Prof. Dr. Samar Farid Ass.Prof.Dr. Nermeen Ahmed Sabry Dr. Mohamed Abd Elghany Karim

20 Pages·2016·0.88 MB·English

by  Rolan Center

Comparison of clopidogrel antiplatelet activity in diabetic versus nondiabetic
patients with acute coronary syndromes and patients undergoing elective stent
placement

Thesis
Submitted for fulfillment of master degree in Clinical Pharmacy, Faculty
of pharmacy, Cairo University

Prepared by
Mina Wageh Mohareb
Bachelor of Pharmaceutical Science
Assiut University

Under Supervision of
Prof. Dr. Samar Farid
Professor of Clinical Pharmacy
Department of Clinical Pharmacy, Cairo University

Ass.Prof.Dr. Nermeen Ahmed Sabry
Dr. of Clinical Pharmacy
Department of Clinical Pharmacy, Cairo University

Dr. Mohamed Abd Elghany Karim
Dr. of Cardiology
Faculty of Medicine , Assiut University

2016

Abstract
Introduction and aim of the study
In clinical practice, oral antiplatelet therapy with adenosine
diphoshate (ADP) p2y12 inhibiting activity such as thienopyridines
(clopidogrel) represent a corner stone in the prevention of major
cardiovascular events in those subjects at high risk (primary prevention)
and in those who have already experienced a cardiovascular event
(secondary prevention). Although antiplatelet therapy reduce ischemic
events in patients with high risk for stent thrombosis, the individual
inhibitory effects of clopidogrel shows large variability. Prospective
studies implementing different methods of platelet function testing have
reported that a certain proportion of patients shows attenuated response to
clopidgrel, which is associated with increased risk of ischemic events.
Diabetes mellitus presents with a high incidence of atherosclerotic
vascular disease and patients with type 2 diabetes mellitus who already
suffered an ischemic event are at higher risk of recurrence than non–
diabetic patients. The rationale for aggressive antiplatelet therapy in
diabetics is strengthened by the observation that circulating platelets from
patients affected by diabetes mellitus show multiple abnormalities. Some
studies which evaluated functional platelet parameters during combined
aspirin and clopidogrel treatment showed that diabetic patients exhibit
lower degree of platelet inhibition after clopidogrel administration in
comparison with non-diabetic patients.
The aim of this study was to determine the effect of diabetes
mellitus on clopidogrel activity(measured by ADP- induced aggregation
after clopidogrel administration) and concentration of clopidogrel active
metabolite in cardiac patients undergoing PCI.
Patients and methods
This is an observational study made on IHD patients undergoing
elective PCI. Recruited patients were categorized according to DM status
into diabetic group (N= 30) and non-diabetic group (N=33). All patients
received clopidogrel-loading dose of 600 mg before PCI. Platelet function
was assessed using light transmittance aggregometry (LTA) technique at
baseline (before clopidogrel loading administration), 24 hour after
clopidogrel loading dose administration and 7-10 days after PCI.
Clopidogrel active metabolite concentrations were measured using liquid
chromatography/ mass spectrometry technique during one day of loading
dose clopidogrel administration. All patients administered a maintenance
dose of 75 mg clopidogrel for at least one year after percutaneous
coronary intervention (PCI). All patients were followed up for two years
year after PCI (by clinic visits once monthly and phone calls twice
monthly) for recurrence of acute cardiac events.
Results
There was no statistically significant difference between diabetic
and non-diabetic groups with respect to 10 µm adenosine di-phosphate
(ADP) induced platelet aggregation - measured at base line (P = 0.64), 24
hour after PCI (P = 0.874) and 7-10 days after PCI (P = 0.643). Diabetics
were non-significantly different from non-diabetics regarding post-PCI
acute stent thrombosis (P = 0.945), sub-acute stent thrombosis (P=0.945),
unstable angina(P = 0.29) and cardiac death (P = 0.64). Both diabetic and
non-diabetic groups were comparable regarding active clopidogrel
metabolite concentration (0.987). There was significant strong negative
correlation between 24 hour ADP aggregation and active clopidogrel
concentration in both diabetics (R = -0.8479 and P = 0.00001) and non-
