Plasma protein binding of catecholamines, prazosin and propranolol in diabetes mellitus.

In the present study equilibrium dialysis has been used to determine the degree of protein binding of the catecholamines adrenaline and noradrenaline and the adrenergic receptor blockers, prazosin and propranolol in diabetics. The binding of the catecholamines in plasma from Type I and II diabetic patients was not significantly different from that of healthy subjects. The ratio of the bound and free catecholamine concentrations was correlated with the level of albumin (HSA). Significantly reduced protein binding of prazosin was observed in Type I and II diabetic subjects compared to healthy volunteers. The binding of propranolol was significantly reduced in Type I patients. The ratios between the bound and unbound concentrations of prazosin and propranolol were significantly correlated with the levels of alpha 1-acid glycoprotein (AAG). The results suggest that non-enzymatic glycosylation of plasma proteins may increase the unbound fraction of the adrenergic blockers prazosin and propranolol.