|
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.
|
