Hemodynamic and humoral effects of low-dose aspirin in treated and untreated essential hypertensive patients.

Aspirin at low doses is used as an inhibitor of platelet aggregation and is frequently administered to essential hypertensive patients with arterial thrombotic complications. However, it is unknown whether aspirin can modify blood pressure values either in treated or untreated hypertensive patients, as described for other non steroidal anti-inflammatory drugs. Thus 30 patients. 10 with mild uncomplicated and untreated essential hypertension, 10 with essential hypertension under chronic treatment with captopril, 50 mg bid, and 10 with essential hypertension under chronic treatment with atenolol, 100 mg oid, received aspirin, 100 mg oid, and the corresponding placebo for one month, according to a double blind randomized cross-over design. At the end of each treatment, blood pressure, heart rate, generated serum thromboxane B2 and urinary excretion of thromboxane B2 and 6 keto prostaglandin F1 alpha and plasma renin activity were measured. Both in treated and untreated essential hypertensive patients, aspirin administration did not affect blood pressure, heart rate and urinary 6 keto prostaglandin F1 alpha, while it significantly reduced serum and urinary excretion of thromboxane B2 and plasma renin activity. In conclusion, while the present data confirm that low doses of aspirin selectively inhibit thromboxane B2 synthesis, they indicate that aspirin at 100 mg oid can be administered to treated and untreated essential hypertensive patients without any harmful effect on blood pressure values.