Patient Information:
Viagra (Sildenafil citrate) developed by the pharmaceutical company Pfizer, is a drug used to treat male erectile dysfunction or better known as impotence and pulmonary arterial hypertension (PAH).
Initially studied for use in and angina pectoris and hypertension (high blood pressure) and concluding that had a little effect on angina and more on a penile erection was approved by the FDA on March 27, 1998 for use in erectile dysfunction, becoming the first pill approved to treat erectile dysfunction in the United States.
Sildenafil the main ingredient of Viagra is a potent and selective inhibitor which prevents degradation of cGMP (Cyclic guanosine monophosphate) in the corpus cavernosum increasing a better blood flow and an erection.
Viagra is not causing an erection without sexual stimulation.
Directions of using Viagra:
Being a prescription drug dosage and direction are indicated by a qualified doctor.
The dose of Viagra is 25 mg to 100 mg which should be taken once per day between 30 minutes and 4 hours prior to sexual activity. It is recommended to start with a dosage of 50 mg and then raise or lower the dosage as needed.
Viagra's Side Effects:
Among Viagra's serious adverse effects are:
- priapism (prolonged erection)
- severe hypotension
- myocardial infarction
- ventricular arrhythmias
- sudden death
- stroke and increased intraocular pressure
Other less serious side effects include headache, sneezing, prolonged erections, flushing, dyspepsia, photophobia and palpitations. Visual changes including blurring of vision and a curious bluish touch have also been reported.
More attention should be advice for the patients who take Protease inhibitors for the treatment of HIV. Protease inhibitors slow down the metabolism of sildenafil, effectively increase the plasma levels of sildenafil, rising the frequency and severity of side-effects. It is suggested that patients using protease inhibitors limit their use of Viagra or sildenafil no more than one 25mg dose every 48 hours.
Some Viagra users have complained of loss of peripheral vision and blurriness. In 2005, the U.S. FDA found that sildenafil could lead to vision damage and various studies have associated sildenafil use with nonarteritic anterior ischemic optic neuropathy.
When used with an alpha blocker, to avoid hypotension take them at least four hours apart
Contraindications to Viagra:
Avoid taking Viagra when taking nitric oxide donors, amyl nitrite ("poppers"), sodium nitroprusside, organic nitrites and nitrates such as glyceryl trinitrate (nitroglycerin).
Men with cardiovascular problems for whom intercourse is not recommended, also for man with severe impairment in renal function, severe hepatic injury (decreased liver function), recent stroke or heart attack, hypotension (low blood pressure), hereditary degenerative retinal disorders.