how many days has it been since patient 49176 first potassium chl 20 meq / 1000 ml d5ns was prescribed in the current hospital encounter?
select 1 * ( strftime('%j',current_time) - strftime('%j',prescriptions.startdate) ) from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 49176 and admissions.dischtime is null ) and prescriptions.drug = 'potassium chl 20 meq / 1000 ml d5ns' order by prescriptions.startdate asc limit 1