91 - Fundamentals of Formulation Development (S7E1)

Welcome back to the Deep Dive listeners. Today
we're diving into something you don't often hear
much about, but it's super important in the world
of pharmaceuticals. Yeah. Formulation development.
Yeah. It's kind of like, you know, when you think
of a groundbreaking new drug, everyone's excited
about the discovery, the science behind it. Right.
But there's this whole other process that happens
before a drug actually makes it to you, to the
patient. Exactly. And that's what we're going
to unpack today. This whole idea of taking the
raw ingredient. the API, as it's called, and
turning it into an actual medicine you can take.
So it's more than just mixing things in a beaker,
I'm guessing. Oh, way more. For this deep dive,
we've pulled together a bunch of sources, like
real depth dives. We got stuff on the regulations
and guidelines, some hardcore chemistry papers,
even studies looking at how drugs work in the
body. A real mix, then. It is. And our mission
today is to basically give you a crash course
on the goals of formulation development and,
maybe even more interesting, the common roadblocks
that researchers hit along the way. I'm already
intrigued. So first things first, let's define
what formulation development actually is. Sure.
So in the simplest terms, it's the process of
turning a raw drug substance, the API, into a
medicine that's both stable and effective. And
I mean, stable in the sense that it doesn't just
fall apart on the shelf and effective in that
it can actually work in your body. So there's
an actual science to making a drug you can actually
use. Absolutely. It's not just about making a
pill that's easy to swallow, though that's important
too. OK, so walk me through this. What are the
big non -negotiable goals when you're developing
a new drug formulation. All right, well first
and foremost you got to think about stability.
The final product has got to stay like chemically
and physically stable over its entire shelf life.
Meaning it doesn't expire before you get to use
it. Exactly, like think about vitamins. Some
of them are super sensitive to air and light.
They got a storm right or they lose their potency.
It's the same idea with drugs. Lots of ingredients
can break down or change if they're not protected
properly. So formulation scientists have to be
super meticulous about the purity of ingredients
and how they interact. Gotcha. So stability,
that's a big one. What else? Next up is efficacy.
This basically means the formulation has got
to allow the drug to reach its target in the
body at a high enough concentration to actually
work. This is where the concept of bioavailability
comes in. Bioavailability, that rings a bell,
but refresh my memory. Basically, it's the proportion
of the drug that actually gets into your system
and is available to do its job. You'd be surprised
how many promising drugs fail, not because they
don't work, but because their bioavailability
is so low. So the drug just like... disappears
before it can even do anything. Kinda. It might
get broken down too quickly or not absorbed properly
so it never reaches the target. Wow, that's wild.
And I know what you eat can affect how your body
absorbs medicine, right? Oh, absolutely. Food
can have a massive impact on bioavailability.
It can change how fast the drug moves through
your digestive system, how well it dissolves,
everything. It's a whole complex interaction.
So you gotta factor in a person's diet, too.
Pretty much. It's all connected. Okay, so we've
covered stability, efficacy. Next up, and this
is a no -brainer, safety. Of course, you've got
to make sure the drug isn't going to harm the
patient. Exactly. The formulation needs to be
safe and rel -tolerated, especially for injectables.
Like drugs that are given through a shot. Yep.
Those are called parenteral products. For those,
it's super important that the drug doesn't clump
up or precipitate at the injection site, especially
for strong drugs like, say, chemotherapy drugs,
which are cytotoxic, toxic to cells. Yeah, that
makes sense. You wouldn't want a clump of chemo
drugs just sitting there. Right. So scientists
use some clever tricks to prevent that, like
encapsulating the drug in tiny fat bubbles called
liposomes or suspending it in oil and water mixtures,
which are called emulsions. There's this really
cool early example of this intralipid, which
was developed back in the 60s as an intravenous
nutrient solution. Intralipid. Yeah. It was like
a proof of concept for safely delivering stuff
directly into the bloodstream using emulsions.
So safety is paramount. What's the last big goal?
This one's all about you, the patient patient
acceptability. It's about making sure the medicine
is actually easy and convenient to take. Because
what good is a life -saving drug if you can't
stomach it? Exactly. So they're thinking about
things like making tablets easy to swallow, liquids
that taste alright, injections that don't hurt
too much. Makes sense. So we've got stability,
efficacy, safety, and patient acceptability.
That's a lot to juggle. And I imagine it doesn't
always go smoothly. What are some of the common
challenges that pop up? Oh, there are tons. But
one of the biggest ones is solubility. Lots of
new drugs just don't like to dissolve in water,
which, as we talked about with bioavailability,
is a huge problem. So like trying to mix oil
and water? Kind of. Our sources talk about how
a drug's lipophilicity, basically how much it
loves fats versus water, can really affect its
pertency and how it behaves. And sometimes making
a drug less fat -loving can actually improve
it overall. Huh. Interesting. So how do they
deal with poor solubility? There are a few techniques.
They can try to make the drug particles super
tiny, or they might create what are called salt
forms of the drug, which sometimes dissolve better.
There's a whole section on this in the process
of new drug discovery and development, if you
want to dig deeper. I have to check that out.
So it's all about making the drug more friendly
to the watery environment of our bodies. Exactly.
