Objective Cigarette smoking, as an inducer of CYP1A2 and increase the CYP1A2 activity, might enhance the generation of the active metabolite of clopidogrel. The study aimed to examine the impact of smoking cessation on platelet inhibition of clopidogrel.
Method Current smoking patients undergoing elective coronary stent implantation were enrolled. Every patient was aggressively advised to quit smoking at admission. All the patients were given loading dose of 300 mg clopidogrel and 300 mg aspirin and daily maintenance dose of 75 mg clopidogrel in addition to 100 mg aspirin. Blood samples were collected before and 24 h after clopidogrel loading and pre-discharge. Platelet aggregation was determined by conventional light transmittance aggregometry after stimulation with 5 mmol/L ADP.
Results 224 male smoking patients were enrolled in our study. During staying in hospital, 157 patients gave up smoking and 67 still kept smoking. Before loading, the maximal platelet aggregation (MPA) was not significantly different between non-smokers and smokers (56.4±12.3% and 58.2±13.8%, p=0.357). However, MPA after clopidogrel loading (42.8±11.5% and 38.6±14.8%, p=0.038) and pre-discharge (40.2±10.3% and 36.5±13.2%, p=0.041) showed significant difference between two groups.
Conclusion Smoking cessation might weaken inhibition effect of clopidogrel on platelet aggregation for smokers.