A3型题患者女，50岁。间歇性牙龈出血1年。体检：双下肢可见散在的出血点及紫癜，肝、脾不大。血红蛋白120g/L，红细胞40×10<img border="0" alt="" src="http://img.weimei168.com/uploads/upimg/20221202/11545049_0.gif">/L，白细胞5.5×10<img border="0" alt="" src="http://img.weimei168.com/uploads/upimg/20221202/11545049_0_1.gif">/L，分类正常，血小板15×10<img border="0" alt="" src="http://img.weimei168.com/uploads/upimg/20221202/11545049_0_2.gif">/L。该患者治疗的首选药物为