Sildenafil citrate tablets. Buy Sildenafil citrate

What is Sildenafil citrate?

Sildenafil citrate is an international name of active ingredient of the well known erectile dysfunction medication sildenafil citrate. Sildenafil citrate tablets restore erection in patients with erectile dysfunction, provide a natural response of the organism to sexual arousal. Sildenaflil citrate tablet do not work without sexual stimulation. Physiological mechanism of erection is related to release of nitrogen oxide in cavernous body during the sexual stimulation. Nitrogen oxide activate the enzyme Guanylate cyclase leading to increase amount of cyclic GMP. This ultimately leads to the relaxation of the smooth muscles of the cavernous body and increasing of blood flow to the penis. Sildenafil citrate is a powerful and selective inhibitor of cyclicGMP- specific  a phosphodiesterase type 5, which is responsible for breaking down of cGMP in the cavernous body.

Sildenafil citrate Pharmacokinetics:
Sildenafil citrate is rapidly absorbed. The concentration of drug in plasma after taking orally on empty stomach is achieved within 30-120 min. Absolute oral bioavailability is averaging 25-63%. When  sildenafil is taken in combination with fatty food the absorption of medicines is reduced.
Sildenafil and its major circulating metabolite M-desmethyl approximately 96% bound to plasma proteins. Protein binding is not dependent on the total concentration of the medicine.
Sildenafil citrate is metabolized primarily by CYP3A4 (major route) and CYP2C9 (optional path) of the liver microsomal isoenzymes. The main circulating metabolite is formed by the N-desmethyl Sildenafil. N-desmethyl Sildenafil is undergone further metabolism, the final period of its half-life is about 4 hours
The half-life period of Sildenafil citrate - 3-5 hours after oral administration, sildenafil is excreted as metabolites primarily in the faeces (approximately 80% of the administered dose) and with 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 was 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 the clearance of sildenafil citrate was reduced.
In volunteers with liver cirrhosis clearance of sildenafil citrate was decreased.

Sildenafil citrate tablets indication:

Sildenafil citrate tablets are taken in patients with erectile dysfunction (organic, psychogenic, mixed), including patients with diabetes, obesity, traumas of the spinal cord.

Sildenafil citate dosage regimen

Sildenafil citrate tablets are taken orally. The average recommended dose is 50mg daily one hour before sexual intercourse.  In reliance of tolerability and effectiveness the dosage of sildenafil citrate tablets can be increased up to 100mg daily or decreased up to 25mg daily. Maximal dose of sildenafil citrate tablets is 100mg daily. Sildenafil citrate tablets should not be taken in women and patients under 18 years of age.

Sildenafil citrate overdose.

Do not exceed the recommended dose of the medication. Patients which abuse sildenafil citrate tablets have a high risk of side effects. The most observed effects of sildenafil citrate tablets were associated with hot flashes, dizziness, severe headache, blurred vision, dyspepsia, decreased blood pressure, fainting. In cases of sildenafil citrate overdose symptomatic treatment should be carried.

Sildenafil citrate contraindications:

Silnefafil citrate tablets are contraindicated in the following conditions:
Hypersensitivity to any component of the drug.
Concomitant use of nitrates (nitrogen oxide donors)
Women
Patients under 18 years of age
Sildenafil citrate tablets should be used with caution in:

Serious disorders of the  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, heart attack and stroke, life-threatening arrhythmias, heart failure, unstable angina.

Use during pregnancy and lactation:
Sildenafil citrate tablets are 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 disorders 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 colors.

Sildenafil citrate tablets side effects
In clinical studies, which were held in various countries, sildenafil citrate tablets were used in 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 sildenafil citrate tablets were low and comparable with that for placebo. Side effects were generally transient and light or moderate.
The most common side effects associated with sildenafil citrate tablets were the followings:
· Headache, flushing, dizziness;
· Dyspepsia;
· Nasal congestion;
• Vision change (mild and transient, mostly change the color of objects, as well as increased perception of light, blurred vision).
When using the drug in doses higher than recommended, adverse events were similar to the above, but usually more often.
Single administration of sildenafil citrate 100ng orally in healthy volunteers was not accompanied by changes in sperm motility or morphology.

Sildenafil citrate cautions and precautions:
For the diagnosis of erectile dysfunction, determine possible causes and choice of adequate treatment is necessary to collect a complete medical history thorough physical examination. Sexual activity is a risk in the presence of heart diseases. That is why it is important to examine a functional condition of the cardiovascular system before taking sildenafil citrate tablets as well having a sexual intercourse.
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 of the activity of phosphodiesterases in the retina. There is no information about the safety of sildenafil citrate tablets in patients with retinitis pigmentosa. Therefore such patients should take sildenafil should be used with caution.

Sildenafil citrate tablets interactions

Inhibitors 3A4 isoforms 2C9 and cytochrome P450 may reduce the clearance of sildenafil citrate. Sildenafil is a weak inhibitor of cytochrome P450 isoenzymes - 1A2, 2C9, 2C19, 206, 2E1 and 3A4.
The clearance of Sildenafil is reduced while the application with ketoconazole, erythromycin, cimetidine.
Tolbutamide, warfarin, selective serotonin reuptake inhibitors, tricyclic antidepressants, thiazides, thiazide diuretics, loop and potassium-sparing diuretics, ACE inhibitors, calcium antagonists, beta-blockers, rifampicin, barbiturates do not affect the pharmacokinetics of sildenafil.
Single application of antacids (magnesium and aluminum hydroxide) did not affect the bioavailability of sildenafil citrate tablets.
Sildenafil has no effect on bleeding time when used in combination with aspirin.
Sildenafil citrate does not intensify antihypertensive effect of alcohol in healthy volunteers.
In patients with arterial hypertension signs of interaction of sildenafil with amlodipine has been found.
Sildenafil increases the hypotensive effect of nitrates In this regard, the use of sildenafil in combination with nitrates or nitric oxide donators is strictly contraindicated.
Safety and efficacy of sildenafil in combination with other drugs used for the treatment of erectile dysfunction, were not studied. Therefore the use of such combinations is not recommended.