• DeTheir effect begins after 30-60 minutes and lasts for the next 4 hours. For the drug to work faster, it is recommended to take it before meals. Depending on the severity of the effect and taking into account the patient's tolerance of the drug, the dose can be adjusted both up and down. In some cases, they adhere to a different scheme - they begin to take the tablets with a minimum dosage, gradually increasing it until a pronounced therapeutic effect occurs.

  • How to take Viagra correctly, the doctor determines the regimen and dose of the medicine individually, taking into account the characteristics of the patient's body. The highest recommended dose is 100 mg. The maximum recommended frequency of receptions is 1 time per day. Elderly patients do not need to adjust the dosage regimen.

  • In the course of studies that were carried out on healthy volunteers, it was found that a single dose of up to 0.8 grams provokes the same side effects that were observed when taking the drug in much lower doses, but the frequency of their occurrence and the degree of severity increased.

  • The use of sildenafil in a dose of 0.2 grams does not lead to an increase in the effectiveness of the drug, but it provokes an increase in the incidence of side effects. The most common are flushing, dizziness, headaches, visual disturbances, dyspeptic symptoms, nasal congestion.

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In case of an overdose of Viagra, the usual supportive treatment is prescribed for such situations. Since sildenafil is characterized by a high degree of binding to blood plasma proteins (the binding rate is 96%) and is not eliminated in the urine, an acceleration of the clearance of the substance during hemodialysis is considered unlikely. Sildenafil is metabolized in the liver, mainly under the influence of CYP3A4 isoenzymes and partly under the influence of CYP2C9, therefore inhibitors of these isoenzymes decrease, and their inducers, respectively, increase the clearance of sildenafil.

After 24 hours, the plasma concentration of sildenafil

With the simultaneous use of 0.1 gram of sildenafil (once) and ritonavir (0.5 grams twice a day), which is a potent inhibitor of isoenzymes of the cytochrome P450 system and an inhibitor of HIV protease, after reaching a constant plasma concentration of ritonavir, the AUC of sildenafil increases 11 times (by 1000%), and Cmax - 4 times (by 300%).

Thus, 0.8 grams of cimetidine, which is a non-specific inhibitor of CYP3A4, in combination with 0.05 grams of sildenafil, provokes an increase in the plasma concentration of the latter by 56%.

When taking 0.1 gram of sildenafil in combination with erythromycin, which is a specific inhibitor of CYP3A4 (in the case when erythromycin is taken twice a day, 0.5 grams for 5 days), after a constant concentration of erythromycin in the blood is reached, Sildenafil AUC increases by 182%.

Simultaneous single dose of 0.1 gram of sildenafil with 1.2 grams of sankvinavir, which is an inhibitor of CYP3A4 and HIV protease, with the frequency of applications of the latter three times a day: against the background of reaching a constant plasma concentration of sankvinavir, the AUC of sildenafil increases by 210%, and Cmax - by 140%. However, sildenafil does not alter the pharmacokinetics of sankvinavir.

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Ketoconazole and itraconazole, which are more potent inhibitors of the CYP3A4 isoenzyme, may have a stronger effect on the pharmacokinetic parameters of sildenafil.

Patients who take sildenafil in the recommended dosage instructions and additionally receive potent CYP3A4 inhibitors tolerate Viagra well. Sildenafil affects the pathways of NO / cGMP metabolism and potentiates the hypotensive effect of nitrates (both when used for acute indications and during long-term treatment with these drugs). In this regard, the use of sildenafil with nitric oxide donors or nitrates is contraindicated.

A single dose of antacid drugs (aluminum hydroxide or magnesium hydroxide) does not affect the bioavailability of the drug. In some sensitive patients, symptomatic hypotension may develop against the background of the simultaneous use of sildenafil and α-blockers.

Any significant interaction of the drug with warfarin (0.04 grams) and tolbutamide (0.25 grams) has not been established. Also, the interaction of sildenafil at a dose of 0.1 gram with amlodipine when using these drugs in patients with arterial hypertension has not been established.


Viagra is included in List B. It is recommended to store the drug in a dry place out of the reach of children. The optimum temperature is not higher than 30 degrees Celsius.

in a dose of 0.1 gram does not change the pharmacokinetics of HIV protease inhibitors at a constant concentration in the blood; at a dose of 0.05 grams, when taken simultaneously with 0.15 grams of acetylsalicylic acid, does not provoke an additional increase in the duration of bleeding; at a dose of 0.05 grams in healthy volunteers does not increase the hypotensive effect of ethanol at the maximum level of the latter in bloodvi about 80 mg / dl; does not provoke additional side effects when used simultaneously with antihypertensive drugs.

Viagra - what is it, what it does and what is it for? Viagra is the first pharmaceutical drug that shows reliable and pronounced efficacy in most patients suffering from erectile dysfunction. The tool promotes the response of the body when exposed to sexual stimuli.

Wikipedia says about the drug that it was originally created to improve blood flow in the heart muscle, treat coronary artery disease and angina pectoris. However, in the early 90s of the XX century, as a result of clinical studies, it was found that the drug has a minimal effect on cardiac blood flow, but at the same time stimulates blood flow in the pelvic organs and, in particular, in the penis.