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AIDS virusViracept belongs to a class of anti-HIV drugs called Protease Inhibitors (PIs). For a description of the life-cycle of the AIDS virus, and the targets of each class of drugs, click here.

Viracept is marketed by ViiV Healthcare. They have a useful web site that includes full prescribing info on this drug: click here.

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Viracept (nelfinavir)

Pronunciation(s): VI-ruh-sept; nell-FIH-nuh-veer

What is Viracept?
  • Viracept is an HIV medication. It is in a category of HIV medications called protease inhibitors (PIs). Viracept prevents T-cells that have been infected with HIV from producing new HIV.
  • Viracept is manufactured by ViiV Healthcare. The U.S. Food and Drug Administration (FDA) approved it for the treatment of HIV infection in 1997.
  • A patient assistance program (PAP) has been established for people living with HIV who do not have private or public health insurance and are unable to afford Viracept. To learn more about the PAP for Viracept, call 877-784-4842 or refer to the program's website for more information. For those with private health insurance, a program has been established to help cover each Viracept co-payment, up to $100 every month. To learn more about this co-pay program, check out

What is known about Viracept?
  • Viracept can be taken either twice a day or three times a day:
    • The twice-daily Viracept dosing schedule involves taking two 625mg tablets every 12 hours.
    • The three-times-daily Viracept dosing schedule involves taking three 250mg tablets every eight hours.  
  • Viracept should be taken with food, preferably a full nutritious meal (e.g., breakfast and dinner). Taking Viracept with food increases the amount of drug in the bloodstream, which could make Viracept more effective against the virus.
  • Viracept is approved for HIV-positive children two years of age and older (the dose depends on body weight and must be taken with food). To learn about treatment options for children, click here.
  • Clinical trials have determined that Viracept is safe and effective when combined with other drugs, most notably two nucleoside reverse transcriptase inhibitors (NRTIs).
  • For HIV-positive adults beginning HIV drug therapy for the first time, Viracept is not listed as either a "preferred" or "alternative" protease inhibitor option by the United States Department of Health and Human Services in its treatment guidelines. While this does not mean that Viracept should not be used, the DHHS emphasizes the effectiveness and safety of the preferred options listed: Norvir-boosted Reyataz or Norvir-boosted Prezista. To learn more about these recommendations and options, click here.
  • If your viral load becomes detectable while taking a drug regimen that contains Viracept, your doctor can order a drug-resistance test to see which drugs your virus are becoming less sensitive to.
  • Many of the currently available protease inhibitors are affected by cross-resistance. This means that, if you've tried and failed a drug regimen in the past that contained a protease inhibitor, your virus might be resistant to Viracept. Similarly, if you take an HIV drug regimen that contains Viracept and your virus becomes resistant to the drug, your virus might also be resistant to many of the other protease inhibitors available. This is why it is very important to use drug-resistance testing to determine which drugs your virus are no longer responding to if you experience a rebound in your viral load while taking an HIV drug regimen. Drug-resistance testing can also help you figure out which protease inhibitors your virus is still sensitive to.

