Effect of talinolol and the optical isomers of propranolol on LCAT activity in vitro

In vitro effects of DL-propranolol (a therapeutically used beta-blocker with local anesthetic properties), L-propranolol (having both beta-blocking and unspecific local anesthetic properties), D-propranolol (having local anesthetic, but much less beta-blocking properties), and talinolol (a therapeutically used beta-1-blocker with much less local anesthetic properties) on lecithin: cholesterol acyl transferase (LCAT) activity in human plasma were compared. Both D-propranolol and L-propranolol inhibited LCAT activity, the former being a little more effective. The racemic mixture showed intermediate dose-effect curves. In no case could a complete inhibition be achieved. Talinolol exhibited no effect on LCAT activity. Therefore, the inhibition of LCAT activity by beta-blocking drugs may be connected with their local anesthetic properties. Because LCAT inhibition is followed by a decrease of HDL cholesterol and an increase of triglycerides in plasma, it is recommended to use only beta-blockers without such side effects on lipoprotein metabolism for therapeutical purposes.