Brand Viagra is a drug applied for the treatment of erectile dysfunction. It contains sildenafil effective in increasing blood flow. Viagra is released in dosages of 25, 50, and 100 mg.

Indications

Treatment of erectile dysfunction, characterized by an inability to achieve or keep an erection sufficient for satisfactory intercourse.

Sildenafil is only effective for sexual stimulation.

Dosage regimen

Brand Viagra is taken orally. Oral tablets should be taken with water. The tablet should be taken immediately after opening the blister. The daily recommended dosage is 50 mg. If the effect is insignificant, it can be increased to 100 mg. The maximum dosage of Viagra is 100 mg. The effect persists for 5 hours.

Side effects

  • The immune system: infrequently – hypersensitivity reactions (including skin rash), allergic reactions.
  • The side of the organ of vision: often – blurred vision, cyanopsia; infrequently – eye pain, photophobia, photopsia, chromatopsia, eye redness/sclera injections, changes in the brightness of light perception, mydriasis, conjunctivitis, hemorrhage in the eye tissue, cataracts, disruption of the lacrimal apparatus; rarely – swelling of the eyelids and adjacent tissues, a feeling of dryness in the eyes, the presence of rainbow circles in the field of vision around the light source; increased eye fatigue, seeing objects in yellow (xanthopsia), seeing objects in red (erythropsia), conjunctival hyperemia, irritation of the mucous membrane eyes, discomfort in the eyes; frequency unknown – non-arteritic anterior ischemic neuropathy of the optic nerve, retinal vein occlusion, visual field defect, diplopia, temporary vision loss or decreased visual acuity, increased intraocular pressure, retinal edema, retinal vascular disease, vitreous detachment/vitreous traction.
  • The side of the organ of hearing: infrequently – a sudden decrease or loss of hearing, tinnitus, ear pain.
  • The cardiovascular system: often – “hot flashes”; infrequently – tachycardia, palpitations, decreased blood pressure, increased heart rate, unstable angina pectoris, AV block, myocardial ischemia, cerebral thrombosis, cardiac arrest, heart failure, abnormal ECG readings, cardiomyopathy; rarely – atrial fibrillation, sudden cardiac death, ventricular arrhythmia.
  • The hematopoietic system: infrequently – anemia, leukopenia.
  • The side of metabolism and nutrition: infrequently – a feeling of thirst, edema, gout, uncompensated diabetes mellitus, hyperglycemia, peripheral edema, hyperuricemia, hypoglycemia, hypernatremia.
  • The respiratory system: often – nasal congestion; infrequently – epistaxis, rhinitis, asthma, dyspnoea, laryngitis, pharyngitis, sinusitis, bronchitis, increased sputum volume, increased cough; rarely – a feeling of tightness in the throat, dryness of the nasal mucosa, swelling of the nasal mucosa.
  • The digestive system: often – nausea, dyspepsia; infrequently – gastroesophageal reflux disease, vomiting, pain in the abdomen, dry mouth, glossitis, gingivitis, colitis, dysphagia, gastritis, gastroenteritis, esophagitis, stomatitis, abnormal liver function tests, rectal bleeding; rarely – hypesthesia of the oral mucosa.
  • The musculoskeletal system: often – back pain; infrequently – myalgia, pain in the extremities, arthritis, arthrosis, tendon rupture, tenosynovitis, bone pain, myasthenia gravis, synovitis.
  • The genitourinary system: infrequently – cystitis, nocturia, enlargement of the mammary glands, urinary incontinence, hematuria, ejaculation disorders, edema of the genitals, anorgasmia, hematospermia, damage to the tissues of the penis; rarely, prolonged erection and/or priapism.
  • The 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.
  • The skin and subcutaneous tissues: infrequently – skin rash, urticaria, herpes simplex, pruritus, increased sweating, skin ulceration, contact dermatitis, exfoliative dermatitis; frequency unknown – Stevens-Johnson syndrome, toxic epidermal necrolysis.
  • Others: infrequently – a feeling of heat, face swelling, photosensitivity reactions, shock, asthenia, fatigue, pain of various localization, chills, accidental falls, chest pain, accidental trauma; rarely – irritability.

Contraindications

  • Severe hepatic impairment;
  • Severe cardiovascular diseases (severe heart failure, unstable angina pectoris, stroke or myocardial infarction within the last 6 months, life-threatening arrhythmias, arterial hypertension (BP> 170/100 mm Hg) or hypotension (BP <90/50 mm Hg));
  • Episodes of non-arteritis anterior ischemic neuropathy of the optic nerve with loss of vision in one eye;
  • Hereditary retinitis pigmentosa;
  • Use in patients taking continuous or intermittent agents of nitric oxide, organic nitrates or nitrites in any form, since sildenafil enhances the hypotensive effect of nitrates;
  • Concomitant use of PDE5 inhibitors, including sildenafil, with guanylate cyclase stimulants such as riociguat; this can lead to symptomatic hypotension;
  • Simultaneous use of the drug with other drugs for the treatment of erectile dysfunction (the safety and effectiveness of combination therapy has not been studied);
  • Lactose intolerance, lactase deficiency, glucose-galactose malabsorption;
  • Children and adolescents up to 18 years old;
  • Use in women;
  • Hypersensitivity to sildenafil or to any other drug components.

Overdose

With a single dose of Brand Viagra in a dose of up to 800 mg, adverse events were comparable to those when taking the drug in lower doses, but they were more common. The use of the drug at a dose of 200 mg did not lead to an increase in the effectiveness of the drug, however, the frequency of adverse reactions (headache, hot flashes, dizziness, dyspepsia, nasal congestion, visual impairment) increased.

Treatment: symptomatic therapy. Hemodialysis does not accelerate sildenafil clearance because the latter actively binds to plasma proteins and is not excreted in the urine.

Drug interactions

  • With the simultaneous use of CYP3A4 inhibitors (erythromycin, cimetidine), the clearance of sildenafil decreases, the concentration of sildenafil in the blood plasma increases.
  • With the simultaneous use of indinavir, saquinavir, ritonavir, the Cmax in the blood plasma and the AUC of sildenafil increase, which is due to the inhibition of the CYP3A4 isoenzyme under the influence of indinavir, saquinavir, ritonavir.
  • Potent inhibitors of the CYP3A4 isoenzyme such as ketoconazole or itraconazole can be expected to increase the plasma concentration of sildenafil.
  • When used simultaneously with nitrates, the hypotensive effect of nitrates is enhanced.
  • A case of the development of rhabdomyolysis symptoms after a single dose of sildenafil in a patient taking simvastatin is described.