by Liz Highleyman
January 2004 (Reviewed and Revised December 2005)
Viracept – brand name
nelfinavir – generic name
Viracept belongs to a class of HIV drugs called protease inhibitors (PIs).
The PIs block protease, a protein that HIV needs to make more copies of itself. This may slow down HIV disease.
The Food and Drug Administration (FDA) has approved Viracept for use in combination with other HIV drugs for the treatment of HIV infection in adults and children over two years old.
Viracept comes in:
- 250 milligram (mg) and 625 mg tablets
The standard adult dose of Viracept can be taken as either:
- Five 250 mg tablets or two 625 mg tablets twice a day (every 12 hours)
- Three 250 mg tablets three times daily (every eight hours)
Viracept should be taken with a meal.
Check with your child’s doctor for children’s dosing.
Viracept must be used with other HIV medications to treat HIV.
Tell your doctor if you have liver or kidney problems.
As with all HIV drugs, it is important to take Viracept as prescribed. Missing or skipping doses can cause your blood levels of the drug to fall too low and resistance can develop. When your virus becomes resistant to an HIV medication, that drug may stop working.
Viracept may be used for people being treated for the first time.
Viracept may be used for people who are switching from other drugs that no longer work, but Viracept may not work as well if HIV is resistant to certain other PIs.
Your doctor can run a resistance test to help determine whether Viracept is likely to work for you.
If your virus develops resistance to Viracept then it may stop working or not work as well for you. However, other PIs may still work.
Sometimes taking more than one medication can cause drug interactions. Taking certain drugs (including methadone, some antifungals, TB drugs, other HIV drugs, drugs to treat erectile dysfunction such as Viagra, and cholesterol-lowering drugs) with Viracept can change the amount of each drug in your blood. Your doctor may need to adjust the doses of your drugs to avoid under- or overdosing.
Viracept decrease the effectiveness of birth control pills, so alternative birth control methods should be used.
Certain medications (including some antihistamines, sedatives, antibiotics, acid reflux/heartburn drugs, headache drugs, and antipsychotic drugs) should not be taken with Viracept. You should not take St. John’s wort with Viracept either.
Be sure your doctor knows about all the medications you are taking (including over-the-counter, prescription, street drugs, and herbs), even if you only use them occasionally.
For more information and additional resources to check interactions between the particular drugs you are taking, see our info sheet on drug interactions.
It is not uncommon to experience Viracept side effects, especially diarrhea. However, they are likely to be temporary and go away as your body adjusts to the medication. If you experience any of the side effects listed below, call your doctor for advice. Do not just stop taking your medication.
- Diarrhea (usually mild to moderate)
- Abdominal pain
- Intestinal gas (flatulence)
- Skin rash
More serious side effects:
- Liver toxicity: this may be indicated by elevated liver enzymes or yellowing of the skin and eyes (jaundice)
- Lipodystrophy, which may include elevated blood sugar (glucose), elevated lipid levels ( cholesterol and triglycerides), and fat gain or loss in certain areas. The exact causes of lipodystrophy are not known, but may include HIV and/or HIV drugs. It is unclear if Viracept will cause or impact symptoms of lipodystrophy. For more information on lipodystrophy, see our info sheet.
If you are experiencing persistent, unusual, or serious side effects, call your doctor right away.
Viracept has been studied in many women. Although some doctors now shy away from protease inhibitors that are not “boosted” by Norvir (ritonavir), unboosted Viracept remains a popular regimen for women, including pregnant women.
Studies of Viracept pharmacokinetics (how the drug is processed by the body) show that the drug behaves similarly in the bodies of women and men. But some research indicates that Viracept blood levels may be lower in pregnant women (about 40 percent lower than in non-pregnant women in one study).
Study 511 compared Viracept plus Retrovir (zidovudine or AZT) plus Epivir (lamivudine or 3TC) to Retrovir plus Epivir in 297 participants who had not taken HIV drugs. Eleven percent (or about 32) of participants in this trial were women. In this trial, people who took Viracept were more likely to achieve undetectable viral loads and increased CD4 cell counts.
The AVANTI-3 trial compared the same drug regimens, and found that people taking Viracept were four times more likely to have an undetectable viral load (but also twice as likely to have diarrhea). This study also included 11 percent women, or about 11 women out of 105 total participants.
Study 542 compared twice-daily versus three-times-daily Viracept along with Zerit (stavudine or d4T) and Epivir, and found that the two dosing schedules were about equally effective. This study included 16 percent women, or about 82 women out of 515 total participants. But another dosing study of 32 women found that twice-daily Viracept seemed to work better than three-times-daily.
