Walsh & Hoyt: Sildenafil

Sildenafil citrate (Viagra, Pfizer Pharmaceuticals, New York, NY) is a phosphodiesterase type 5 inhibitor that is prescribed for erectile dysfunction. This drug facilitates erections by augmenting nitric oxide induced vasodilation in the corpus cavernosum. Systemic side effects are related to drug induced systemic vasodilation and include headache, flushing, and systemic hypotension. Severe systemic hypotension may occur when sildenafil is ingested with other nitrate medications. The most common ocular side effect is a transient alteration of color perception that presumably occurs from sildenafils weak inhibitory effect on phosphodiesterase type 6, a phototransduction enzyme present in the retinal photoreceptor outer segments