what was the total hemorrhoidal suppository dose that was prescribed on the last hospital encounter to patient 50480?
select sum(prescriptions.dose_val_rx) from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 50480 and admissions.dischtime is not null order by admissions.admittime desc limit 1 ) and prescriptions.drug = 'hemorrhoidal suppository'