Viasan-LF
Instructions for use of the drug to increase potency Viasan-LF (Viasan-LF)
International name: viasan-lf
Composition and release form.
Film-coated tablets 1 tablet contains sildenafil (in the form of citrate) 50 mg.
* non-proprietary international name recommended by WHO - sildenafil.
Tablets, coated film-coated, 50 mg: 2, 4 or 10 pcs. Tablets, coated film-coated, 100 mg: 2, 4 or 10 pcs.
2 pcs. - blisters (1) - cardboard packs. 4 things. - blisters (1) - cardboard packs. 10 pieces. - blisters (1) - cardboard packs.
Form of release - by prescription
Pharmachologic effect.
Selective inhibitor of cycloguanosine monophosphate (cGMP)-specific PDE5. PDE5, responsible for the breakdown of cGMP, is found not only in the corpus cavernosum of the penis, but also in the vessels of the lungs.
Restores impaired erectile function and provides a natural response to sexual arousal. Sildenafil does not have a direct relaxing effect on the corpus cavernosum, but actively enhances the relaxing effect of nitric oxide on this tissue.
During sexual arousal, local release of NO under the influence of sildenafil leads to inhibition of PDE5 and an increase in the level of cGMP in the corpus cavernosum, resulting in relaxation of smooth muscles and increased blood flow in the corpus cavernosum.
As a PDE5 inhibitor, sildenafil increases the content of cGMP in the smooth muscle cells of the pulmonary vessels and causes them to relax.
In patients with pulmonary hypertension, taking sildenafil leads to dilation of the blood vessels of the lungs and, to a lesser extent, other vessels. Sildenafil is selective for PDE5 in vitro. E
Its activity against PDE5 is 10 times higher than that against other known PDE isoenzymes: PDE6, which is involved in transmitting the light signal in the retina of the eye; PDE1 - 80 times; PDE2, PDE4, PDE7-PDE11 - more than 700 times.
The activity of sildenafil against PDE5 is more than 4000 times greater than its activity against PDE3, a cAMP-specific PDE involved in heart contraction.
Sildenafil may cause mild and transient impairment of color discrimination (blue/green). The putative mechanism for color vision impairment is the inhibition of PDE6, which is involved in the process of light transmission in the retina. In vitro studies have shown that the effect of sildenafil on PDE6 is 10 times lower than its activity on PDE5.
Pharmacokinetics of Viasan-LF
After oral administration, sildenafil is rapidly absorbed. Absolute bioavailability averages 40% (25-63%). After a single oral dose of 100 mg, Cmax is 18 ng/ml and is achieved when taken on an empty stomach for 30-120 minutes.
When taking sildenafil in combination with fatty foods, the rate of absorption is reduced; Tmax increases by 60 minutes, and Cmax decreases by an average of 29%. The Vd of sildenafil at steady state is on average 105 liters. Sildenafil and its main circulating N-desmethyl metabolite are approximately 96% bound to plasma proteins.
Protein binding is independent of the total concentration of sildenafil. Less than 0.0002% of the dose (mean 188 ng) was detected in semen 90 minutes after sildenafil administration.
Sildenafil is metabolized mainly by the liver microsomal isoenzymes CYP3A4 (the main route) and CYP2C9. The main circulating metabolite, which is formed as a result of N-desmethylation of sildenafil, undergoes further metabolism.
In terms of selectivity of action on PDE, the metabolite is comparable to sildenafil, and its activity against PDE5 in vitro is approximately 50% of the activity of sildenafil itself.
The concentration of the metabolite in plasma is approximately 40% of that of sildenafil. The N-desmethyl metabolite undergoes further metabolism; its terminal T1/2 is about 4 hours. The total clearance of sildenafil from the body is 41 l/h, and T1/2 in the terminal phase is 3-5 hours.
After oral administration, sildenafil is excreted in the form of metabolites mainly in feces (approximately 80% of the dose) and to a lesser extent in urine (approximately 13% of the dose).
In elderly patients (65 years and older), the clearance of sildenafil is reduced, and the concentration of the free active substance in plasma is approximately 40% higher than its concentration in young (18-45 years) patients.
