HIV Drugs Flashcards
What are the 4 categories of HIV drugs?
Protease inhibitors
NRTIs
NNRTIs
Other drugs
Protinavir, Ritonavir, Indinavir
Protease Inhibitors
Protease inhibitors work by
inhibiting HIV protease blocks polypeptide cleavage into reverse transcriptase, protease, integrase and structural proteins
Virus particles will bud off cell but be noninfectious
What does HIV protease do?
Product of pol gene
Cleaves polypeptides into smaller, functional units
gag forms
p24 (capsid)
pol forms
reverse transcriptase, integrase, protease
env forms
GP160: gp120+gp41 (envelope)
Protease Inhibitor S/E
N/D
Hyperlipidemia, Hyperglycemis (Insulin Resistance)
-Higher rate of CVD among HIV pts
-Fat redistribution
Indinavir
Protease Inhibitor
S/E: Kidney stones (hydration important)
Ritonavir
Inhibits cytochrome p450 system
Added as a booster to other protease inhibitors to avoid S/E
Example: Ritonavir & Lopinavir
How does reverse transcriptase synthesize a strand of DNA from RNA
It picks up triphosphorylated nucleotides (CGAT) to synthesize DNA from RNA
How do NRTIs inhibit reverse transcriptase?
They mimic one of the nucleosides (CGAT) but lack -OH group on 3’ carbon. This inhibits reverse transcriptase and terminates DNA chain.
Zidovudine (AZT), Lamivudine, Tenofovir, Didanosine
NRTIs
Which was the first HIV drug on the market?
Zidovudine (AZT) NRTIs
What nucleotide does Zidovudine (AZT) mimic?
Thymidine
- Same base and ribose sugar
- Zidovudine is missing -OH group on 3’ carbon of ribose sugar
What must NRTIs undergo to be incorporated into a DNA strand?
triphosphorylation by kinases
Which NRTI mimics a nucleotide instead of a nucleoside?
Tenofovir (has phosphate group)
-undergoes diphosphorylation instead of triphosphorylation
Nucleoside NRTIs
Zidovudine (AZT) and Lamivudine
-No phosphate group attached
NRTIs: important S/E
Mitochondrial Toxicity
- All mitochondria have their own DNA
- DNA polymerase gamma synthesizes mitochondrial DNA
- NRTIs can inhibit these
Mitochondrial Toxicity Sx
Peripheral neuropathy (pain, paresthesias)
Myopathy
Pancreatitis
Lactic Acidosis
Mitochondria is responsible for
Oxidative phosphorylation
How does lactic acidosis occur?
Oxidative phosphorylation inhibited so anaerobic metabolism
Severe, life-threatening cases of lactic acidosis w/ NRTIs
Zidovudine (AZT) S/E
Bone marrow suppression
Zidovudine (AZT) can be inserted into DNA strands in bone marrow
Administer G-CSF or Epo
Which NRTI is administered to pregnant women
Zidovudine (AZT)
Lamivudine is also called
3TC
Abacavir S/E
NRTI
- 5% pts get hypersensitivity rxn (fever, rash, resp. distress, GI upset)
- mistaken for opportunistic infection
Abacavir mimics which nucleoside?
guanosine
Which NRTI is the least toxic and can also be used for Hep B?
Lamivudine (3TC)
-Hep B also uses reverse transcriptase
Lamivudine (3TC) mimics which nucleoside?
Cytidine
Tenofovir S/E that causes limitation
Severe GI upset
Tenofovir mimics which nucleoside?
Adenosine
What special S/E does Tenofovir have?
Polyuria and muscle weakness indicate Fanconi Syndrome
- Loss of proximal tubule function
- proteinuria, urinary phosphate wasting, glucosuria
- metabolic acidosis, hypophosphatemia, hypokalemia
Nevirapine, Efavirenz, Delavirdine
NNRTIs
How do NNRTIs work?
Bind to reverse transcriptase and modifies the protein so it can no longer function
Do NNRTIs require phosphorylation?
No
Can NNRTIs cause bone marrow suppression?
No. Only inhibits reverse transcriptase. Do not alter other DNA synthesis enzymes.
Why are NNRTIs not effective for HIV-2?
It has a different reverse transcriptase which cannot be inhibited by the drugs
NNRTIs S/E
GI upset Skin rash (rare progression to SJS)
NNRTIs are metabolized by what?
P450 system of the liver
Why do NNRTI levels in the blood go up/down with co-administration with other drugs?
NNRTIs are metabolized by P450 system
Nevirapine
NNRTI
Induces P450 system
Delaviridine
NNRTI
Inhibits P450 system
Efavirenz
NNRTI
mixed effects on P450 system
Raltegravir
Integrase Inhibitor
Enfuvirtide
Binds to gp41
Inhibits fusion/entry into cells
Maraviroc
Blocks CCR5 receptor on macrophages