Sildenafil - a regulator of potency, is a new oral medication for the treatment of erection disorders and lack of genital response. He restores impaired erectile function and provides a natural response to sexual stimulation.
Dosage forms:
Tablets.
Sildenafil
Properties / Action:
Sildenafil is a new oral medication for the treatment of erectile dysfunction. He restores impaired erectile function and provides a natural response to sexual stimulation. To develop a favorable pharmacological effect of sildenafil requires sexual stimulation.
The physiological mechanism of erection of the penis involves release of nitric oxide (N0) in the cavernous body during sexual stimulation. Nitric oxide activates the enzyme guanilattsikpazu, which leads to increased levels of cyclic guanosine monophosphate (cGMP), which, in turn, causes relaxation of smooth muscles of corpus cavernosum and increased blood flow to the penis. Sildenafil - a powerful and selective inhibitor of cGMP-specific phosphodiesterase type 5 (PDE5), which is responsible for the breakdown of cGMP in the cavernous body.
Pharmacokinetics:
Sildenafil is rapidly absorbed. The concentration of drug in plasma after taking it inside an empty stomach reaches a peak within 30-120 min. Absolute oral bioavailability averaging 25-63%. When receiving sildenafil in combination with fatty food intake rate decreases.
Sildenafil and its major circulating metabolite M-desmetilovy approximately 96% bound to plasma proteins. Protein binding is not dependent on the total concentration of the drug.
Sildenafil metabopiziruetsya primarily by CYP3A4 (major route) and CYP2C9 (optional path) of the liver microsomal isoenzymes. The main circulating metabolite is formed by the M-desmetilirovaniya Sildenafil. On the selectivity of action on PDE metabolite comparable with sildenafil, and its activity against PDE5 approximately 50% of the activity of the drug. M-desmetilmetabolit undergoes further metabolism, the final period of its half-life is about 4 hours
The final half-life Sildenafil - 3-5 hours after oral administration, sildenafil is excreted as metabolites primarily in the faeces (approximately 80% of the administered dose) and to a lesser extent in the urine (approximately 13% of the administered dose).
In healthy elderly volunteers (65 years and older) sildenafil clearance was reduced, and the concentration of free drug substance in the plasma by approximately 40% higher than its level in healthy young volunteers (18-45 years).
In volunteers with mild to moderate renal insufficiency pharmacokinetics of sildenafil after single oral administration (50 mg) did not change. In volunteers with severe renal insufficiency decreased clearance of sildenafil.
In volunteers with liver cirrhosis decreased clearance of sildenafil.
Indications:
Sildenafil is used to treat erection disorders (organic, psychogenic, mixed), including patients with diabetes mellitus, obesity, after radical prostatectomy or spinal cord injury.
Dosage and administration:
Sildenafil tablets are inside.
Recommended dose of 50 mg taken only when needed about one hour before planned sexual activity. Given the efficacy and tolerability the dose may be increased to 100 mg or decreased to 25 mg. The maximum recommended dose is 100 mg. The maximum recommended frequency of application - once a day.
In elderly people and patients with impaired renal function or liver recommended scheme of the same.
Sildenafil should not be given to children.
Overdose:
In studies in healthy volunteers in single dose of the drug in doses up to 800 mg of adverse events were comparable with those in the receiving sildenafil at lower doses, but occurred more frequently.
Feeling is manifested fever, dizziness, facial flushing, headache, blurred vision breach, dyspeptic phenomena, reduced blood pressure.
In case of overdose should adopt standard symptomatic measures. Dialysis should not accelerate the clearance of sildenafil, as the latter is actively bound to plasma proteins and excreted in the urine.
Contraindications:
Hypersensitivity to any component of the drug.
Through certain influence on the exchange of nitric oxide / cGMP, sildenafil enhanced the hypotensive effect of nitrates, so it is contraindicated in patients receiving nitric oxide donator or nitrates in any form.
Restrictions apply to:
Serious violations of liver and kidney functions, anatomical deformation of the penis, multiple myeloma, acute leukemia, sickle cell anemia, an increased tendency to bleeding, hereditary retinitis pigmentosa, the aggravation of gastric ulcer and duodenal ulcer, severe arterial hypertension and hypotension, anamnestic indications transferred in the previous 6 months of a heart attack and stroke, life-threatening arrhythmias, heart failure, unstable angina, age 18 years.
