Effects of Quyu Xiaoban capsules on clinical outcomes and platelet activation and aggregation in patients with unstable angina pectoris

Objectives: To investigate the effects of the Traditional Chinese Medicine (TCM) Quyu Xiaoban capsules (QYXB) on clinical outcomes and platelet activation and aggregation in patients with unstable angina pectoris (UAP) and phlegm and blood stasis syndrome. Design: Ninety patients with UAP were randomly divided into two groups: a control group that received a loading dose of 300 mg aspirin and a maintenance dose of 100 mg of aspirin plus baseline therapy for 4 weeks, and a trial group that received the same doses of aspirin and baseline therapy plus QYXB for 4 weeks. The severity of anginal attacks, alterations of TCM symptoms and signs, and electrocardiographic (ECG) changes were assessed in all patients before and after treatment. The plasma platelet aggregation (PAG) rate and P-selectin level were measured in all patients at baseline and at the end of the fourth week of treatment. Results: After treatment for 4 weeks, both group of patients showed improvement in the severity of angina pectoris and TCM symptoms and signs, but there was a significant difference in the two groups' rates of clinical improvement, whereas the rate of ECG improvement of the two groups showed no difference. As compared with the baseline value, the PAG rate in both groups decreased significantly at the end of the fourth week (63.74 +/- 11.18% vs. 55.69 +/- 10.40% in the control group, and 63.83 +/- 12.70% vs. 50.04 +/- 8.91% in the trial group). Similar changes in P-selectin levels were observed in the two groups (9.40 +/- 1.25 ng/mL vs. 8.90 +/- 1.34 ng/mL in the control group, and 9.56 +/- 1.16 ng/mL vs. 7.80 +/- 0.98 ng/mL in the trial group). However, both the PAG rate and P-selectin level decreased to a greater extent in the trial group than in the control group after treatment, and the difference between the two groups was significant (both p < 0.05). Nevertheless, these biochemical changes were too small to fully explain the beneficial clinical outcomes achieved with QYXB capsules. Conclusions: In comparison with both the respective baseline values and with aspirin therapy, QYXB capsules significantly attenuated anginal attacks and improved TCM symptoms and signs in patients with UAP. The exact mechanisms underlying these therapeutic effects remain to be explored.