how many hours have passed since polysaccharide iron complex was prescribed to patient 96833 last during their current hospital encounter?
select 24 * ( strftime('%j',current_time) - strftime('%j',prescriptions.startdate) ) from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 96833 and admissions.dischtime is null ) and prescriptions.drug = 'polysaccharide iron complex' order by prescriptions.startdate desc limit 1