diabetics (R = -0.8895 and P = 0.00001). Also, strong negative
association could be detected between 7-10 days ADP aggregation and
active clopidogrel concentration in both diabetic group (R = -0.7233, P =
0.00001) and non-diabetic groups (R = -0.893, P = 0.00001). Using
multiple linear regression test, Diabetes as a co-morbidity could not be
found as a significant predictor for 24-hour ADP aggregation (p = 0.469),
7-10 days ADP aggregation (P = 0.769), or post PCI acute cardiac events
(P = 0.865).
Conclusion
Diabetic patients may have comparable post-PCI platelet
aggregation, post-PCI acute cardiac events and active clopidogrel
concentration with non-diabetic patients when high loading dose 600 mg
clopidogrel is administered before percutaneous coronary intervention
(PCI).
Introduction
It has been anticipated that by year 2030, 8.6 million adults in
Egypt can have diabetes making it the country with the tenth largest
population of diabetes in the world . Patients with diabetes mellitus (DM)
suffer from high risk of cardiovascular diseases . DM patients undergoing
percutaneous coronary intervention (PCI) are mainly at high hazard for
recurrent cardiovascular events. Dual antiplatelet therapy with aspirin and
clopidogrel is the standard therapy for acute coronary syndromes (ACS)
and for patients undergoing PCI with stenting, inclusive of DM patients .
However, diabetic patients undergoing PCI are susceptible to more
recurrent ischemic events than non-diabetics despite being maintained on
usual dual antiplatelet therapy . High platelet reactivity (HPR) and/or
suboptimal reaction to antiplatelet agents might justify partly the high
recurrent rates of ischemic events in DM patients . For instance, diabetic
patients show less responsiveness to daily 81 mg of aspirin compared to
non-diabetic patients, overcome in part by higher dose of aspirin . The
ADP P2Y12 receptor blockade with clopidogrel was superior in
decreasing recurrent ischemic events over aspirin alone in diabetic
patients with coronary artery disease . Angiolillo et al, validated that,
DM patients have a lower level of platelet inhibition versus non-diabetic
patients each in the acute phase, following administration of 300 mg
loading dose (LD) of clopidogrel, and in the chronic phase, whereas on
75 mg/day maintenance dose (MD). It has been reported that, 600 mg
clopidogrel LD is associated with higher degree of platelet inhibition and
lower probability of clopidogrel non-responsiveness in comparison to 300
mg clopidogrel LD . However, platelet inhibitory activity of 600 mg
clopidogrel LD during PCI has not been well-established in diabetic
patients compared to non-diabetics .
Aim of the Study
Aims
The main purpose of the present observational study was to
examine the differences in the platelet function and post-PCI acute
cardiac events between diabetic and non-diabetic coronary artery disease
(CAD) patients after administration of 600 mg loading dose of
clopidogrel.
Methodology
This study was a prospective observational single center study
conducted to observe the effect of diabetes mellitus on patients’ response
of already prescribed loading dose of clopidogrel administered before
elective PCI.
Recruitment methods
Study subjects and study site
Study subjects were recruited from those patients who were
admitted to the catheterization unit in Assuit University Teaching
Hospital for PCI during the period between April 2011 and March 2012.
Patients were screened for the following inclusion and exclusion
criteria before their approvals were sought.
Inclusion criteria
 Adult patients > 18 years old,
 patients with documented history of coronary artery disease
(CAD),
 patients had diagnostic catheterization within 2 weeks before
stenting, and
 diabetic patients(insulin and non-insulin dependent) for the
diabetics arm group (diabetes defined as serum glucose level ≥ 126
mg/dl or administration of anti-hyperglycemic drug (141).
Exclusion criteria
 Patients who received any glycoprotein IIb/IIIa inhibitors before
the procedure,
 patients who had a family or personal history of bleeding, serious
bleeding tendency, history of intracranial hemorrhage, or any sign
of active bleeding,
 patients with platelet count < 100 x 103/µl, Hemoglobin level < 10
g/dl, and Haematocrit level < 30%, (142)
 patients undergone major surgery within one week of enrollment,
