Sildenafil citrate, the active ingredient in Viagra, is a drug that treats both erectile dysfunction (MED) and pulmonary hypertension (PH). It is a potent inhibitor of phosphodiesterase 5 (PDE5), an enzyme that breaks down cyclic guanosine monophosphate (cGMP) which is responsible for maintaining erection of the penis and opening of the blood vessels in the penis. Inhibition of PDE5 leads to increased blood flow into the penis, causing an erection.
Sildenafil citrate treats erectile dysfunction by improving blood flow to the penis and helping the penis stay firm for longer. It is especially effective in men with diabetes because it helps them retain an erection longer which in turn reduces the risk of erectile injury. Sildenafil is also known to improve the quality of erection, making it more satisfying for both partners.
Sildenafil citrate also has a positive effect on pulmonary hypertension, or hardening of the arteries in the lungs. Inhibitors of PDE5, like sildenafil citrate, can help prevent the enlargement of the heart muscles and the development of abnormal blood vessels in the lungs, which can lead to serious problems. This occurs because PDE5 inhibits the production of oxygen radicals in leukocytes and thus prevents platelet aggregation and activation which are two factors that contribute to the formation of clots in blood vessels and subsequent heart damage.
Viagra is the brand name of the drug sildenafil citrate. The drug was originally approved for the treatment of erectile dysfunction in men and has since then been used to treat a variety of conditions. Today the drug is commonly prescribed for the treatment of sexual dysfunction in men. It is most effective when taken 15 to 20 minutes before sexual activity. The effect of Viagra wears off after about four hours and it has to be taken at least once every 24 hours to maintain its therapeutic action.
How Does Viagra Work?
When a man is aroused and interested in sexual activity, his body produces chemicals called nitric oxide (NO) which act as chemical messengers between nerves and muscles to help maintain an erection. The release of NO triggers a chain of events leading to an erection. Erection begins with an increase in blood flow into the penis which causes the tunica albuginea (the outer layer of the penis) to become engorged with blood. The spongy erectile tissue between the layers of penile tunica albuginea then swells, opening up the veins and arteries in the penis. This increased blood flow into the penis makes it rigid and visible, a condition known as tumescence.
Sexual arousal is also responsible for triggering the release of endorphins which is why many men experience a positive mood boost and loss of fatigue following sexual activity. Erection is a natural and healthy action and should not be held up as a sign of psychological weakness or illness. However, for some men, natural erections may be temporarily avoided due to anxiety or depression. In these cases, treatment with Viagra may be advisable to boost the blood flow into the penis and restore normal erectile function.
The key components of the erectile response include:
- Increased blood flow into the penis
- Lubrication
- Spongy tissue between the layers of penile tunica albuginea
- Nerve endings (sensory receptors) in the penis (dorsal penile nerve endings)
- Papillae on the surface of the tongue (lingual papillae)
Sildenafil citrate works by inhibiting an enzyme called phosphodiesterase-5, which breaks down cyclic-guanosine monophosphate (cGMP), an important substance in the regulation of blood flow in the body. As a result, the blood flow into the penis is increased and the erection ensues. This blood vessels dilation is a direct result of sildenafil citrate, not an artificial substance such as nitric oxide or prostaglandin E1 (PGE1).
What Are The Possible Side Effects Of Viagra?
Since Viagra is a relatively new drug, relatively little is known about its side effects. However, in clinical trials, some men taking the drug experienced the following side effects:
- Headache (less than 1% of patients)
- Dyspepsia (which is indigestion, or worse stomach acid reflux)
- Gastrointestinal discomfort, nausea and diarrhoea (less than 1% of patients)
- Flatulence (which is foul gas)
- Visual disturbances (less than 1% of patients)
- Chest pain and palpitations (less than 1% of patients)
- Muscle cramps and spasms (less than 1% of patients)
- Tinnitus (ringing in the ears) (less than 1% of patients)
While some of these side effects are undesirable, most are not dangerous and tend to disappear once the drug is discontinued. The only significant side effect associated with Viagra is heart-related toxicity which can occur if the drug is used in combination with other medications that are heart-depressing. In this case, the side effects of Viagra may be enhanced and more serious. Patients who take nitroglycerin (a substance that relaxes and expands blood vessels) and Viagra should be cautioned against taking this combination therapy as it may cause a significant decrease in blood pressure, resulting in dizziness, faintness or even fainting. In such cases, the use of Viagra may be contraindicated.
Are There Any Concomitant Medications That I Should Avoid While Taking Viagra?
Since Viagra is a drug that is commonly used to treat erectile dysfunction, it is not surprising that many men taking the medication are prescribed other medications for the relief of coexisting conditions. In clinical trials, men taking Viagra in addition to tadalafil (a medication for erectile dysfunction) were more likely to experience the following side effects:
- Headache (5% of patients)
- Dyspepsia (7% of patients)
- Photophobia (which is sensitivity to light)
- Dizziness (7% of patients)
- Gastrointestinal discomfort, nausea and diarrhoea (9% of patients)
- Flatulence (7% of patients)
- Visual disturbances (4% of patients)
If a man is already taking a medication that he thinks may interact unfavourably with Viagra, then he should not take the latter drug without consulting his physician. Certain medications such as erythromycin and cimetidine should be avoided by men with erectile dysfunction taking Viagra as they may potentiate the hypotensive effects of the drug. In these cases, another anti-impotence medication should be tried instead.
It is also advisable not to take Viagra without consulting your physician if you are undergoing an operation or have recently had an injury to the penis (about 48 hours have passed since the operation or injury). In these cases, surgery may be necessary to restore full erectile function. Some surgeons report that the addition of Viagra delays the recovery time of the penis following an operation, making it easier for the patient to resume normal activity.
In summary, Viagra is a safe and effective medication for the treatment of erectile dysfunction. However, it is not for everyone, as it has some very significant side effects which must be considered. If you are taking the drug, then you should not hesitate to consult your physician if you experience any adverse reactions. Your doctor can advise you on the ideal dosage for your condition and there is also a possibility that alternative medications may be safer and more effective for you.