An increase in the ratio of thromboxane A2 to prostacyclin in association with increased blood pressure in patients on cyclosporine A

The aim of this study was to determine the effect of two years of treatment with cyclosporine A on blood pressure and the rates of secretion into the circulation of the vasoconstrictor thromboxane A2 and the vasodilator prostacyclin. Seven patient suffering from multiple sclerosis took part. Their blood pressures and urinary concentrations of 2,3-dinor-thromboxane A2 (a major urinary metabolite of thromboxane A2) and of 2,3-dinor-6-keto-prostaglandin F1 alpha (the major urinary metabolite of prostacyclin) were determined at the end of two years of treatment with cyclosporine A, and once again three months after cessation of this treatment. No other drugs were given during or after cyclosporine A. Mean arterial blood pressure was 113 +/- 5 mmHg (mean +/- SEM) during the cyclosporine A treatment, but fell to 94 +/- 4 mmHg after the three-month's wash-out period. Urinary excretion of the thromboxane metabolite decreased slightly from 674 +/- 150 pg.mg-1 creatinine during cyclosporine A therapy to 503 +/- 90 pg.mg-1-creatinine after the end of therapy. At the same time the prostacyclin metabolite increased significantly from 82 +/- 17 pg.mg-1 creatinine to 113 +/- 23 pg.mg-1 creatinine (P less than 0.05). The ratio of 2,3-dinor-thromboxane B2 to 2,3-dinor-6-keto-prostaglandin F1 alpha (taken as a measure of vasoconstrictor prostanoid activity) fell significantly from 8.4 +/- 0.8 4.7 +/- 0.6 (P less than 0.005). The shift in prostanoid production observed during cyclosporine A treatment could be one causal factor for the hypertensive and thromboembolic events associated with the use of this drug.