what are the four most frequent drugs prescribed to male patients of the 50s within the same month after they have been diagnosed until 1 year ago with esophageal reflux?
select t3.drug from ( select t2.drug, dense_rank() over ( order by count(*) desc ) as c1 from ( select admissions.subject_id, diagnoses_icd.charttime from diagnoses_icd join admissions on diagnoses_icd.hadm_id = admissions.hadm_id where diagnoses_icd.icd9_code = ( select d_icd_diagnoses.icd9_code from d_icd_diagnoses where d_icd_diagnoses.short_title = 'esophageal reflux' ) and datetime(diagnoses_icd.charttime) <= datetime(current_time,'-1 year') ) as t1 join ( select admissions.subject_id, prescriptions.drug, prescriptions.startdate from prescriptions join admissions on prescriptions.hadm_id = admissions.hadm_id where admissions.subject_id in ( select patients.subject_id from patients where patients.gender = 'm' ) and admissions.age between 50 and 59 and datetime(prescriptions.startdate) <= datetime(current_time,'-1 year') ) as t2 on t1.subject_id = t2.subject_id where t1.charttime < t2.startdate and datetime(t1.charttime,'start of month') = datetime(t2.startdate,'start of month') group by t2.drug ) as t3 where t3.c1 <= 4