In another study, researchers compared the effects of Viracept-containing regimens on 162 women and 324 men who had not been on HIV treatment before. They found that the women were more likely to achieve an undetectable viral load, and that the drugs worked longer in women before treatment failure occurred.
Other studies have compared different three-drug regimens, which is how we usually use Viracept today. The Ecureuil 2 study compared Retrovir plus Epivir plus Viracept to Retrovir plus Epivir plus Ziagen (abacavir) in 195 participants who had not taken HIV drugs before, including 25 percent (or about 48) women. People taking Viracept and those taking Ziagen had similar response rates, but more people taking Viracept changed their drug regimens due to side effects.
Another study found that Viracept worked about as well as Crixivan (indinavir), but in this comparison more people taking Crixivan switched drugs due to side effects.
Study 863 compared Zerit plus Epivir plus Viracept to Zerit plus Epivir plus Kaletra (lopinavir/ritonavir) in people who had not taken protease inhibitors before. This study included 20 percent women, or about 130 women out of 653 total participants. In this trial, Kaletra worked better than Viracept, especially in people with high viral loads.
The NEAT study compared Viracept to Lexiva (fosamprenavir) in 249 participants who had not taken HIV drugs before, including 31 percent (or about 77) women. In this study, Viracept and Lexiva worked similarly overall, but Lexiva worked better among participants with a high viral load.
In terms of side effects, an analysis of data from different trials (including a total of 78 women and 616 men) found that women taking Viracept were less likely than men to experience diarrhea, but were more likely to have:
- Abdominal pain – about 7 percent in women versus about 2 percent in men
- Itching – 3 percent in women versus practically none in men
- Skin rash – 5 percent in women versus 2 percent in men
Some studies suggest that the metabolic side effects (lipodystrophy) associated with PIs may be somewhat different in women and men. However, it is still unclear if women are more likely to gain or lose body fat in certain areas than men.
One lipodystrophy study (ESS40002) found that a regimen containing Viracept was more likely to cause increased blood fat levels than regimens that did not contain a PI, and that men were more likely than women to develop abnormal blood fats. This small study was unusual in that it included 50 percent women, 40 percent African Americans, and 37 percent Latinos.
Studies have shown that pregnant women who use HIV drugs can greatly reduce the risk of passing HIV on to their babies. Viracept has been used during pregnancy without any significant negative effects on mothers or babies; however, long- term effects on children are not known.
Check with your doctor about the best treatment options for you and your baby if you are thinking of getting pregnant.
Click this link for more information about pregnancy.
People who are starting HIV treatment for the first time may develop Immune Reconstitution Syndrome or IRS (also called Immune Reconstitution Inflammatory Syndrome or IRIS). IRS can happen as a result of the immune system getting stronger and responding to an HIV-related infection such as Mycobacterium avium infection (MAC), cytomegalovirus (CMV), Pneumocystis jirovecii pneumonia (PCP), or tuberculosis (TB). People may have been treated for these infections in the past or not even know they have them. If you notice any unusual symptoms soon after starting HIV drugs for the first time, let your doctor know right away so you can be evaluated and, if necessary, treated.
Albrecht, M., et. al. (2001). Nelfinavir, efavirenz, or both after the failure of nucleoside treatment of HIV infection. New England Journal of Medicine, 345(6). 398-407.
Keiser, P., et. al. (2003). The effect of gender and weight on treatment outcome in nelfinavir-treated patients: a case-control study. 10th Conference on Retroviruses and Opportunistic Infections. Boston, MA. Abstract 927.
Markowitz, M., et. al. (1998). A preliminary evaluation of nelfinavir mesylate, an inhibitor of human immunodeficiency virus (HIV)-1 protease, to treat HIV infection. Journal of Infectious Diseases, 177(6). 1533-1540.
Rodriguez-French A., et al. (2004). The NEAT study: A 48-week open-label study to compare the antiviral efficacy and safety of GW433908 versus nelfinavir in antiretroviral therapy-naive HIV-1-infected patients. J Acquir Immune Defic Syndr, 35. 22-32.
Squires, K.E., et. al. (1999). Efficacy and safety of BID and TID regimens of nelfinavir (NFV) + saquinavir (SQV) + stavudine (d4T) + lamivudine (3TC) in HIV-infected women: 48 week results of the Women First study. 39th Interscience Conference on Antimicrobial Agents and Chemotherapy. San Francisco, CA. Abstract 1988