Use during pregnancy and lactation:
Sildenafil is not intended for use in women. Reproduction studies in rats and rabbits, oral use of sildenafil did not exert teratogenic effects, had no effect on reproductive function and did not cause any violation of the peri / postnatal development of the fetus and newborn.
Effect on driving ability:
When driving or mechanisms are required precautions, because the application of the drug may occur rapidly undergoing change in color-response with a predominance of blue flowers.
Side effects:
In clinical studies, which were held in various countries, sildenafil was used more than 3700 patients (aged 19 to 87 pet). Over 550 patients received treatment for more than one year. Tolerability of Sildenafil was good. In placebo controlled clinical studies, the frequency of discontinuation due to adverse events was low and comparable with that for placebo. Adverse events were generally transient and light to moderate. In studies with any design nature adverse events in patients receiving sildenafil was similar. In studies with fixed doses of the frequency of adverse events increased with increasing dose. In studies with titration nature of adverse events was comparable to that in studies with fixed doses.
In clinical studies, with an individual selection of doses, most often met the following adverse events whose relationship with the drug taking was possible, probable or unknown:
• Headache, flushing, dizziness;
• Dyspepsia;
• nasal congestion;
• Change in vision (mild and transient, mostly change the color of objects, as well as increased perception of light and a violation of clarity of vision).
When using the drug in doses greater than recommended, adverse events were similar to the above, but usually more often.
Single reception sildenafil orally at a dose of 100 mg in healthy volunteers was not accompanied by changes in sperm motility or morphology.
Cautions and precautions:
For the diagnosis of erectile dysfunction, determine possible causes of their choice and adequate treatment is necessary to collect a complete medical history and thorough physical examination. Sexual activity is a risk in the presence of heart disease. In this connection, before any therapy at the violations of erection doctor may deem it necessary to study the cardiovascular system.
Preparations intended for the treatment of erectile dysfunction, should be used with caution in patients with anatomical deformation of the penis (eg, angulation, cavernous fibrosis or Peyronie's disease) and persons suffering from diseases that predispose to the development of priapism (such as sickle cell anemia, multiple myeloma, or leukemia).
Preparations intended for the treatment of erectile dysfunction, should not be given to men for whom sexual activity is undesirable.
A small number of patients with hereditary retinitis pigmentosa are inherited disorders the activity of phosphodiesterases in the retina. No information about the safety of sildenafil in patients with retinitis pigmentosa no. Therefore such patients sildenafil should be used with caution.
Drug Interactions:
Ingibitory ZA4 isoforms 2C9 and cytochrome P450 may reduce the clearance of sildenafil. Sildenafil is a weak inhibitor of cytochrome P450 isoenzymes - 1A2, 2C9, 2C19, 206, 2E1 and ZA4.
Reduced clearance Sildenafil is observed, while the application with ketoconazole, erythromycin, cimetidine.
Tolbutamide, warfarin, selective serotonin reuptake inhibitors, tritsikpicheskie antidepressants, thiazides and tiazidopodobnye diuretics, loop and potassium-sparing diuretics, ACE inhibitors, calcium antagonists, beta-blockers, rifampicin, barbiturates do not affect the pharmacokinetics of sildenafil.
Single reception antacids (magnesium and aluminum hydroxide) did not affect the bioavailability of sildenafil.
Sildenafil has no effect on bleeding time, including the appointment in combination with aspirin.
Sildenafil not intensify antihypertensive effect of alcohol in healthy volunteers.
In patients with arterial hypertension signs of interaction with sildenafil amlodipine has been found.
Sildenafil increased the hypotensive effect of nitrates in the acute sample and with prolonged use of the latter. In this regard, the use of sildenafil in combination with nitrates or nitric oxide donators contraindicated.
Safety and efficacy of sildenafil in combination with other tools designed for the treatment of erectile dysfunction, were not studied. In this regard, the use of such combinations is not recommended.
Dispensed by prescription.