BUY NOW For Sale 70%!
buy viagra

Viagra grapefruit warning

By Sean R. Hosein

The original formulation of the protease inhibitor saquinavir -- Invirase -- became available in North America around the mid-1990s. However, Invirase was poorly absorbed. The manufacturer suggested that taking Invirase with concentrated grapefruit juice would enhance the absorption of this drug. This effect occurs because grapefruit juice contains compounds that impair the activity of certain enzymes in the intestine -- enzymes that help break down Invirase.

A few years later, doctors began to use another protease inhibitor, ritonavir (Norvir), in combination with Invirase. Ritonavir is much more effective than grapefruit juice at inhibiting enzymes in the intestine and liver. Examples of other drugs affected by grapefruit juice include the following:

  • beta blockers -- Cardizem (diltiazem)
  • sedatives/sleeping pills -- Halcion (triazolam), Versed (midazolam)
  • transplant drug -- cyclosporine (Neoral, Sandimune)

Now it appears that grapefruit juice can also affect the absorption of the popular erectile dysfunction drug Viagra (Sildenafil). Because erectile dysfunction is common in some males with HIV/AIDS, we report on the interaction between grapefruit juice and Viagra.

Study Details

Advertisement

Researchers in Köln, Germany, conducted a study using 24 healthy, HIV negative male subjects whose average age was 29 years. The men received a glass of grapefruit juice on an empty stomach and then one hour later another glass of grapefruit juice with Viagra 50 mg. Blood samples were collected over the next 24 hours. A week later the experiment was repeated with water being substituted for grapefruit juice.

Results

Researchers found that the absorption of Viagra increased by 23% when taken with grapefruit juice instead of water. Grapefruit juice also delayed the absorption of Viagra. This latter point is important because Viagra is supposed to be taken one hour before sex, and taking the drug with grapefruit juice may result in disappointment for some users of Viagra.

The grapefruit juice used in this study was white juice and supplied by Döhler-Euro Citrus NBI, GmbH. Other brands, types and doses of grapefruit juice may have different effects. The researchers suggest that the combination of Viagra and grapefruit juice be "avoided."

Men who use protease inhibitors are usually prescribed less-than-normal doses of Viagra because protease inhibitors can raise levels of Viagra several times greater than normal, which can cause dangerous side effects. Therefore, men who use protease inhibitors and Viagra may wish to also avoid taking Viagra with grapefruit juice.

References

  1. Jetter A., Kinzig-Schippers M., Walchner-Bonjean M., et al. Effects of grapefruit juice on the pharmacokinetics of sildenafil. Clinical Pharmacology and Therapeutics 2002; 71:21-29.
  2. Hyland R., Roe E. G., Jones B. C. and Smith D. A. Identification of the cytochrome P450 enzymes involved in the N-demethylation of sildenafil. British Journal of Clinical viagra grapefruit warning Pharmacology 2001; 51(3):239-248.
  3. Muirhead G. J., Wulff M. B., Fielding A., et al. Pharmacokinetic interactions between sildenafil and saquinavir/ritonavir. British Journal of Clinical Pharmacology 2000; 50(2):99-107.

Source: http://www.thebody.com/content/art30246.html


.
Viagra and Grapefruit Juice? - Penis Enlargement at Thunder s Place L-arginin nebenwirkungen viagra

Viagra grapefruit warning GRAPEFRUIT : Uses, Side Effects, Interactions and Warnings - WebMD
Viagra grapefruit warning Viagra and Grapefruit Combination Possible Dangerous Side Effects
Viagra grapefruit warning Grapefruit and medication: A cautionary note - Harvard Health
Viagra grapefruit warning Viagra and Grapefruit Juice - Not a Good Mix - m
Viagra grapefruit warning Grapefruit viagra warning - Onyx Investments
Viagra grapefruit warning Viagra and Grapefruit (Sildenafil) - m
Viagra grapefruit warning 88 Keys ft Kanye West - Stay Up - Instrumental - Digital DJ Pool
Viagra grapefruit warning All Products Available at m
Viagra grapefruit warning Are Tesco and Boots the cheapest places to buy Viagra? - Doctor Fox
Buy Cheap Generic Online ViagraBuy Cheap Sildenafil Cialis One Day Effetti Collaterali #1 - Online Support Erectile dysfunction - WebMD Free Viagra Samples - Price Comparison - Institut za varilstvo Meadowview Cabin - Viagra E Cetoconazol Order viagra 100 mg 50 mg 25 mg - Atlantic Drugs Recipes Whole Foods Market Tadalafil (Cialis marchio registrato) informazioni .