What are PDEI medications?

The FDA-approved oral medications used to treat Erectile Dysfunction (ED) are called phosphodiesterase-5 inhibitors or PDEI’s. The 3 most well-known PDEI’s are Viagra® (sildenafil), Cialis® (tadalafil) and Levitra® (vardenafil).

How do PDEI medications work?

PDEI’s do not give you an erection, but instead help make it easier to get an erection. For them to work, sexual stimulation in the brain is still needed to generate a signal which is carried by the nerves to the arteries in the penis.

This electrical impulse causes the production and release of nitric oxide from the endothelial cells lining the inside of the artery. The nitric oxide then enters the smooth muscle cells in the wall of the artery and activates a pathway to produce a chemical called cGMP (cyclic guanosine monophosphate). cGMP relaxes the muscle cells and causes the blood vessel to dilate, increasing blood flow in the erectile tissue and resulting in an erection. cGMP is broken down by the PDE5 enzyme. By blocking the PDE5 enzyme, these medications increase the amount of cGMP present and the blood vessels can dilate more leading to a better erection.

What are the side effects of PDEI’s?

Because these medications travel thru the entire blood stream, they can cause side effects by dilating arteries in places other than the penis. Common side effects are facial flushing, headache and nasal congestion. They can also cause muscle aches, indigestion, dizziness and visual changes. Most of the time, these side-effects are mild, last an hour or so, and are not troublesome. Very rarely, they can cause visual or hearing loss or a pronged erection (priapism). It is important to remember that PDEI’s should not be taken by men who are on nitrate drugs or suffer from unstable heart disease.

Are PDEI medications available to you at the Charleston Men’s Clinic?

Tablets need to be taken at least 60 minutes prior to sex and should be taken on an empty stomach. At the Charleston Men’s Clinic, we prescribe the same PDEI medication in stronger, generic, under-the-tongue dissolving tablets which get into the blood stream faster than oral tablets and are less affected by having eaten. They are also much less expensive than the medication you buy at the pharmacy.
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