The Sample

The drugs selected for inclusion are drawn from a subset of the Intercontinental Medical Statistics’ (IMS) British Pharmaceutical Index covering the 600 leading products in the UK in December 1976. The number finally included in the study is 192. All of these are brand name Pharmaceuticals. Appendix 2 lists them in alphabetical order and also gives their anatomical classification. The names used are those relevant to the UK. Changes in names between countries proved to be a real problem. As far as possible alternative names have been traced, and where it is pretty clear that drugs are the same they have been treated as single products. However where there is any doubt it has been assumed that a different name signifies a different drug. The identification problem occupied many hours and was particularly difficult in the case of Japan. Personnel in the London office of IMS were especially helpful and without their assistance Japanese introductions would not have been included. Because this study is based on branded products and not on generic equivalents, a somewhat false impression may be created. The emphasis here is to trace the inter country spread of branded products. The fact that a particular named pharmaceutical is not for sale in a given country, does not necessarily imply that this therapy is missing. The generic equivalent may already be in use there. This somewhat misleading impression does not matter. The concern here is not to comment on the global availability of treatments or on the health implications of drug distribution patterns, but rather to determine the factors influencing the timing of the diffusion process. Branded products serve this purpose reasonably well.