what is the name of the drug that patient 59728 has been prescribed two or more times until 04/2101?
select t1.drug from ( select prescriptions.drug, count( prescriptions.startdate ) as c1 from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 59728 ) and strftime('%y-%m',prescriptions.startdate) <= '2101-04' group by prescriptions.drug ) as t1 where t1.c1 >= 2