What is sildenafil citrate?
Sildenafil in medical practice was originally synthesized and studied as a substance capable of lowering arterial hypertension and improving the flow of blood to the heart muscle. However, as a result of the research it was revealed that this medication affects cardiac blood flow in a volume that is clearly insufficient to recognize its therapeutic effect. At the same time, a side effect of the substance being tested was discovered, namely, its ability to significantly increase blood flow in the pelvic organs, especially in the cavernous bodies of the penis. On this effect, all further studies of the preparation were concentrated.
Sildenafil in medical preparations is used in the form of the chemical compound with citric acid, or citrate. On the effect on the body, this substance is a blood vessel expander, or vasodilator. It is a selective phosphodiesterase inhibitor of the fifth type, abbreviated as PDE-5.
What is sildenafil citrate used for?
With natural excitation, the human body begins to release nitric oxide (NO) - a substance that causes the relaxation of smooth muscles and the walls of the vessels to expand. However, nitric oxide acts on the walls of the vessels not directly, but through the intermediary - cyclic guanosine monophosphate (cGMP). Since everything inside human body is balanced, there is a special enzyme that disintegrates cGMP - this is the previously mentioned PDE-5. This enzyme is the one that affected by sildenafil. It inhibits (slows down) activity of PDE-5, thereby the action of cGMP on the walls of the vessels (cavernous bodies of the penis) is prolonged and intensified. As a result, the penis is actively filled with blood and there is a long lasting permanent erection.
It is not difficult to guess that in itself sildenafil is not an exciting drug, its action is auxiliary in a natural for the organism chain of excitation, excretion and cleavage of substances that dilate the walls of blood vessels. When natural excitation takes place, the presence of the medicine in the blood will slow down the process of cleavage of cGMP and lead to increased blood filling of the male sexual organ. If there is no sexual arousal, the use of this medicine in order to achieve an erection is useless. Similarly, with the disappearance of excitement (when sexual activity is completed), the effect of the drug also ceases as the concentration of nitric oxide in the blood decreases. Summarizing all the above, sildenafil citrate does not contribute to the appearance of an erection in the absence of natural sexual arousal and sexual stimulation, and does not contribute to its long-term maintenance after the sexual intercourse stopped and the excitement went to a decline, that is, at the end of the sexual act, the erection will subside naturally.
How to use sildenafil citrate?
Tablets containing sildenafil are available in three versions of dosage - 25 mg, 50 mg and 100 mg. It means that, for example, drug that marked as sildenafil citrate tablets 100mg contains 100mg of active substance in every tablet. Usually the medication with it starts with the dosage of 50 mg. This quantity can be decreased to 25 mg or increased to 100 mg, depending on effect, but maximal safe dose is 100 mg of sildenafil, it is highly recommended to avoid exceeding this amount. Virtually every drug has side effects. Sildenafil citrate is not an exception. When taking this med, such conditions as blood flow to the face, dizziness, headache, dry mouth, palpitations (tachycardia), as well as nasal congestion, changes in photosensitivity, color perception, and visual impairment may occur (all these phenomena are reversible and most often disappear in the process of sexual activity). Taking the drug together with alcohol and fatty foods makes it difficult to absorb the active component into the bloodstream, so it is undesirable.
In addition to treating the symptoms of erectile dysfunction, sildenafil citrate is used in the therapy of pulmonary hypertension. The most famous medicine, in which sildenafil citrate is used as the main active ingredient, is without doubt the famous "blue pill", Viagra of Pfizer Company. After entering the pharmaceutical market in 1998, this drug was so widely known that the name Viagra became essentially synonymous with sildenafil. Such state of affairs for a long time was reinforced by the fact that patent protection was applied to Viagra and its main active component, so no other pharmaceutical company, apart from Pfizer, could produce and sell drugs based on sildenafil. Due to the high demand in the market, as well as the monopoly on production and sale, Pfizer could afford to keep a fairly high price for tablets. The situation changed when the patent protection period for the active substance expired. Now medicines based on sildenafil can be produced by other pharmaceutical companies using a ready-made formula. As a result, at this time other drugs containing sildenafil citrate such as Viagra began to appear on the market:
This led to the fact that the price of the medicine began to decline actively, generic drugs of some manufacturers can be bought several times cheaper than the original drug of Pfizer. They differ in the composition of the auxiliary components, as well as in the degree of purity of active substance from impurities.
The best degree of purification of the active substance at the moment is Sildenafil Ratiofarm (manufacturer - Croatia), Potential (producer - Ukraine) and Revatio (manufacturer - Germany). The group of generics produced by Indian pharmaceutical corporations (Camagra, Maxigra, Sildigra, Viprogra, Sukhagra, Pemegra, Pfiagra, Edegra) is less pure, but cheaper.