instruction: how many hours have pass since the last time patient 49176 was prescribed erythromycin on their current hospital encounter?
response: SELECT 24 * (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 = 'erythromycin' ORDER BY prescriptions.startdate DESC LIMIT 1