What about drug interactions?
  • Viracept is broken down (metabolized) by the liver, like many medications used to treat HIV and AIDS. This means that Viracept can interact with other medications. Viracept can lower or raise the levels of other medications in the body. Similarly, other medications can lower or raise the levels of Viracept in the body. While many interactions are not a problem, some can cause your medications to be less effective or increase the risk of side effects.
  • Tell your doctors and pharmacists about all medicines you take. This includes those you buy over-the-counter and herbal or natural remedies, such as St. John’s Wort. Bring all your medicines when you see a doctor, or make a list of their names, how much you take, and how often you take them. Your doctor can then tell you if you need to change the dosages of any of your medications.
  • The following medications should not be taken while you are being treated with Viracept:
    Acid reflux/heartburn medications: Propulsid (cisapride), Prilosec (omeprazole), Prevacid (lansoprazole), Aciphex (rabeprazole), Protonix (pantoprazole) and Nexium (esomeprazole)
    Antibiotics: Rifadin (rifampin)
    Antimigraine medications: Ergostat, Cafergot, Ercaf, Wigraine (ergotamine) or D.H.E. 45 (dihydroergotamine)
    Cholesterol-lowering drugs (statins): Zocor (simvastatin ) and Mevacor (lovastatin)
    Heart medications: Cordarone (amiodarone) and Quinaglute/Quinidex (quinidine)
    Enlarged prostate: Uroxatral (Alfuzosin)
    Pulmonary arterial hypertension:
    Revatio (sildenafil)
    Orap (pimozide)
    Sedatives: Versed (midazolam) and Halcion (triazolam)
    Herbal products: St. John's wort
  • Anticonvulsants, such as Tegretol (carbamazepine), phenobarbital, and Dilantin (phenytoin), may decrease the amount of Viracept in the bloodstream. It might be necessary to increase your dose of Viracept if you are taking any of these drugs.
  • HIV protease inhibitors can interact with Viracept. We know that Norvir (ritonavir) increases the amount of Viracept in the bloodstream (the recommended dose is two or three 250mg Viracept tablets combined with four 100mg Norvir capsules). Kaletra (lopinavir/ritonavir) can also increase Viracept levels, but Viracept decreases blood levels of the lopinavir in Kaletra (no dose has been recommended). Viracept increases Agenerase (amprenavir) and Lexiva (fosamprenavir) levels in the bloodstream (no dose has been recommended). When Viracept is combined with Invirase (saquinavir), blood levels of both drugs are increased (the dose of Invirase should be 1200mg twice daily and the dose of Viracept should be 1250mg twice daily, with no Norvir added). Viracept also increases Crixivan (indinavir) levels, but no dose has been confirmed.
  • HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs) can also interact with Viracept. Sustiva (efavirenz), Viramune (nevirapine), and Rescriptor (delavirdine) can all increase Viracept levels in the bloodstream, although it's probably not necessary to change the doses.
  • Viracept can interact with some medications used to treat TB, MAC and other bacterial infections. Rifadin (rifampin) can decrease Viracept levels in the bloodstream; these two drugs should not be used together. Viracept can increase Mycobutin (rifabutin) levels and Mycobutin can decrease Viracept levels (the Mycobutin dose should be reduced to 150mg every day and the Viracept dose should be increased to four 250mg tablets three times a day). It is not known if Viracept effects Biaxin (clarithromycin) levels in the bloodstream.
  • Viracept can increase the blood levels of the antibiotic Zithromax (azithromycin). No dose adjustment is necessary, but using the two in combination could potentially increase the risk of Zithromax side effects.
  • Viracept decreases the amount of oral contraceptives (taken by women to help avoid pregnancy) in the bloodstream. This means that there may be a higher risk of becoming pregnant if Viracept and oral contraceptives are taken at the same time. To reduce the risk of pregnancy, barrier protection (e.g., condoms) should be used.
  • Methadone, commonly used to treat drug addiction, can interact with Viracept. Methadone levels in the bloodstream can decrease when combined with Viracept. Because of this, it might be necessary to increase the dose of methadone.
  • Desyrel (trazodone) is used to treat depression. Viracept can increase blood levels of this drug, leading to an increase risk of Desyrel side effects. Using a lower dose of Desyrel may be necessary.
  • Cholesterol-lowering drugs, also known as "statins," can interact with Viracept. There are two statins that should not be used with Viracept: Zocor (simvastatin) and Mevacor (lovastatin). Levels of these two drugs can become significantly increased in the bloodstream if they are combined with Viracept, which increases the risk of side effects. The two statins that are considered to be the safest in combination with Viracept are Pravachol (pravastatin) and Lescol (fluvastatin). It is also possible to take Viracept with Lipitor (atorvastatin) or Crestor (rosuvastatin), although Viracept can increase Lipitor and Crestor levels in the bloodstream. If Lipitor or Crestor is prescribed, it's best to begin treatment with the lowest possible dose of the drug and then increase the dose if necessary.
  • Viracept can increase blood levels of Advair, Flovent, or Flonase (fluticasone), the inhalable medications that are used to treat allergies and asthma. In turn, these drugs may decrease blood levels of Viracept. Alternatives to these drugs should be considered, especially for long-term use. Viracept can also increase blood levels of an asthma medication called Serevent (salmeterol), a drug that is used to open the air passages in the lungs during an asthma attack. This can result in heart rhythm problems. Use of the two drugs together is not recommended.
  • There is a class of drugs, known as PDE-5 inhibitors that are used to treat both erectile dysfunction and pulmonary arterial hypertension. Their brand names differ, depending on their use. Viracept can significantly increase blood levels of these drugs.

