Antiretroviral Drugs Flashcards
Which of the following conditions increase urgency to initiate HAART
- Pregnancy
- AIDS-defining conditions
- Acute opportunistic infections
- Lower CD4 counts
- HIV-associated nephropathy
- Acute/early infection
- HIV/hepatitis B or C coinfection
How long until HAART shows efficacy?
Predictors of virological success?
After initiation of HAART, viral load reduction to below limits of assay detection usually occurs within
the first 12 to 24 weeks of therapy.
Predictors of virologic success include the following: • low baseline viremia, • high potency of the ARV regimen, • tolerability of the regimen, • convenience of the regimen, and • excellent adherence to the regimen
List current HIV Drug Classes?
• Nucleoside/-tide Reverse Transcriptase Inhibitors (NRTIs) • Nonnucleoside Reverse Transcriptase Inhibitors (NNRTIs) • Protease Inhibitors (PIs) • Entry/fusion Inhibitors • Integrase Inhibitors (INSTIs) • Pharmacokinetic Enhancers
Name two Pharmacokinetic enhancers and MOA?
Currently two commonly used:
• Ritonavir (protease inhibitor)
• Cobicistat
MOA
• Potent inhibitors of CYP 3A4
• Increase plasma concentrations of ARV allowing for lower and/or less frequent dosing
• Improve tolerability of ARV
Characteristic of Ritonavir dosing regimen?
• Used in combination with most protease inhibitors
(not nelfinavir)
• Never used alone
Combinations of cobicistat?
• Used commonly in combination with the INSTI
elvitegravir
• Also found in combination with darunavir and
atazanavir
List the nucleoside/tide reverse transcriptase inhibitors(NRTIs)?
- Abacavir
- Didanosine
- Emtricitabine
- Lamivudine
- Stavudine
- Tenofovir
- Zidovudine
MOA of NRTIs?
• Analogs of native ribosides (lack 3’OH)
• Phosphorylated by cellular enzymes and incorporated into viral DNA by reverse transcriptase
• Lack of 3’OH terminates DNA elongation
ie. they are competitive inhibitors of reverse
transcriptase
• Most have activity against HIV-2 as well as HIV-1
NRTIs resistance and PK?
- Emerges rapidly if used alone
* Cross-resistance between agents of same analog class can occur
NRTIs AE?
• If more than one NRTI given toxicities may overlap
• AE mainly due to inhibition of mitochondrial DNA
polymerase: peripheral neuropathy, myopathy,
lipoatrophy & lactic acidosis
• Pancreatitis, myelosuppression & cardiomyopathy can
also occur
• Liver toxicity is rare but fatal (lactic acidosis,
hepatomegaly with steatosis).
• Zidovudine & stavudine may be particularly associated
with dyslipidemia & insulin resistance
NRTIs drug interactions?
• Didanosine & tenofovir
Tenofovir increases plasma didanosine levels ~60%.
Doses of didanosine have to be reduced.
• NRTIs are not generally metabolized by cytochrome
enzymes
Zidovudine abbreviation, analog, AE, recommendation?
Abbreviation: ZDV, AZT
Nucleoside Analog
Thymidine
Adverse effects
• Bone marrow suppression (neutropenia, anemia)
• GI intolerance, headaches, insomnia
- Zidovudine is no longer recommended in current
guidelines due to unacceptable toxicity
Stavudine moa, abbreviation, analog, AE, recommendation?
Strong inhibitor of b and g DNA polymerases (high
affinity for mitochondrial DNA polymerase, which can lead to toxicity)
Abbreviation: d4T
Nucleoside Analog
Thymidine
Adverse Effects • Peripheral neuropathy, lactic acidosis • Hyperlipidemia, neuromuscular weakness * Stavudine is no longer recommended in current guidelines due to unacceptable toxicity
Didanosine abbreviation, analog, AE, recommendation?
Abbreviation DDL
Nucleoside Analog
Adenosine
Adverse Effects
High affinity for mitochondrial DNA polymerase
• Pancreatitis (esp. alcoholics and patients with hypertriglyceridemia)
• Peripheral neuropathy, diarrhea, hepatic dysfunction, CNS effects
- Didanosine is no longer recommended in current
guidelines due to unacceptable toxicity
Tenofovir AE, analog, and recommendation?
One of preferred NRTIs in currently recommended
regimens
Abbreviation: TDF
Nucleotide Analog (only NRTI that is nucleoTIDE) Adenosine
Adverse Effects
• GI (nausea, diarrhea, vomiting, flatulence)
Tenofovir contraindications?
• Serum creatinine monitored with renal insufficiency
• Only NRTI with sig. drug interactions (increases
didanosine concentrations and dosage reductions are
usually required)
• Decreases concentrations of atazanavir. Atazanavir
can be ‘boosted’ with ritonavir
Lamivudine Abbreviation, analog, resistance, AE, and effect?
DOES NOT affect mitochondrial DNA synthesis or bone marrow precursor cells
Abbreviation: 3TC
Nucleoside Analog
Cytosine
Resistance
• High level resistance occurs with single amino acid substitutions
Adverse effects
• Few significant (headache, dry mouth)
Emtricitabine abbreviation, structure, analog, AE, recommendation?
Abbreviation: FTC
Structural relative of lamivudine
One of preferred NRTIs in currently recommended
regimens
Nucleoside Analog
Cytosine
Adverse effects
• Hyperpigmentation of palms and soles (occurs most frequently in dark-skinned people)
Abacavir abbreviation, analog, clinical use, and resistance?
Abbreviation: ABC
Nucleoside Analog
Guanosine
Clinical Uses
• Contraindicated if patient has HLA-B*5701 mutation
Resistance
• HIV resistance requires several mutations and tends to develop slowly.
Abacavir AE?
Adverse Effects
• GI, headache, dizziness
• 5% - ‘hypersensitivity’ reaction (one or more of rash, GI, malaise, respiratory distress).
Contraindicated if patient has HLA-B*5701 mutation
• Sensitized individuals should NEVER be re-challenged
(can be genetically screened)