Another biggie is stability problems. As we mentioned
before, APIs can break down over time due to
things like oxidation reacting with oxygen, hydrolysis
react... with water, even light exposure. That's
why those instructions on medication bottles
are so important, right? Store in a cool dry
place and all that. Exactly. Those aren't just
suggestions. It's all about maintaining stability.
And the guidelines for this are outlined in good
manufacturing practice or GMP handbooks like
the Certified Pharmaceutical GMP Professional
Handbook. Okay, GMP. Got it. What about when
a patient is taking multiple medications. Can
the formulation cause problems there? Absolutely.
Drug interactions or DDIs are a major concern.
The way a drug is formulated can totally change
how it interacts with other drugs you're taking.
Oh, that sounds potentially dangerous. It can
be. So there's this family of enzymes in your
liver called cytochrome P450, often shortened
to P450, that plays a big role in breaking down
tons of medications. Imagine them like little
workers in a factory. If two drugs need the same
worker, they can end up competing. So one drug
might hog the worker and the other one gets left
behind. Exactly. One drug might build up to toxic
levels, or the other might not work as well because
it gets broken down too quickly. And there's
this one particular P450 enzyme, CYP3A4, that's
involved in metabolizing a huge number of drugs.
CYP3A4, got it. So interactions with that one
are a big deal. Huge. There's even been cases
where drugs had to be pulled from the market
because of serious interactions involving CYP3A4.
But it's not just the P450 system. There are
other enzyme systems systems like MAO and UGT
that also need careful consideration. So formulating
a drug is like a delicate balancing act, making
sure it doesn't mess with anything else a patient
might be taking. Absolutely. And another challenge
is achieving the right release profile. Sometimes
you need a drug to work. right away, like for
immediate pain relief. Other times you want a
slow sustained release over hours or even days.
Right, like those once a day allergy pills. Exactly.
So scientists have to design modified release
drug products like extended release capsules
or patches to control exactly how the drug is
released. So that's why some meds you take once
a day and others you got to pop every few hours.
All in the formulation. What else is tricky?
Oh, we got to talk about elemental impurities.
Even tiny, tiny amounts of certain metals or
other elements can be harmful. So they have to
use super sensitive techniques to make sure the
final product is clean. Wow, that's getting down
to the nitty gritty. What kind of techniques
are we talking about? One of the big ones is
called ICP -MS, which stands for inductively
coupled plasma mass spectrometry. It's super
sensitive, but it also needs what's called low
abundance sensitivity. Say that again? Low abundance
sensitivity. Yeah. It's basically the ability
to detect tiny amounts of something even when
there's a ton of other stuff around. It's like
finding a needle in a haystack. Gotcha. So you're
making sure there are no hidden nasties in the
final product. Exactly. OK, now imagine you've
got a formulation that works perfectly in the
lab. You're ready to go big to produce millions
of doses. That's where scale up comes in, and
it can three some curve balls. Like what works
on a small scale might not translate to mass
production. Totally. Our sources actually give
this cool example with the Suzuki Miara reaction,
which is used in making tons of drugs. In one
case, when they scaled up, the Teflon lining
of their giant reaction vessel started absorbing
tiny amounts of the palladium catalyst at low
concentrations. Hold up. The container itself
was causing problems. Yep. And because there
was so little catalyst to begin with, this tiny
absorption was enough to mess up their yields.
It just shows that even the materials you use
in manufacturing can have a huge impact. You
really got to think of everything. What about
drugs that come in special devices, like inhalers
or insulin pens? Those got to be tricky to formulate,
right? Absolutely. When you're dealing with the
drug device combo, things get even more complex.
In the US, for devices that are considered higher
risk, you might need an investigational device
exemption, or IDE, from the FDA before you can
even start clinical trials. IDE, huh? What's
that about? It's basically permission to test
your new device in humans, and you usually also
need approval from an institutional review board
or IRB, which makes sure the study is ethical.
Got it. So more hoops to jump through when you're
dealing with devices. Yep. It adds another layer
of complexity. We've covered a ton of ground
today from the basic goals of formulation to
a whole slew of challenges. Can you give us a
quick wrap up of the key takeaways? Absolutely.
So listeners, formulation development is this
essential but often hidden process of turning
a promising drug molecule into a medicine that
actually works and is safe for you to take. Right.
And the big goals are stability, efficacy, safety,
and patient acceptability. But achieving all
of that requires overcoming a ton of hurdles,
from the properties of the drug itself to how
it interacts with your body and how it can be
manufactured on a large scale. It's a whole lot
more complicated than just mixing ingredients
in a lab, that's for sure. Definitely not. It's
this constant process of problem -solving and
innovation to make sure that those groundbreaking
discoveries actually make it to the patients
who need them. And as we're seeing more and more
complex drugs being developed, like those large
protein -based drugs or nanomedicines... It makes
you wonder what the future holds for formulation
science, right? Totally. How are they going to
adapt and develop new strategies to formulate
these cutting -edge therapies and deliver them
safely and effectively? It's a really exciting
field to watch. They will have to do another
deep dive on that sometime. But for now, that's
a wrap on formulation development. Thanks for
listening, everyone. Thanks for joining us.