Viagra (Sildenafil citrate)

Viagra (medical name Sildenafil citrate) is a drug to treat impotence. It is an inhibitor of phosphodiesterase-5 (PDE5). Viagra has some usual side effects that are: pain in stomach, headache, stuffiness in nose, diarrhea, vomiting, facial blush, lose of ability to distinguish between blue and green colors. Sometimes you may also have ringing sound in ears, deafness, and giddiness.

It is recommended to take Viagra from half an hour to four hours before having sex. The dose of this medication can be from 25 mg to 100 mg. If you are taking any medicine against high blood pressure, Viagra may increase its effect. This medicine neutralizes lowering effects of blood pressure that nitrates give. Sometimes they can be presented by isosorbide dinitrate, which is used during first symptoms of angina. It is forbidden to use Viagra for those, who are using nitrates. Also it can not be combined with inhibitors of PDE5 like Cialis (tadalafil), Revatio (sildenafil) or Levitra (vardenafil). The other drugs like erothromycin, Tagamet (cimetidine), Posicor (mibefradil), and Sporanox (itraconazole) can cause in your body huge increases of Viagra's amount. If patients are taking this kind of medication, they need to consult to a doctor about using of Viagra.

Failure during sexual interaction

First of all sildenafil was developed to treat the symptoms of impotence or erectile dysfunction, which is an incapacity to support erection during coitus to complete it. At all conditions, including diabetes, sildenafil is the standard drug to cure erectile dysfunction.
Some people that use antidepressants may have impotence. It can happen as a result of such treatment or as an outcome of their sickness. Studies that were made in 2003 had proved that sildenafil helps men in such condition. That was followed by the studies that were made four years before with female patients that took antidepressants. Their sexual function was much better after taking sildenafil.

Hypertension in lungs

Sildenafil citrate can also be used to cure such seldom sickness as pulmonary arterial hypertension. It makes arterial wall relaxed decreasing the pressure and resistance of pulmonary arteries.

As a result, the load to the heart's right ventricle decrease and the symptoms of right sided heart attack fade away. When PDE5 diffuses through penis's and lungs' smooth muscles of arterial walls, sildenafil just acts on the appropriate areas and it doesn't cause vasorelaxation in other areas of your organism. So, in the middle of 2005, Pfizer decided to register sildenafil additionally in FDA for this treatment. The name of this medicine is Revatio, so the people will not confuse it with Viagra. The doze of tablet is 20 milligrams, and they are round and white. In this condition, the drug is used together with prostacyclin-based and bosentan therapies.

Mountain sickness

The results of clinical researches showed that sildenafil can also be used to treat and prevent high-altitude pulmonary edema. This disease is suffered my people who do mountain climbing. It was discovered only lately about such effect of sildenafil, but it is already widely used in treating this condition. Especially it is recommended to those that can not have standard treatment.


Most patients take a 50 mg dose about one hour before having sex. But actually, a person may take the drug from four to half an hour before having sex. Tolerance and effectiveness of the drug may vary the dose. The minimum recommended dose is 25 mg and it could be increased to 100 mg. It is recommended to take the medicine only one time a day.

There are some factors that can increase sildenafil's plasma levels. For example hepatic impression (cirrhosis, 80%), associative use of potent cytochrome P4503A4 inhibitors (e.g. erythromycine (182%), saquinavir (210%) itraconazole, ketoconazole), age older than 65 (40% increase in AUC) and strong renal impression (creatinine clearance becomes less than 30mL/min, 100%). For these patients, a primary dose should be 25 mg, because a high plasma level can raise the rate and effectiveness of negative incidents.

A new medicine Ritonavir provoked the studies in volunteers who don't have problems with health and are HIV-negative. This increased the systemic level of sildenafil a lot. Pharmacokinetic data says that the single 25 mg dose should not be increased within the period of two days.

It was resulted that Viagra increases hipotensive activity to those who take nitrates. The possible danger was indicated to patients that take any form of nitrates or nitric oxide donors together with Viagra.

The medicine is also co-administered with any class of drugs that prevent that prevent the stimulation of alpha adrenoceptors. At first, patient needs to stabilize his condition concerning alpha-blocker and then take Viagra with a minimum dose.


Like all the medicine in the pharmacy, Viagra has some precautions that people should know before they take it. We are advising you to consult a doctor before taking the drug, since he can professionally assess your medical condition. He will advise the best Viagra treatment for you if you are taking other medications.

Please, be honest during your consultation at a doctor, when he is asking question about your situation and health. We assure you, that you will be the one who suffers, if he gets wrong information. Your body could have a negative reaction to Viagra and the doctor will forbid you to take it.

