during the last hospital encounter, when was the last time patient 26195 was prescribed amikacin?
select prescriptions.startdate from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 26195 and admissions.dischtime is not null order by admissions.admittime desc limit 1 ) and prescriptions.drug = 'amikacin' order by prescriptions.startdate desc limit 1