when was the last time during the last hospital encounter that patient 4326 was prescribed for a medication?
select prescriptions.startdate from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 4326 and admissions.dischtime is not null order by admissions.admittime desc limit 1 ) order by prescriptions.startdate desc limit 1