Drug name:
 
Brand Viagra (Sildenafil as Sildenafil Citrate). Manufacturer: Pfizer.
 
Usage indications:
 
Viagra is intended for the treatment of adult men, suffering from erection problems (psychogenic, organic or mixed erectile dysfunction). The main treatment goals are to help men overcome current sexual health problems, increase confidence in intimate moments of life, and improve long-term well-being.
 
Advantages of Viagra:
 
•    Fast action onset (on average 28 minutes, range: 12–75 minutes);
•    Sufficient time for a spontaneous intercourse;
•    The drug is active for 4 hours and is partially effective for up to 10-12 hours;
•    It is the most popular and well-studied ED drug;
•    Low risk of side effects.
 
Administration mode:
 
Swallow Viagra with a glass of water to help the pill dissolve quickly. Food, especially high in fat, can slow down, yet not cancel the effect of the medication.
 
Dosing recommendations:
 
•    The optimal dose: one 100 mg pill
•    Frequency of use: as required
•    Administration time: 30-60 minutes before sex
 
The body's response to Viagra is usually predictable and consistent. Do not take the drug more than once every 24 hours.
 
Drug class and mechanism of action:
 
Viagra is the first PDE 5 inhibitor approved to improve erection. PDE5 is a type of enzyme (also found in the cavernous body), which affects the biochemical reactions in the soft tissues. "Inhibition" means that the drug interferes with the work of the enzymes.
 
Just like other drugs of the PDE5 group, Viagra helps the blood rush to the penis through:
 
•    Strengthening the action of nitric oxide;
•    Relaxing the smooth muscles of the cavernous bodies;
•    Reducing the vascular resistance.
 
This is the way that Viagra causes an erection at any time within 4 hours after dosing. However, this does not mean that the penis will remain increased in size for 4 hours in a row. An erection occurs during sexual arousal and disappears after an orgasm.
 
Missed dose:
 
Since you do not have sex at the same time every day, there is no such thing as a regular dosing regimen for Viagra.
 
If you took Viagra 10–20 minutes before sex, an erection may occur, yet it may be not as strong as if you have waited for 30 minutes or more.
 
Storage:
 
Store the drug in its original package at room temperature (up to 30°C/86°F). Keep the drug out of the reach of children and pets. Do not use Viagra after the expiration date.

Warnings/precautions:
 
Viagra is a popular and highly effective medication, which helps men achieve and maintain an erection. However, the ED treatment may be suspended, or Viagra doses should be lowered, if the man uses such drugs, as:
 
•    Organic nitrates
•    PDE5 inhibitors
•    CYP3A4 inhibitors
•    HIV protease inhibitors
•    Antacids (only with extended use)
 
NOTE. This is not a complete list. Other medications may also cause interactions.
 
Viagra dilates the walls of blood vessels and affects blood pressure. Therefore, you should pay special attention to the use of any medications that affect the cardiovascular system during your ED treatment.
 
If you have any medical conditions or are taking any medications (prescription or OTC), consult your health care provider before you start using Viagra.
 
Consult with your doctor and be especially cautious while using Viagra, if one of the following situations applies to you:
 
•    If you have a disease of the muscles (myasthenia gravis);
•    If you regularly consume large quantities of alcohol or if you use drugs;
•    If you have a poor kidney function and/or poor liver function (kidney and liver failure);
•    If you have had a stroke or if you have recently had bleeding inside the skull;
•    If your heart is not working properly (heart failure);
•    If you suffer from other heart or vascular diseases;
•    If you have an abnormally high or low intra-arterial pressure;
•    If you suffer from any other disease.
 
Some serious side effects may make Viagra an inappropriate option for you.

Possible side effects:
 
For a start, it is always helpful to check out the patient information leaflet, which you find inside the package of Viagra pills. You will find out that Viagra can cause adverse reactions, most of which are not medically important.
 
The list of very common side effects contains only one item:
 
•    Headache
 
Other possible bad reactions or problems are abdominal discomfort, burning/itchy skin, nausea, flushing (reddish skin), dry mouth or nose, and vertigo.
 
Other information:
 
Brand Viagra facilitates the penetration of blood into the penis and causes an erection only in response to sexual arousal or sexual stimulation. After an orgasm and ejaculation, the blood pressure in the male organ decreases to normal levels. The erection disappears in a natural way.