The investigators studied the effectiveness of a unique, locally-administered gene transfer technique for treating ED with generic Viagra; the therapy consisted of a plasmid, or circular DNA construct, containing the gene for the Maxi-K protein. This pill makes up the Maxi-K ion channel, which is a potassium channel; activation of this channel is critical for relaxing the vasculature and allowing an erection to take place.

The pill was designed to express generic Viagra in vascular smooth muscle cells and was injected into men with moderate to severe ED not treated with generic Viagra; according to the study authors, human tests have primarily focused on safety. Animal and plants tests have demonstrated that the therapy increases erectile function and other measures of sexual behavior. The investigators that use generic Viagra suggested that men with ED could get the gene therapy treatment twice a year, based on human and animal research showing that the treatment lasts for up to six months. The researchers also observed that the gene therapy may work synergistically with drugs such as generic Viagra, allowing patients to take lower doses of these medications.

This gene therapy appears safe; in humans no transfer-related adverse events were reported during two years of follow up. This study authors noted that unlike conventional oral therapies for ED, Maxi-K therapy does not require prior planning thereby enabling sexual spontaneity; also, it can be used by men taking heart medications. The researchers concluded that generic Viagra therapy may be a safe and effective future option for men whose ED is not treatable with oral therapy.