Composition

In the composition of Viagra, sildenafil  can be in the concentration of 25, 50 or 100 mg.

In addition to sildenafil, the composition contains microcrystalline cellulose, calcium hydrogen phosphate, sodium croscarmellose sodium, magnesium stearate.

For the manufacture of the coating film-coated tablets, Opadry is blue and transparent.

The composition of Viagra does not differ depending on the concentration of the active substance.

Form of issue

The drug form of Viagra is a film-coated tablet.

Tablets slightly biconvex, have a rhomboid shape, their edges are cut and rounded, the color – blue. On one side of the tablet there is the inscription “Pfizer”, on the other – “VGR 25/50/100” (depending on the concentration of sildenafil ).

In one package can be 1, 2, 4 or 12 tablets.

Pharmachologic effect

The drug is aimed at restoring a physiological reaction to sexual arousal.

Pharmacodynamics and pharmacokinetics

The drug Viagra is intended for the treatment of erectile dysfunction.

In the event of sexual arousal, the remedy updates with a low erectile function by increasing the flow of blood to the penis.

The natural mechanism of erection is associated with the release during sexual stimulation in the cavernous (cavernous) body of the penis NO (nitric oxide), which promotes the activation of the enzyme guanylate cyclase.

The latter, in turn, stimulates an increase in the concentration of cGMP ( cyclic guanosine monophosphate ). As a result, the smooth musculature of the cavernous body relaxes and the blood flow increases.

viagraSildenafil is a potent and selective inhibitor of cGMP-specific PDE-5 (phosphodiesterase-5) in the cavernous body, where PDE-5 plays an important role in the process of cGMP decay.

The effect of the substance on the erectile function is peripheral: the drug does not have a direct relaxing effect on the isolated human cavernous body, while powerfully enhancing the relaxing effect of nitric oxide on it.

In order to develop the necessary therapeutic effect under the influence of sildenafil, sexual arousal is required.

TCmax (the time to reach the maximum plasma concentration) with oral fasting sildenafil is 0.5 to 2 hours, the bioavailability is between 25 and 60%.

When taking the drug with fatty foods, the how to buy viagra pharmacokinetic index of Cmax decreases by at least 20% (sometimes up to 40%), it takes from 1.5 to 3 hours to achieve it.

Metabolization of sildenafil occurs in the liver under the influence of microsomal isozymes of the cytochrome system.

The half-life of sildenafil in pure form and N-desmethyl metabolite, which is its main metabolite , is from 3 to 5 hours. The drug is excreted as inactive metabolic products . About 80% is eliminated with the contents of the intestine, about 15% is eliminated by the kidneys.

Indications for use: for what tablets Viagra?

The description of the drug states that Viagra is intended for the treatment of erectile dysfunction , which is a consequence of vascular disorders or nervous disorders and is defined as the inability to achieve penile erection and maintain it for  the time necessary for successful sexual intercourse.

To ensure the effectiveness of the drug requires sexual stimulation.

Contraindications

Viagra has a number of contraindications. So, it is forbidden to use the drug when:

  • hypersensitivity to the constituent components;
  • simultaneous application with nitrites and nitrates in any form, as well as with donators of nitric oxide (for example, with amyl nitrite );
  • the presence of contraindications to the conduct of sexual activity (for example, if the patient is diagnosed with serious heart disease and vascular disorders – severe form of heart failure or unstable angina );
  • loss of vision in one eye, which was triggered by anterior ischemic optic neuropathy ( neuropathy of the optic nerve ) of non-arterial genesis, regardless of whether this pathology has a connection with previous use of PDE inhibitors of the fifth type;
  • severe liver dysfunction.

Also, do not take Viagra  for women, children and adolescents under the age of 18. With caution, the drug is prescribed:

  • at anatomic deformations of a sexual member (including, at a fibroplastic inducing of a sexual member , a fibrosis of cavernous bodies , angulation , etc.);
  • with diseases that can become a predisposing factor to the development of priapism leukemia , sickle-cell anemia , thrombocytopenia , multiple myeloma, etc.);
  • with diseases that are accompanied by bleeding;
  • stomach ulcer or ulcer 12 duodenal ulcer in the stage of exacerbation;
  • if the patient has suffered a myocardial infarction or stroke in the past six months ;
  • if the patient has a hereditary degenerative disease of the retina (for example, retinitis pigmentosa );
  • with unstable angina or heart failure ;
  • with arrhythmia , which may pose a threat to the life of the patient;
  • arterial hypotension (in cases when arterial pressure indices do not exceed 90/50 mm Hg) orhypertension (in cases when blood pressure indices do not exceed 170/100 mm Hg)

Side effects

As a rule, the side effects that buy viagra develop against the background of the use of Viagra, are characterized as light or moderately expressed and have a transient nature. The incidence of unwanted symptoms increases with increasing dosage.

The use of Viagra can cause:

  • pain in the abdomen, back, muscles or joints;
  • asthenia;
  • influenza-like syndrome;
  • take viagrainfection (including respiratory tract and urinary system);
  • diarrhea;
  • nausea;
  • increased muscle tone;
  • insomnia;
  • nasal congestion;
  • inflammation of lymphoid tissue and pharyngeal mucosa ( pharyngitis );
  • inflammation of the paranasal sinuses ( sinusitis );
  • dysfunction of breathing;
  • rashes on the skin;
  • violation of color perception of objects (usually this change in vision is expressed in a mild form and has a transient character);
  • conjunctivitis;
  • impaired prostate function;

During clinical trials, such side effects as blurred vision, increased perception of light, rhinitis, dizziness, vasodilation were also recorded.

When using the Dianabol Side Effects drug in high doses, the patient has the same side effects, but they appear an order of magnitude more often than when the prescribed dosage regimen is observed.

In the process of post-marketing Viagra application, in individual patients, in connection with the use of the drug, the following were recorded:

  • syncope, arterial hypotension, palpitation, tachycardia;
  • vomiting;
  • prolonged erection and / or priapism;
  • redness of the eyes and pain in them;
  • allergic reactions.

Viagra, instructions for use

The instructions for the use of Viagra indicate that the drug should be taken orally. Tablets are recommended to drink before eating, because in this case their action develops more quickly.

Viagra – how to take for men?

The drug is available in three dosages – 25, 50 and 100 mg. Typically, for most patients, the starting dose is 50 mg. Tablets are taken one at about an hour before sexual activity.

Their action begins after 30-60 minutes and remains for the next 4 hours. To make the drug act faster, it is recommended to take it before eating.

Depending on the severity of the effect and taking into account the patient’s tolerance of the drug, the dose can be adjusted both in the large and in the lower side.

In some cases, another scheme is followed – the tablets begin to be taken with a minimum dosage, gradually increasing it until a pronounced therapeutic effect.

How to properly take Viagra, the scheme of application and the dose of medicine the doctor determines individually, taking into account the characteristics of the patient’s body.

 

Overdose

In studies that were conducted on healthy volunteers, it was found that a single dose intake 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 equal to 0.2 grams does not lead to an increase in the effectiveness of the remedy, but it provokes an increase in the incidence of side effects. The most frequent are blood rashes, dizziness, headaches, impaired vision, dyspeptic symptoms, nasal congestion.

In case of an overdose, Viagra is prescribed a maintenance treatment that is usual for such situations. Since sildenafil is characterized by a high degree of binding to blood plasma proteins (binding index is 96%) and is not eliminated with urine, acceleration of the clearance of the substance during hemodialysis is considered unlikely.