Have you misunderstood Viagra - Sildenafil mechanism of action

In clinical work, I often encounter the problem that ED patients have concerns about giving them oral Viagra (Weige), even rejection and fear. The main reason is that they are worried about the drug as a hormone drug with side effects. Or it is worried that there will be dependence on addiction. There are not many male friends who have such an idea, mainly because the majority of male friends do not understand the drug. It is also the lack of popular science work for our male health workers so that many male patients miss a simple and effective opportunity to obtain sexual health. Sometimes they can't heal even if they seek medical treatment everywhere, and suffer the pain of economic, physical and mental and even family splitting! It is very necessary to introduce you to Viagra here, in order to guide the maze!

Viagra, which is the transliteration of the chemical drug sildenafil, Viagra (commonly known as Viagra), was officially approved by the FDA (US Food and Drug Administration) in March 1998 and was listed in China in July 2000. For more than ten years, the use of more than 20 million people worldwide has confirmed its long-term stable safety. It has brought the gospel to ED patients around the world, and has also greatly improved countless family life.

Viagra is an oral ED drug developed by Pfizer USA. It is the citrate of sildenafil. Its mechanism of action is to inhibit a type of phosphodiesterase (PDE5) in our body. The protein works. This enzyme has a higher concentration in the penile erectile tissue. By inhibiting it, it can raise a substance called cyclic guanosine monophosphate (cGMP), which can cause the corpus cavernosum ( The erectile tissue of the penis is filled with a blood-filled cavity like a sponge. When the erection is carried out, the pores of the perforated blood will thicken and eventually harden. Smooth muscle relaxation, increased cavernous congestion, and treatment of Erectile dysfunction ED. The efficacy generally lasts for up to 4 hours, but the maximum effect is around 2 hours.

Therefore, male friends should not be misled by some false propaganda. They think that these drugs are hormones and harmful to the human body! Or it may be addictive to dependence. Female friends also need to pay attention. When your boyfriend or husband has a temporary erectile dysfunction, doctors should not make a fuss when they need such drugs, which is considered unacceptable. These drugs are simply like the situation where we are watering the land. There are pumps and water pipes to complete. The pump is like our engine, which is the occurrence of sexual desire, but if the water pipeline is not smooth, you are increasing horsepower. It is also impossible to irrigate the land. Only if the pipeline is unblocked, it will naturally be a matter of course. Viagra is the tool for clearing this, and there is no need to create an illusion! In fact, the so-called quick-acting aphrodisiac drugs and healthcare products currently on the market contain similar chemical drugs. In the propaganda, they hang the sheep's head and sell dog meat. The thief shouts as a thief to promote the harm of western medicine Viagra. Naturally, the blind man swindles and swindles, and seeks ill-gotten gains! In fact, this kind of behavior has misled the patient's understanding of the formal treatment of western medicine, and also tarnished the reputation of Chinese medicine, resulting in great social and cultural harm. Because the effective content of the drug itself is not accurate, there is an unstable factor in the patient's taking process. If some patients have the special body, it will have extremely dangerous adverse effects, so don't try to be cheap and fake. "Fudge!" Choosing a regular Viagra is safe and effective as long as you have the indications and contraindications, but you must take it under the guidance of a doctor because he is a prescription drug and can only be used under the guidance of a male or urologist.

Regarding sildenafil, let's take a look Sildenafil mechanism of action

[alias]:

Viagra, Viagra, Cisdorf, West Timor, West Lofir, Viagra.

[Pharmacology]:

Sildenafil inhibits phosphodiesterase type 5 (PDE5) and reduces cGMP degradation, which relaxes the smooth muscle of the penis sponge, increases the maximum blood flow velocity of the corpus cavernosum artery, increases blood flow, and promotes penile erection. It takes effect 10 to 40 minutes after oral administration and the effect lasts for 4 hours. There is no positive inotropic effect, but large doses can cause a drop in blood pressure.

The oral absorption was good, the absolute F was 40%, the Tmax was 1 h, and the peak value was 440 ng/ml in the fasting state. If it was taken with the high fat food, the plasma drug concentration peaked for 1 h, and the plasma drug concentration peaked by 29% on average. The tissue distribution was good, the apparent volume of distribution (Vd) was 105 L/kg, and the PPB was 96%. T1/2 is 4h. This product is mainly metabolized by the CYP3A4 microsomal enzyme in the liver, and its N-demethyl metabolite is still 50% active. After administration, 80% was excreted by feces, 13% was excreted by the kidney, and the elimination rate of the elderly and severe liver and kidney dysfunction was reduced.

[Use and usage]:

For penile erectile dysfunction.

Po, 25 ~ 100 mg each time, about 1 hour (0.5 ~ 4 h) before sexual activity, generally take 50mg of the drug, do not take more than 1 time per day. The initial dose of abnormal liver function, severe renal insufficiency, and elderly people over 65 years old is 25 mg.

【Adverse reactions】:

Domestic reports, 614 patients with organic, functional or complex penile erectile dysfunction after oral sildenafil, the main adverse reactions were: facial flushing rate of 11.4%, dizziness 7.4%, headache 3.6%, visual abnormalities 3.8 %, nasal congestion 3.6%.

【preparation】:

Viagra, tablets, each containing sildenafil citrate 25mg, 50mg, 1 tablet / box, 5 tablets / box, Dalian Pfizer. Viagra, tablets, coated with blue diamond-shaped film, each containing sildenafil citrate 25mg, 50mg, 100mg, 20 tablets / bottle, 30 tablets / bottle, 50 tablets / bottle. Pfizer, USA.

[Clinical evaluation]:

According to foreign reports, 1218 patients with penile erectile dysfunction were randomly divided into 2 groups. The experimental group received 777 oral sildenafil, qd, once 25-100 mg, taken 1 h before sexual intercourse for 14 to 28 days: 444 patients in the control group. Oral placebo, the same course of treatment. Results The experimental group was effective in 544 cases. The satisfaction rate of sexual activity increased after taking the drug. The effective rate was 70%: 93 cases were effective in the placebo group, and the effective rate was 21%.

Multi-center, double-blind, phase II clinical trials conducted by 7 clinical units including Beijing Medical University Affiliated Hospital showed that 614 patients with organic, functional or complex penile erectile dysfunction were treated with sildenafil orally. It was 81%, and the effective rate for patients with psychological penile erectile dysfunction was 81%, the organic quality was 84%, and the composite was 79%.

【Precautions】:

1 This product can increase the antihypertensive effect of nitrate drugs, and is being banned by using nitroglycerin, sorbate dinitrate, sodium nitroprusside or other organic nitrate drugs, antihypertensive drugs. 2 disabled for allergic to this product. Patients with myocardial infarction, stroke, fatal arrhythmia, hypotension (<12/6.5 kPa) or hypertension (>24/15 kPa), unstable angina, coronary artery disease and retinal pigmentation in 36 months . 4 penile anatomical deformity (penis curvature, corpus cavernosum fibrosis or induration) should be used with caution. 5 people who are not suitable for sexual life (acute coronary syndrome, coronary heart disease, obvious ischemia, heart failure, acute myocardial infarction, stroke, arrhythmia) should not be used. 6CYP3A4 isoenzyme inhibitors such as erythromycin, ketoconazole, itraconazole, and cimetidine can increase plasma levels of sildenafil. 7 If the erection time exceeds 4 h or a painful erection should be treated immediately. 8 This product does not affect the nervous system, and does not increase the sexual desire of people with normal sexual function.