table patient
unsigned integer autoincrement patientid
varchar(40) namelast
varchar(40) namefirst
varchar(128) addressline1
varchar(128) addressline2
varchar(128) addressline3
unsigned integer guardianid

table medicine
unsigned integer autoincrement medicineid
varchar(128) medicinename

table prescription
unsigned integer autoincrement prescriptionid
unsigned integer patientid
unsigned integer medicineid
mediumtext doseage
date prescriptionstart
date prescriptionend

Just my suggestion.