Competitive Development in Pharmacologic Classes: Market Entry and the Timing of Development.

We examined data on the entry rates of second and later entrants in 43 pharmacologic classes, as well as the timing of patent filings and development milestones for 79 later-in-class drugs. The median time to when a second entrant was approved was 2.7 years. A substantial majority of later-in-class drugs had a patent filed and were in clinical development prior to the approval of the first-in-class drug.