    When used to treat erectile dysfunction, it is best to use a lower dose of Viagra (sildenafil), Levitra (vardenafil) and Cialis (tadalafil) in order to reduce the risk of side effects. When used to treat pulmonary arterial hypertension, the dose of tadalafil (Adcirca) must be reduced if combined with Viracept. Revatio (sildenafil) and Viracept should not be used together.

  • Tracleer (bosenstan) is another type of drug used to treat pulmonary arterial hypertension, called an endothelin receptor antagonist. Viracept can increase Tracleer blood levels, so the dose of Tracleer should be reduced.

  • Prezista can increase blood levels of cochicine, which is used to treat gout. Lower doses of colchicine are recommended, and the two drugs should not be used together in people with liver or kidney impairment. 

  • Herbal products can also interact with Viracept. St. John's wort should not be used with Viracept, since it can greatly reduce the amount of Viracept in the bloodstream. HIV-positive people should also be cautious about using garlic supplements or milk thistle with Viracept—test tube studies suggest that both herbal products can interact with the same liver enzyme system (cytochrome P450 3A4) responsible for metabolizing Viracept. This may alter the amount of Viracept in the bloodstream. These and other herbal products should be used with caution, until further studies are conducted.
  • A number of other negative drug interactions are possible if Viracept is combined with Norvir. To learn more about these drug interactions, click here.

What about side effects?
  • Diarrhea is the most common side effect of Viracept. To learn some tips and tricks that can help reduce the severity of diarrhea, click here.
  • Other short-term side effects include appetite loss, headaches, feeling crummy (malaise), nausea, and vomiting. Very often, these side effects improve within a few months/weeks of starting Viracept.
  • HIV drug regimens containing protease inhibitors, including Viracept, can cause increased fat levels (cholesterol and triglycerides) in the blood, abnormal body-shape changes (lipodystrophy; including increased fat around the abdomen, breasts, and back of the neck, as well as decreased fat in the face, arms, and legs), and diabetes. These side effects of HIV drug therapy are reviewed in our lessons on Lipodystrophy, Facial Lipoatrophy, and Risks To Your Heart (Hyperlipidemia).

Can pregnant women take Viracept?

  • Viracept is classified by the FDA as a pregnancy category B drug. Pregnancy category B means that animal studies have failed to demonstrate a risk to the fetus, but there are no adequate and well-controlled studies in pregnant women. To learn more about treatment options during pregnancy, click here.
  • It is not known whether Viracept passes into breast milk and what effects it may have on a nursing baby. However, to prevent HIV transmission of the virus to uninfected babies, it is recommended that HIV-positive mothers not breast-feed.

Who should not take Viracept?

  • Before taking this medication, tell your doctor if you have kidney disease or liver disease. You may not be able to take Viracept, or you may require a dosage adjustment or special monitoring during treatment if you have any of these conditions.

Where can I learn more about clinical trials that are using Viracept?
  • If you would like to find out if you are eligible for any clinical trials that include Viracept, visit, a site run by the U.S. National Institutes of Health. The site has information about all HIV-related clinical studies in the United States. For more info, you can call their toll-free number at 1-800-HIV-0440 (1-800-448-0440) or email

Last Revised: February 07, 2011

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