The
Food and Drug Administration has approved four protease
inhibitors, members of a class of antiretrovirals that are
generally considered to be the most potent therapeutic agents for
HIV to date. In order for these drugs to be effective, and to
minimize the risk of resistance, it is important that these drugs
are prescribed and taken in accordance with the products'
approved labeling. These drugs have shown improvements in
surrogate markers (increased CD4 and decreased viral load
levels), leading to accelerated approval. In addition, clinical
benefit has been shown with Norvir™, Invirase™, and
Crixivan®, which demonstrated reductions in both mortality and
AIDS-defining clinical events.
Under
dosing, noncompliance, or partial-compliance with dosing regimens
for these drugs may result in development of a resistant
strain(s) of HIV that will not be susceptible to treatment with
protease inhibitors. Patients must be aware of the need to take
the complete dose to lessen the risk of potential drug
resistance. Patients should not modify the dosage in any way to
"extend" their prescription. The protease inhibitors
are partially metabolized by the cytochrome P450 oxidase system
and have a potential for serious interactions with a large number
of commonly prescribed drug products metabolized by the same
pathway.
The
following tables profile the similarities and differences of each
approved protease inhibitor, and provide useful information about
dosing, storage, potential drug interactions, and therapeutic
options.
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AdvertisementWarnings/Precautions
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Table I -- Comparison of Currently
Available Protease Inhibitors
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Table II -- Pediatric
Information
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Table A -- Pediatric Dosage
Guidelines Norvir™ (ritonavir) oral solution
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Table B -- Pediatric Dose
Viracept®(nelfinavir) to be Administered Three Times Daily
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Table III -- Medications that
should NOT be used with Protease Inhibitors
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Table IV -- Effects of
Protease Inhibitors and Other Commonly Used Medications as Determined by
Drug Interaction Studies
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Table V -- Drugs that May
Interactwith Protease Inhibitors via CYP3A4 Metabolism
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