Antiretroviral Therapy
HIV medications can help lower your viral load,
fight infections, and improve your quality of life. But even if you take them,
you can still give HIV to others. They're not a cure for HIV.
The goals for these medicines are to:
Control the growth of the virus
Improve how well your immune system works
Slow or stop symptoms
Prevent transmission of HIV to others
The FDA has approved more than two dozen
antiretroviral drugs to treat HIV infection. They're often broken into six groups
because they work in different ways. Doctors recommend taking a combination or
"cocktail" of at least two of them. This is called antiretroviral
therapy, or ART.
Your doctor will let you know specifically how
you should take your medications. You need to follow the directions exactly,
and you shouldn't miss even one dose. If you miss doses, you could develop
drug-resistant strains of HIV, and your medication may stop working.
Classes of drugs
Schematic description of the mechanism of the
four classes of currently available antiretroviral drugs against HIV
There are six classes of drugs, which are
usually used in combination, to treat HIV infection. Antiretroviral (ARV) drugs
are broadly classified by the phase of the retrovirus life-cycle that the drug
inhibits. Typical combinations include 2 Nucleoside reverse transcriptase
inhibitors (NRTI) as a "backbone" along with 1 Non-Nucleoside reverse
transcriptase inhibitor (NNRTI), protease inhibitor (PI) or Integrase
inhibitors (also known as integrase nuclear strand transfer inhibitors or
INSTIs) as a "base."
Entry inhibitors
Entry inhibitors (or fusion inhibitors)
interfere with binding, fusion and entry of HIV-1 to the host cell by blocking
one of several targets. Maraviroc and enfuvirtide are the two currently
available agents in this class. Maraviroc works by targeting CCR5, a
co-receptor located on human helper T-cells. Caution should be used when
administering this drug however due to a possible shift in tropism which allows
HIV to target an alternative co-receptor such as CXCR4. In rare cases,
individuals may have a mutation in the CCR5 delta gene which results in a
nonfunctional CCR5 co-receptor and in turn, a means of resistance or slow
progression of the disease. However, as mentioned previously, this can be
overcome if an HIV variant that targets CXCR4 becomes dominant. To prevent
fusion of the virus with the host membrane, enfuvirtide can be used.
Enfuvirtide is a peptide drug that must be injected and acts by interacting
with the N-terminal heptad repeat of gp41 of HIV to form an inactive hetero
six-helix bundle, therefore preventing infection of host cells.
Nucleoside/nucleotide reverse transcriptase
inhibitors
Nucleoside reverse transcriptase inhibitors
(NRTI) and nucleotide reverse transcriptase inhibitors (NtRTI) are nucleoside
and nucleotide analogues which inhibit reverse transcription. HIV is an RNA
virus and hence unable to become integrated into the DNA in the nucleus of the
human cell; it must be "reverse" transcribed into DNA. Since the
conversion of RNA to DNA is not done in the mammalian cell it is performed by a
viral protein which makes it a selective target for inhibition. NRTIs are chain
terminators such that once incorporated, work by preventing other nucleosides
from also being incorporated into the DNA chain because of the absence of a 3'
OH group. Both act as competitive substrate inhibitors. Examples of currently
used NRTIs include zidovudine, abacavir, lamivudine, emtricitabine, and
tenofovir.
Non-nucleoside reverse transcriptase inhibitors
Non-nucleoside reverse transcriptase inhibitors
(NNRTI) inhibit reverse transcriptase by binding to an allosteric site of the
enzyme; NNRTIs act as non-competitive inhibitors of reverse transcriptase.
NNRTIs affect the handling of substrate (nucleotides) by reverse transcriptase
by binding near the active site. NNRTIs can be further classified into 1st
generation and 2nd generation NNRTIs. 1st generation NNRTIs include nevirapine
and efavirenz. 2nd generation NNRTIs are etravirine and rilpivirine. HIV-2 is
naturally resistant to NNRTIs.