Groups with risk

It doesn't mean that people from this group can not take Viagra at all. They just need to know and be very attentive about precaution of the medicine. Also they need to be informed about its impact. The doctor may advise you a small dose and he will ask you to inform him regularly about your condition. In the following we list people from this group:

• Those who are passed middle age
• People whose liver has poor function
• Those who have sicknesses with effect on blood or heart vessels
• People with hemophilia
• Men with unusual form of penis
• People whose peptic ulcer is active

Forbidden groups

It is forbidden to take Viagra under any circumstances for people from this group to cure erectile dysfunction (impotence). All packs have these warnings. The following list has not been made to make all men uncomfortable. Everybody should understand the precautions of Viagra and the danger that it may bring. People are forbidden to take this drug if:

• You are female
• Your age is younger than 18
• Your condition now forbids you to do any exercises or to have sex (angina)
• You had a heart attack recently
• In a recent time you had apoplexy
• Your blood pressure is low
• You are using nitrates
• Have problems with sight
• Have any liver disease
• You have an allergy to the ingredients that are contained in the drug

All of these precautions should be carefully examined and seriously taken. It is necessary to be honest during medical observance, because you may see the dangerous risks from which you could suffer. You can ask our team if you are not sure if the medicine that you are using together with Viagra will affect you. The same is if you are in the forbidden group and you still want to try Viagra, you should speak to a doctor about the dosage.


Viagra is a drug that is sold by prescription. It was studied carefully during lots of clinical trials and medical studies to find all side effects that can be possible and that can bring any damage to the person that uses it.

Every man's body reacts differently to any medication, that is why Viagra's side effects can be vary for anyone who takes it. There are cases when people suffer from taking Viagra, and some cases, where nothing bothers them during treatment. If you noticed that you are having side effects, you need to consult your doctor on changing the dosage or look for another drug for treating your impotence.

Usual side effects

Usual side effects from taking Viagra are not very arduous and as a rule they go away when the medication leaves your body. Once if you felt one of the side effects, you need to relax and lie on a bed, it will go away. If you still experience them, you need to go to a doctor. The most usual Viagra side effects are the following:

• Pain in head
• Head swimming
• Blushing
• Blue vision, bad sight, haziness
• Difficulty in digesting food

Unusual side effects

In the following we listed most unusual side effects which do not mean that it is bad to experience them. Approximately from one to one hundred people have these side effects from taking Viagra. The same is like with usual side effects, if you experience them much longer than Viagra is staying in your organism, you need to go to a doctor immediately. The following are side effects that are considered unusual:

• Vision disorders
• Eruption
• Too frequent beating of your heart
• Pain in muscles and chestIncreased heart rate
• Constant condition of being tired and sleepy
• Dryness in your mouth
• Condition when it is hard to feel your body
• Feeling of vomiting

Occasional side effects

Such side effects are very rare and they occur not so often, but there have been such cases. You should have a medical assistance immediately when you experienced it, because they are very serious. Contact your doctor straightway if you are feeling one of there occasional side effects:

• Too high or too low blood pressure
• Complete or partial deafness
• Bleeding of nose
• Weakness
• Heart attack
• Apoplexy

Side effects that happen very rare

A very seldom side effect is prolonged painful erection of penis. There have been registered a few cases with priapism and everything finished with success. It happens when a person has a long erection. It is usually for more than 4 hours. This occasion can ruin the tissues on your organ and you will recover for a long time. So as soon as you noticed it, go to the hospital immediately. Don't worry, it will not threaten your life, but can bring a lot of damage to your generative organ.


Physically erection takes place when NO or nitric oxide is released to cavernous body during stimulation of sex. Nitric oxide makes enzyme guanylate cyclase active and the amount of (cGMP) cyclic guanosine monophosphate increases, causing relaxation in muscles of cavernous body. This relaxation helps more blood to flow into it. Actually, this drug doesn't really make cavernous body too relaxed but at the same time it inhibits PDE5 by increasing the action of NO. Phosphodiesterase is responsible for decreasing of cGMP in penis. At some doses this medicine doesn't work without previous sexual stimulation.

Some laboratory tests presented that PDE5 is selected more often by sildenafil. The other phosphodiestrates react less effective than PDE5 to this medicine. For example 10-fold for PDE6, >80-fold for PDE1, >700-fold for PDE2, PDE3, PDE4, PDE7, PDE8, PDE9, PDE10, and PDE11. Phosphodiestrate 3 is an enzyme that takes part in contractility of heart. It is very significant comparing to PDE5 that has an approximate 4,00-fold selectivity. PDE5 has 10-fold selectivity comparing to PDE6, which is a phosphodiestrate that consist in retina. It helps retina to make its own phototransduction trajectory. Such abnormalities like loosing the sight and mixing colors is a result of this low selectivity. It happens at plasma levels or when the given dose is too high.

