Abstract
One hundred and ninety-seven new chemical entities (NCEs) were investigated in man for the first time between 1964 and 1980 by the seven UK-owned pharmaceutical companies. Thirty-five of these NCEs have been marketed and 137 withdrawn from further research and development. There was an increase in the number of NCEs investigated each year, but this was counter-balanced by an increase in the number rejected. Development times increased from about 4.5 years in the 1960s to 9 years in the 1970s with an accompanying reduction in the effective patent life.