is an anti-HIV medication. It is in a category
of HIV medications called protease inhibitors
(PIs). Norvir prevents T-cells that have been
infected with HIV from producing new HIV.
is manufactured by Abbott Laboratories. The
U.S. Food and Drug Administration (FDA) approved
it for the treatment of HIV infection in 1996.
Does it Work?
with all the protease inhibitor drugs, its mechanism
of action is by blocking HIV's key protease
enzyme that HIV needs to reproduce. This results
in defective HIV particles that are unable to
infect new cells.
taken regularly as prescribed, Norvir combination
therapy usually leads to a profound decrease
in HIV viral load (RNA) in the blood and substantial
increases in the CD4 (T) cell count.
benefits have led to decreased rates of AIDS
opportunistic infections, improved quality of
life and increased survival.
Are the Side Effects?
The most common side effects of Norvir
therapywhich are usually more severe if
the standard dose (600mg twice-daily) is usedare
related to the gut. Nausea, vomiting, diarrhea,
and appetite loss are common.
Another possible side effect of Norvir is numbness/tingling
around the mouth (oral paresthesias).
Anti-HIV drug regimens containing protease inhibitors,
including Norvir, 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
Both the capsule and liquid formulations contain
alcohol. Those who are taking disulfiram (Antabuse)
therapy as a deterrent to alcohol use should
choose a different protease inhibitor or a disulfiram
reaction could occur. Note that a similar problem
can occur when taking Norvir with the antibiotic
(and anti-parasitic) metronidazole (Flagyl,
Metrogel); therefore, Norvir and metronidazole
should not be taken together.
Norvir capsules should preferentially be stored
in the refrigerator, but it is not essential
as long as the drug is used within 60 days and
is kept at temperatures of approximately 70°
F and is not exposed to extreme cold or heat.
Avoid exposure to light. It is recommended to
store the capsules in the original container
with the cap on tightly in between usage.
The liquid formulation should be stored at room
temperature (68-77° F or 20-25° C) and
not refrigerated. The solution should be shaken
well before pouring. Solution should be used
by the expiration date. Discard any unused Norvir
solution after 30 days. After using the dosing
cup, it should be washed with soap and warm
water as soon as possible. The dosing cup is
not dishwasher safe.
Liver toxicity associated with Norvir occurs
more frequently among those with pre-existing
liver disease, including hepatitis B or C viral
The safety and dosing in infants and toddlers
under age 2 has not been determined.
Tobacco use (smoking or chewing) leads to an
18% decreased blood level of Norvir. However,
a dose increase of Norvir is not specifically
recommended for users of tobacco.
If you miss a dose of Norvir, take that dose
as soon as possible and the next dose at the
scheduled time. However, if a dose is accidentally
skipped altogether, do not double the next dose.
Take that next dose at the regularly scheduled
time. Better yet, try not to miss any doses;
HIV only sleeps when you take your medications
Norvir combination therapy does not completely
eliminate HIV DNA (genes) in semen and vaginal-cervical
fluids. To help prevent HIV transmission to
sex partners, barrier protection (safer sex)
is warranted. This includes using either a male
(external, penis) or female (internal) condom.
Potential benefits of using an internal condom
in the rectum during anal intercourse have not
If Videx is a part of your Norvir combination
therapy, dosing of the 2 should be separated
by at least 2 1/2 hours.
Severe allergic reactions to Norvir can be life
threatening if untreated. Life threatening heart
attack or chest pain due to clogged heart arteries
can result from abnormal increases in blood
fats (cholesterol) due to Norvir. A rare vein
blood clot due to Norvir could break off and
lodge in the lung (pulmonary embolus), which
can be life threatening. Symptoms include shortness-of-breath,
palpitations and chest pain with breathing.
Some persons develop immune system flare illnesses
within a few months after starting potent combination
therapy for HIV infection. These occur due to
inflammation associated with an improved immune
system. The risk of these illnesses decreases
significantly after the first 3-6 months of
The long-term effects (many years to decades)
from Norvir are unknown.
Do not take Norvir as monotherapy (only one
anti-HIV drug) as this will quickly lead to
drug resistance. Always take anti-HIV therapy
as a combination of several anti-retroviral
When Norvir is being used as the primary protease
inhibitor, not as a booster of the other protease
inhibitor in the regimen, the standard dose
of Norvir is six 100 mg capsules (600 mg) every
12 hours, although there are some data that
indicate that four 100 mg capsules (400 mg)
every 12 hours is also effective. When given
as a protease inhibitor booster, the dosing
may range from 100-400mg twice daily or, if
used as a part of a once-daily regimen, 100-200mg
once-daily. While Norvir is rarely used as the
only protease inhibitor, and is generally used
for protease inhibitor boosting, the decision
regarding which dose of Norvir to use should
be made by a clinician with experience in treating
It is recommended that Norvir capsules be taken
with food, since this increases the absorption.
