when was patient 77177 prescribed medications through the iv drip route for the last time in their last hospital encounter?
select prescriptions.startdate from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 77177 and admissions.dischtime is not null order by admissions.admittime desc limit 1 ) and prescriptions.route = 'iv drip' order by prescriptions.startdate desc limit 1