"Take two tablets by mouth twice daily." This printed instruction, common on prescription pill bottles, might seem straightforward. Yet in a study, nearly half of patients misunderstood what it or other common label instructions meant. Now the nonprofit organization that sets quality and safety standards for drugs approved by the Food and Drug Administration is aiming to simplify, clarify and standardize the labels that are affixed to those drugs. The U.S. Pharmacopeia proposal, developed in conjunction with a group of independent experts, was released early this year for public comment. If adopted by state pharmacy boards nationwide, its developers hope it will help remove one of the many barriers that discourage people from taking their prescription drugs. Medication adherence is a big problem. Despite the fact that 87% of people in a recent survey said they thought prescription medicines were important to their health, only about half of them took their drugs as directed.