The long-term effect of alprenolol on plasma apolipoproteins A-I and B.

The concentration of lipids, lipoproteins and apolipoprotein A-I and B was measured in the plasma of 33 patients, enrolled in a double-blind, controlled trial of alprenolol in myocardial infarction, after one year on the study medication and again after 6 months off the medication. Sixteen patients received 200 mg alprenolol twice daily and 17 received placebo. There were no statistically significant differences between the parameters in the two groups after one year on medication. However, when medication was stopped, the ratio of apolipoprotein B to apolipoprotein A-I fell by 9% in the alprenolol group and increased by 2% in the placebo group. This difference was statistically significant. Our results suggest that alprenolol, a beta-blocker with weak intrinsic sympathomimetic effect, has slight effects on plasma lipoproteins. These effects were apparent only by measurements of apolipoproteins.