Lack of information on gender differences in the package inserts of prescription drugs in Japan.

The package inserts of prescription drugs provide essential information for the proper administration of pharmacotherapy. The incidence of adverse reactions for several drugs is known to be higher in women than in men. However, no studies have examined whether information on gender differences is included in Japanese package inserts. Therefore, this study investigated information on gender differences in the package inserts of Japanese prescription drugs, using the drug information database JAMES provided by the Medical Information System Development Center and the Japan Pharmaceutical Information Center. Non-proprietary names of prescription drugs were yielded 1,679 in Japan. Of the 1,679 ingredients in package inserts of prescription drugs, 76 (4.5%) included information on gender differences. The number of inserts that contained information on gender differences in the "DOSAGE AND ADMINISTRATION," "ADVERSE REACTIONS," and "PHARMACOKINETICS" sections was 3, 16, and 62, respectively. Furthermore, in the "ADVERSE REACTIONS" section, 15 of the 16 inserts mentioned a higher frequency of adverse reactions in women compared with men. Importantly, most of the inserts with information on gender differences in the "PHARMACOKINETICS" section mentioned a higher area under the curve for women than for men. Most of the package inserts of prescription drugs with information on gender differences provide useful information aimed at preventing risks in women. However, there is an extreme lack of information on gender differences in the package inserts of prescription drugs in Japan, and we consider enhancing information on gender difference as an urgent issue.