Purchase viagra online – sildenafil information and reviews

Viagra (Sildenafil) is refined basically by the CYP3A4 (main way) and CYP2C9 (secondary way) hepatic microsomal isoenzymes. The basic Sildenafil metabolite is a result from N-desmethylation, and undergoes further metabolism. This main metabolite restricts selectively PDEs like Sildenafil and shows the properties for PDE5 about 50% of the parent medication. This metabolite has 40% plasma levels of those noted for Sildenafil, and thus the metabolite amounts to 20% of Viagra’s pharmacologic effects.

Sildenafil is eliminated as metabolites basically in the feces – about 80% of the received dose and in the urine – about 13% of the dose.

The half life of Sildenafil is about 4 hours, this means that during a period of 4 hours a person may get and maintain an erection. Still the response of a patient decreases after 2 hours after the oral dose. So it is recommended to take Viagra 30 minutes – 2 hours before sexual activity to receive the most pleasant results.

Viagra effect on blood pressure was estimated during special clinical trials which revealed  that the max 100 mg dose of Sildenafil given  to healthy test participants decreases  sitting blood pressure. The reduction in systolic/diastolic blood pressure noted in the participants was maximum 8.3/5.3 mmHg. Such blood pressure decrease was mostly observed about 1–2 hours after oral dose.

The same Viagra effect on blood pressure was observed with other doses 25 mg, 50 mg. So the effect on blood pressure is not associated to dose or plasma levels within this dosage range.

The serious Viagra effect on blood pressure was noted in patients receiving nitrate- containing medications. The concomitant use of Viagra with nitrates is contraindicated because it can produce dangerous drop in blood pressure. Men with ED and uncontrolled blood pressure or taking nitrates should consult a doctor before using Viagra.

Eight double-blind, placebo-controlled crossover studies were conducted to evaluate the effects of Viagra on erectile response in patients having problems with getting and keeping erections.

The patients taking part in the studies had either organic or psychogenic erectile dysfunction. The administration of Viagra to the participants (with the sexual stimulation) led to improved erections. It was estimated with the help of an objective measurement of hardness and duration of erections (RigiScan).

Most studies proved the efficacy of Viagra about an hour after the dose adjustment. The erectile response significantly increased with the dose enlargement and plasma concentration. The duration of the effect of Viagra was evaluated and stated up to 4 hours.

The physiologically penile erection requires activation of several processes such as local release of nitric oxide (NO) in the corpus cavernosum when sexual stimulation occurs, the production of enzyme guanylate cyclase  and production of  cyclic guanosine monophosphate (cGMP. All these processes result in smooth muscle relaxation in the corpus cavernosum and extra inflow of blood into penile tissues.

Sildenafil enhances the effect of nitric oxide by restricting phosphodiesterase type 5 (PDE5). PDE5 is known for its effect to diminish cGMP in the corpus cavernosum. When sexual stimulation occurs nitric oxide is released, Sildenafil inhibits PDE5 and this causes enlarged levels of cGMP in the corpus cavernosum. The whole process has a smooth muscle relaxation effect. Sildenafil requires sexual stimulation to start working.

According to the results of the studies of pharmacological effects of Viagra, the medication is rapidly absorbed. It was noted that maximum plasma concentrations reached within 30 to one hour after oral administration. The reduction of absorption was monitored when Viagra was taken with a high fat meal.  The delay was in Tmax of an hour and a mean reduction in Cmax of 29%. The moderate steady volume of distribution for Viagra taken orally is 105 L, indicating dissimilation into the penile tissues. The study has shown that Sildenafil and its metabolites are approximately 96% bound to plasma proteins and protein binding is not related to the complete drug concentrations.

The appearing of Sildenafil in semen of healthy volunteers was measured and presented less than 0.001% of the administered dose after 1.5 hour of oral intake.

Viagra (sildenafil) is produce in the dosage form of  tablets and indicated to treat ED problems in men of different ages, still the medication is not recommended to be used in young men (younger than 18 years of old) and with caution in geriatrics. Sildenafil citrate is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). It loosens the muscles and improves the blood flow to the genital area.

Sildenafil citrate is designated chemically as 1 – [[3 - (6,7 - dihydro - 1 - methyl - 7 - oxo - 3 - propyl - 1H - pyrazolo[4,3 - d]pyrimidin – 5 – yl) – 4 – ethoxyphenyl]sulfonyl] – 4 – methylpiperazine citrate.

