Potentsagra (capsules 0,025 g and 0,05 g)
Capsulae "Potentsagra" 0,025 et 0,05
International unlicensed name
Sildenafil citrate.
Composition
1 capsule contains sildenafil citrate 25 mg or 50 mg.
Pharmacotherapy group
Preparations for treatment of erection failure.
Pharmacological action
Pharmacodynamics
The preparation inhibits cyclic-guanosine monophosphate-dependent phosphodiesterase of type 5 contained mainly in smooth muscles of the cavernous body and prevents the destruction of cyclic-guanosine monophosphate. The increase of the level of the former leads to reduction in the calcium concentration in cells and relaxation of smooth muscle cells of the cavernous body accompanied by subsequent higher sinus infilling with blood (on the basis of increased arterial blood flow in the penis) and depression of revehent veins.
The preparation intensifies and prolongs the erection following the sexual stimulation. Efficiency of the preparation is conditioned by its prolonged use (1 year).
It inhibits retina phosphodiesterase of type 6 (though to a lower extent than phosphodiesterase of type 5, action selectiveness 10:1) and may impair color sense. It increases antiaggregate and disaggregate effects of nitric oxide (II) and its donors, blocks the formation of clots ex vivo. On administration of high doses the preparation significantly increases the period of blood flow (though it does not affect the fibrillation). Single administration in the doses more than 30 mg induces a higher level of cyclic-guanosine monophosphate in plasma. It dilates either arterial, or venous vessels, induces reduction of systolic and diastolic blood pressure and increases cardiac contraction frequency. It has a antidiuretic action.
It does not affect a reproductive function. The preparation does not have an impact on the morphology, mobility and viability of spermatozoa, and volume and viscosity of ejaculate. It does not have teratogenic, mutagenic, clastogenic and carcinogenic characteristics.
Pharmacokinetics
On oral administration and empty stomach the preparation is absorbed quickly and completely. Max.concentration in plasma is achieved in 0,5—2 hours. Absolute bioavailability constitutes 41% (subject to presystemic metabolism). Fat food decreases the level of absorption and max.concentration in blood, increases the period of attaining of max.concentration in blood for an hour. It is bound with plasma protein by 96%. The half-period is 4 hours (can vary from 2 to 8 hours). It is accumulated in the organism: on administration 3 times a day during 9 days the cumulation makes 36%.
In elderly patients the clearance is reduced, sildenafil concentration in plasma increases. On kidney failure the value of max.concentration in plasma is twice higher than that in healthy patients. In patients with steady cirrhosis the clearance of sildenafil is lower by 46%, max.concentration in plasma is higher by 47%.
The preparation is subject to intensive biotransformation. Metabolite has an action similar to that of sildenafil, but its activity is lower by appr.50%. Up to 80% of sildenafil metabolites are excreted in faeces and urine.
Indication
Erection failure (organic, psychogenic, mixed), including in patients with diabetes, obesity, after radical prostatectomy or spinal cord injury.
Route and dosage
The preparation is administered orally, 1 hour before the coitus. For the majority of patients the recommended dose is 0,05 g. On insufficient efficiency, but on the basis of a good tolerance, the dose may be increased up to 0,1 g.
Recommended max.frequency of the preparation administration is once per day.
On administration of the preparation in patients older than 65 years old, in patients with compromised liver functions, severe kidney failure and in case of simultaneous administration of preparations inhibiting CYP3А4 (cytochrome isozym Р450) a higher suldenafil concentration in plasma. Due to this fact the efficiency of the preparation may be increased, as well as intensification of side effects (it is necessary to reconsider the advisability of the dose 0,025 g).
Special indications
The preparation is not indicated for patients younger than 18 years old.
Side effects
On administration of the preparation the following cases are possible: headache, dizziness, vasodilatation (congestions), hypotension, asthenia, stuffiness in nose, watering, compromised light and color sense, vision acuity, dyspepsia, diarrhea, nausea, abdominalgia, lumbodynia, arthralgia, myalgia, muscle hypertony, insomnia, dyspnea, rush, disposition to respiratory infections or infections of urinary tracts, prolonged painful erection.
Contraindications
Hypersensitivity, nitrate therapy.
Overdosing
Symptoms: Fever, dizziness, redness of face, headache, compromised vision acuity, dyspepsia, blood pressure drop. Symptomatic therapy; dialysis is of no use.
Severe kidney and liver disturbances, anatomic deformations of penis, myelomatosis, acute leucosis, sicklemia, high disposition to hemorrhage, inherited pigmented retinitis, excerbation of stomach and duodenum ulcer, severe forms of arterial hypertension and hypotension, anamnestic indications to infarction and stroke transmitted in previous 6 months, life threatening arrhythmia, heart failure, non stable stenocardia, age up to 18 years old.
Precautions
Before the administration of the preparation for diagnosis of erection disturbance, determination of its reasons and choosing of adequate treatment methods, it is recommended to collect a complete clinical anamnesis and carry out thorough urological and clinical tests, especially in patients with accompanying cardiovascular diseases, on which sexual activity is not recommended (for instance, severe forms of ischemic heart diseases and hypertonic disease).
High doses are not recommended to elderly patients. Frequent (more than once a day) use in elevated doses increases the risk of side effects occurrence. Patients with accompanying ischemic heart disease constitute a risk group. Ratio benefit/risk is required in patients with heart failure and low volume of circulating blood. The preparation is prescribed with care to patients with arterial hypertension (blood pressure 170/110 mm merc.) and arterial hypotension (blood pressure 90/50 mm merc.). Special care is required in patients with accompanying arterial hypertension than take multicomponent hypotension pharmacotherapy.
The preparation is also prescribed with care to patients with diseases predisposing to priapism development (sicklemia, multiple myeloma, leucaemia).
It is not recommended to combine the preparation with other preparation for treatment of erectile dysfunction.
Interaction with other medications
It increases orthostatic hypotension induces by nitroglycerine, as well as antiaggregate effects of sodium nitroprusside.
Cimetidine, ketoconazole, itraconasole, erythromycin, sacvinavir, ritonavir and other medications (CYP3А4 inhibitors) increase sildenafil concentration in plasma, and rifampicin and other CYP3А4 inductors decrease the concentration in plasma.
Product form
Capsules 25 mg and 50 mg. 2 capsules in a blister.
