A comparative analysis of drug safety withdrawals in the UK and the US (1971-1992): implications for current regulatory thinking and policy.

By going beyond individual case studies and solely quantitative surveys, this paper systematically examines why there were over twice as many new prescription drugs withdrawn from the market on grounds of safety in the UK as there were in the US between 1971 and 1992. Drawing on interviews with regulators, industry scientists and others involved, and on regulatory data never before accessed outside governments and companies, five key hypotheses which might explain this difference in drug safety withdrawals are analysed. These are: (1) simply because the UK approved more new drugs than the US; (2) because of an industrial corporate strategy to seek approval of 'less safe' drugs in the UK earlier; (3) because British regulators were more vigilant at spotting post-marketing safety problems than their US counterparts; (4) because the slowness of the US in approving new drugs enabled regulators there to learn from, and avoid, safety problems that had already emerged in the UK or European market; and (5) because more stringent regulation in the US meant that they approved fewer unsafe drugs on to the market in the first place. It is concluded that the main explanation for fewer drug safety withdrawals in the US is that the regulatory agency there applied more stringent pre-market review and/or standards, which took longer than UK regulatory checks, but prevented unsafe drugs marketed in the UK from entering the US market. Contrary to the claims frequently made by the pharmaceutical industry and regulatory agencies on both sides of the Atlantic, these results imply that it is likely that acceleration of regulatory review times in the US and the UK since the early 1990s is compromising drug safety.