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Drugs reference index «nelfinavir»

nelfinavir (Oral route)


Commonly used brand name(s):

In the U.S.

  • Viracept

Available Dosage Forms:

  • Tablet
  • Powder for Suspension

Therapeutic Class: Antiretroviral Agent

Pharmacologic Class: Protease Inhibitor

Uses For nelfinavir

Nelfinavir is used, usually in combination with other medicines, in the treatment of the infection caused by the human immunodeficiency virus (HIV). HIV is the virus that causes acquired immune deficiency syndrome (AIDS).

Nelfinavir will not cure or prevent HIV infection or AIDS; however, it helps keep the HIV virus from reproducing and appears to slow the destruction of the immune system. This may help delay the development of problems related to AIDS or HIV disease. Nelfinavir will not keep you from spreading HIV to other people. People who take nelfinavir may continue to have other problems related to AIDS or HIV disease.

nelfinavir is available only with your doctor's prescription.

Before Using nelfinavir

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For nelfinavir, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to nelfinavir or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of nelfinavir in children. However, safety and efficacy have not been established in children below 2 years of age. .


Appropriate studies on the relationship of age to the effects of nelfinavir have not been performed in the geriatric population. However, no geriatric-specific problems have been documented to date.


Pregnancy CategoryExplanation
All TrimestersBAnimal studies have revealed no evidence of harm to the fetus, however, there are no adequate studies in pregnant women OR animal studies have shown an adverse effect, but adequate studies in pregnant women have failed to demonstrate a risk to the fetus.

Breast Feeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Interactions with Medicines

Using nelfinavir with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

  • Amiodarone
  • Astemizole
  • Cisapride
  • Dihydroergotamine
  • Dronedarone
  • Eplerenone
  • Ergoloid Mesylates
  • Ergonovine
  • Ergotamine
  • Methylergonovine
  • Midazolam
  • Pimozide
  • Quinidine
  • Ranolazine
  • Sildenafil
  • Silodosin
  • Tolvaptan
  • Triazolam

Using nelfinavir with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Aprepitant
  • Carbamazepine
  • Cerivastatin
  • Colchicine
  • Dasatinib
  • Esomeprazole
  • Etravirine
  • Everolimus
  • Fentanyl
  • Fluticasone
  • Garlic
  • Iloperidone
  • Ixabepilone
  • Lansoprazole
  • Lapatinib
  • Lovastatin
  • Nilotinib
  • Omeprazole
  • Pantoprazole
  • Pazopanib
  • Rabeprazole
  • Rifabutin
  • Rifampin
  • Romidepsin
  • Salmeterol
  • Simvastatin
  • St John's Wort
  • Sunitinib
  • Tadalafil
  • Tamsulosin
  • Temsirolimus
  • Terfenadine
  • Tipranavir
  • Venlafaxine

Using nelfinavir with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Amprenavir
  • Atorvastatin
  • Azithromycin
  • Cyclosporine
  • Delavirdine
  • Didanosine
  • Ethinyl Estradiol
  • Etonogestrel
  • Felodipine
  • Lopinavir
  • Mestranol
  • Methadone
  • Norethindrone
  • Norgestrel
  • Phenytoin
  • Pravastatin
  • Rifapentine
  • Saquinavir
  • Tacrolimus
  • Voriconazole
  • Zidovudine

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of nelfinavir. Make sure you tell your doctor if you have any other medical problems, especially:

  • Diabetes or
  • Hyperglycemia (high blood sugar)—May make these conditions worse.
  • Hemophilia (bleeding disorder)—May increase the possibility of bleeding.
  • Liver disease—The effects of the medicine may be increased because of slower removal from the body.
  • Phenylketonuria (PKU) (a metabolic disease)—The oral powder form contains phenylalanine, which may cause a problem for patients with this condition.

Proper Use of nelfinavir

Take nelfinavir exactly as directed by your doctor. Do not take it more often, and do not take it for a longer time than your doctor ordered. Also, do not stop taking nelfinavir without checking with your doctor first. Keep taking nelfinavir for the full time of treatment, even if you begin to feel better.

It is important to take nelfinavir together with other medicines for HIV. Be sure to take all of the medicines your doctor ordered, and to take them at the right times.

Nelfinavir works best if it is taken with food.

If you are also taking didanosine (e.g., Videx®), nelfinavir should be taken at least 2 hours before or 1 hour after you take the didanosine dose.

If you cannot swallow the tablet whole, you may dissolve it in a small amount of water. Be sure to drink or swallow the entire mixture right away. Then refill your glass with water and drink it so that none of the medicine is left on the sides of the glass.

Measure the powder carefully using the measuring scoop provided with the medicine. Mix the powder with a small amount of water, milk, soy milk, baby formula, or a dietary supplement drink. Do not use apple juice, orange juice, or apple sauce. After mixing your medicine with a liquid, use the mixture right away. Be sure to drink or swallow all of the mixture. If not used right away, you may store this mixture in the refrigerator for up to 6 hours.

nelfinavir works best when there is a constant amount in the blood. To help keep the amount constant, do not miss any doses. Also, it is best to take the doses at evenly spaced times during the day. For example, if you are to take three doses each day, the doses should be spaced about 8 hours apart. If you need help in planning the best times to take your medicine, check with your doctor.