In less amounts, PDE5 also consists in other organs, like skeletal muscle, platelets and visceral smooth muscles. PDE5 presence in these organs in a form of sildenafil can be a reason for increasing the antiaggregatory activity of increased platelet of NO, that was noticed during laboratory tests also as peripheral dilation of arteries and veins and formation of platelet thrombus.


In 1989, British newspapers wrote that Pfizer workers Albert Wood and Peter Dunn had invented sildenafil, known as Viagra now. These two men had produced the medicine at the same time with their co-workers from England on a company's Sandwich, Kent investigating plant.

Viagra's history is always connected with three Pfizer worker from England whose names are Dr. Nicholas Terrett, Dr. David Brown and Andrew Bell. These guys made a lot of researches for discovering the main chemical compounds that belong to the class of pyrazolopyrimidinone. This composition helps to treat angina and other problems with heart.

In 1991 Dr. Nicholas Terrett received a British patent to use sildenafil as a treatment for heart. There are experts that name him the creator of Viagra, but he was just a leader of the team that proved the usefulness of the drug. In 1989 the drug was synthesized by Dunn and Wood. Actually these two people had put all of the Viagra components together with the right dosage into one tablet.

Patent application for manufacturing citrate of sildenafil includes Wood and Dunn. Still the Pfizer Company says that a lot of their workers had done a lot to the development of the actual compound UK-92,480/sildenafil/sildenafil citrate/Viagra.

At first, this drug was researched as a cure for those who have ischaemic heart disease and high blood pressure. During clinical trial of phase 1 that was directed by Ian Osterloh it was considered that this medicine is not very effective to cure angina. At the same time they discovered that it provokes erections in penis.

Clinical trials of phase 2 proved that it doesn't show effect on treating angina. So the company decided to make more researches on its reaction to erectile dysfunction. Pfizer received their patent on the drug in 1996. Later, in 27th of March, 1998 American Food and Drug Administration gave their approval to use this drug in erectile dysfunction. Viagra was the first medicine in America to use oral in treating impotence. Later, after it was approved it began to be sold all over United States. Each year Viagra selling bring to the company over $1 billion.

Dr. Simon Campbell had supervised the Viagra researches and is one of the main people in its discovery, since he was in Medicinal Discovery a Senior Vice President. On the 8th of June on 1998, a press release of Pfizer wrote about his retirement on that year, that he was "the main person in Pfizer stuff who made a lot in discovery of the three new drugs that were important to company... including Viagra, which is the first erectile dysfunction oral medication..."

A lot of people say that Pfizer advertised Viagra as a drug that can be taken for pleasure and not for medical reasons, considering the fact that sildenafil can only be sold by doctor's prescription.

A lot of different politicians and celebs advertised this medicine on radio, TV and in printed outputs. It helped a lot in selling the product all over the world. This considers a Brazilian soccer player Pele who advertised it in Latin America and Europe and American Senator Bob Dole that increased sales in United States. Mark Martin, ex NASCAR driver, Rafael Palmeiro, former baseball player and Rush Limbaugh, a politician analyst had also made a lot being mouthpieces.

Nowadays you can receive Viagra via online pharmacies with a doctor that can give you an online consultation. Such consultations, usually include a set of questions on a form about your health.

Lots of countries that are not located in America begun to produce and sell the medicine illegally after Viagra received a huge popularity in 1998. These products are "professional Viagra", "herbal Viagra" and "generic Viagra". Of course Pfizer didn't give any permission to these fake-manufacturing companies to use the name of Viagra or to sell the products that have this name and were not approved by FDA. Usually these fake and not real Viagra versions are much cheaper and can bring a lot of trouble to your health. They include some ingredients that are unknown to the consumer and could generate bad results.

In the year 2000, sales of Viagra had brought about 92 percent of the world market in the field of impotence treatment pills that are sold by prescription. Seven years later its global share was decreased to 50 percent. That was caused by several factors that included an appearance of Cialis and Levitra that were approved by FDA in 2003 together with the other clones and fakes. Between years 2011 and 2013 Pfizer will finish to have worldwide patents for selling sildenafil citrate.

Does generic Viagra exist?

Viagra (sildenafil citrate) is a medicine that has a license to be sold by prescription for curing impotence (erectile dysfunction). Pfizer is the only official manufacturer of the drug. Right now it has a patent to prevent the manufacturing of any generic Viagra.

A great number of companies that sell it will be given to you, if you search for Generic Viagra in the web. The only thing is that these drugs may be very dangerous for your health, because they are spurious. You should buy a generic version of Viagra only when it will be approved.

When can I buy generic Viagra?

Viagra has its patent until 2012. After that date, you may find Generic Viagra. But this period could be shortened before 2012. Some lawsuits or a license for another Viagra treatment can do this. At the time when Viagra's patent will be finished, a lot of companies will fight to produce the generic version of Viagra.

