Sildenafil was launched in Europe in 1998 and was the first truly effective oral treatment for erectile dysfunction.
It currently has the greatest body of evidence relating to its use.
In fasted patients it is effective within 30 minutes, but food delays its absorption, and it is usually best to tell patients to leave an hour after dosing before attempting sexual intercourse. The half-life of the drug is around 4 hours, giving a useful duration of action of around 6–8 hours.
Original uses (on-label)
Viagra is approved for the treatment of male impotence
. It achieves this by relaxing the smooth muscle cells of the corpus cavernosum in the penis, which leads to penile erection.
Newly discovered uses (off-label)
, dyspareunia, esophageal motility disorders, female orgasmic disorder secondary to SSRI use, pulmonary hypertension
Potential side effects
Headache, flushing, dyspepsia, nasal congestion and altered visual perception of color hue or brightness, potentially severe hypotension and cardiovascular effect (if used with nitrates).
- Contraindicated in patients treated with nitrates in any forms, as it can interact with them to produce profound hypotension.
- Use with cautions in patients with conditions that may predispose to priapism and in patients with anatomic deformation of the penis.
Erytromycin, ketoconazole, and itraconazole increase serum levels. Hypotension and severe cardiovascular effects when used with nitrates.
Grapefruit juice, high fat meal. Avoid substantial alcohol intake.
St. John's wort
Pregnancy and breast-feeding cautions
FDA Pregnancy Risk Category B. Not for use in women, and not recommended during breast-feeding.
Buy Viagra online
Where can I buy Sildenafil without prescription?
Sildenafil is a prescription drug that comes in 25 mg, 50 mg, 100 mg pills.
It is available on prescription only as tablets for oral use, but the online pharmacy, will sell Viagra without prescription.
You may be able to order Viagra from them online and save the local pharmacy markup.
Most online pharmacies offer discounted prices when you buy Viagra in large quantities.
If I'm buying Viagra online for the first time?
If you are buying Sildenafil without prescription for the first time, start with a small amount to make sure that Viagra works for you and then order more later.
Remember to consider the total cost of your Viagra order when you compare prices, including any doctor consultation fees and delivery charges.
Sildenafil in treatment of anal fissure
This drug is normally prescribed for the treatment of impotence, but does not cause sexual stimulation.
Rather, it solves an underlying problem that causes impotence.
It enhances nitric oxide-induced relaxation of smooth muscles.
This mechanism might be useful in reducing tight anal sphincters in people with anal fissures.
Topical gel versions of sildenafil have already been available because they have been used with some success in clinical trials for post-menopausal women with sexual difficulties, as reported in the British Journal of Obstetrics & Gynecology
, and The Journal of Reproductive Medicine
An article in Diseases of the Colon and Rectum
reported on a small trial conducted in Marbella, Spain, and the Southeast Georgia Regional Medical Center, Brunswick, Georgia.
Researchers treated 19 people with chronic anal fissures with a topical sildenafil cream (which is not available in the United States).
The data reported maximum resting anal sphincter pressures dropped approximately 18% in all patients.
Only one did not achieve a reduction of more than 10%. These declines occurred within three minutes of applying sildenafil.
The most common side effect was transient anal itching or burning, reported in 26%.
Although this drug significantly reduced anal sphincter pressure in this small group, researchers believe that trials of larger groups are needed.
Viagra in treatment of pulmonary hypertension
A study reported in Thorax explored a strategy for treating high altitude pulmonary arterial hypertension (HAPH).
In the study, 689 patients living at high altitudes were screened for HAPH by medical examination and electrocardiography (ECG).
At three months, patients on sildenafil for every eight hours had a significantly lower pulmonary artery pressure at the end of the dosing interval than those on placebo.
It also improved six minute walk distance by 45.4 m. Sildenafil was well tolerated. Therefore, researchers feel that Viagra is an attractive drug for the treatment of HAPH.
It should be noted that this drug has the potential for significant drug interactions, and you should not use it if you are maintained on nitrates.
What is Sildenafil?
Viagra is used to treat male sexual function problems (impotence or erectile dysfunction) by blocking a certain enzyme in the body.
Brands & Classes
CGMP specific phosphodiesterase inhibitor
Tablets - Oral 25 mg, 50 mg, 100 mg.
25-100 mg PO 60 min before sexual intercourse. Max recommended use once/day. Start with 25 mg in patients with cirrhosis, severe renal impairment, or age >65 and in those undergoing concomitant treatment with erythromycin, ketoconazole, or itraconazole.