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Brand Viagra

Brand Viagra is effective for the situational elimination of erectile problems of different natures. It helps restore male sexual function.

Indications

This drug is applied as treatment of erectile dysfunction characterized by an inability to achieve or maintain an erection of the penis sufficient for satisfactory intercourse. Sildenafil is effective only with sexual stimulation.

Mechanism of action

The implementation of the physiological mechanism of erection is associated with the release of nitric oxide (NO) in the cavernous body during sexual stimulation. This, in turn, leads to an increase in cGMP level, subsequent relaxation of the smooth muscle tissue of the cavernous body and an increase in blood flow.

Sildenafil does not have a direct relaxing effect on an isolated human cavernous body but enhances the effect of nitric oxide. It takes place due to inhibiting PDE-5, which is responsible for the cGMP breakdown.

Sildenafil is selective against PDE-5 in vitro. Its activity against PDE-5 is superior to activity against other known PDE isoenzymes: PDE-6 – 10 times; PDE-1 – more than 80 times; PDE-2, PDE-4, PDE-7 – PDE-11 – more than 700 times. Sildenafil is 4,000 times more selective for PDE-5 compared to PDE-3, which is crucial because PDE-3 is one of the key enzymes in the regulation of myocardial contractility.

A prerequisite for sildenafil effectiveness is sexual stimulation.

Sildenafil restores impaired erectile function under conditions of sexual stimulation by increasing blood flow to penile cavernous bodies.

Dosage and administration

Oral administration. It can be taken with or without water. The recommended dose for most adult patients is 50 mg approximately 1 hour before sexual intercourse. Given the effectiveness and tolerability, the dose can be increased to 100 mg or reduced to 25 mg. The maximum recommended dose is 100 mg. The maximum recommended frequency of use is 1 time per day. The absorption of sildenafil is significantly slowed when used in combination with fatty foods.

Contraindications

  • Hypersensitivity to sildenafil or any other drug component;
  • Use in patients receiving continuously or intermittently nitric oxide donors, organic nitrates or nitrites in any form, since sildenafil enhances the hypotensive effect of nitrates;
  • The combined use of PDE-5 inhibitors, including sildenafil, with guanylate cyclase stimulants, such as Riociguat, as this can lead to symptomatic hypotension;
  • Combined use with other agents for the treatment of erectile dysfunction (the safety and effectiveness of branded Viagra have not been studied with combined use;
  • Lactose intolerance, lactase deficiency, glucose-hapactose malabsorption;
  • Severe liver failure;
  • Concomitant use of ritonavir;
  • Severe cardiovascular diseases (severe heart failure, unstable angina pectoris, a stroke or myocardial infarction during the last 6 months, life-threatening arrhythmias, hypertension or arterial hypotension;
  • Patients with episodes of development of non-arteritic anterior ischemic optic neuropathy (NPINS) with loss of vision in one eye;
  • Hereditary retinitis pigmentosa;
  • It is not intended for use in women;
  • It is not intended for use in children under 18 years of age.

Side effects

  • Immune system: infrequently – hypersensitivity reactions (including skin rash), allergic reactions.
  • Organ of vision: often – blurred vision, impaired vision, cyanopsia; infrequently – eye pain, photophobia, photopsy, chromatopsia, redness of the eyes, changes in brightness of light perception, mydriasis, conjunctivitis, hemorrhage in eye tissue, cataracts, malfunctioning of the lacrimal apparatus; rarely – swelling of the eyelids and adjacent tissues, a feeling of eyes dryness, increased eye fatigue, seeing objects in yellow (xanthopsia), seeing objects in red (erythropsy), conjunctival hyperemia, irritation of the mucosa eyes’ lining, discomfort in the eyes; the frequency is unknown – occlusion of the retinal veins, visual field defect, diplopia, temporary loss of vision or decreased visual acuity, increased IOP, retinal edema, retinal vascular disease, vitreous detachment/vitreous traction.
  • Hearing organ: infrequently – a sudden decrease or loss of hearing, tinnitus, earache.
  • Cardiovascular system: often – tides; infrequently – tachycardia, palpitations, decreased blood pressure, increased heart rate, unstable angina, AV block, myocardial infarction, cerebral thrombosis, cardiac arrest, heart failure, ECG abnormalities, cardiomyopathy; rarely – atrial fibrillation, sudden cardiac death, ventricular arrhythmia.
  • Blood and lymphatic system: infrequently – anemia, leukopenia.
  • Metabolism and nutrition: infrequently – thirst, swelling, gout, uncompensated diabetes, hyperglycemia, peripheral edema, hyperuricemia, hypoglycemia, hypernatremia.
  • Respiratory system: often – nasal congestion; infrequently – nosebleeds, rhinitis, asthma, dyspnea, laryngitis, pharyngitis, sinusitis, bronchitis, increased sputum discharge, increased cough; rarely – a feeling of tightness in the throat, dryness of the mucous membrane of the nasal cavity, swelling of the mucous membrane of the nasal cavity.
  • Digestive tract: often – nausea, dyspepsia; infrequently – GERD, vomiting, pain in the abdomen, dry oral mucosa, glossitis, gingivitis, colitis, dysphagia, gastritis, gastroenteritis, esophagitis, stomatitis, abnormal liver function tests, rectal bleeding; rarely – hypoesthesia of the oral mucosa.
  • Musculoskeletal system: often – back pain; infrequently – myalgia, pain in the limbs, arthritis, arthrosis, tendon rupture, tenosynovitis, bone pain, myasthenia gravis, synovitis.
  • Genitourinary system: infrequently – cystitis, nocturia, breast enlargement, urinary incontinence, hematuria, impaired ejaculation, genital edema, anorgasmia, penile tissue damage; rarely – prolonged erection and/or priapism.
  • Central and peripheral nervous system: very often – headache; often dizziness; infrequently – drowsiness, migraine, ataxia, hypertonicity, neuralgia, neuropathy, paresthesia, tremor, vertigo, symptoms of depression, insomnia, unusual dreams, increased reflexes, hypesthesia; rarely – convulsions, repeated convulsions, fainting.
  • Skin and subcutaneous tissues: infrequently – a skin rash, urticaria, herpes simplex, itching, increased sweating, skin ulceration, contact dermatitis, exfoliative dermatitis; frequency unknown – Stevens-Johnson syndrome, toxic epidermal necrolysis.
  • Other: infrequently – a sensation of heat, face swelling, photosensitivity reaction, shock, asthenia, increased fatigue, the pain of various localization, chills, accidental falls, pain in the chest area, accidental injuries; rarely irritability.

Overdose

Symptoms: a single dose of Viagra in a dose of up to 800 mg provokes the adverse events the same as when taking the drug in lower doses. The use of a 200-mg dose did not increase the drug effectiveness, but the frequency of adverse reactions (headache, hot flashes, dizziness, dyspepsia, nasal congestion, visual impairment) increased.

Treatment: symptomatic. Hemodialysis does not accelerate clearance of sildenafil, as the latter actively binds to plasma proteins and is not excreted by the kidneys.