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Drugs reference index «Nelfinavir mesylate»

Nelfinavir mesylate

Nelfinavir mesylate

Brand names: Viracept

Why is Nelfinavir mesylate prescribed?

Viracept is one of the drugs prescribed to fight HIV, the human immunodeficiency virus that causes AIDS (acquired immune deficiency syndrome). Once inside the body, HIV spreads through certain key cells in the immune system, weakening the body's ability to fight off other infections. Viracept works by interfering with an important step in the virus's reproductive cycle. This slows the spread of the virus and prolongs the strength of the immune system.

Viracept belongs to the new class of drugs that has successfully reversed the course of HIV infection in many people. Called protease inhibitors, these drugs work better when used in combination with other HIV medications called nucleoside analogues (Retrovir, Hivid, and others) which act against the virus in other ways.

Most important fact about Nelfinavir mesylate

Although Viracept can keep HIV at bay, it is not a complete cure. If you stop taking the drug, the infection will re-emerge and progress to AIDS, leaving you vulnerable to a host of opportunistic infections (rare infections that develop only when the immune system falters, such as certain types of pneumonia, tuberculosis, and fungal infections). It's imperative, therefore, that you continue to see your doctor regularly and keep all your follow-up appointments.

How should you take Nelfinavir mesylate?

Take Viracept every day, exactly as prescribed. Do not stop taking it or change the dose without first consulting your doctor.

To achieve higher blood levels of the drug, always take Viracept with a meal or light snack.

If your child is taking Viracept oral powder, mix it with a small amount of water, milk, formula, soy formula, soy milk, or a liquid nutritional product such as Ensure, Sustacal, or Advera, then use within 6 hours. Make sure the child drinks the entire dose. Do not mix the powder with apple juice, applesauce, or orange juice; these combinations will taste bitter.

  • If you miss a dose...Take it as soon as possible. If it is almost time for the next dose, skip the one you missed and go back to your regular schedule. Never double the dose.
  • Storage instructions...Both tablets and powder may be stored at room temperature. Doses of the powder mixed with liquid may be kept for up to 6 hours under refrigeration. Keep container tightly closed.

What side effects may occur?

Side effects cannot be anticipated. If any develop or change in intensity, tell your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue taking Viracept.

The most frequent side effect associated with Viracept is diarrhea. If it develops, it can be controlled with over-the-counter medications such as Imodium A-D.

  • Side effects may include:Abdominal pain, gas, loss of strength, nausea, skin rash

Why should Nelfinavir mesylate not be prescribed?

If you have ever had an allergic reaction to Viracept or any of its ingredients, do not take Nelfinavir mesylate.

Special warnings about Nelfinavir mesylate

Although Viracept reduces the amount of HIV in the blood, its long-term effect on survival is still unknown. We do know, however, that the drug does NOT reduce the risk of passing HIV to others through sexual contact or blood contamination. You will need to continue avoiding practices that spread the virus.

If you have been using oral contraceptives, you'll need to take other measures. Viracept dramatically reduces the effectiveness of the Pill.

Viracept may trigger diabetes or make existing diabetes worse. If this occurs, you may have to start taking insulin or oral diabetes medication, or have your present dosage adjusted.

People with hemophilia type A and B may experience increased bleeding. If this happens, alert your doctor immediately. Make sure, too, that your doctor is aware of any liver problems you may have.

Viracept oral powder contains phenylalanine. If your child has the hereditary disease known as phenylketonuria, do not give the powder form.

Possible food and drug interactions when taking Nelfinavir mesylate

Do not take Viracept with any of the following medications. The combination could cause serious or even life-threatening problems.

Amiodarone (Cordarone)Ergot derivatives such as Cafergot, D.H.E., Methergine, and MigranalLovastatin (Mevacor)Midazolam (Versed)Pimozide (Orap)Quinidine (Quinaglute, Quinidex)Rifampin (Rifadin, Rimactane)Simvastatin (Zocor)St. John's wortTriazolam (Halcion)

Viracept may also interact with certain other drugs, and the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining Viracept with the following:

Atorvastatin (Lipitor)Azithromycin (Zithromax)Carbamazepine (Tegretol)Cyclosporine (Neoral, Sandimmune)Delavirdine (Rescriptor)Indinavir (Crixivan)MethadoneNevirapine (Viramune)Oral contraceptivesPhenobarbitalPhenytoin (Dilantin)Rifabutin (Mycobutin)Ritonavir (Norvir)Saquinavir (Invirase)Sildenafil (Viagra)Sirolimus (Rapamune)Tacrolimus (Prograf)

If you're also taking the HIV drug didanosine (Videx), be aware that it should be taken on an empty stomach. Since Viracept should be taken with food, you should take your didanosine dose 1 hour before or 2 hours after your Viracept dose.

Special information if you are pregnant or breastfeeding

The effects of Viracept during pregnancy have not been adequately studied. If you are pregnant or plan to become pregnant, tell your doctor immediately.

Do not breastfeed your baby. HIV appears in breast milk and can infect a nursing infant.

Recommended dosage for Nelfinavir mesylate


The recommended dose is 1,250 milligrams (five 250-milligram or two 625-milligram tablets) twice a day or 750 milligrams (three 250-milligram tablets) 3 times a day. Take with a meal or snack.


Viracept oral powder is available for children who are unable to take tablets. The recommended dose for children 2 to 13 years of age is 20 to 30 milligrams per 2.2 pounds of body weight, 3 times a day with a meal or snack. The oral powder can be measured out with the provided scooper or a teaspoon—your doctor will tell you how much—and mixed with a small amount of water or any other fluid listed under "How should you take Nelfinavir mesylate?".

The safety and effectiveness of Viracept in children below age 2 have not been established.


Information on acute overdose with Viracept is limited. However, any medication taken in excess can have serious consequences. If you suspect an overdose, seek emergency medical treatment immediately.

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