NCPA - National Center for Policy Analysis


July 12, 2007

Follow-on drugs -- drugs that are structurally very similar to already known drugs -- play a central role in World Health Organization (WHO) drug policy, suggesting that initiatives which impede follow-on drug research and development would likely have a detrimental impact on public health, according to a study by the Tufts Center for the Study of Drug Development (CSDD).

According to the study's authors:

  • Since 1987, the share of follow-on drugs on WHO's essential drug list (EDL) surged by 14 percentage points; today, 60 percent of medicines on the EDL are follow-on drugs.
  • While follow-on drugs as a share of drugs on the EDL increased from 47 percent to 63 percent since 1977, the share of follow-on indications -- subsequent uses for drugs -- fell from 19 percent to 15 percent.
  • The U.S. Food and Drug Administration assigned a priority rating to 49 percent of post-1962 approved follow-on drugs on the EDL, further highlighting the therapeutic value accorded these medicines.
  • The number of follow-on drugs in each WHO-defined category appears to be a function of the category's age: the older the category, the more follow-on drugs it includes.

"Growing reliance on follow-on drugs by the World Health Organization reflects the role of incremental improvement on first-in-class drugs as a critical mechanism of pharmaceutical innovation," said Tufts CSDD Research Fellow Joshua Cohen, who conducted the analysis.

He added, "Follow-on drugs provide back-up if the first-in-class drug is withdrawn and also enhance choice for patients who may not respond well to other similar medicines. If development of follow-on drugs were curtailed, many people, especially in poorer regions of the world, would likely suffer."

Source: "Follow-on drugs and indications play key role for World Health Organization," Tufts University Center for the Study of Drug Development, July 10, 2007.


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