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.
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