just count the number of patients who had been prescribed neo*po*mct oil in the last year.
select count( distinct admissions.subject_id ) from admissions where admissions.hadm_id in ( select prescriptions.hadm_id from prescriptions where prescriptions.drug = 'neo*po*mct oil' and datetime(prescriptions.startdate,'start of year') = datetime(current_time,'start of year','-1 year') )