Current situation and issues regarding termination of risk management plans in Japan.

Introduction: In Japan, drugs approved after the 2013 implementation of the risk management plan (RMP) have the opportunity to be evaluated for RMP termination. However, the guidelines for risk management following the termination of an RMP remain unclear. Drugs are evaluated for RMP termination at the timing of reexamination. Reexamination system is unique to Japan and initiated in 1979, verifies the approved efficacy and safety of a newly marketed drug based on the data from its actual use over a certain period. This study investigated drugs in Japan for which the RMP requirement was lifted upon reexamination and those for which it was not. We organized their characteristics and considered future issues. Methods: We identified drugs with RMPs and obtained information on RMP termination from the public website of the Pharmaceuticals and Medical Devices Agency (PMDA). The survey period spanned 10 years, from April 2013, when the RMP was implemented, to March 2023. Results: During the survey period, 72 drugs with RMPs completed reexamination in Japan. The RMP requirement was lifted for 69 drugs (95.8%) and remained for three drugs (4.2%). Upon RMP termination, 16 out of 69 drugs (23.2%) had important potential risks not listed in the package insert, with malignant neoplasm being the most common. Eleven drugs (15.9%) had important missing information not listed in the package insert, with the most common being the impact on cardiovascular risk. Two drugs (2.9%) had ongoing additional pharmacovigilance activities, and 43 drugs (62.3%) had additional risk minimization activities. Conclusion: Upon reexamination completion, the RMP requirement was lifted for many drugs and remained for a few. Should safety concerns require continued attention following reexamination, we advocate for the continuation of the RMP, guided by more explicit rules. In light of the harmonization of RMP rules with those of other countries, there is a desire for enhanced drug safety management.

Induction of a T-Helper 1 (Th1) immune response in mice by an extract from the Pleurotus eryngii (Eringi) mushroom.

To assess the effect of edible mushroom extracts on the induction of T-helper 1 (Th1) immunity, we examined differences in interferon-gamma (IFN-γ) and interleukin (IL)-4 production in mice induced by hot-water extracts of 15 species of edible mushroom. Extracts from Agaricus bisporus, Flammulina velutipes, Hypsizigus marmoreus, Lentinula edodes, and Lyophyllum decastes induced both IFN-γ and IL-4 production in mice, whereas extracts from Pleurotus ostreatus only induced IL-4. In contrast, extracts from Agaricus blazei, Grifola frondosa, Morchella esculenta, Pholiota nameko, Pleurotus citrinopileatus, and Pleurotus eryngii induced only IFN-γ production. In particular, the extract from P. eryngii induced high levels of IFN-γ and reduced levels of IL-4. We further investigated the use of a trial immunogen using the P. eryngii extract as a Th1 immunostimulator. An oil-in-water emulsion of the hot-water extract from P. eryngii (immunostimulator) and ovalbumin (OVA; antigen) was used as a trial immunogen. This immunogen induced strong OVA-specific IgG2a antibody production in mice compared with the negative controls. In addition, OVA-specific IgG1 antibody levels were lower than those for the negative controls. Marked increases in serum IFN-γ levels and high-level production of IFN-γ in the culture supernatant from the CD4(+) spleen cells in the trial immunogen group mice were observed. Our results suggested that the hot-water extract from P. eryngii induced Th1 immunity by acting as an immunostimulator.

Gender differences in tail-skin flushing induced by nitrates and phosphodiesterase type 5 inhibitors in a climacteric mouse model.

Flushing is one of the most common vasodilation-related adverse effects associated with both nitrates and phosphodiesterase type 5 (PDE5) inhibitors. The present study aimed to investigate the effects of orchidectomy and ovariectomy on isosorbide dinitrate-, sildenafil-, vardenafil- and tadalafil-induced flushing of tail-skin in mice. Both orchidectomy and ovariectomy markedly increased the tail-skin temperature, a good parameter of flushing, induced by isosorbide dinitrate (500 microg/kg, i.p.). These observations suggest that both testosterone withdrawal and estrogen withdrawal are risk factors for isosorbide dinitrate-induced flushing. In contrast, sildenafil (100 mg/kg, p.o.)-, vardenafil (10 mg/kg, p.o.)- and tadalafil (40 mg/kg, p.o.)-induced flushing of tail-skin in mice was aggravated by ovariectomy but not by orchidectomy. Orchidectomized male mice, but not ovariectomized female mice, showed significantly lower levels of PDE5 mRNA expression in tail artery compared with those of sham-operated mice. The present findings suggest that estrogen withdrawal, but not testosterone withdrawal, is a risk factor for PDE5 inhibitor-induced flushing. These gender differences in the vascular adverse reactions of PDE5 inhibitors may be interpreted as occurring due to differences in the levels of PDE5 mRNA expression in peripheral arteries.