Sir

I strongly agree with Curtis Chong and David Sullivan's Commentary calling for the development of new uses for existing medications (Nature 448, 645–646; 2007). However, I don't believe that establishing a database of all the drugs known to clinical medicine would be sufficient to spur fresh applications of drugs in the developed world. The stumbling block here is not information gathering but economics and patent laws.

Frederick Goodwin, former director of the US National Institute of Mental Health, recently commented that lithium remains underused in high-risk patients — despite strong evidence that, unlike most other psychiatric medications, it significantly lowers the risk of suicide in people with manic-depressive illness (see R. J. Baldessarini et al. Bipolar Disord. 8, 625–639; 2006). Similarly, although folic acid has been shown to increase the efficacy of antipsychotic medications in certain patients (see J. Levine et al. Biol. Psychiat. 60, 265–269; 2006), a psychiatrist at a recent meeting told me that he could not persuade his colleagues to prescribe this comparatively harmless vitamin.

Such difficulties stem from the failure of intellectual property laws to assign sufficient value to 'use' patents, involving new uses for old medications. In effect, a discovery of immense human value — preventing suicide — is assigned a negligible economic value that fails to motivate the pharmaceutical industry to develop the drug. The antiquated laws governing new uses for existing medications need to be reformed if life-saving discoveries are to be exploited.