Transcript Slide 1

Delivery of Hydrophobic Drugs
By: Chandra Varney and Sophia Cai
Mentor: Tanja Homrichhausen
Dr. Michelle Bothwell
INTRODUCTION
Scientists searching for a cure for cancer
must create drugs that can pass clinical trials.
One obstacle is that the majority of cancerfighting drugs are hydrophobic, while
bloodstreams are hydrophilic. In order to
effectively mix the drug in your blood,
emulsifiers must be used to prevent the drug
from grouping together.
Even if an emulsifier works well, sometimes
only a small amount of the drug can be
released into the bloodstream. An effective
cure has a balance between how well its
emulsifier works and how much of the actual
drug is released.
Background: Emulsifiers
Surfactant
Hydrophobic
Tail
Hydrophilic
Head
Surfactants
within a
hydrophobic
drug (heads are
in the
hydrophilic
bloodstream).
Experiment 1:
Emulsifier Effectiveness
In the experiment, we tested different emulsifiers
(Tween 80 and Lysozyme) to compare their
effectiveness. We mixed an emulsifier with a
hydrophobic drug and tested both the emulsifying
activity and emulsion stability.
1. Make buffer (fake blood) with a pH of 7.4.
2. Homogenize buffer, drug (edible oil), and an
emulsifier.
3. Dilute mixture and test absorption level with a
Spectrophotometer after 1, 2, 3, 4, 5, and 10
minutes.
Experiment 2:
Drug Release Rate
Ideally, the vast majority of the drug will
be released into the bloodstream. The speed
of delivery can be chosen, depending on the
drug’s cause.
1. Mixed hydrophobic drug with emulsifier (Tween
2.
3.
4.
80) and dilute with buffer.
Put samples into Centrifuge to separate the
released drug from the oil (unused drug).
Dilute with buffer and test absorption level.
Compare results with a standard curve to see
how much of the drug was actually released.
Definitions
Emulsifier – substance that mixes a drug in the
bloodstream (includes surfactants and proteins)
Surfactants – emulsifier that has a hydrophilic
head and a hydrophobic tail; mixes drug quickly
for a short amount of time (ex: Tween 80)
Protein – bulky emulsifier; mixes drug slowly,
stabilizes quickly (ex: Lysozyme)
Hydrophobic – “water hating,” attracts to other
hydrophobic substances (non-polar substance)
Hydrophilic – “water loving,” attracts to other
hydrophilic substances (polar substance)
Homogenizer – a tool that blends substances
together
Spectrophotometer – tool that measures a
liquid’s light absorption
Centrifuge - tool that separates molecules of
different densities by spinning quickly
Emulsifying Activity - the mixed state just after
mixing the drug and blood
Emulsion Stability – a measure of how stable an
emulsifier works by seeing how long it takes to
reach emulsifier’s half life
Our Emulsifier
•
•
•
Combined Tween 80 and Lysozyme to create
our own emulsifier. Why?
Tween 80 mixes the drug and blood almost
instantly, but slows down in a couple minutes.
Lysozyme mixes the drug at a slow rate, but
stabilizes soon, instead of dropping its mixing
rate.
We created our own emulsifier with 75%
Tween 80 and 25% Lysozyme. We hoped to
create a drug that immediately mixes the drug
and stabilizes before dropping in speed.