Examples Abound of Gaps in Medical Knowledge Because of Groups Excluded From Scientific Study

CONVENTIONAL WISDOM held that propranolol is more powerful in Asians because they are "small." "I didn't believe that," says Hong-Hao Zhou, MD, a clinical pharmacology researcher at Vanderbilt University, Nashville, Tenn. He is one of a growing number of researchers rejecting facile explanations for age, sex, and race differences in drugs approved solely on the basis of study in middle-aged white men. Zhou found a far more complex reason why his Chinese patients need less than half as much of the β-blocker as whites to produce a 20% heart rate drop and are 4.5 times more sensitive to blood pressure reduction measured upright and 10 times more so supine. Metabolic, Elimination Differences Asians have much faster metabolism and elimination rates for propranolol, which lower plasma concentrations. That would weaken its effect, except that it is inactivated by protein binding more in the plasma of whites. So Chinese men receive less