Viagra has a tablet formulation blue in color, rounded in shape with 25 mg, 50 mg and 100 mg of Sildenafil for oral intake. Other inactive ingredients of the tablets are: microcrystalline cellulose, anhydrous dibasic calcium phosphate, croscarmellose sodium, magnesium stearate, hypromellose, titanium dioxide, lactose, triacetin, and FD & C Blue #2 aluminum lake. If you have allergic reactions to Sildenafil citrate or to other components of Viagra, do not use the medication.

Viagra recommended dose for a healthy man is 50 mg, the dose may be changed based on the response of a patient and his tolerability to the drug. Viagra is to be taken only when necessary before sexual activity with a period or 24 hours between doses. Viagra acts after half an hour of oral administration with a max effect lasting to 4 hours. Viagra requires a person to be sexually aroused to start acting. Sildenafil has certain contraindications, most serious of which are the administration with nitrates, antihypertensive medications and other ED oral therapies.

A number of medications, recreational and illegal drugs can have a negative effect on sexual function of men. Still the medication- induced impotence may develop in one male but not affect another male.

In case you suspect that you are taking a medication which possibly negates your sexual function, consult your doctor for more information, dose changes or altering the therapy.  But remember that some treatments (such as antihypertensive therapy) should not stop suddenly.

Here is a list of medications, recreational and illegal drugs that may cause erectile difficulty:

High blood pressure medicines among which the thiazide containing medications cause ED most frequently:

• Bethanidine
• Bumetanide
• Captopril
• Enalpril
• Nifedipine
• Prazosin and many others.

Diuretic medications:

• Furosemide
• Chlorothiazide
• Phentolamine.

Parkinson’s disease medications:

• Levodopa
• Procyclidine
• Trihexyphenidyl.

Antidepressants and antipsychotic medications:

• Amitriptyline
• Buspirone
• Diazepam
• Desipramine
• Lorazepam
• Mesoridazine
• Oxazepam
• Sertraline and many others.

Antihistamine medications and hormonal medications:

• Antiandrogens
• Busulfan
• Ketoconazole.

The medications to treat other disorders:

• Clofibrate
• Estrogen
• Cyproterone
• Finasteride
• Lipid-lowering agents
• Metoclopramide
• Pseudoephedrine
• Licorice.

Opiate analgesics – pain relievers:

• Codeine
• Fentanyl
• Meperidine
• Morphine
• Oxycodone

Recreational and illegal drugs:

• Alcohol
• Amphetamines
• Barbiturates
• Marijuana
• Nicotine
• Heroin
• Cocaine

To avoid the negative effects of the medications on your sexual function  it is advised to take the medications only when your doctor prescribes it for you. Besides you may discuss the possible adverse reactions with your doctor to choose the best treatment for you.

Most men do not like even speaking about erectile dysfunction problem hoping that they will never face it. Still many men suffer from this disorder because of different other medical conditions contributing to ED, age and other factors. ED is usually defined as a persistent or constant inability to get or keep an erection rigid enough for sexual intercourse.

ED in most cases is not accompanied by other sexual disorders such as low sexual desire, orgasm or reproduction difficulties. ED sufferers commonly have normal sexual libido and are able to be sexually active but due to the erectile problem may get depressed and lose self –esteem. ED is a very serious problem affecting normal life and thus it should be treated without delay.

ED may be caused by psychological issues such as stress and depression; other most common ED causes are diabetes, atherosclerosis, medication or drugs abuse.

It is necessary to consult a medical professional to make sure that your symptoms are erectile dysfunction.

In 1998 Viagra – Sildenafil the first oral ED treatment was approved by US FDA with an indication to fight impotence in men. Since that time Viagra and its generics has become the best seller medical product, appreciated by doctors and patients as credible, high effective and safe medication helping to combat even severe forms of ED in men.

Since Viagra’s first appearing on the pharmaceutical market the medication has obtained a worldwide honor for its excellent treatment of erectile dysfunction. In spite the fact that other ED therapies have been designed and approved, Viagra stays in the top rating of the best selling medications. The majority of doctors and ED sufferers have confidence in Viagra for its capacity to overcome any sexual obstacles.

Viagra’s active component is Sildenafil which was approved as a prescription drug to treat impotency caused by different disorders.
This site is designed to help those Viagra consumers who start the treatment with this medication or rely on it for many years. We provide you with essential information about Viagra facts, mechanism of action, side events, food and drug interactions, etc. We believe that you can find here new information about the well known medication.