when was the last time when patient 25965 was prescribed syringe (chemo) and chlorhexidine gluconate 0.12% oral rinse at the same time until 08/2105?
select t1.startdate from ( select admissions.subject_id, prescriptions.startdate from prescriptions join admissions on prescriptions.hadm_id = admissions.hadm_id where prescriptions.drug = 'syringe (chemo)' and admissions.subject_id = 25965 and strftime('%y-%m',prescriptions.startdate) <= '2105-08' ) as t1 join ( select admissions.subject_id, prescriptions.startdate from prescriptions join admissions on prescriptions.hadm_id = admissions.hadm_id where prescriptions.drug = 'chlorhexidine gluconate 0.12% oral rinse' and admissions.subject_id = 25965 and strftime('%y-%m',prescriptions.startdate) <= '2105-08' ) as t2 on t1.subject_id = t2.subject_id where datetime(t1.startdate) = datetime(t2.startdate) order by t1.startdate desc limit 1