Transcript A Step Toward Flexible Dosing

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
•
•
•
•
•
•
•
1. "FDA Grants Priority Review To Plavix(R) (Clopidogrel Bisulfate) Supplemental New
Drug Application (sNDA) For Additional Type Of Heart Attack." Medical News Today:
Health News. 30 Jan. 2006. 10 Feb. 2009
http://www.medicalnewstoday.com/articles/36782.php .
2. Mitakos A, Panderi I. “A validated LC method for the determination of clopidogrel in
pharmaceutical preparations.” J Pharm Biomed Anal. 431.8 (2002): 28.
3. Dow Jones Company, Inc. “US Patent Office Orders Re-examination of Plavix Patent”
Aug. 18. Aug. 2009. 24 Aug. 2009.
http://money.cnn.com/news/newsfeeds/articles/djf500/200908181126DOWJONESDJON
LINE000222_FORTUNE5.htm.
4. White R, Brandam V. Handbook of Drug Administration via Enteral Feeding Tubes.
London: Pharmaceutical Press, 2006. 169.
5. Freedman J, Hylek E. “Clopidogrel, genetics, and drug responsiveness.” New England
Journal of Medicine 360.4 (2009): 411 - 413.
6. Mega J, et al. “Cytochrome P-450 Polymorphisms and response to clopidogrel.” New
England Journal of Medicine. 360.4 (2009): 354-362.
5. Rueters. "USATODAY.com - Apotex delivering generic Plavix soon." News, Travel,
Weather, Entertainment, Sports, Technology, U.S. & World - USATODAY.com. 8 Aug.
2006. 10 Feb. 2009. http://www.usatoday.com/money/industries/health/2006-08-08generic-plavix_x.htm
References
•
•
•
•
•
•
•
•
6. Dailey, R. "Sanofi-Aventis and Bristol-Myers Squibb Victorious Over Apotex in Plavix
Case -- Seeking Alpha." Stock Market News, Opinion & Analysis, Investing Ideas -Seeking Alpha. 26 June 2007. 10 Feb. 2009. http://seekingalpha.com/article/39363sanofi-aventis-and-bristol-myers-squibb-victorious-over-apotex-in-plavix-case
7. Camara MG, Almeda FQ. “Clopidogrel (Plavix) desensitization: a case series.”
Catheter
Cardiovascular Interv. 2005; 65(4):525-527.
8. Dolence E, Yamreudeewong, W, Teixeira, M. “Evaluating Microbial Growth and
Stability of Clopidogrel in Various Extemporaneously Prepared Oral Liquid Mixtures.”
University of Wyoming, School of Pharmacy, 2008.
9. Trissel L. An Update on USP Chapter 797, The New National Standard for Sterile
Preparation. 07 April 2005. 10 Feb. 2009.
http://www.hospira.com/Files/Hospira797_final4-7-05.pdf
10. Butler M, et al. 2009 “The effect of intended duration of clopidogrel use on early and
late mortality and major adverse cardiac events in patients with drug-eluting stents.”
American Heart Journal. 2009. May. 157;5. 899-907
11. Urooj M, Farkouh M, Badimon JJ, et al. :Early and greater bioavailability of crushed
vs. whole tablet clopidogrel [abstract]. Circulation. 2003. 108;17. IV-570. Abstract 2599.
12. Angiolillo, Dominick J., Fernandez-Ortiz, Antonio, Bernardo, Esther, Alfonso,
Fernando, Macaya, Carlos, Bass, Theodore A., Costa, Marco A.
Variability in Individual Responsiveness to Clopidogrel: Clinical Implications,
Management, and Future Perspectives
J Am Coll Cardiol 2007 0: j.jacc.2006.11.044
Questions?