The numbers are staggering. Each year as many as 15% of all U.S.
hospital admissions, some 100,000 deaths and $136 billion in
medical costs result from harmful reactions to drugs. But relief
is on the way. All too aware of the toll on the nation's health
and pocketbook, medical researchers are devising a host of safer
and more effective drug-delivery systems, many of them also
designed to overcome the pain and inconvenience of traditional
remedies. They range from such low-tech items as anal
suppositories to innerspace-age microcraft reminiscent of the
tiny ship that carried Raquel Welch through a patient's blood
vessels in the movie Fantastic Voyage. In their pursuit of
better systems, researchers are finding ingenious ways to bypass
such natural body defenses as the blood-brain barrier and the
macrophages of the immune system, which can block or gobble up
newly administered drugs. Another problem, says M.I.T. professor
of biomedical engineering Robert Langer, is adverse effects that
result even when "people