However, it is not mandatory to do so. When
first starting Norvir, a gradual lead-in dosing
over 2 weeks is recommended to help minimize
side effects. The lead-in dosing still allows
for therapeutic drug levels in blood, since
the drug slowly induces its own metabolism.
Start with 300 mg every 12 hours for up to 2
days. Then increase to 400 mg every 12 hours
for up to 4 days. Then increase to 500 mg every
12 hours for up to 8 days. Then increase to
the full dose of 600 mg every 12 hours no later
than 15 days after starting.
The standard pediatric dose is 400 mg per square
meter twice daily and should not exceed 600
mg twice daily. Body surface area in square
meters can be calculated by: square root of
[(height in centimeters X weight in kilograms)
÷ 3,600]. (Note 2.54 centimeters = one
inch) A lead-in dosing is also recommended for
pediatric patients. On day 1, start with 250
mg per square meter, twice daily. Then increase
the twice daily dose by 50 mg per square meter
every 2-3 days until the recommended maximum
dose is reached.
to extremely potent effects upon liver enzymes
that metabolize many drugs, Norvir has the longest
list of drugs (among the anti-HIV drugs) that
cannot be taken with it.
should not be taken with any of the following
drugs due to life-threatening complications:
Pain medications: meperidine (Demerol);
medication alternatives that may be taken with
aspirin; acetaminophen (Tylenol, others).
propafenone (Rythmol); and
quinidine (Quinaglute, Quinidex).
is limited experience with alternative heart
antibiotics: rifabutin (Mycobutin). Anti-mycobacterial
alternatives that may be taken with Norvir include
clarithromycin (Biaxin) and ethambutol (Myambutol).
pressure calcium channel blocker drugs: bepridil
(Vascor). There is limited experience with alternative
calcium channel blockers.
and allergy antihistamines: astemizole (Hismanal)
and terfenadine (Seldane). Cold and allergy
antihistamine alternatives that may be taken
with Norvir include loratadine (Claritin).
headache (blood vessel constricting) drugs:
dihydroergotamine (D.H.E. 45) and ergotamine
(several). There is limited experience with
alternative ergot drugs.
pro-movement drugs: cisapride (Propulsid). There
is limited experience with alternative pro-movement
drugs: bupropion (Wellbutrin, note also used
as an aid in tobacco cessation as Zyban). Antidepressant-psychotropic
alternatives that may be taken with Norvir include
desipramine (Norpramin); however, a dose reduction
of desipramine may be necessary.
drugs: clozapine (Clozaril) and pimozide (Orap).
There is limited experience with alternative
drugs: clorazepate (Tranxene); diazepam (Valium);
estazolam (ProSom); flurazepam (Dalmane); midazolam
(Versed); triazolam (Halcion); and zolpidem
(Ambien). Alternative psychotropic-sedative-hypnotic
drugs that may be taken with Norvir include:
temazepam (Restoril); lorazepam (Ativan); and
alprazolam (Xanax--note that a slightly lower
dose of alprazolam may be necessary; reference
Frye, 37th Interscience Conference on Antimicrobial
Agents and Chemotherapy abstract A-59)
taken with didanosine (ddI, Videx), dosing should
be separated by 2 1/2 hours to prevent formulation
incompatibility, according the package insert.
taken with the oral contraceptive ethinyl estradiol,
blood levels of the hormone decreased significantly.
Since this would prevent adequate contraception,
hormone dosage increase or alternate (non-hormone)
contraceptive measures are necessary (condoms).
taken with the thyroid supplement hormone thyroxine,
hormone levels may decrease significantly, requiring
a dose increase of thyroxine.
taken with the asthma drug theophylline (Theodur,
others), the blood levels of theophylline decreased
significantly. Increased theophylline dosing
may be necessary.
using the nose-allergy steroid spray fluticasone
(Flonase), Cushing's syndrome may result (adrenal
gland hormone excess with weight gain and diabetes)
due to Norvir's inhibition of fluticasone's
normal metabolism. The 2 drugs should not be
to the presence of alcohol in both the capsule
and liquid formulations of Norvir, neither disulfiram
(Antabuse) nor metronidazole (Flagyl, Metrogel)
should be taken with Norvir. A serious disulfiram
reaction could occur.
decreases the drug concentration of methadone
(used to treat narcotic heroin addiction) by
approximately one-third. The dose of methadone
may need to be increased in patients taking
that there are 136 other medications listed
in the Norvir package insert whose levels may
be significantly affected by co-administration
with Norvir. Make sure you and your physician
know what they are before you take any other
medication with Norvir.
drug interactions occur when Norvir is combined
with any other anti-HIV protease inhibitor.
Only take 2 protease inhibitors as prescribed
by your physician.