L11 - Treatment of HIV Infection Flashcards
What sort of genetic material does the HIV virion have?
ssRNA (+)
Describe the two types of glycoprotein expressed by the HIV virion
gp41 (transmembrane glycoprotein)
gp120 (surface glycoprotein)
Describe the two antigens expressed by the HIV virion
p17 (matrix antigen)
p24 (capsid antigen)
What sort of membrane does the HIV virion have?
Lipid bilayer envelope
What three enzymes are responsible for inserting the HIV ssRNA (+) into the human genome?
Reverse Transcriptase
Integrase
Protease
What is the function of reverse transcriptase?
To convert the ssRNA viral genome into cDNA
What is the function of integrase?
To integrate the dsDNA produced by RT into the human genome
What is the function of protease?
To cleave larger combination proteins into their functional forms
What is Azidothymidine?
A nucleoside analogue reverse transcriptase inhibitor (NRTI) - 2’3’ dideoxy nucleoside analogue that is phosphorylated by host cells
What is the MoA of Azidothymidine?
It acts as a DNA chain terminator and RT inhibitor
What is the therapeutic life of Azidothymidine?
6 months
What are ddC and ddI?
Both NRTIs (2’3’ dideoxy NAs) with the same MoA as Azidothymidine
Define NRTIs
Nucleoside/Nucleotide Reverse Transcriptase Inhibitors
Describe the general structure of NRTIs
All analogues of nucleotides, lack a 3’OH group on the ribose ring
Require phosphorylation by cellular kinases
Give four examples of NRTIs and their corresponding nucleosides
Zidovudine/AZT (Thymidine)
Lamivudine (Cytosine)
Abacavir (Guanosine)
Didanosine (Adenosine)
What is Tenofovir DF?
A nucleotide analogue RT inhibitor
What is the MoA of Tenofovir DF?
Tenofovir DF is converted to Tenofovir (serum esterases)
Tenofovir is a nucleotide analogue of adenosine monophosphate
What are the currently used NRTIs?
Zidovudine (AZT) Stavudine (D4T) Lamivudine (3TC) Emtricitabine (FTC) Abacavir (ABC) Didanosine (DDI) Tenofovir DF (TDF)
What are the adverse effects of NRTIs?
Lactic acidosis Hepatic steatosis Peripheral neuropathy Myopathy Lipoatrophy
What causes the adverse effects of NRTIs?
They may inhibit the activity of normal cellular DNA polymerases (mitochondrial DNA pol-Y)
May also interfere with CYP450 enzymes (D/D interactions)
What are the first choice NRTIs?
Abacavir (ABC) Tenofovir DF (TDF)
Why are ABC & TDF the first choice NRTIs?
Minimal DNA pol-Y inhibitory effects
No interaction with CYP450 enzymes
What is the main side effect of ABC?
Associated with a potentially fatal hypersensitivity syndrome
What is the main side effect of TDF?
Nephrotoxicity
Define NNRTIs
Non-Nucleoside Analogue Reverse Transcriptase Inhibitors
What is the MoA of NNRTIs?
They are non-competitive RT inhibitors that induce conformational changes within RT
Give three examples of NNRTIs
Nevirapine
Efavirenz
Etavirine
Describe combination therapy
Giving NRTIs AND NNRTIs together to increase and sustain the decrease in viral load
What are the side effects of NNRTIs?
CNS s/e (vivid dreams, insomnia, hallucinations, depression)
Teratogenicity
Substrates of CYP enzymes (D/D interactions)
What are Protease Inhibitors?
A class of antiretroviral HIV drugs
What is the MoA of PIs?
PIs inhibit HIV protease-mediateed cleavage of HIV polyprotein precursors
Renders virus particles non-infectious
What are the problems associated with PIs?
They are heavily metabolised by CYP enzymes (+Ritonavir)
Resistance can develop
What is the mechanism by which resistance to PIs arises?
Mutations modify the number/nature of points of contact between PI and protease
What are the side effects of PIs?
Dyslipidaemia (leading to atherosclerosis)
Insulin resistance
Lower GI symptoms
Give four examples of commonly used PIs
Lopinavir + Ritonavir (Kaletra)
Atazanavir
Darunavir
What is the MoA of Entry Inhibitors
They block co-receptor binding/fusion to prevent the HIV virion binding to and entering human cells
Give two examples of EIs
Maraviroc (block binding)
Enfurvitide (block fusion)
Define INSTIs
Integrase Strand Transfer Inhibitors
What is the MoA of INSTIs?
They block the strand transfer effect of HIV integrase
Inhibit both HIV-1 AND HIV-2
What is the 1st approved INSTI?
Raltegravir
Define HAART
Highly Active Antiretroviral Therapy
Define cART
combination Antiretroviral Therapy
blocks selection of mutants
How does cART block the selection of mutants?
Due to combination therapy multiple mutations are required simultaneously for resistance to occur to all drugs in the regimen
When should ART begin?
History of AIDS-defining illness Symptomatic HIV disease CD4 count <350/ul HIV-infected pregnant women HIV-associated nephropathy When treating HBV infection Upon first diagnosis
What is the ideal HAART regimen?
Two NRTIs + NNRTI/PI/INSTI
Tenofovir + Abacavir + Rilpiravirine/Darunavir/Raltegravir