how many times has patient 9519 been prescribed bupropion (sustained release) until 8 months ago.
select count(*) from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 9519 ) and prescriptions.drug = 'bupropion (sustained release)' and datetime(prescriptions.startdate) <= datetime(current_time,'-8 month')