Is Sildenafil Citrate a generic version of Viagra?

You are wrong! It is the main ingredient in this medicine. It is not generic Viagra. The active ingredient of a drug is often thought that it is its generic name. Actually, generic version differs a lot from a generic name of drug. If another manufacturer wants to produce a generic version of the product, the real manufacturer should loose its patent.


Most erectile dysfunction treating medications like Viagra (based on the active component - Sildenafil) should be used very carefully because of possible adverse reactions. Among medications that can cause health hazards when taken along with Viagra are nitrates, any drugs that can affect blood pressure, Cimetidine, Ritonavir and many others. Before applying Viagra, please, read the list of drug interactions this ED medicine has.

• Cimetidine (Tagamet)

Viagra vs CYP 3A4 inhibitors
 
• CYP 3A4 inhibitor drugs:
  • Amprenavir (Agenerase)
  • Atazanavir (Reyataz)
  • Clarithromycin (Biaxin)
  • Conivaptan (Vaprisol)
  • Darunavir (Prezista)
  • Delavirdine (Rescriptor)
  • Erythromycin
  • Fosamprenavir (Lexiva)
  • Imatinib (Gleevec)
  • Indinavir (Crixivan)
  • Isoniazid
  • Itraconazole (Sporanox)
  • Ketoconazole (Nizoral)
  • Lopinavir and ritonavir (Kaletra)
  • Miconazole
  • Nefazodone (Serzone)
  • Nelfinavir (Viracept)
  • Nicardipine (Cardene)
  • Posaconazole (Noxafil)
  • Quinidine
  • Ritonavir (Norvir)
  • Saquinavir (Invirase, Fortovase)
  • Telithromycin (Ketek)
  • Voriconazole (VFEND)

Viagra vs alpha blockers
 
• Alpha blockers for hypertension or benign prostatic hyperplasia:
  • Alfuzosin (Uroxatral)
  • Doxazosin (Cardura)
  • Phenoxybenzamine (Dibenzyline)
  • Phentolamine (Regitine)
  • Prazosin (Minipress)
  • Silodosin (Rapaflo)
  • Tamsulosin (Flomax)
  • Terazosin (Hytrin)
• Blood pressure medications
• Nitrates:
  
  
  Viagra vs nitrates

   
  • Isosorbide dinitrate (BiDil, Dilatrate SR, Isordil, Isochron)
  • Isosorbide mononitrate (Ismo, Imdur, Monoket)
  • Nitroglycerin tablets or capsules (Nitro-Time, Nitrostat)
  • Nitroglycerin ointment (Nitro-Bid)
  • Nitroglycerin anal ointment (Rectiv)
  • Nitroglycerin patches (Nitro-Dur, Minitran)
  • Nitroglycerin spray (NitroMist, Nitrolingual)
• Some PDE5 inhibitors:
  • Avanafil (Stendra)
  • Other forms of sildenafil (Revatio, Kamagra)
  • Tadalafil (Adcirca, Cialis)
  • Vardenafil (Levitra, Staxyn)

Cimetidine
Cimetidine should be avoided for an intake at the same time as Viagra because it can increase significantly the amount of Sildenafil in blood. You are to consider preparations replacing Cimetidine if you need to use this medication while being on Viagra.

Alpha-blockers and blood pressure meds
Alpha-blockers and blood pressure drugs (antihypertensive meds) are given to people suffering from BPH (short for benign prostatic hyperplasia) or hypertension. If to use any medication of these drug families with Viagra at the same time, blood pressure can be increased frequently followed by such symptoms as dizziness, fainting after sitting or lying position. Please, make sure you use Viagra with alpha-blockers safely - it is allowed to take no more than 25 mg of Viagra in four hours after taking an alpha-blocker or antihypertensive agent.

CYP 3A4 Inhibitors
Viagra can lose its efficacy when metabolized with particular liver enzymes (CYP 3A4 enzymes, to be specific). That is why CYP 3A4 inhibitors that weaken these enzymes' activity can lead to Viagra overdose. In this scenario, there are possible very negative health consequences.

Nitrates
Nitrates are drugs based on nitroglycerine and they are given to treat heart conditions to prevent a stroke. It is strongly recommended to drop using Viagra when taking nitrates, even if you use nitroglycerine-based medications very occasionally.

Viagra and PDE5 Inhibitors intake
Since all PDE5 inhibitors (Levitra and Cialis) work pretty much in the same way, the intake of these meds along with Viagra may lead to overdose and serious by-effects like priapism.

Conclusion
When starting to take Viagra blue pills, try to avoid negative drug interactions listed above. Keep in mind there are other medications affecting negatively your health conditions if taken along with Viagra. Ask your therapist before using any other drugs simultaneously with Viagra.