instruction: what was the name of the drug, which was prescribed to patient 006-158759 first in 04/2104?
response: SELECT medication.drugname FROM medication WHERE medication.patientunitstayid IN (SELECT patient.patientunitstayid FROM patient WHERE patient.patienthealthsystemstayid IN (SELECT patient.patienthealthsystemstayid FROM patient WHERE patient.uniquepid = '006-158759')) AND STRFTIME('%y-%m', medication.drugstarttime) = '2104-04' ORDER BY medication.drugstarttime LIMIT 1