In case of mild (creatinine clearance 50-80 ml/min) and moderate (creatinine clearance 30-49 ml/min) renal failure, the pharmacokinetic parameters of sildenafil after a single oral dose (50 mg) do not change.
In severe renal failure (creatinine clearance <30 ml/min), the clearance of sildenafil is reduced, which leads to an approximately twofold increase in AUC (100%) and Cmax (88%) compared to those with normal renal function in patients of the same age group.
In patients with liver cirrhosis (class A and B on the Child-Pugh scale), the clearance of sildenafil is reduced, which leads to an increase in AUC (84%) and Cmax (47%) compared to those with normal liver function in patients of the same age group .
Indications for use of Viasana-lf. Treatment of erectile dysfunction, characterized by the inability to achieve or maintain a penile erection sufficient for satisfactory sexual intercourse. Dosage regimen and method of use of Viasan-lf. Treatment of erectile dysfunction: taken orally approximately 1 hour before planned sexual activity.
A single dose is 50 mg. Taking into account effectiveness and tolerability, the dose can be increased to 100 mg or reduced to 25 mg.
The maximum single dose is 100 mg. The maximum frequency of use is 1 time/day. For elderly patients over the age of 65 years and with concomitant impaired renal or liver function, the dose is 25 mg.
Pulmonary hypertension: orally 20 mg 3 times a day with an interval of about 6-8 hours, regardless of meals. The maximum daily dose is 60 mg. In patients with impaired renal function, no dose adjustment is required, however, if tolerated poorly, the dose is reduced to 20 mg 2 times a day.
Side effect
Very often - more than 1/10, often - more than 1/100 and less than 1/10, sometimes - more than 1/1000 and less than 1/100, rarely - more than 1/10000 and less than 1/1000.
From the immune system: rarely - hypersensitivity.
From the nervous system: very often - headache; often - dizziness; sometimes - drowsiness, hypoesthesia; rarely - stroke, fainting; frequency unknown - transient ischemic attack, convulsions, incl. recurrent.
On the part of the organ of vision: often - visual impairment, impaired color perception; sometimes - damage to the organ of vision, incl. damage to the conjunctiva, impaired lacrimation; frequency unknown - anterior non-arteritic ischemic optic neuropathy, retinal vascular occlusion, narrowing of visual fields.
From the organ of hearing: sometimes - vertigo, tinnitus; rarely - deafness.
From the cardiovascular system: often - “hot flashes”; sometimes - palpitations, tachycardia, increased heart rate; rarely - increased or decreased blood pressure, myocardial infarction, atrial fibrillation; frequency unknown - ventricular arrhythmias, unstable angina, sudden cardiac death.
From the respiratory system: often - nasal congestion; rarely - nosebleeds.
From the digestive system: often - dyspepsia; sometimes - vomiting, nausea, dryness of the oral mucosa. From the skin: sometimes - skin rash.
From the musculoskeletal system: sometimes - myalgia. From the reproductive system: frequency unknown - priapism, prolonged erection. Other: sometimes - chest pain, fatigue.
Contraindications to the use of Viasan-lf. Simultaneous use of nitric oxide donors or nitrates in any form, hypersensitivity to sildenafil. Use for impaired liver function For impaired liver function, the dose is 25 mg.
Use for impaired renal function For impaired renal function, the dose is 25 mg.
Use of the drug in children
Sildenafil is not used in patients under 18 years of age.
Use in elderly patients
For elderly patients over the age of 65 years, the dose is 25 mg.
Special instructions for use
Before starting pharmacotherapy in order to diagnose erectile dysfunction and the causes that caused it, it is necessary to collect anamnesis and conduct a medical examination.
Before starting treatment for erectile dysfunction, it is necessary to assess the risk of developing cardiovascular complications caused by sexual activity.
Sildenafil causes a mild, reversible decrease in blood pressure. Before starting to use sildenafil, the risk of adverse effects from lowering blood pressure, especially against the background of sexual activity, should be excluded. Patients with LV obstruction (including aortic stenosis, HOCM) or the rare multiple atrophy syndrome, characterized by impaired blood pressure regulation, are most susceptible to the hypotensive effect of vasodilators.
Most cardiovascular side effects develop in people with pre-existing heart or vascular disease. Most often, such complications developed either immediately after sexual intercourse or a short time after it.