Integrase inhibitors
Integrase inhibitors (also known as integrase
nuclear strand transfer inhibitors or INSTIs) inhibit the viral enzyme
integrase, which is responsible for integration of viral DNA into the DNA of
the infected cell. There are several integrase inhibitors currently under clinical
trial, and raltegravir became the first to receive FDA approval in October
2007. Raltegravir has two metal binding groups that compete for substrate with
two Mg2+ ions at the metal binding site of integrase. As of early 2014, two
other clinically approved integrase inhibitors are elvitegravir and
dolutegravir.
Protease inhibitors
Protease inhibitors block the viral protease
enzyme necessary to produce mature virions upon budding from the host membrane.
Particularly, these drugs prevent the cleavage of gag and gag/pol precursor
proteins. Virus particles produced in the presence of protease inhibitors are
defective and mostly non-infectious. Examples of HIV protease inhibitors are
lopinavir, indinavir, nelfinavir, amprenavir and ritonavir. Darunavir and
atazanavir are currently recommended as first line therapy choices. Maturation
inhibitors have a similar effect by binding to gag, but development of two
experimental drugs in this class, bevirimat and vivecon, was halted in
2010.Resistance to some protease inhibitors is high. Second generation drugs
have been developed that are effective against otherwise resistant HIV
variants.
Nucleoside/Nucleotide Reverse Transcriptase
Inhibitors (NRTIs)
NRTIs force the HIV virus to use faulty
versions of building blocks so infected cells can't make more HIV.
Abacavir, or ABC (Ziagen)
Didanosine, or ddl (Videx)
Emtricitabine, or FTC (Emtriva)
Lamivudine, or 3TC (Epivir)
Stavudine, or d4T (Zerit)
Tenofovir, or TDF (Viread), or TAF (Vemlidy)
Zidovudine, or AZT or ZDV (Retrovir)
Non-nucleoside Reverse Transcriptase Inhibitors
(NNRTIs)
These are also called "non-nukes."
NNRTIs bind to a specific protein so the HIV virus can't make copies of itself,
similar to jamming a zipper.
Delavirdine, or DLV (Rescriptor)
Efavirenz, or EFV (Sustiva)
Etravirine, or ETR (Intelence)
Nevirapine, or NVP (Viramune)
Rilpivirine, or RPV (Edurant)
Protease Inhibitors (PIs)
These drugs block a protein that infected cells
need to put together new HIV virus particles.
Amprenavir (Agenerase)
Atazanavir, or ATV (Reyataz)
Darunavir, or DRV (Prezista)
Fosamprenavir, or FPV (Lexiva)
Indinavir, or IDV (Crixivan)
Lopinavir + ritonavir, or LPV/r (Kaletra)
Nelfinavir, or NFV (Viracept)
Ritonavir, or RTV (Norvir)
Saquinavir, or SQV (Invirase, Fortovase)
Tipranavir, or TPV (Aptivus)
Fusion Inhibitors
Unlike NRTIs, NNRTIs, and PIs -- which work on
infected cells -- these drugs help block HIV from getting inside healthy cells
in the first place.
Enfuvirtide, or ENF or T-20 (Fuzeon)
CCR5 Antagonist
Maraviroc, or MVC (Selzentry), also stops HIV
before it gets inside a healthy cell, but in a different way than fusion
inhibitors. It blocks a specific kind of "hook" on the outside of
certain cells so the virus can't plug in.
Integrase Inhibitors
These stop HIV from making copies of itself by
blocking a key protein that allows the virus to put its DNA into the healthy
cell's DNA. They're also called integrase strand transfer inhibitors (INSTIs).
Bictegravir, or BIC (combined with other drugs
as Biktarvy)
Dolutegravir, or DTG (Tivicay)
Elvitegravir, or EVG (Vitekta)
Raltegravir, or RAL (Isentress)
Monoclonal Antibody
This is a new class of antiviral medication
specifically for adults living with HIV who have tried multiple HIV medications
and whose HIV has been resistant to current available therapies.
Ibalizumab-uiyk (Trogarzo) blocks your body’s HIV infected cells from spreading
the virus into those which are uninfected. It is administered by IV.
