New indications for already-approved drugs: time trends for the new drug application review phase

For 55 individual drugs, the time required for approval of the original new drug application (NDA) was compared with the time required for approval of supplemental NDAs. The mean time required for the original NDAs was 22.2 +/- 18.1 months; the mean for review of all 46 follow-on indications was similar (19.1 +/- 17.9 months). Since subsequent applications do not ordinarily require new assessment of clinical safety or animal toxicity studies, one would expect the subsequent applications to be processed more expeditiously. Such is not the case. The negative implications of these facts are discussed.