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Viracept (Nelfinavir)
Articles on Viracept
Full US Prescribing Information

Patient Information
What is Viracept?
What is known about Viracept?
What about drug interactions?
What about side effects?
Safety Information

Articles on Viracept

ViiV Patient Savings Card Now Covers All Former GlaxoSmithKline and Pfizer HIV Drugs

FDA and Pfizer Set Specifications Allowing Nelfinavir (Viracept) To Again Be Prescribed for Children and Pregnant Women

What is Viracept?

Viracept is an anti-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 Agouron Pharmaceuticals, a division of Pfizer Inc. The U.S. Food and Drug Administration (FDA) approved it for the treatment of HIV infection in 1997.

What is known about Viracept?

Viracept can be taken either three times a day or twice a day:

The three-times-daily Viracept dosing schedule involves taking three 250mg tablets every eight hours.

The twice-daily Viracept dosing schedule involves taking two 625mg tablets every 12 hours. An alternative option is to take five 250mg tablets every 12 hours. The twice-daily dosing schedule, using the 625mg tablets, is preferred by many healthcare providers, as it involves taking the fewest number of pills the fewest number of times a day.

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). However, a warning regarding Viracept use in children was issued by the manufacturer in September 2007. Low levels of a manufacturing impurity, ethyl methanesulfonate (EMS), has been found in U.S. batches of Viracept. Due to its cancer-causing potential in animals, Pfizer is recommending that children beginning a new regimen not take Viracept until further notice. Children who are stable on a Viracept containing regimen, however, may continue to take it.

HIV-positive pregnant women are also being urged not to take Viracept, due to the discovery of EMS in the drug. Pregnant women currently taking a regimen that contains Viracept should speak with their doctors immediately about switching it for a comparable drug. Pregnant women starting a new regimen should not take Viracept.

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 anti-HIV drug therapy for the first time, Viracept is listed as a "possible" protease inhibitor option by the United States Department of Health and Human Services in its treatment guidelines. This means that it can be used, but because of lingering concerns about effectiveness and/or safety, it is considered to be inferior to "preferred" or "alternative" protease inhibitor options (e.g., Norvir-boosted Reyataz, Norvir-boosted Lexiva, or Kaletra).

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 anti-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 anti-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)
Antibiotics: Priftin (rifapentine) and Rifadin (rifampin)
Antimigraine medications: Ergostat, Cafergot, Ercaf, Wigraine (ergotamine) or D.H.E. 45 (dihydroergotamine)
Antihistamines: Hismanal (astemizole) or Seldane (terfenadine)
Cholesterol-lowering drugs (statins): Zocor (simvastatin ) and Mevacor (lovastatin)
Antipsychotics: Orap (pimozide)
Sedatives: Versed (midazolam) and Halcion (triazolam)

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.

Anti-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.

Anti-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 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.

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), although Viracept can increase Lipitor levels in the bloodstream. If Lipitor is prescribed, it's best to begin treatment with the lowest possible dose of the drug and then increase the dose if necessary. Little is known about the newest statin, Crestor (rosuvastatin), although it is not expected to have any serious drug interactions with Viracept or the other protease inhibitors.

Viagra (sildenafil), Levitra (vardenafil) and Cialis (tadalafil) levels in the bloodstream likely increase when combined with Viracept. In turn, it is best to use a lower dose of these drugs in order to reduce the risk of side effects.

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.

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.

Anti-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 anti-HIV drug therapy are reviewed in our lessons on Lipodystrophy, Facial Lipoatrophy, and Risks To Your Heart (Hyperlipidemia).

Viracept - Safety Information

VIRACEPT in combination with other antiretroviral agents is indicated for the treatment of HIV infection.

Nelfinavir is principally metabolized by the liver; it can be used in patients with mild hepatic impairment without any dose adjustment. VIRACEPT should not be use in patients with either moderate or severe hepatic impairment.

Exercise caution when administering VIRACEPT with drugs that induce CYP3A, and with potentially toxic drugs that are metabolized by CYP3A, including those that prolong the QT interval.

In clinical studies (n>5000), the most common adverse event, diarrhea, was moderate to severe in 14% to 20% of patients.

Immune reconstitution syndrome has been reported in patients treated with combination antiretroviral therapy, including VIRACEPT.

Redistribution/accumulation of body fat has been reported in patients receiving antiretroviral therapy. A causal relationship has not been established, and long-term consequences are not known at this time.

New onset diabetes mellitus, exacerbation of pre-existing diabetes mellitus, and hyperglycemia have been reported with protease inhibitors.

There are no adequate and well-controlled studies in pregnant women taking VIRACEPT. VIRACEPT should be used in pregnancy only if clearly needed.

VIRACEPT use is contraindicated with amiodarone, quinidine, triazolam, midazolam, ergot derivatives, and pimozide. VIRACEPT should not be coadministered with St. John's wort, simvastatin, lovastatin, rifampin, and omeprazole. Rifabutin dose should be reduced by 50%. PDE5 inhibitors should be prescribed with caution.

Increased bleeding in patients with hemophilia type A or B has been reported with protease inhibitors.