Influence of Sample Size on the Results of Bioequivalence Studies
Great number of drugs coming from different manufactures is available on the market. The bioequivalence studies give substantial evidence if these drugs, given in same doses and under similar conditions, have similar bioavailability. Studies of bioequivalence are performed on healthy young volunteers in crossover designs and artificially controlled environment to minimize factors, other than the drug, which can affect bioavailability. They usually include 24 healthy volunteers with about 20 blood analyzes giving a total of 500. This kind of research is of big importance for the determination of pharmacokinetic drug characteristics but is very expensive, especially in small countries. Considering the importance of cost decrement, we set the hypothesis that bioequivalence studies can be performed on smaller number of subjects. This hypothesis is confirmed by the results of our analysis (6) included in cross-over study can be an adequate number.