how much potassium chloride is prescribed the first time since 162 months ago to patient 27177?
select prescriptions.dose_val_rx from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 27177 ) and prescriptions.drug = 'potassium chloride' and datetime(prescriptions.startdate) >= datetime(current_time,'-162 month') order by prescriptions.startdate asc limit 1