Bridging studies/trials

NR Cutler, JJ Sramek. Scientific and ethical concerns in clinical trials in Alzheimer s patients the bridging study. Eur J Clin Pharmacol 48 421-428, 1995. 

Foreign clinical results are acceptable except in areas where there are immunological and ethnic differences between Japanese and foreigners. The ethnic factors are divided into two components intrinsic factors such as racial factors and physiological differences and extrinsic factors, which include cultural and environmental issues. In these cases, the MHLW may require that some bridging comparative clinical trials be performed with dose ranging protocols. This will enable absorption, distribution, metabolism, and excretion studies to be carried out on Japanese individuals and provide better dosage and indication for the Japanese people. The MHLW also requires that application be accompanied by one year of real-time stability data and that sterility test results be included. 

During 1995-1997, the information from past studies, almost 5000 field trials, new surveys of growers, and a weed control model developed by Dr. David Bridges (Bridges, 1998) were used to provide USEPA with estimates of the economic benefits of triazine and atrazine on all crops labeled with these products in the United States. A summary of the economic and biological models and some of the components are available (Bridges, 1998 Carlson, 1998). 

This comprehensive biological and economic study for the field com and sorghum sectors included large amounts of data to give separate cost estimates if atrazines or triazines were not available. University weed scientists efficacy ratings on all major herbicides on all weed species, unit costs of all herbicides and cultivation treatments, acres or hectares planted, weed densities, and current herbicide use patterns were compiled for each of the 10 USDA production regions as described by Ciba Crop Protection (1995) and Bridges (1998). Almost 5000 university and Ciba Crop Protection field trials were compiled in these analyses. 

Black S. Perspectives on the design and analysis of prelicensure trials bridging the gap to postlicensure studies. Clin Infect Dis 2001 33(Suppl 4) S323-6. 

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