Classifying improvements to drug marketing and justifications for claims of efficacy.

Five ways to compare drug companies' replies to enquiries about drugs are reviewed. Classification of improvements to marketing and justifications for claims of efficacy are the most useful measures. Between July 1989 and June 1990 eight transnational drug companies were asked to supply their best evidence to support their claims for nine products. There was no reply from two companies: Abbott and Takeda. Improvements in the marketing of five products were promised ranging from withdrawal of claims to withdrawal of the drug. Justifications for claims of efficacy ranged from endorsement by the company's own staff to use of a clinical trial with severe methodological flaws. Possible reasons for pharmaceutical executives deciding not to answer questions about their products are discussed.