In this study, we identified that the degradation of tigecycline after reconstitution is accelerated by exposure to light. It is well known that tigecycline degradation is oxygen-dependant and that such measures as purging oxygen from tigecycline solutions, preparing fresh solutions and culture media or using oxygenreactive enzymes such as Oxyrase for in vitro experiments, and decreasing storage temperatures can significantly improve tigecycline stability at neutral pH. The destabilization of tigecycline in solution exposed to UV-containing light could be due to the production of free radicals from oxygen, which become major players in the oxidative degradation of the drug. In the light-protected novel formulation, the known antibacterial and antileukemic activities of tigecycline were maintained, and comparable activity was observed whether tigecycline solutions were freshly prepared or after several days of preincubation. In addition, the novel tigecycline formulation displayed similar pharmacodynamics and pharmacokinetics as compared to tigecycline following intraperitoneal administration. Moreover, the novel tigecycline formulation preserved the antileukemic activity in a mouse model of human AML. Thus, after completing appropriate additional toxicology and pharmacology studies, this formulation could be advanced to testing in human patients, where more flexibility in dosing schedules, drug preparation timelines, and/or the ability to administer ambulatory infusions would be beneficial. Recently, for secondary prevention of many kinds of coronary heart disease and thrombotic diseases, antithrombotic agents, including anti-platelet agents such as aspirin and anticoagulants such as warfarin, have been widely prescribed for patients, and sometimes two or more types of ATA are used concomitantly. Among patients receiving ATA, bleeding complications such as intracerebral hemorrhage are becoming the issue of most concern. The Japanese population shows a relatively high incidence of ICH according to the Hisayama and Shibata studies. According to reports from the Japanese Ministry of Health, Labour, and Welfare, cerebrovascular disease is the third most common cause of death in Japan. Furthermore, in Japan as well as other countries, ICH is among the major causes of stroke. For example, ICH is the second-most common cause of stroke in Italy, and is responsible for 15% of strokes reported in the USA. With this background, increasing concern has emerged about the possibility of an ICH in patients receiving APA for a background chronic medical condition. The actual risk of ICH with APA is estimated as 0.2–0.3% per year. Several articles have recently been published showing inferior prognosis of ICH patients who are taking APA compared to those without APA treatment. The predominant APAs are cyclooxygenase-1 inhibitors such as aspirin and anti-P2Y12 antagonists such as clopidogrel and ticlopidine.