In some cases, such side effects developed after taking sildenafil without subsequent sexual intercourse. The cause-and-effect relationship between these side effects and the described factors has not been established. Doses greater than 200 mg do not increase effectiveness, but increase the frequency and severity of dose-dependent side effects.
Precautionary measures
Before starting treatment to diagnose erectile dysfunction, determine its possible causes and select adequate treatment methods, it is necessary to collect a complete medical history and conduct a thorough urological and general clinical examination, especially in patients with concomitant cardiovascular diseases for whom increased sexual activity is undesirable (for example, in severe forms of coronary artery disease and arterial hypertension).
In patients over 65 years of age, with hepatic and severe renal failure (creatinine Cl less than 30 ml/min), as well as with simultaneous use of cytochrome P450 3A4 inhibitors (erythromycin, ketoconazole, itraconazole, saquinavir, etc.), the initial dose is 25 mg.
When taking ritonavir concomitantly, the maximum single dose should not exceed 25 mg over 48 hours.
There are post-marketing reports of rare cases of erections lasting more than 4 hours and priapism, requiring immediate medical intervention to avoid damage to penile tissue and irreversible impotence.
The safety of sildenafil when taken concomitantly with other drugs for the treatment of erectile dysfunction has not been studied, and concomitant use is not recommended. Not indicated for use in neonates, children and women.
Interactions with other drugs
With simultaneous use of CYP3A4 inhibitors (erythromycin, cimetidine), the clearance of sildenafil decreases and the concentration of sildenafil in the blood plasma increases.
With the simultaneous use of indinavir, saquinavir, ritonavir, the plasma Cmax and AUC of sildenafil increases, which is due to inhibition of the CYP3A4 isoenzyme under the influence of indinavir, saquinavir, ritonavir.
Stronger CYP3A4 inhibitors, such as ketoconazole or itraconazole, can be expected to increase plasma concentrations of sildenafil
When used simultaneously with nitrates, the hypotensive effect of nitrates is enhanced.
A case of the development of symptoms of rhabdomyolysis after a single dose of sildenafil in a patient receiving simvastatin has been described.
Storage conditions
List B: In a dry place, protected from light, at a temperature not exceeding 25 °C.
Best before date
24 months
Package
2, 4 or 10 tablets in a blister pack.
One blister pack per pack. Use of the drug Viasan-lf only as prescribed by a doctor
To get acquainted, we also recommend looking at the rating of drugs for potency
Contraindications
Hypersensitivity; simultaneous intake of nitric oxide donors or nitrates in any form; severe forms of arterial hypertension and hypotension, anamnestic indications of a heart attack and stroke suffered in the previous 6 months, life-threatening arrhythmias, heart failure, unstable angina; Severe liver and kidney dysfunction, hereditary retinitis pigmentosa; age up to 18 years. The drug is contraindicated in patients with rare hereditary diseases such as galactose intolerance, lactase deficiency or glucose-galactose malabsorption. The drug should be used with caution in patients with heart disease, anatomical deformities of the penis, sickle cell anemia, multiple myeloma, leukemia; increased tendency to bleeding, peptic ulcer of the stomach and duodenum in the acute stage. Prescribe with caution to patients with arterial hypertension (blood pressure (BP) 170/110 mm Hg) and arterial hypotension (BP 90/50 mm Hg). Prescribe with extreme caution to patients with concomitant arterial hypertension receiving multicomponent antihypertensive pharmacotherapy.
Interaction
You should not combine the drug with treatment with nitrates (nitroglycerin and other drugs in this group), molsidomine, and other nitric oxide donors. Enhances the hypotensive effect of nitrates (the combination of sildenafil with nitrates can be fatal); co-administration with slow calcium channel blockers (SCBCs), beta-blockers and oral hypoglycemic drugs is potentially life-threatening. Enhances the antiplatelet effect of sodium nitroprusside. Itraconazole, saquinavir, ritonavir increase the concentration of sildenafil in the blood plasma, rifampicin reduces the concentration of sildenafil in the blood plasma. Cimetidine, ketoconazole, erythromycin reduce clearance and increase the concentration of sildenafil in the blood plasma.