The dose of nelfinavir will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of nelfinavir. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For treatment of HIV infection:
    • For oral dosage form (oral powder):
      • Children 2 to 13 years of age—Dose is based on body weight and must be determined by your doctor. The usual dose is 25 to 35 milligrams (mg) per kilogram (kg) of body weight three times a day or 45 to 55 mg per kg two times a day.
      • Children less than 2 years of age—Use and dose must be determined by your doctor.
    • For oral dosage form (tablets):
      • Adults and teenagers—750 milligrams (mg) three times a day or 1250 mg two times a day.
      • Children 2 to 13 years of age—Dose is based on body weight and must be determined by your doctor. The usual dose is 25 to 35 milligrams (mg) per kilogram (kg) of body weight three times a day or 45 to 55 mg per kg two times a day.
      • Children less than 2 years of age—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of nelfinavir, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.


Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Precautions While Using nelfinavir

If you will be taking nelfinavir for a long time, it is very important that your doctor check your progress at regular visits to make sure nelfinavir is working properly and to check for unwanted effects.

You should not breastfeed if you have HIV or AIDS, because you may give the infection to your baby through your breast milk.

nelfinavir may decrease the effects of some oral contraceptives (birth control pills). To avoid an unwanted pregnancy, it is a good idea to use additional contraceptive methods with your birth control pills while you are taking nelfinavir.

You should NOT take nelfinavir if you are taking any of the following medicines:

  • Amiodarone (e.g., Cordarone®) or
  • Ergot medicines (dihydroergotamine [e.g., DHE 45®], ergoloid mesylate [e.g., Hydergine®], ergonovine [e.g., Ergotrate®], ergotamine [e.g., Ergomar®], methylergonovine [e.g., Methergine®], methysergide [e.g., Sansert®]) or
  • Esomeprazole (e.g., Nexium®) or
  • Lansoprazole (e.g., Prevacid®) or
  • Lovastatin (e.g., Altocor®) or
  • Midazolam (e.g., Versed®) or
  • Omeprazole (e.g., Prilosec®) or
  • Pantoprazole (e.g., Protonix®) or
  • Pimozide (e.g., Orap®) or
  • Quinidine (e.g., Quinaglute®) or
  • Rabeprazole (e.g., Aciphex®) or
  • Rifampin (e.g., Rifadin®) or
  • Simvastatin (e.g., Zocor®) or
  • St. John’s Wort (hypericum perforatum) or
  • Triazolam (e.g., Halcion®).

Tell your doctor if you are taking rifabutin (e.g., Mycobutin®). Your doctor may need to reduce the dose of rifabutin if you are taking it together with nelfinavir.

Tell your doctor if you are also taking sildenafil (e.g., Viagra®), tadalafil (e.g., Cialis®), or vardenafil (e.g., Levitra®). Taking these medicines together with nelfinavir may increase your risk of having side effects such as low blood pressure, changes in vision, or prolonged erection of the penis.

Do not take any other medicines without first checking with your doctor. To do so may increase the chance of side effects from nelfinavir.

nelfinavir may cause you to have excess body fat. Tell your doctor if you notice changes in your body shape, such as an increased amount of fat in the upper back and neck, or around the chest and stomach area. You might also lose fat from the legs, arms, and face.

When you start taking HIV medicines, your immune system may get stronger. If you have certain infections, such as pneumonia or tuberculosis, you may notice new symptoms when your body tries to fight them. If this occurs, be sure to tell your doctor.

nelfinavir Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Less common
  • Confusion
  • dehydration
  • dry or itchy skin
  • fatigue
  • fruity mouth odor
  • increased hunger
  • increased thirst
  • increased urination
  • nausea
  • vomiting
  • weight loss
Incidence not known
  • Abdominal or stomach pain
  • chills
  • clay-colored stools
  • cough
  • dark urine
  • difficulty breathing
  • dizziness
  • drowsiness
  • fever
  • headache
  • irregular heartbeat
  • loss of appetite
  • muscle tremors
  • noisy breathing
  • rapid, deep breathing
  • recurrent fainting
  • restlessness
  • shortness of breath
  • skin rash
  • stomach cramps
  • tightness in the chest
  • unpleasant breath odor
  • unusual tiredness or weakness
  • vomiting of blood
  • wheezing
  • yellow eyes or skin

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
  • Diarrhea
Less common
  • Intestinal gas
  • redistribution or accumulation of body fat

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

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  • Nelfinavir MedFacts Consumer Leaflet (Wolters Kluwer)
  • Viracept Prescribing Information (FDA)
  • Viracept Detailed Consumer Information (PDR)
  • Viracept Consumer Overview

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