Anti HIV drugs
Terms
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- What are the two major classes of anti HIV drugs?
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Antimetabolite inhibitors of RT
Viral aspartate protease inhibitors - Nucleoside reverse transcriptase inhibitors - mechanism
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Selective for virally encoded RNA dependent DNA polymerase
Lack a 3’ OH so they cause chain termination - Mechanism of resistance to NRTIs?
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Resistance via mutations of the DNA pol gene can result in:
Impairment of NRTI incorporation into DNA
Removal of NRTI from the terminated DNA chain
Mutants that arise during combination therapy are cross-resistant to all NRTIs in clinical use - NNRTIs mechanism?
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Bind to a site different from NRTIs
Don’t require phosphorylation to be active and don’t compete with nucleoside triphosphates
Bind to a hydrophobic subdomain near the active site of HIV-RT producing allosteric inhibition, enzyme can no longer bind normal substrate - NNRTIs toxicity?
- relatively low, contraindicated in pregnancy
- NNRTI drug interactions?
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Nevaripine and efavirenz both induce and are metabolized by CYP3A4
Delavirdine is metabolized by and inhibits CYP3A4 - How do protease inhibitors work?
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Protease cleaves large proteins into function proteins for HIV,
Selective for HIV protease inactive vs human proteases - How are NRTI and NNRTIs used together?
- Used in combination to minimize resistance NNRTI + 2NRTIs
- How are PIs used with other HIV drugs?
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in combination with NRTIs to minimize resistance strains and for synergistic effect
Additive or synergistic effects with NRTIs because they inhibit a late pathway - Toxicity of protease inhibitors?
- GI distress, increased bleeding in hemophiliacs, hepatoxicity, metabolic alterations hyperglycemia, hyperlipidemia, insulin resistance, lipodystrophy (wasting or redistribution of fat)
- which PIs are least toxic?
- Nelfinivir and saquinavir are well-tolerated rotinarvir is poorly tolerated at full dose
- Drug interactions of PIs?
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Drug interactions drugs that inhibit cytochrome P-450 CYP3A4, increase plasma concentration of PI toxicity
All Pis are substrates and inhibitors of CYP3A4. rotinavir is the most potent and saquinivir the least potent inhibitor. - what is enfurivitide?
- Peptide that interferes with virus cell interaction and blocks viral fusion with the CD4 cell membrane
- Which class of HIV drugs is contracindicated in pregnancy?
- NNRTI
- Which drug is good for prevention of vertical transmission?
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NRTI - Zidovudine
NNRTI - Nevaripine given at onset of labor