Download Chemical Stability of Clopidogrel in Various Aqueous Media

A Step Toward Flexible Dosing:
Chemical Stability of Clopidogrel
in Various Aqueous Media
Jen Steiner with Kurt Dolence and Glaucia Teixeira
University of Wyoming School of Pharmacy
Overview
• What Clopidogrel is
• Why we need flexible
dosing
• Research Method
• Results
• Discussion
• Future Research
Clopidrogrel… Plavix®
• Approved 1997
• Platelet aggregation
inhibitor
• Indicated for:
– Acute coronary
syndrome: non-STsegment elevation,
ST-elevation
myocardial infarction
– Recent myocardial
infarction (MI), recent
stroke, or established
peripheral arterial
disease.
Prodrugs and Genetics
• Clopidogrel is a prodrug – must be
converted into its active form by the liver
enzyme, CYP2C19 in order to stop platelet
clumping
• 3% of population are poor metabolizers
• Stop, time for some research – And
Chocolate!!!!
A little more about Plavix…
• Inhibits
clotting by
selectively
binding to
adenosine
diphosphate
(ADP)
receptors
How did that taste?
• Fast Metabolizers:
– How much chocolate effect did you get?
• Slow Metabolizers:
– How much chocolate effect did YOU get?
Pharmacogenetics of Clopidogrel
• Normally, poor metabolizers = more drug effect
(like the chocolate effect)
• But, prodrugs aren’t active yet until they are
converted (metabolized)
• Clopidogrel + CYP2C19 = active Clopidogrel
• Consequently, the less CYP2C19 activity
(slower metabolization), the less effect
Clopidogrel has and the more may need to be
taken to avoid clotting events
One size fits… ALL?
• Some people may require a different
amount of Clopidogrel in their systems to
be as effective
• Why is there only the 75mg size for daily
maintenance?
• Too much = increased bleeding
• Too little = increased clotting
The BIG Idea
• Liquid dosage forms allow for flexible
dosing
• BUT – the drug must be stable:
• Microbial Stability – 28 days stable
proven by Yamreudeewong, W, “Mui”
Cheyenne, 2009
• Chemical Stability – 28 days, same
compound (Proven?? – Let’s see…)
Compounded Solutions
• Mixed triturated clopidogrel in three aqueous
solutions:
– Apple Juice
– Sugar Free Maple Syrup
– Water
• Stored at:
– Room Temp & Fridge
• Measured at
– 0, 7,14, 21, and 28 days
Measurement
• High Pressure Liquid Chromatography
– Measures the amount of a pre-identified
compound in solution by measuring the time it
takes for a sample to travel through a specific
column - creating peaks
– Can indicate whether a compound has
changed
– FIRST calibrate the graph to properly identify
the compound and measure the area under the
curve to determine that concentration
– If Clopidogrel degrades, a smaller area under
the curve is expected over time
Naproxen (Control) and Clopidogrel
Chromatograph of a mixture of Clopidogrel test suspension and Naproxen
Preparing the HPLC Sample
• Method of Preparation:
– Shake the bottle
– Pipette Sample
– Pull and thaw Naproxen Sample
– Shake both samples
– Pipette Clopidogrel Mix into Naproxen sample
– Shake (distribute into suspension)
– Centrifuge (don’t want to clog the HPLC)
– Withdraw and “Shoot” Sample
Analysis
• All samples shot in triplicate
• Analysis of Clopidogrel content average
with standard deviation
• All samples were collected at the
appropriate times and frozen at -80° C
until combination with Clopidogrel
analyzed via HPLC
• Monitored for any new peak formation
(new compound) during tests
Anticipated Results
Clopidogrel Concentration (ng/10 μl)
Concentration of Clopidogrel in Water, Apple Juice, and SF Syrup
Mixtures over 20 Day Exposure to 40°C Thermal Accelerated
Decomposition
6000
5500
Water/Clopidogrel
5000
4500
Apple
Juice.Clopidogrel
4000
3500
SF
Syrup/Clopidogrel
3000
2500
2000
Day 0
Day 20
Time Stored (days)
Results
Stability of Refrigerated and Room Temperature
Clopidogrel/Water Mixture Over Time
Clopidogrel Concentration (ng/10 μl)
6500
6000
10% Deviation of
Expected Value
5500
Refrigerator
5000
Room Temp
4500
4000
Day 0
Day 7
Day 14
Day 21
Time Stored (days)
Day 28
Results
Clopidogrel Concentration (ng/10 μl)
Stability of Refrigerated and Room Temperature
Clopidogrel/Apple Juice Mixture Over Time
6500
10% Deviation of
Expected Value
6000
5500
Refrigerator
5000
Room Temp
4500
4000
Day 0
Day 7
Day 14
Day 21
Time Stored (days)
Day 28
Results
Clopidogrel Concentration (ng/10 μl)
Stability of Refrigerated and Room Temperature Clopidogrel/SF
Syrup Mixture Over Time
6500
6000
10% Deviation of
Expected Value
5500
Refrigerator
5000
Room Temp
4500
4000
Day 0
Day 7
Day 14
Day 21
Time Stored (days)
Day 28
Discussion
• Shouldn’t the Clopidogrel decrease at a
linear rate?
• Possible Causes:
– Poor Pipetting
– Apple Juice – low concentration from the start
– Fast Sedimentation Rate
• Is Clopidogrel Chemically Stable?
Recall…..Preparing the HPLC
Sample
• Method of Preparation:
– Shake the bottle (sedimentation)
– Pipette Sample
– Pull and thaw Naproxen Sample
– Shake both samples (sedimentation)
– Pipette Clopidogrel Mix into Naproxen sample
– Shake (distribute into suspension)
(sedimentation)
– Centrifuge (don’t want to clog the HPLC)
– Withdraw and “Shoot” Sample
Clopidogrel Is Chemically Stable
• The reason for the uneven results from
sample to sample has a lot to do with its
sedimentation rate
• Upon compounding the apple juice
suspension, the carnauba wax coating of the
Clopidogrel tablet probably trapped much of
the drug
• Future Mixtures to Research should include a
different viscous vehicle such as Sorbitol,
although diluting it for sample analysis will
likely reduce its suspending properties as
well.
When to Try New Research?
• Generic Clopidogrel will be available to the
public when the patent runs out in 2012
• New research should begin with the
generic in order to save patients money
and still give them therapeutic dosing.
Acknowledgements
•
•
•
•
•
Kurt Dolence and Glaucia Teixeira, Mentors
Jesse Robinson, Pharmacy Student
University of Wyoming EPSCoR
University of Wyoming Honors Program
University of Wyoming School of Pharmacy
References
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References
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Questions?