Acetylsalicylic acid therapy: influence of metformin use and other variables on urinary 11-dehydrothromboxane B2 levels.

BACKGROUND: The effect of acetylsalicylic acid (ASA) may be measured through the analysis of urinary concentrations of 11-dehydrothromboxane B2 (11-dhTXB2), a metabolite of thromboxane A2, which is a potent platelet aggregant agent. It has been suggested that metformin (an oral antidiabetic drug) could improve oxidative stress and control platelet activation in type 2 diabetic patients, potentially reducing cardiovascular risk. We determined the concentrations of urinary 11-dhTXB2 in type 2 diabetic patients taking ASA and its concentrations with metformin use and several other clinical variables (hypertension, age, gender, smoking, body mass index, insulin and statin use), considering a reduction of at least 75% in the concentrations of this marker as a target, compared to results before ASA intake. METHODS: Urinary concentrations of 11-dhTXB2 of 81 type 2 diabetic patients were measured before and at 15 days taking 100 mg of aspirin daily. RESULTS: Most patients who presented a reduction of 11-dhTXB2 above 75% were under metformin use. This reduction was achieved in 51.5% of patients taking this drug, against 20.0% in the patients who were not (p=0.027). The analysis of the other variables did not show a significant difference. The use of metformin appears to play a role in the reduction of 11-dhTXB2 concentrations in type 2 diabetic patients. CONCLUSION: According to previous reports, hyperglycemia control seems to be a determinant factor for the success of ASA therapy, given the influence of metformin in the reduction of 11-dhTXB2 concentrations.

Urinary 11-dehydro thromboxane B2 levels in type 2 diabetic patients before and during aspirin intake.

BACKGROUND: Diabetic patients commonly present an increased risk for cardiovascular events, for which aspirin is the most frequently used medication for primary prevention. Urinary 11-dehydro thromboxane (11-dhTXB2) concentrations assess the effect of aspirin on platelets and identify patients who are at risk of cardiovascular events. The present study investigated whether or not type 2 diabetic patients who took a daily dose of 100mg of aspirin had a significant reduction in urinary 11-dhTXB2 concentrations and whether these results were associated with clinical and laboratory variables. METHODS: Eighty-one type 2 diabetic patients were enrolled in the study. Laboratory tests included the determination of lipidic profile, glycated hemoglobin, platelets count, molecular analysis for both GPIIbIIIa and COX-1 polymorphisms, and urinary 11-dhTXB2. RESULTS: Patients' median value for urinary 11-dhTXB2 before aspirin intake was 179 pg/mg of creatinine. After 15days taking aspirin, the patients presented median of 51 pg/mg of creatinine, thus revealing a significant difference between medians (p=0.00). A reduction of 95% in urinary 11-dhTXB2 concentrations could only be identified in 4 patients (5%). A BMI of ≥ 26 presented a significant association with a reduction of urinary 11-dhTXB2 concentrations (p=0.010), as shown by the multiple logistic regression model. Other clinical and laboratory variables showed no association. CONCLUSIONS: Regardless of the mechanisms related to aspirin non-responsiveness, most patients enrolled in the present study also presented a reduced or minimal response to low-dose aspirin therapy, thereby indicating a clear variability related to aspirin effectiveness. Moreover, BMI appears to be independently associated to the reduction of urinary 11-dhTXB2 concentrations in type 2 diabetic patients taking aspirin.