Sildenafil is a prescription, allopathic medicine, used in the treatment of erectile problems in men. It was the first phosphodiesterase-5 (PDE5) inhibitor approved for use and received US Food and Drug Administration approval for use in erectile dysfunction on March 27, 1998.
Sildenafil was initially developed to treat hypertension and chest pain. But during the clinical trials, it was observed that it works well for inducing erections and that’s how the story began.
Erectile Dysfunction is a big problem worldwide with over 100 million men having erectile problems, sometimes in life. Sildenafil drug has been widely used over the last two decades, under the popular name of Viagra. With the introduction of Sildenafil, it was observed that men overcame the stigma and embarrassment of discussing their erectile problems.
How Sildenafil Drug Works?
Sildenafil acts by causing penile tissues to relax, increasing blood flow to the penile arteries, when a person is sexually aroused, thereby making it rigid and hard. It cannot cause erections in absence of arousal.
It works by inhibiting cGMP specific phosphodiesterase type-5 enzyme which regulates blood flow in the corpus cavernosum ( spongy tissue) of Penis.
Nitric Oxide (NO) released during this reaction helps in the activity of guanylate cyclase receptor which helps in increasing levels of cGMP, leading to smooth muscle relaxation (vasodilatation) of Helicine Arteries of Penis.
This smooth muscle relaxation leads to vasodilatation and increased blood flow in the spongy tissue of the penis thereby causing penile erection.
Sildenafil Drug Uses
Sildenafil is used to treat male sexual function problems (impotence or -erectile dysfunction, ED). In combination with sexual stimulation, sildenafil works by increasing blood flow to the Penis to help a man get and keep an erection. In lower doses, Sildenafil is also used to treat pulmonary hypertension.
Following are the dosage regimes for Sildenafil
|Disease||Initial Dose||Maintenance Dose||Maximum Dose|
|Erectile Dysfunction||50 mg orally once a day 1 hour prior to sexual activity||25-100 mg orally once a day 1 hour prior to sexual activity||Doses greater than 100 mg have resulted in no increase in efficacy|
|Pulmonary Hypertension||5-20 mg orally thrice a day
2.5-10mg IV bolus thrice a day
|20 mg orally thrice a day||Doses greater than 100 mg have resulted in no increase in efficacy|
Sildenafil citrate is rapidly absorbed after oral administration and attains bio-availability of 40% in blood. Sildenafil is metabolized mainly by liver enzymes and excreted through feces.
Sildenafil should not be taken along with Nitrates. ( ex- Nitroglycerine or isosorbide) Nitrates increase cGMP formation, while sildenafil inhibits cGMP degradation causing the combination to produce severe life-threatening hypotension (Low Blood pressure) synergistically. Always take the drug on the doctor’s advice only.
Side Effects of Sildenafil Drug:
The side effects are usually mild and short-lived.
- Nasal congestion
- Back pain
- Skin rashes
- Sildenafil in lower doses is used to treat pulmonary arterial hypertension but chronic usage of low doses of sildenafil may cause hypersensitivity to any component of the cardiopulmonary system.
The awareness that Sildenafil brought about regarding Erectile Dysfunction was phenomenal. Men began to discuss their erection problems with doctors and seek treatment. Erectile dysfunction was a big problem as it effected the self esteem of men, caused anxiety and led to relationship issues and divorces.