Top drugmakers seem to be coming out of the slump in R&D productivity that has plagued the pharmaceutical industry in recent years – at least if the number of clinical trials being undertaken is a valid indicator.

A just-release study from the Tufts Center for the Study of Drug Development has found a 52% increase in the number of new clinical trials started by US drug companies between 2003 and 2005. This compared to a 21% decline in the five year period ending 2002 compared to 1993-1997.

There have been deepening concerns about the fall-off in R&D productivity in the drug industry in recently years, with the number of new drugs coming to market each year in decline since the mid-1990s, when upwards of 30 new active substances were introduced each year, Last year the tally was just 20.

Various reasons have been put forward for the phenomenon, including that a lot of the ‘low-hanging fruit’ in drug discovery has already been plucked and companies are being forced to pursue riskier and less well-characterised targets. Widespread adoption of newer high throughput technologies in molecular biology and combinatorial chemistry in ‘rational’ drug discovery, generating huge volumes of data that must be managed and sifted through, may also be a factor.

There has also been something of a bottleneck in the clinical arena, with development candidates piling up in Phase II but not so many making it through to Phase III. This could be because regulators are getting tighter on safety and companies are more likely to kill off products with safety signals in mid-stage testing, or indeed a lack of public funding to help smaller companies finance expensive pivotal studies.

Kenneth Kaitin, director of the Tufts Center, said the improvement is in part due to an increase in products licensed from other companies, as well as companies adopting technologies that allow them to spot unpromising compounds earlier. 25% of the drugs entering clinical tests were licensed from other companies in the three years ended in 2005, up from 24% in the five years to 2002 and just one in seven in the period ended in 1997.

In the three years ended in 2005, the companies placed an average of 84 drug candidates a year in clinical trials, up from the average of 55 in the five years ended in 2002 and 70 in the period ended in 1997.