trials, two different questions

Fixed treatment levels and flexible adjustment answer different questions. Their outcome percentages should not be pooled into one success rate.

Supporting source

Mechanism does not resolve diagnosis

Relief of an erectile symptom does not identify whether its cause was vascular, psychological or hormonal.

Supporting source

Exposure and interaction context

The label reports an approximately 4 hour terminal half-life. Food, organ function and interacting medicines can change exposure; that number is not a guaranteed clearance time or a self-selected nitrate interval.

Supporting source

What visual symptoms mean

Transient visual disturbance is a reported adverse effect, but sudden vision loss needs prompt medical evaluation. Treating every visual complaint as an ordinary expected effect would erase that important distinction.

Supporting source