An Interesting Finding!

I found this interesting study concerning the effects of smoking on the anti-platelet activity of clopidogrel and it was found that in smoker, the anti-platelet activities of clopidogrel is enhanced!! 

Reference:

Bliden KP et al. The association of cigarette smoking with enhanced platelet inhibition by clopidogrel. J Am Coll Cardiol  2008 Aug 12; 52:531.The association of cigarette smoking with enhanced platelet inhibition by clopidogrel.

Note: 

Disclaimer: In no way, do I ever advocate smoking! This is just an association, and is expected because of the mechanisms of action of clopidogrel. Smoking is bad for health (see the linked image below)

Clopidogrel is metabolically activated by several hepatic cytochrome P450 (CYP) isoenzymes, including CYP1A2. 

Cigarette smoking induces CYP1A2 and may, therefore, enhance the conversion of clopidogrel to its active metabolite.

In the study mentioned above, the investigators examined the effect of smoking on platelet response to clopidogrel after elective coronary stenting in 104 current smokers and 155 nonsmokers. 

Platelet aggregation was assessed by conventional light-transmission aggregometry 18 to 24 hours after PCI in patients who did not receive a glycoprotein (GP) IIb/IIIa inhibitor and ≥5 days after PCI in those who did.

Aggregation induced by adenosine diphosphate (ADP; 20 µmol/L) was lower in smokers (43%) than in nonsmokers (52%, P=0.008). 

ADP-stimulated GP IIb/IIIa-receptor expression was also lower in smokers (7 mean fluorescence intensity) than in nonsmokers (19 mean fluorescence intensity; P=0.0007). 

Reference:

Bliden KP et al. The association of cigarette smoking with enhanced platelet inhibition by clopidogrel. J Am Coll Cardiol  2008 Aug 12; 52:531.The association of cigarette smoking with enhanced platelet inhibition by clopidogrel.