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HAART treatment for HIV - Who, what, why, when, and how | NCLEX-RN | Khan Academy

- You may have heard the term HAART

referring to HIV treatment.

But what exactly does that mean?

Well, HAART, which stands for

highly active antiretroviral treatment

refers to the sort of modern day, present

treatment regimen for treating HIV infections.

And it's called highly active

because compared to the previous treatment regimen,

HAART is just a lot more effective

and so the name just kind of stuck.

So before we give just one type of drug

to help control an HIV infection,

we usually give an NRTI

which stops the reverse transcriptive step

and infection of a CD4 cell.

But, you know, HIV likes to mutate a lot

and it turned out that when only one type of drug

was given for an infection,

the HIV would eventually become resistant

to that type of drug.

So, of course, the drug didn't work anymore

and the person's infection would almost sort of

pick up where it left off

it would start to worsten again.

Except this time, almost more aggressively in a way

because now it would be resistant

to that original type of treatment.

But in comes HAART,

highly active treatment.

And you know, it's not that we're using

totally different drugs, I mean,

sure we've got a few more types at our disposal now,

but the key thing is that nowadays

we know that if we give two or three drugs,

which is what we usually do in HAART.

So if we give two or three drugs,

instead of just one,

the HIV infection can be really well controlled.

And what do I mean by that?

Well, each of the drugs in a particular HAART regimen

works in a slightly different way,

stopping HIV at different points

during its replication.

So these drugs used together

are really effective at preventing HIV

from making copies of itself.

It's life cycle just won't be able to continue,

so new varions just don't end up being made.

And you know, if we do encounter, by chance,

an HIV particle that's resistant

to one of the antiretroviral drugs,

chances are it wouldn't be resistant

to the other two drugs that make up that

particular HAART cocktail.

And you know it would be really hard

for HIV to become resistant

to all of the drugs in a particular HAART regimen.

I mean, here, let's do some math.

Not super hard math,

I'll leave that to Sal,

but in your body HIV multiplies essentially,

and it creates a few billion new viral particles per day.

And during replication,

it's reverse transcriptive enzymes

makes a lot of mistakes,

in fact, for every about 10,000 nucleotides

it adds on to a new strand of DNA

it makes a mistake,

and it inserts the wrong base.

One in every 10,000 bases is wrong.

And it doesn't have a very good repair mechanism

like we do for our DNA,

so this mistake sticks around.

So let's say, for arguments sake,

that one of these mistakes affects one of our

drugs target proteins within the HIV.

Let's say this stretch of DNA here

was supposed to code for intergrace.

So this virus's intergrace enzyme

will still work,

but our intergrace inhibitors

might not be able to stop it anymore

because it's mutated.

Well, our HAART cocktail

would still be able to stop this mutant HIV

because we have other places in the replication cycle

that we can inhibit it.

So essentially, a virus would have to mutate,

either randomly, or sort of evolve

by selective pressure

to become resistant to all of

the HAART drugs that we're throwing at it

in a given cocktail.

And, in fact, the chance that it could become resistant

to all three of the types of drugs

would be at the very least

one in ten to the twelfth power,

that's one in a trillion chance.

I'm just multiplying one in 10,000 here

by one in 10,000 here,

by one in 10,000 here.

And, you know, I'm being really generous here,

because this is assuming that

the one in 10,000 base mutations

are even occuring at the target enzymes

coding sequence of DNA.

So, bottom line here

is that it will be extremely unlikely

for an HIV particle to mutate

during replication in a way that would let it

escape from all three of the HAART drugs.

And you know, of course, it would be

extremely unlikely to thus find an HIV particle

just floating around in the bloodstream

that's resistant to multiple drugs.

Because remember, replication is actually suppressed

by taking the ARV,

so once you're on HAART,

potential mutants aren't even being created anymore.

Or, at least a lot less so.

So now you have an idea

of what HAART is,

a drug cocktail,

two to three different types of drugs

all taken together that

A. Makes drug resistance by HIV really unlikely,

and, B. That's still able to fight off

resistance strains that we might encounter.

But you know, there's a few other things to consider

with HAART.

I mean, for example, who gets HAART?

And when is it prescribed

during the course of the infection?

And, how do you sort of take it?

I mean, is it a bunch of pills?

Is it an injection?

Well, let's start here

with who and when.

Because you might reasonably think

that, you know, everyone who's diagnosed with HIV

gets started on HAART right away

and you know there's good evidence

that that is a good idea.

But it gets a little complex

because there are some drawbacks

to starting therapy early

and by early, I just mean before the onset of any symptoms

or AIDS defining illnesses, and,

you know, these drawbacks need to be considered.

For example, there are some side effects

of the ARV drugs,

such as an increased risk of cardiovascular disesases

like heart attacks, or strokes.

There's potential problems with bone health too,

long term exposure to these ARVs are

associated with a greater loss of bone density

as a person gets older.

More than the normal loss that happens as you age.

There can be psychiatric side effects, too,

like feeling a bit sort of sluggish in your thinking.

And there can be gastroinestinal side effects, too,

like chronic diarrhea.

So you can imagine that if someone has HIV

but they're in the latent phase,

in other words they're not having any symptoms,

starting them on antiretrovirals

might actually cause a decrease

in their quality of life

at that given time period.

The other thing that needs consideration

is that, you know, if you do start a HAART

treatment regimen then you need to stick to it

for the rest of your life,

taking your medication

every single day without fail.

Because studies have repeatedly shown

that stopping your ARVs,

or not taking them every single day

as prescribed,

is associated with the HIV in your body

becoming drug resistant.

So that means that in the future

if you decide to start your treatment again,

your drugs just may not work as well anymore.

They may not work at all, anymore.

So when you talk to your doctor

about the right time to start your treatment

you'll probably go over some strategies

to make sure you can take your medication

every single day

to minimize drug resistance

from happening in your infection.

And one thing that's helped out in a huge way

for people taking their medication every day,

is the fact that these combinations of these drugs,

remember, you're taking cocktails of usually

three of these types,

combinations are available in a single daily pill,

nowadays, and that makes it a lot

easier to stick to your treatment schedule.

I mean, a few years ago,

and actually still in some countries,

you'd have to take a handful of pills

every single day,

sometimes multiple times a day.

And now you can get your whole combo

in one single pill, taken once a day,

so that's really, really useful.

So now we know there's potential problems

with starting HAART too early.

But you know, when is the right time to start, then?

Well, it is a little different for each person,

so you'll have to have a chat with your doctor

about the right time to start,

but there's a few general principles

that'll help guide the decision

that you guys come to.

So for one, we know that if your CD4 T cell count

is less than about 350 to 500 cells

per cubic millimeter of blood

then it's time to start HAART.

Remember, CD4 count is sort of used as a marker

for how far along the illness is, right?

The lower the CD4 count

the more damaged the immune system is.

Viral load is important too.

If the amount of HIV in your bloodstream

is higher than 100,000 copies per millimeter of blood,

it's time to start HAART.

And, I know, the last thing I'll say about this is

is if a person is pregnant,

if they're a young child,

if they progress to AIDS,

of, it there's an opportunistic infection

or an AIDS defining illnesss present,

then regardless of CD4 count,

even if you're higher than that 350 to 500 cutoff,

HAART needs to be started right away

to hep your immune system recover

as much as possible.