The effect of phenobarbital on the nonenzymatic glycation of hemoglobin

The effect of phenobarbital (PB) on nonenzymatic glycation of hemoglobin in vivo and in vitro was studied. In epileptic patients on long-term therapy with PB, the yield of glycated hemoglobin fraction HbA1c was found to be significantly higher than in normal control. In samples of Hb exposed to glucose in vitro in the presence of PB, HbA1c was also found to be significantly higher than in those exposed to glucose in the absence of PB. Enhanced reactivity of beta-NH2 terminus of Hb with glucose, was partly explained by observing that its pKa was decreased in the presence of PB. It was shown that the effect of PB on pKa of beta-NH2 terminus is one of the consequences of the Hb-PB interactions which were studied in this work by electrophoretic and NMR techniques.