As the elderly male population continues to increase, we can assume the prevalence of ED will also continue to grow. A few oral therapies have been tried in the past, such as yohimbine or phentolamine, but were not very successful in providing normal erectile function. Early after its release, pharmacies were swamped with prescriptions for Viagra, but the number of prescriptions has leveled off. Many insurance companies are either not covering Viagra prescriptions or are requiring prior authorization, and limiting the number of tablets to five or six a month. Many insurers require the doctor to fax or send in a diagnosis, and it may take three or four more days until insurance companies approve the prescription.
Some patients give up and pay for the drug themselves.
The inhibition of phosphodiesterase-5 and subsequent elevation of cGMP leads to smooth muscle relaxation. The drug works by enhancing the nitric oxide mediated relaxation of the corpus cavernosal smooth muscle. This, in turn, allows for blood to flow into the penis and produce erections in response to sexual stimulation. The drug produces no effect in the absence of sexual stimulation. Sildenafil is 40 percent absorbed after an oral dose on an empty stomach.