[in Japanese]

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Objective : The incidence rate is used frequently in drug safety assessment. The incidence rate of adverse events is defined as the number of patients experiencing a certain adverse event divided by the number of patients administered a drug in spite of duration of administration (observation). In post-marketing surveillance, the duration of administration (observation) typically differs by patient and most of the analyses fail to take into account the differences in duration of administration (observation). Therefore, we investigated the usefulness of hazard functions in a drug safety assessment using the interim results from Clinical Experience Investigation of the oral anticancer drug, TS-1.
Methods : About three thousand patients with gastric cancer were enrolled in this Clinical Experience Investigation. TS-1 was administrated orally twice daily. One course consisted of consecutive administration for 28 days and 14 days rest. Administration was repeated in two courses. Hematological measurements, stomatitis, anorexia, nausea/vomiting, diarrhea, malaise were analyzed. Adverse events were evaluated in accordance with the criteria of the Japan Society for Cancer Therapy, which were established based on criteria established by the WHO. Time to occurrence of an adverse event was calculated from the first day of administration until the adverse event was first observed. Hazard functions were estimated by smoothing methods using kernel functions.
Results : The occurrence of adverse events using smoothed hazard functions had one peak around 10 days in the first course and decreased by administration rest. With the resumption of administration, the occurrence increased again. The occurrence in the second course were less than that of the first course.
Conclusion : The occurrence peaks of adverse events were estimated graphically by smoothed hazard functions. We conclude that hazard functions are useful as an analytical tool in drug safety assessment.

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Individualization of pharmacotherapy is essential for rational drug use. Specific, drug information is essential to individualize the pharmacotherapy in order to obtain the optimized pharmacological effect and to avoid serious side effects. Drug information can be divided into two categories ; one is the drug information necessary to select an appropriate drug and to establish a rational dose schedule for each patient, and the other is the information needed to instruct the patient to take medicine correctly. Drug information must be based on the scientific evidence obtained via pharmaceutical analysis and evaluation.

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