Monitoring of the plasma concentration of a beta blocker with retarded effect (Slow Trasicor, 160 mg) in humans.

The plasma oxprenolol concentrations were measured in nine cases for 3 days following the application of 1 dragee (160 mg) daily of Slow Trasicor (CIBA). Blood sampling was carried out at the 1st, 6th, 12th, and 24th h during the 1st day, and at the 12th and 24th h during the 2nd and 3rd days, respectively. Oxprenolol reached a considerable plasma level already after the 1st h: 140 ng/ml on the average during the 1st day. The average concentrations were 284 and 202 at the 6th and 12th h, respectively. It decreased to 43 ng/ml by the 24th h. During the 2nd and 3rd days 124 and 122 ng/ml values were found at the 12th h, and 42 and 50 ng/ml at the 24th h. The results of these studies prove the good absorption of Slow Trasicor, as well as its prolonged presence in the plasma. The corresponding clinical improvements in the patients indicate the therapeutic effect of the plasma levels.