Sildenafil (Viagra)

SILDENAFIL (VIAGRA®)

Primary Use

For the management of erectile dysfunction.

Clinical Concerns

Ocular side effects are uncommon, dosage dependent and thus far have all been fully reversible.

Reported Side Effects

Non-arteritic ischemic optic neuropathy (NAION)

•   Possible side effect, but no plausible explanation for the mechanism has yet been described (Fraunfelder, 2005; Fraunfelder and Pomeranz, 2005; Egan and Fraunfelder, 2005).

Changes in color perception

Objects have colored tinges that are usually blue or blue/green, may be pink or yellow

•   Diminished color vision

•   Dark colors appear darker

Blurred vision

•   Central haze

•   Transitory decreased vision

Changes in light perception

•   Increased perception of brightness

•   Flashing lights, especially when blinking

Conjunctival changes

•   Hyperemia

•   Subconjunctival hemorrhages – not proven to be drug related

•   Ocular pain

•   Photophobia

The above ocular side effects are dose dependent.

Incidence is as follows:

•   50 mg 3%

•   100 mg 10%

•   200 mg 40%–50%

Ocular side effects occur in direct proportion to silde-nafil levels in the blood. The side effects based on dosage start at 15–30 min and usually peak 1h after ingestion of the drug.

•   50 mg gone in 1h

•   100 mg gone in 2h

•   200 mg gone in 4–6h

Guidelines for Following Patients (Modified After Laties and Fraunfelder, 2000)

This class of drugs is contraindicated or should be used with extreme caution in patients who have

•   Retinitis pigmentosa

•   Congenital stationary night blindness

•   Deficiency or mutation of photoreceptor cGMP PDF

•   History of NAION in either eye

•   Informed consent advised; no data to prove it is harmful, but it theoretically could be