what is the last drug that is prescribed to patient 40435 via ih route during a month before?
select prescriptions.drug from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 40435 ) and prescriptions.route = 'ih' and datetime(prescriptions.startdate,'start of month') = datetime(current_time,'start of month','-1 month') order by prescriptions.startdate desc limit 1