Last week President Clinton announced that drug companies will be required to test whether the medicines they sell for adults are safe and effective for children, and to put the pediatric doses on the label. Critics point out that the requirement will impose tremendous costs on manufacturers -- costs that will only be passed along to consumers in sharply higher prices.

• By the Food and Drug Administration's own conservative estimate, the requirement will boost drug developers' costs by more than $200 million annually.

• Some familiar with the economics of medicine say regulations such as these are the reason drugs that used to cost a few dollars now command prices of hundreds of dollars per week.

• A more reasoned approach being suggested is to require a label or logo on drugs whose safety and efficacy have not yet been determined for children -- or the FDA could publish a list of such drugs each year.

• The child-labeling requirement could actually delay the availability of new drugs, if the FDA withholds approval for adult uses while data from pediatric studies are being evaluated.

A pediatric form of Glaxo Wellcome's antibiotic Seftin, approved in 1990, required more than double the cost and man hours to develop that its adult form did.

Experts say clinical trials are difficult when they involve children, because a given disease may be rare in children, because parents are reluctant to enroll their sick children in an experiment and because several distinctly different age groups are lumped into the category "children" -- ranging from newborns to teens.

As regulatory requirements increase, drugs are moving more sluggishly through the pipeline. The total time for drug development has more than doubled since 1964 -- to 14.8 years from 6.5. And the $500 million tab for each new drug approved in the U.S. is by far the most expensive in the world.