Humans are not good at delivering drugs. Doctors, nurses, pharmacists and pharmacy techs can mix pills up, provide too many or too few, or fail to dispense them quickly enough. In some cases, controlled substances disappear from hospitals, bound for the black market. Medication errors lead to some 1.5 million “preventable drug-related injuries” every year, at a cost of $3.5 billion, a report by the National Academies found. The stakes are highest in trauma units, where lifesaving drugs must be given within the “golden hour”--when medications are most effective.