Viagra: Chemistry, Ingredients & Description

1707-22Viagra, since its introduction into the market has gone from strength to strength. It has rapidly become one of the most popular and prescribed medications in the entire world.

Manufactured and marketed by Pfizer Inc., Viagra was first introduced to the general public in 1998. A prescription drug, Viagra is used to treat erectile dysfunction and impotence in men.

According to research, 9 Viagra tablets are prescribed every second worldwide, while over 600,000 doctors have recommended Viagra as their choice of prescription medication to treat erectile dysfunction.


Viagra is available in doses of 25mg, 50mg and 100mg film coated tablets. The active ingredient in Viagra is Sildenafil citrate. Each tablet contains 25 mg, 50mg, and 100 mg of Sildenafil citrate respectively.

Other ingredients of Viagra include, microcrystalline cellulose, calcium hydrogen phosphate (anhydrous), croscarmellose and magnesium stearate. The film coat of the tablet contains hypermellose, titanium dioxide (E171), Lactose, triacetin and indigo carmine aluminum lake (E132).

Chemical Description

Viagra, is the citrate salt of sildenafil, a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). 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.

Sildenafil citrate has a solubility of 3.5 mg/ml in water and a molecular weight of 666.7.

Physical Description

Each Viagra tablet is film coated and blue in colour. It is shaped like a rounded diamond. On one side is marked “Pfizer,” while on the other side is marked “VGR 25”, “VGR 50” and “VGR 100”.


Viagra belongs to a class of medications called phosphodiesterase type 5 inhibitors. It works by helping relax the blood vessels in the male sexual organ, allowing the blood to flow more freely. Viagra does not cause an erection; it only aids a person who is already sexually stimulated to have an erection. Viagra is a prescription medication and should not be taken by men who do not suffer from erectile dysfunction. Viagra is meant for treating impotence in men only. It is not an aphrodisiac.

Viagra needs to be taken 30 minutes before commencing any sexual activity, and goes on to work for around four hours in the body. Viagra should only be taken once a day, unless prescribed by your doctor.

Before you take Viagra

It is important to consult your doctor before you take Viagra, as it is a prescription medication. Do not take this drug if you;

  • Are taking any medication containing nitrates or nitric oxides such as amyl nitrate, as Viagra can cause a serious increase in the effects of these medications.
  • Are allergic to Viagra or any of its other active ingredients.
  • Have a severe heart or liver problem.
  • Have recently had a heart attack or stroke or if you have low blood pressure.
  • Have a rare eye disease known as retinitis pigmentosa.
  • Have sickle cell anaemia or Leukaemia.
  • Have multiple myeloma (bone marrow cancer).
  • Currently have a stomach ulcer or a bleeding disorder.

Safety Information

Although Viagra has successfully treated erectile dysfunction in many men, it is not meant for everyone. Do not use Viagra with nitrate drugs, as your blood pressure can drop to unsafe and/or life-threatening levels.

Also, speak to your doctor and make sure your heart is healthy for any sexual activity. If you experience chest pain, nausea or any discomfort during sex or have an erection longer than 4 hours contact your doctor immediately.

Do not take Viagra with any other medication for erectile dysfunction. Special precautions need to be taken for men over the age of 65. Viagra is not meant for women or children under the age of 18.

Side effects of Viagra

Viagra is usually well tolerated in most men, however mild side effects do occur. They include:

  • Headaches
  • Facial flushing
  • Dizziness
  • Indigestion

Less common side effects include; muscle aches and changes in vision, with blurriness or a bluish tinge. If you have an erection that lasts longer than 4 hours contact your doctor immediately.

The only way to determine if Viagra is the right medication for you is to speak to your doctor. It is important that you visit your doctor and let him decide if you can take Viagra. Also, make sure that you give your doctor your entire medical history and all the prescription and non-prescription medications you are taking.

Taking Viagra

Take Viagra only as prescribed by the doctor. Never take more Viagra then prescribed. Viagra should be taken only once a day, and half an hour before commencing any sexual activity. Viagra can be taken with or without food, and should be swallowed whole with a glass of water.

Do not take Viagra with alcohol, as alcohol can impair the ability to have an erection.


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