Because clinical trials are conducted under widely varying conditions and durations of follow up, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
Clopidogrel bisulfate has been evaluated for safety in more than 54,000 patients, including over 21,000 patients treated for 1 year or more. The clinically important adverse reactions observed in trials comparing clopidogrel plus aspirin to placebo plus aspirin and trials comparing clopidogrel bisulfate alone to aspirin alone are discussed below.
Bleeding
CURE
In CURE, clopidogrel bisulfate use with aspirin was associated with an increase in major bleeding (primarily gastrointestinal and at puncture sites) compared to placebo with aspirin (see Table 1). The incidence of intracranial hemorrhage (0.1%) and fatal bleeding (0.2%) were the same in both groups. Other bleeding events that were reported more frequently in the clopidogrel group were epistaxis, hematuria, and bruise.
The overall incidence of bleeding is described in Table 1.
Ninety-two percent (92%) of the patients in the CURE study received heparin or low molecular weight heparin (LMWH), and the rate of bleeding in these patients was similar to the overall results.
COMMIT
In COMMIT, similar rates of major bleeding were observed in the clopidogrel bisulfate and placebo groups, both of which also received aspirin (see Table 2).
Table 1: CURE Incidence of Bleeding Complications (% patients)Table 1: CURE Incidence of Bleeding Complications (% patients) |
Event | Clopidogrel Bisulfate (+aspirin) * (n=6259) | Placebo (+ aspirin) * (n=6303) |
Major bleeding † | 3.7 ‡ | 2.7 § |
Life-threatening bleeding | 2.2 | 1.8 |
Fatal | 0.2 | 0.2 |
5 g/dL hemoglobin drop | 0.9 | 0.9 |
Requiring surgical intervention | 0.7 | 0.7 |
Hemorrhagic strokes | 0.1 | 0.1 |
Requiring inotropes | 0.5 | 0.5 |
Requiring transfusion (>4 units) | 1.2 | 1.0 |
Other major bleeding | 1.6 | 1.0 |
Significantly disabling | 0.4 | 0.3 |
Intraocular bleeding with significant loss of vision | 0.05 | 0.03 |
Requiring 2 to 3 units of blood | 1.3 | 0.9 |
Minor bleeding ¶ | 5.1 | 2.4 |
* Other standard therapies were used as appropriate.
† Life-threatening and other major bleeding.
‡ Major bleeding event rate for clopidogrel bisulfate + aspirin was dose-dependent on aspirin: <100 mg = 2.6%; 100 to 200 mg = 3.5%; >200 mg = 4.9%.
Major bleeding event rates for clopidogrel + aspirin by age were: < 65 years = 2.5%, ³ 65 to < 75 years = 4.1%, ³ 75 years = 5.9%.
§ Major bleeding event rate for placebo + aspirin was dose-dependent on aspirin: <100 mg = 2.0%; 100 to 200 mg = 2.3%; >200 mg = 4.0%.
Major bleeding event rates for placebo + aspirin by age were: < 65 years = 2.1%, ³ 65 to < 75 years = 3.1%, ³ 75 years = 3.6%.
¶ Led to interruption of study medication.
Ninety-two percent (92%) of the patients in the CURE study received heparin or low molecular weight heparin (LMWH), and the rate of bleeding in these patients was similar to the overall results.
COMMIT
In COMMIT, similar rates of major bleeding were observed in the clopidogrel bisulfate and placebo groups, both of which also received aspirin (see Table 2).
Table 2: Incidence of Bleeding Events in COMMIT (% patients)
Type of bleeding | Clopidogrel bisulfate (+ aspirin) (n=22961) | Placebo (+ aspirin) (n=22891) | p-value |
Major* noncerebral or cerebral bleeding** | 0.6 | 0.5 | 0.59 |
Major noncerebral | 0.4 | 0.3 | 0.48 |
Fatal | 0.2 | 0.2 | 0.90 |
Hemorrhagic stroke | 0.2 | 0.2 | 0.91 |
Fatal | 0.2 | 0.2 | 0.81 |
Other noncerebral bleeding (non-major) | 3.6 | 3.1 | 0.005 |
Any noncerebral bleeding | 3.9 | 3.4 | 0.004 |
* Major bleeds were cerebral bleeds or non-cerebral bleeds thought to have caused death or that required transfusion.
** The relative rate of major noncerebral or cerebral bleeding was independent of age. Event rates for clopidogrel bisulfate + aspirin by age were: <60 years = 0.3%, ≥60 to <70 years = 0.7%, ≥70 years = 0.8%. Event rates for placebo + aspirin by age were: <60 years = 0.4%, ≥60 to <70 years = 0.6%, ≥70 years = 0.7%.
CAPRIE (Clopidogrel bisulfate vs. Aspirin)
In CAPRIE, gastrointestinal hemorrhage occurred at a rate of 2.0% in those taking clopidogrel bisulfate vs. 2.7% in those taking aspirin; bleeding requiring hospitalization occurred in 0.7% and 1.1%, respectively. The incidence of intracranial hemorrhage was 0.4% for clopidogrel bisulfate compared to 0.5% for aspirin.
Other bleeding events that were reported more frequently in the clopidogrel bisulfate group were epistaxis and hematoma.
Other Adverse Events
In CURE and CHARISMA, which compared clopidogrel bisulfate plus aspirin to aspirin alone, there was no difference in the rate of adverse events (other than bleeding) between clopidogrel bisulfate and placebo.
In CAPRIE, which compared clopidogrel bisulfate to aspirin, pruritus was more frequently reported in those taking clopidogrel bisulfate. No other difference in the rate of adverse events (other than bleeding) was reported.