 patient with any known hypersensitivity to clopidogrel,
 patients with uncontrolled hypertension who were not responsive
to hypotensive drugs,
 patients with severe decompensated liver diseases,
 patients with creatinine clearance less than 25 ml/min,
 patients with current gastrointestinal disorders such as severe
diarrhea, severe constipation, inflammatory bowel disease,
paralytic illus or any other disorder that may dramatically affect
gastrointestinal absorption,
 patients taking medications that may increase likelihood of life
threatening hemorrhage by serious pharmacodynamic synergistic
interaction (such as antithrombinalfa, antithrombin iii, apixban,
argatroban and bivalirudin) or by stimulation of hepatic
metabolizing enzymes responsible for clopidogrel bioactivation (
such as carmabazepine rifampin, rifabutin and St.John Wart) (143),
or
 patients taking medications that may seriously decrease serum
levels and antiplatelet effect of clopidogrel by inhibition of CYP
450 enzymes responsible for clopidogrel bioactivation (such as
variconazole, esmoprazole, fluconzole, itraconazole, erythromycin,
clarithromycin and etravirine) (143).
Study design
This was a prospective, randomized, and observational parallel
study using the simple restricted randomization technique. The study was
approved by the research and ethics committee of Faculty of Pharmacy,
Cairo University (Appendix I), which followed the tenets of the
Declaration of Helsinki (162). Informed consent was obtained from all
subjects or their surrogate after explaining the nature, purpose, and
potential risks of the study (Appendix II).
The recruited patients were divided according to the presence of
diabetes mellitus (DM) as a co-morbidity into two groups; diabetic and
non-diabetic groups. Diabetes was defined as a fasting blood glucose
concentration ≥ 126 mg/dL or administration of anti-hyperglycemic
medications (141).While the patients in the other (non-diabetic group)
were selected based on normal fasting blood glucose(less than 126 mg/dl)
and no previous administration of hypoglycemic drugs.
Baseline screening
All recruited patients in both groups were screened at baseline
(before clopidogrel initiation and conducting PCI) for the following data:
A. Biochemical laboratory data
This included measuring serum glucose level (mg/dL), serum
creatinine level (g/dL), total cholesterol(mg/dL), serum
triglycerides(mg/dL), serum sodium level (meq/L), serum potassium level
(meq/dL), prothrombin concentration(%), and platelet count.
B. Medical history
In this section, current smoking status (any amount of daily
cigarette smoking (Smoking is a practice in which a substance-mainly
tobacco is burned and the resulting smoke breathed in to be tasted and
absorbed into the bloodstream) (163), previous history of hypertension,
previous history of myocardial infarction, previous history of unstable
angina, previous PCI with one or more stents, previous coronary artery
bypass graft were recorded.
C. Medication history
Previous chronic administration of beta-blockers, angiotensin
converting enzyme inhibitors or statins, calcium channel blockers and
long acting nitrates were recorded (most widely used classes in patients
with coronary artery disease) (85-88), in order to exclude the effect of
medication interaction effect (other than clopidogrel) on ADP
aggregation results and post-PCI cardiac events in both study groups.
Patients in both groups received clopidogrel with a loading dose of
600 mg immediately before undergoing PCI, followed by 75 mg
maintenance dose for at least one-year post PCI.
Study outcomes and Follow-up evaluation
A. Platelets aggregation
The primary outcome of this study was measuring ADP induced
platelet aggregation using light transmittance analysis technique at
baseline before clopidogrel loading, 24 hours and 7-10 days after
initiating clopidogrel therapy. Platelet aggregation was quantitatively
measured by recording the transmission of a light beam across a
suspension of constantly agitated platelets in an APACT-4004 aggregom-
eter (LABiTec, Ahrensburg, Germany) (140). The blood is collected in
3.8% sodium dihydrate citrate (one part per nine parts of blood) and
centrifuged at 190 g for 15 min at ambient temperature. The cPRP is
stored at ambient temperature in stoppered tubes under CO to avoid pH
2