Cobicistat (Tybost) is a drug that helps some
drugs (atazanavir, darunavir, elvitegravir) work better, but it can increase
the levels of other medicines you may be taking (always tell your doctor about
these other medicines).
Atazanavir + cobicistat, or ATV/c (Evotaz)
Darunavir + cobicistat, or DRV/c (Prezcobix)
Elvitegravir + TDF + FTC + cobicistat, or
EVG/c/TDF/FTC (Stribild)
Elvitegravir + TAF + FTC + cobicistat, or
EVG/c/TAF/FTC (Genvoya)
Fixed-Dose Combinations
Some drug manufacturers put together specific
medicines into a single pill so they're easier to take, including:
Abacavir + dolutegravir + lamivudine, or
ABC/DTG/3TC (Triumeq)
Abacavir + lamivudine, or ABC/3TC (Epzicom)
Abacavir + lamivudine + zidovudine, or
ABC/3TC/ZDV (Trizivir)
Atazanavir + cobicistat, or ATV/c (Evotaz)
Atazanavir + cobicistat, or ATV/c (Evotaz)
Bictegravir +
emtricitabine + tenofovir alafenamide, or BIC/FTC/TAF (Biktarvy)
Dolutegravir + rilpivirine, or DTG/RPV (Juluca)
Durunavir + cobicistat, or DRV/c (Prezcobix)
Efavirenz + emtricitabine + tenofovir, or
EFV/FTC/TDF (Atripla)
Elvitegravir + cobicistat + emtricitabine +
tenofovir, or EVG/c/FTC/TAF (Genvoya)
Elvitegravir + cobicistat + emtricitabine +
tenofovir, or EVG/COBI/FTC/TDF or ECF/TDF (Stribild)
Emtricitabine + rilpivirine + tenofovir, or
FTC/RPV/TAF (Odefsey)
Emtricitabine + rilpivirine + tenofovir, or
FTC/RPV/TDF (Complera)
The following are some of the HIV medications
available in the U.S.:
abacavir (Ziagen)
abacavir/lamivudine or 3TC (Epzicom)
abacavir/dolutegravir/lamivudine or 3TC”
(Triumeq)
amprenavir (Agenerase)
atazanavir (Reyataz)
atazanavir/cobicistat (Evotaz)
bictegravi/emtricitabine/ tenofoviralafenamide
(Biktarvy)
delavirdine (Rescriptor)
didanosine or ddI (VidexEC)
dolutegravir (Tivicay)
dolutegravir/rilpivirine (Juluca)
durunavir (Prezista)
durunavir/cobicistat (Prezcobix)
efavirenz (Sustiva)
elvitegravir (Vitekta)
elvitegravir/tenofovir disoproxil
fumarate/emtricitabine/cobicistat (Stribild)
elvitegravir/tenofovir
alafenamide/emtricitabine/cobicistat (Genvoya)
emtricitabine/tenofovir alafen (Truvada)
enfuvirtide (Fuzeon)
emtricitabine or FTC (Emtriva)
etravirine (Intelence)
fosamprenavir (Lexiva)
ibalizumab-uiyk (Trogarzo)
indinavir (Crixivan)
lamivudine or 3TC (Epivir)
lopinavir ritonavir (Kaletra)
maraviroc (Selzentry)
nelfinavir (Viracept)
nevirapine (Viramune)
raltegravir (Isentress)
rilpivirine (Edurant)
rilpivirine/ tenofovir disoproxil fumarate or
TDF (Complera)
rilpivirine/tenofovir alafenamide (“TAF”)/FTC
(Odefsey)
ritonavir (Norvir)
saquinavir (Fortovase, Invirase)
stavudine (Zerit)
tenofovir alafenamide or TAF (Vemlidy)
tenofovir alafenamide/FTC (Descovy)
tenofovir disoproxil fumarate or TDF (Viread)
tenofovir disoproxil fumarate/FTC (Truvada)
tipranavir (Aptivus)
zalcitabine or ddC (Hivid)
zidovudine or AZT (Retrovir)
zidovudine/3TC (Combivir)
zidovudine/3TC/abacavir (Trizivir)